The effects of the composition and structure of quantum dots combined with cobalt phthalocyanine and an aptamer on the electrochemical detection of prostate specific antigen
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
The electrochemical detection of prostate specific antigen on glassy carbon electrode modified with combinations of graphene quantum dots, cobalt phthalocyanine and an aptamer
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185013 , vital:44316 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111462"
- Description: Herein, a novel aptasensor is developed for the electrochemical detection of prostate specific antigen (PSA) on electrode surfaces modified using various combinations of a Cobalt phthalocyanine (CoPc), an aptamer and graphene quantum dots (GQDs). Electrochemical impedance spectroscopy (EIS) as well as differential pulse voltammetry (DPV) are employed for the detection of PSA. In both analytical techniques, linear calibration curves were observed at a concentration range of 1.2–2.0 pM. The glassy carbon electrode where CoPc and GQDs are placed on the electrode when non-covalently linked followed by addition of the aptamer (GQDs-CoPc(ππ)-aptamer (sequential)) showed the best performance with a limit of detection (LoD) as low as 0.66 pM when using DPV. The detection limits were much lower than the dangerous levels reported for PSA in males tested for prostate cancer. This electrode showed selectivity for PSA in the presence of bovine serum albumin, glucose and L-cysteine. The aptasensor showed good stability, reproducibility and repeatability, deeming it a promising early detection device for prostate cancer.
- Full Text:
- Date Issued: 2021
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185013 , vital:44316 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111462"
- Description: Herein, a novel aptasensor is developed for the electrochemical detection of prostate specific antigen (PSA) on electrode surfaces modified using various combinations of a Cobalt phthalocyanine (CoPc), an aptamer and graphene quantum dots (GQDs). Electrochemical impedance spectroscopy (EIS) as well as differential pulse voltammetry (DPV) are employed for the detection of PSA. In both analytical techniques, linear calibration curves were observed at a concentration range of 1.2–2.0 pM. The glassy carbon electrode where CoPc and GQDs are placed on the electrode when non-covalently linked followed by addition of the aptamer (GQDs-CoPc(ππ)-aptamer (sequential)) showed the best performance with a limit of detection (LoD) as low as 0.66 pM when using DPV. The detection limits were much lower than the dangerous levels reported for PSA in males tested for prostate cancer. This electrode showed selectivity for PSA in the presence of bovine serum albumin, glucose and L-cysteine. The aptasensor showed good stability, reproducibility and repeatability, deeming it a promising early detection device for prostate cancer.
- Full Text:
- Date Issued: 2021
The first record of Omosita nearctica Kirejtshuk (Coleoptera, Nitidulidae) in South Africa, with the first description of its mature larva
- Williams, Kirstin A, Clitheroe, Crystal-Leigh, Villet, Martin H, Midgley, John M
- Authors: Williams, Kirstin A , Clitheroe, Crystal-Leigh , Villet, Martin H , Midgley, John M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440640 , vital:73799 , https://africaninvertebrates.pensoft.net/article/58842/
- Description: Sap beetles of the genus Omosita Erichson are stored-product pests that are also associated with carrion, potentially making them biosecurity risks and forensic tools. The discovery of a specimen of the Nearctic species Omosita nearctica Kirejtshuk in South Africa prompted an investigation a decade later to determine if this species had established itself in the country, which was confirmed by the collection of further breeding specimens that also facilitated the first description of mature larvae of O. nearctica. A new key to adults of all Omosita species is presented.
- Full Text:
- Date Issued: 2021
- Authors: Williams, Kirstin A , Clitheroe, Crystal-Leigh , Villet, Martin H , Midgley, John M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440640 , vital:73799 , https://africaninvertebrates.pensoft.net/article/58842/
- Description: Sap beetles of the genus Omosita Erichson are stored-product pests that are also associated with carrion, potentially making them biosecurity risks and forensic tools. The discovery of a specimen of the Nearctic species Omosita nearctica Kirejtshuk in South Africa prompted an investigation a decade later to determine if this species had established itself in the country, which was confirmed by the collection of further breeding specimens that also facilitated the first description of mature larvae of O. nearctica. A new key to adults of all Omosita species is presented.
- Full Text:
- Date Issued: 2021
The forest avifauna of Arabuko Sokoke Forest and adjacent modified habitats
- Chiawo, David O, Kombe, Wellington N, Craig, Adrian J F K
- Authors: Chiawo, David O , Kombe, Wellington N , Craig, Adrian J F K
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449953 , vital:74867 , https://doi.org/10.1101/2021.04.19.440426
- Description: Arabuko Sokoke Forest (ASF) is the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. The study analysed data from point count surveys over 15 months in three land use types; primary forest (PF), plantation forest (PL), and farmlands (FM), and compared these to the first comprehensive bird checklist for the forest, as well as recent surveys from other studies. Avifaunal diversity and abundance were compared using multivariate analysis to determine bird responses to different land use characteristics. The primary forest held a distinctive bird community, while the bird communities of farmlands and plantation forest were more similar to each other. Land use had a significant effect on overall avian diversity and abundance. The current forest avifauna was divided into forest specialists (16 species), forest generalists (26 species) and forest visitors (30 species). Seven species of forest specialist and generalists recorded prior to 1980 may no longer occur in the forest. Of 38 specialists and generalists recorded in our point counts, 19 were also recorded on farmland and 28 in plantations. One forest specialist, the Green Barbet, was most encountered outside the forest. Future research should focus on habitat use by these bird species, and the extent of movement by forest birds between the remaining patches of coastal forest. Patterns of habitat use by birds in the area suggest that vegetation heterogeneity and habitat complexity are especially significant in sustaining diverse and abundant bird populations. The management of plantations and farmland will be critical for the conservation of forest generalists and forest visitors.
- Full Text:
- Date Issued: 2021
- Authors: Chiawo, David O , Kombe, Wellington N , Craig, Adrian J F K
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449953 , vital:74867 , https://doi.org/10.1101/2021.04.19.440426
- Description: Arabuko Sokoke Forest (ASF) is the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. The study analysed data from point count surveys over 15 months in three land use types; primary forest (PF), plantation forest (PL), and farmlands (FM), and compared these to the first comprehensive bird checklist for the forest, as well as recent surveys from other studies. Avifaunal diversity and abundance were compared using multivariate analysis to determine bird responses to different land use characteristics. The primary forest held a distinctive bird community, while the bird communities of farmlands and plantation forest were more similar to each other. Land use had a significant effect on overall avian diversity and abundance. The current forest avifauna was divided into forest specialists (16 species), forest generalists (26 species) and forest visitors (30 species). Seven species of forest specialist and generalists recorded prior to 1980 may no longer occur in the forest. Of 38 specialists and generalists recorded in our point counts, 19 were also recorded on farmland and 28 in plantations. One forest specialist, the Green Barbet, was most encountered outside the forest. Future research should focus on habitat use by these bird species, and the extent of movement by forest birds between the remaining patches of coastal forest. Patterns of habitat use by birds in the area suggest that vegetation heterogeneity and habitat complexity are especially significant in sustaining diverse and abundant bird populations. The management of plantations and farmland will be critical for the conservation of forest generalists and forest visitors.
- Full Text:
- Date Issued: 2021
The hermeneutics of recovery
- Kong, Camillia, Campbell, Megan, Kpobi, Lily, Swartz, Leslie, Atuire, Caesar
- Authors: Kong, Camillia , Campbell, Megan , Kpobi, Lily , Swartz, Leslie , Atuire, Caesar
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302554 , vital:58207 , xlink:href="https://doi.org/10.1177/13634615211000549"
- Description: The widespread use of faith-based and traditional healing for mental disorders within African contexts is well known. However, normative responses tend to fall within two camps: on one hand, those oriented towards the biomedical model of psychiatry stress the abuses and superstition of such healing, whilst critics adopting a more ‘local’ perspective have fundamentally challenged the universalist claims of biomedical diagnostic categories and psychiatric treatments. What seemingly emerges is a dichotomy between those who endorse more ‘universalist’ or ‘relativist’ approaches as an analytical lens to the challenges of the diverse healing strands within African contexts. In this article, we draw upon the resources of philosophy and existing empirical work to challenge the notion that constructive dialogue cannot be had between seemingly incommensurable healing practices in global mental health. First, we suggest the need for much-needed conceptual clarity to explore the hermeneutics of meaning, practice, and understanding, in order to forge constructive normative pathways of dialogue between seemingly incommensurable values and conceptual schemas around mental disorder and healing. Second, we contextualise the complex motives to emphasise difference amongst health practitioners within a competitive healing economy. Finally, we appeal to the notion of recovery as discovery as a fruitful conceptual framework which incorporates dialogue, comparative evaluation, and cross-cultural enrichment across divergent conceptualisations of mental health.
- Full Text:
- Date Issued: 2021
- Authors: Kong, Camillia , Campbell, Megan , Kpobi, Lily , Swartz, Leslie , Atuire, Caesar
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302554 , vital:58207 , xlink:href="https://doi.org/10.1177/13634615211000549"
- Description: The widespread use of faith-based and traditional healing for mental disorders within African contexts is well known. However, normative responses tend to fall within two camps: on one hand, those oriented towards the biomedical model of psychiatry stress the abuses and superstition of such healing, whilst critics adopting a more ‘local’ perspective have fundamentally challenged the universalist claims of biomedical diagnostic categories and psychiatric treatments. What seemingly emerges is a dichotomy between those who endorse more ‘universalist’ or ‘relativist’ approaches as an analytical lens to the challenges of the diverse healing strands within African contexts. In this article, we draw upon the resources of philosophy and existing empirical work to challenge the notion that constructive dialogue cannot be had between seemingly incommensurable healing practices in global mental health. First, we suggest the need for much-needed conceptual clarity to explore the hermeneutics of meaning, practice, and understanding, in order to forge constructive normative pathways of dialogue between seemingly incommensurable values and conceptual schemas around mental disorder and healing. Second, we contextualise the complex motives to emphasise difference amongst health practitioners within a competitive healing economy. Finally, we appeal to the notion of recovery as discovery as a fruitful conceptual framework which incorporates dialogue, comparative evaluation, and cross-cultural enrichment across divergent conceptualisations of mental health.
- Full Text:
- Date Issued: 2021
The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers
- Mapukata, Sivuyisiwe, Britton, Jonathan, Osifeko, Olawale L, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
The influence of biophysical and socio-economic factors on the effectiveness of private land conservation areas in preventing natural land cover loss across South Africa
- Shumba, Tafadzwa, de Vos, Alta, Biggs, Reinette, Esler, Karen J, Clements, Hayley S
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
- Full Text:
- Date Issued: 2021
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
- Full Text:
- Date Issued: 2021
The photodynamic activities of the gold nanoparticle conjugates of phosphorus (V) and gallium (III) A3 meso-triarylcorroles
- Soy, Rodah C, Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
The photophysicochemical properties and photodynamic therapy activity of Schiff base substituted phthalocyanines doped into silica nanoparticles and conjugated to folic acid
- Magadla, Aviwe, Babu, Balaji, Sen, Pinar, Nyokong, Tebello
- Authors: Magadla, Aviwe , Babu, Balaji , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185407 , vital:44384 , xlink:href="https://doi.org/10.1016/j.poly.2021.115227"
- Description: This work explores the synthesis, photophysicochemical properties and photodynamic activity (PDT) of tetrakis [N,N’–bis (4-(diethylamino)benzylidene) amino)propan-2-yl)oxy) phthalocyaninato] Zn (II) (3) and tetra-phenoxy N,N-dimethyl-4-((methylimino) Zn (II) (4) when the encapsulated into silica nanoparticles (SiNPs) followed by conjugation of folic acid (FA). The synthesised complexes and their doped analogues are examined for their PDT activity using MCF-7 cells. All the complexes showed dark toxicity that is >80%. The folic acid conjugates, MPc@SiNPs-FA showed greater photocytoxicity against MCF-7 cells upon irradiation with laser light.
- Full Text:
- Date Issued: 2021
- Authors: Magadla, Aviwe , Babu, Balaji , Sen, Pinar , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185407 , vital:44384 , xlink:href="https://doi.org/10.1016/j.poly.2021.115227"
- Description: This work explores the synthesis, photophysicochemical properties and photodynamic activity (PDT) of tetrakis [N,N’–bis (4-(diethylamino)benzylidene) amino)propan-2-yl)oxy) phthalocyaninato] Zn (II) (3) and tetra-phenoxy N,N-dimethyl-4-((methylimino) Zn (II) (4) when the encapsulated into silica nanoparticles (SiNPs) followed by conjugation of folic acid (FA). The synthesised complexes and their doped analogues are examined for their PDT activity using MCF-7 cells. All the complexes showed dark toxicity that is >80%. The folic acid conjugates, MPc@SiNPs-FA showed greater photocytoxicity against MCF-7 cells upon irradiation with laser light.
- Full Text:
- Date Issued: 2021
The potential influence of commercial plant nurseries in shaping the urban forest in South Africa
- Arnoldi, Marco, Shackleton, Charlie M
- Authors: Arnoldi, Marco , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398408 , vital:69409 , xlink:href="https://doi.org/10.1016/j.ufug.2021.127254"
- Description: A substantial portion of urban green infrastructure is under private tenure in residents’ and business/corporate gardens. Therefore, the ways that urban residents manage their gardens can influence the type, quantity and quality of ecosystem services and disservices in urban areas. Plant nurseries are a major source of trees for urban residents, and so the types of trees and species that nurseries stock influence the composition of private gardens. Consequently, this study aimed to examine the roles that plant nurseries play in shaping the urban forest in South Africa. To do so, an online and direct questionnaire was used to gather data from 30 nurseries across 19 urban centres in South Africa. The main questions included species selection criteria, customer tree inquiries, best-selling tree species, attitudes towards increasing urban tree cover and diversity and whether they think climate change will affect the selection of species to stock. The results show that there is a strong preference for indigenous trees, which were also most commonly listed as best-sellers. Non-native species that were commonly sold were ones that provided provisioning services, particularly edible fruits. Drought tolerance influenced selection criteria and customer demand. Vachellia spp. and Olea europaea were commonly inquired about and most commonly listed amongst the best-sellers. Nursery owners valued the importance of increasing tree cover and diversity in urban areas, listing many perceived benefits for doing so. We conclude that there is a clear preference for indigenous tree species by customers and nursery owners, which in time could increase the proportion and cover of native species.
- Full Text:
- Date Issued: 2021
- Authors: Arnoldi, Marco , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398408 , vital:69409 , xlink:href="https://doi.org/10.1016/j.ufug.2021.127254"
- Description: A substantial portion of urban green infrastructure is under private tenure in residents’ and business/corporate gardens. Therefore, the ways that urban residents manage their gardens can influence the type, quantity and quality of ecosystem services and disservices in urban areas. Plant nurseries are a major source of trees for urban residents, and so the types of trees and species that nurseries stock influence the composition of private gardens. Consequently, this study aimed to examine the roles that plant nurseries play in shaping the urban forest in South Africa. To do so, an online and direct questionnaire was used to gather data from 30 nurseries across 19 urban centres in South Africa. The main questions included species selection criteria, customer tree inquiries, best-selling tree species, attitudes towards increasing urban tree cover and diversity and whether they think climate change will affect the selection of species to stock. The results show that there is a strong preference for indigenous trees, which were also most commonly listed as best-sellers. Non-native species that were commonly sold were ones that provided provisioning services, particularly edible fruits. Drought tolerance influenced selection criteria and customer demand. Vachellia spp. and Olea europaea were commonly inquired about and most commonly listed amongst the best-sellers. Nursery owners valued the importance of increasing tree cover and diversity in urban areas, listing many perceived benefits for doing so. We conclude that there is a clear preference for indigenous tree species by customers and nursery owners, which in time could increase the proportion and cover of native species.
- Full Text:
- Date Issued: 2021
The role of causal knowledge in stigma considerations in African genomics research
- Matshabane, Olivia P, Campbell, Megan, Appelbaum, Paul S, Marshall, Patricia A, Stein, Dan J, de Vries, Jantina
- Authors: Matshabane, Olivia P , Campbell, Megan , Appelbaum, Paul S , Marshall, Patricia A , Stein, Dan J , de Vries, Jantina
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302578 , vital:58209 , xlink:href="https://doi.org/10.1016/j.socscimed.2021.113902"
- Description: Introduction: Advances in genomics research have raised several ethical concerns. One concern is the potential impact of genomics research on stigma experienced by people affected by a disease. Studies have found that the type of illness as well as disease causal beliefs impact on the relation between genetic attribution and stigma. This study explored the potential impact of genetic attribution of disease on stigma among Xhosa people with Rheumatic Heart Disease (RHD). Methods: Study participants were 46 Xhosa people with RHD living in the Western Cape Province of South Africa. Using video vignettes in 7 focus group discussions we explored whether and how genetic attribution may impact on disease-stigma. Vignettes introduced participants to non-genetic and genetic causal explanations and were followed-up with a series of open-ended questions eliciting their perceptions of non-genetic disease causes as well as genetic causation and its impact on internalised stigma. Results: This study found that Xhosa people with RHD have a general understanding of genetics and genetic attribution for disease. Additionally, and not withstanding their genetic knowledge, these participants hold multiple disease causal beliefs including genetic, infectious disease, psychosocial, behavioural and cultural explanations. While there was evidence of internalised stigma experiences among participants, these appeared not to be related to a genetic attribution to the disease. Discussion: The findings of this study provide clues as to why it is unlikely that a genetic conceptualisation of disease impacts internalised stigma experiences of Xhosa people. The causal explanations provided by participants reflect their cultural understandings and their context, namely, living in low-income and poverty-stricken environments. Divergence in these findings from much of the evidence from high-income countries emphasises that context matters when considering the impact of genetic attribution on stigma and caution against generalising findings from one part of the globe to another.
- Full Text:
- Date Issued: 2021
- Authors: Matshabane, Olivia P , Campbell, Megan , Appelbaum, Paul S , Marshall, Patricia A , Stein, Dan J , de Vries, Jantina
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302578 , vital:58209 , xlink:href="https://doi.org/10.1016/j.socscimed.2021.113902"
- Description: Introduction: Advances in genomics research have raised several ethical concerns. One concern is the potential impact of genomics research on stigma experienced by people affected by a disease. Studies have found that the type of illness as well as disease causal beliefs impact on the relation between genetic attribution and stigma. This study explored the potential impact of genetic attribution of disease on stigma among Xhosa people with Rheumatic Heart Disease (RHD). Methods: Study participants were 46 Xhosa people with RHD living in the Western Cape Province of South Africa. Using video vignettes in 7 focus group discussions we explored whether and how genetic attribution may impact on disease-stigma. Vignettes introduced participants to non-genetic and genetic causal explanations and were followed-up with a series of open-ended questions eliciting their perceptions of non-genetic disease causes as well as genetic causation and its impact on internalised stigma. Results: This study found that Xhosa people with RHD have a general understanding of genetics and genetic attribution for disease. Additionally, and not withstanding their genetic knowledge, these participants hold multiple disease causal beliefs including genetic, infectious disease, psychosocial, behavioural and cultural explanations. While there was evidence of internalised stigma experiences among participants, these appeared not to be related to a genetic attribution to the disease. Discussion: The findings of this study provide clues as to why it is unlikely that a genetic conceptualisation of disease impacts internalised stigma experiences of Xhosa people. The causal explanations provided by participants reflect their cultural understandings and their context, namely, living in low-income and poverty-stricken environments. Divergence in these findings from much of the evidence from high-income countries emphasises that context matters when considering the impact of genetic attribution on stigma and caution against generalising findings from one part of the globe to another.
- Full Text:
- Date Issued: 2021
The role of mass-rearing in weed biological control projects in South Africa
- Hill, Martin P, Conlong, Desmond, Zachariades, Costas, Coetzee, Julie A, Paterson, Iain D, Miller, Benjamin E, Foxcroft, Llewellyn, van der Westhuizen, L
- Authors: Hill, Martin P , Conlong, Desmond , Zachariades, Costas , Coetzee, Julie A , Paterson, Iain D , Miller, Benjamin E , Foxcroft, Llewellyn , van der Westhuizen, L
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407094 , vital:70335 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a22"
- Description: It has been documented that the continual release of high numbers of biological control (biocontrol) agents for weeds increases the likelihood of agent establishment and has been shown to reduce the time between the first release and subsequent control of the target weed. Here we review the mass-rearing activities for weed biocontrol agents in South Africa between 2011 and 2020. Some 4.7 million individual insects from 40 species of biocontrol agent have been released on 31 weed species at over 2000 sites throughout South Africa during the last decade. These insects were produced at mass-rearing facilities at eight research institutions, five schools and 10 Non-Governmental Organizations. These mass-rearing activities have created employment for 41 fulltime, fixed contract staff, of which 11 are people living with physical disabilities. To improve the uptake of mass-rearing through community engagement, appropriate protocols are required to ensure that agents are produced in high numbers to suppress invasive alien plant populations in South Africa.
- Full Text:
- Date Issued: 2021
- Authors: Hill, Martin P , Conlong, Desmond , Zachariades, Costas , Coetzee, Julie A , Paterson, Iain D , Miller, Benjamin E , Foxcroft, Llewellyn , van der Westhuizen, L
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407094 , vital:70335 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a22"
- Description: It has been documented that the continual release of high numbers of biological control (biocontrol) agents for weeds increases the likelihood of agent establishment and has been shown to reduce the time between the first release and subsequent control of the target weed. Here we review the mass-rearing activities for weed biocontrol agents in South Africa between 2011 and 2020. Some 4.7 million individual insects from 40 species of biocontrol agent have been released on 31 weed species at over 2000 sites throughout South Africa during the last decade. These insects were produced at mass-rearing facilities at eight research institutions, five schools and 10 Non-Governmental Organizations. These mass-rearing activities have created employment for 41 fulltime, fixed contract staff, of which 11 are people living with physical disabilities. To improve the uptake of mass-rearing through community engagement, appropriate protocols are required to ensure that agents are produced in high numbers to suppress invasive alien plant populations in South Africa.
- Full Text:
- Date Issued: 2021
The shame of drinking alcohol while pregnant: The production of avoidance and ill-health
- Matebese, Sibongile, Macleod, Catriona I, Tsetse, Nontozamo
- Authors: Matebese, Sibongile , Macleod, Catriona I , Tsetse, Nontozamo
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441360 , vital:73880 , xlink:href="https://doi.org/10.1177/0886109920985139"
- Description: In this article, we examine the operation of shame in the alcohol use habits of pregnant women and the responses of their families and associated institutions. Using a narrative–discursive approach, we interviewed 13 women, living in a low-resource setting in South Africa, who had consumed alcohol while pregnant. Narratives showed how both the act of drinking and “inappropriately” timed pregnancy (early and out of wedlock) were judged to be unacceptable. Women who engaged in these activities were positioned as bad mothers or promiscuous. Their actions were seen as resulting in the suffering of others—the future child, the family, and even the community. These narratives were underpinned by cultural and religious discourses. Women managed the shame accruing to them through avoidance and concealment; families instructed women to self-exclude or distanced themselves from the women’s behavior; and institutions subtly or overtly excluded women. The shaming of these women, and the mechanisms by which such shame was managed, did little to decrease drinking or to increase maternal health and welfare. Overall, this article demonstrates how the shame of drinking alcohol during pregnancy produces avoidance behavior, concealment, and exclusion, which are not constructive in terms of maternal health and well-being. The implications for a feminist narrative approach to drinking during pregnancy are outlined: moving beyond a focus on individual behavior change to locating personal stories within the meta-narratives and social discourses that shape pregnant women’s lives.
- Full Text:
- Date Issued: 2021
- Authors: Matebese, Sibongile , Macleod, Catriona I , Tsetse, Nontozamo
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441360 , vital:73880 , xlink:href="https://doi.org/10.1177/0886109920985139"
- Description: In this article, we examine the operation of shame in the alcohol use habits of pregnant women and the responses of their families and associated institutions. Using a narrative–discursive approach, we interviewed 13 women, living in a low-resource setting in South Africa, who had consumed alcohol while pregnant. Narratives showed how both the act of drinking and “inappropriately” timed pregnancy (early and out of wedlock) were judged to be unacceptable. Women who engaged in these activities were positioned as bad mothers or promiscuous. Their actions were seen as resulting in the suffering of others—the future child, the family, and even the community. These narratives were underpinned by cultural and religious discourses. Women managed the shame accruing to them through avoidance and concealment; families instructed women to self-exclude or distanced themselves from the women’s behavior; and institutions subtly or overtly excluded women. The shaming of these women, and the mechanisms by which such shame was managed, did little to decrease drinking or to increase maternal health and welfare. Overall, this article demonstrates how the shame of drinking alcohol during pregnancy produces avoidance behavior, concealment, and exclusion, which are not constructive in terms of maternal health and well-being. The implications for a feminist narrative approach to drinking during pregnancy are outlined: moving beyond a focus on individual behavior change to locating personal stories within the meta-narratives and social discourses that shape pregnant women’s lives.
- Full Text:
- Date Issued: 2021
Thien-2-yl substituted chlorins as photosensitizers for photodynamic therapy and photodynamic antimicrobial chemotherapy
- Babu, Balaji, Sindelo, Azole, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
- Date Issued: 2021
- Authors: Babu, Balaji , Sindelo, Azole , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190578 , vital:45007 , xlink:href="https://doi.org/10.1016/j.dyepig.2020.108886"
- Description: The synthesis and characterization of meso-tetra(thien-2-yl)chlorin (1) and meso-tetra(5-bromothien-2-yl)chlorin (2) is reported. These dyes have red-shifted absorption maxima compared to those of the analogous meso-tetraphenylchlorin (3). 1 and 2 have Q bands at 660 and 664 nm, respectively, singlet oxygen quantum yields of 0.60 and 0.64 and exhibit good photostability. The triplet states were found to have lifetimes of 8.6 μs in N2 purged DMF. Time-dependent cellular uptake of chlorins reached a maximum in MCF-7 cancer cells after 12 h. Upon irradiation with a Thorlabs M660L3 LED (280 mW cm−2), 2 exhibited better photocytotoxicity with an IC50 value of 2.7 μM against MCF-7 cells. The 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate (DCFDA) assay provided evidence for intracellular generation of reactive oxygen species. Photodynamic inactivation of bacteria by the chlorins was also studied. 2 exhibits better activity with log reduction values of 7.42 and 8.34 towards Staphylococcus aureus and Escherichia coli, respectively, under illumination for 60 min at 660 nm with a Thorlabs M660L3 LED (280 mW cm−2). These results demonstrate that 2 is a promising candidate for future in vivo experiments and merits further in-depth investigation.
- Full Text:
- Date Issued: 2021
Thirty years of Male Daughters, Female Husbands
- Magadla, Siphokazi, Magoqwana, Babalwa, Motsemme, Nthabiseng
- Authors: Magadla, Siphokazi , Magoqwana, Babalwa , Motsemme, Nthabiseng
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298685 , vital:57727 , xlink:href="https://doi.org/10.1080/02589001.2021.1926442"
- Description: This paper examines the legacy of Ifi Amadiume's Male Daughters, Female Husbands: Gender and Sex in an African Society (1987) to African gender theorisation three decades after its publication. We argue that Amadiume's detailed ethnography of the Nnobi society provides an example of what can be achieved when African scholars centre local histories, languages, and kinship ties to provide contextualised understandings of sex and gender. In southern African societies, we assess the ways in which gender fluidity, drawing from local languages, age, seniority and lineage do not strictly fix sex to gender, thus providing possibilities for flexible gender structures that allow women to access institutions of power through the lineage as first daughters (umafungwashe) and wives, among others. We further examine the ways conservative patriarchal discourses continue distorting African cultures and traditions, thus undermining women's rights and access to social, cultural, economic and political power. We argue that current Eurocentric attempts that aim to delink sex and gender do not move us beyond the universalised binaries of gender and sex. Through revisiting local social and linguistic histories that practised gender fluidity and tolerance, we can also begin to challenge the conservative attitudes towards the LGBTQIA+ communities. Given the continued sexual and gender diversities that are being challenged daily in the African continent, it is timely that we revisit the historical meanings along with their contemporary implications for sexual citizenship and gendered power relations today.
- Full Text:
- Date Issued: 2021
- Authors: Magadla, Siphokazi , Magoqwana, Babalwa , Motsemme, Nthabiseng
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298685 , vital:57727 , xlink:href="https://doi.org/10.1080/02589001.2021.1926442"
- Description: This paper examines the legacy of Ifi Amadiume's Male Daughters, Female Husbands: Gender and Sex in an African Society (1987) to African gender theorisation three decades after its publication. We argue that Amadiume's detailed ethnography of the Nnobi society provides an example of what can be achieved when African scholars centre local histories, languages, and kinship ties to provide contextualised understandings of sex and gender. In southern African societies, we assess the ways in which gender fluidity, drawing from local languages, age, seniority and lineage do not strictly fix sex to gender, thus providing possibilities for flexible gender structures that allow women to access institutions of power through the lineage as first daughters (umafungwashe) and wives, among others. We further examine the ways conservative patriarchal discourses continue distorting African cultures and traditions, thus undermining women's rights and access to social, cultural, economic and political power. We argue that current Eurocentric attempts that aim to delink sex and gender do not move us beyond the universalised binaries of gender and sex. Through revisiting local social and linguistic histories that practised gender fluidity and tolerance, we can also begin to challenge the conservative attitudes towards the LGBTQIA+ communities. Given the continued sexual and gender diversities that are being challenged daily in the African continent, it is timely that we revisit the historical meanings along with their contemporary implications for sexual citizenship and gendered power relations today.
- Full Text:
- Date Issued: 2021
Three new biological control programmes for South Africa: Brazilian pepper, Tamarix and Tradescantia
- Byrne, Marcus J, Mayonde, Samalesu, Venter, Nic, Chidawanyika, Frank, Zachariades, Costas, Martin, Grant D
- Authors: Byrne, Marcus J , Mayonde, Samalesu , Venter, Nic , Chidawanyika, Frank , Zachariades, Costas , Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414490 , vital:71152 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Three weed biological control (biocontrol) programmes are described, all of which are considered to be ‘transfer projects’ that were initiated elsewhere, and on which South Africa has piggybacked its biocontrol efforts. Using knowledge and expertise from international collaborators, South African weed researchers are following a long tradition of transfer projects, which has been a largely successful and practical approach to biocontrol. Two Brazilian weeds, the Brazilian pepper tree Schinus terebinthifolia and the spiderwort Tradescantia fluminensis are being targeted, along with the Old-World trees Tamarix ramosissima and T. chinensis. The potential biocontrol agents are described and ranked for the two trees according to what has been discovered elsewhere, while the agent already released against T. fluminensis is rated (as poor), and other potential agents are considered. The addition of molecular techniques, climate matching and remote sensing in transfer projects can increase the chance of successful biocontrol and the inclusion of these techniques in the three new programmes is discussed. Transfer projects are a cost-effective and pragmatic way to pick winning biocontrol programmes.
- Full Text:
- Date Issued: 2021
Three new biological control programmes for South Africa: Brazilian pepper, Tamarix and Tradescantia
- Authors: Byrne, Marcus J , Mayonde, Samalesu , Venter, Nic , Chidawanyika, Frank , Zachariades, Costas , Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414490 , vital:71152 , xlink:href="https://hdl.handle.net/10520/ejc-cristal-v10-n1-a7"
- Description: Three weed biological control (biocontrol) programmes are described, all of which are considered to be ‘transfer projects’ that were initiated elsewhere, and on which South Africa has piggybacked its biocontrol efforts. Using knowledge and expertise from international collaborators, South African weed researchers are following a long tradition of transfer projects, which has been a largely successful and practical approach to biocontrol. Two Brazilian weeds, the Brazilian pepper tree Schinus terebinthifolia and the spiderwort Tradescantia fluminensis are being targeted, along with the Old-World trees Tamarix ramosissima and T. chinensis. The potential biocontrol agents are described and ranked for the two trees according to what has been discovered elsewhere, while the agent already released against T. fluminensis is rated (as poor), and other potential agents are considered. The addition of molecular techniques, climate matching and remote sensing in transfer projects can increase the chance of successful biocontrol and the inclusion of these techniques in the three new programmes is discussed. Transfer projects are a cost-effective and pragmatic way to pick winning biocontrol programmes.
- Full Text:
- Date Issued: 2021
Top-Down Synthesis of a Lamivudine-Zidovudine Nano Co-Crystal
- Witika, Bwalya A, Smith, Vincent J, Walker, Roderick B
- Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183172 , vital:43918 , xlink:href="https://doi.org/10.3390/cryst11010033"
- Description: Lamivudine (3TC) and zidovudine (AZT) are antiretroviral agents used to manage HIV/AIDS infection. A wet media milling top-down approach was used to develop and produce nano co-crystals of 3TC and AZT. Micro co-crystals were prepared by solvent evaporation and subsequently milled in the presence of two surfactants, viz., sodium lauryl sulfate (SLS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000). Optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) to establish and identify parameters that may affect the manufacturing of nano co-crystals. The impact of SLS and TPGS 1000 concentration, milling time, and number of units of milling medium on the manufacturing of nano co-crystals, was investigated. The critical quality attributes (CQA) monitored were particle size (PS), Zeta potential (ZP), and polydispersity index (PDI). Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, energy dispersive X-ray spectroscopy scanning electron microscopy, and cytotoxicity assays were used for additional characterization of the optimised nano co-crystal. The mean PS, PDI, and ZP of the optimised top-down nanocrystal were 271.0 ± 92.0 nm, 0.467 ± 0.073, and −41.9 ± 3.94 mV, respectively. In conclusion, a simple, inexpensive, rapid, and precise method of nano co-crystal manufacturing was developed, validated, and optimised using DoE and RSM, and the final product exhibited the target CQA.
- Full Text:
- Date Issued: 2021
- Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183172 , vital:43918 , xlink:href="https://doi.org/10.3390/cryst11010033"
- Description: Lamivudine (3TC) and zidovudine (AZT) are antiretroviral agents used to manage HIV/AIDS infection. A wet media milling top-down approach was used to develop and produce nano co-crystals of 3TC and AZT. Micro co-crystals were prepared by solvent evaporation and subsequently milled in the presence of two surfactants, viz., sodium lauryl sulfate (SLS) and α-tocopheryl polyethylene glycol succinate 1000 (TPGS 1000). Optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) to establish and identify parameters that may affect the manufacturing of nano co-crystals. The impact of SLS and TPGS 1000 concentration, milling time, and number of units of milling medium on the manufacturing of nano co-crystals, was investigated. The critical quality attributes (CQA) monitored were particle size (PS), Zeta potential (ZP), and polydispersity index (PDI). Powder X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, transmission electron microscopy, energy dispersive X-ray spectroscopy scanning electron microscopy, and cytotoxicity assays were used for additional characterization of the optimised nano co-crystal. The mean PS, PDI, and ZP of the optimised top-down nanocrystal were 271.0 ± 92.0 nm, 0.467 ± 0.073, and −41.9 ± 3.94 mV, respectively. In conclusion, a simple, inexpensive, rapid, and precise method of nano co-crystal manufacturing was developed, validated, and optimised using DoE and RSM, and the final product exhibited the target CQA.
- Full Text:
- Date Issued: 2021
Turn-on detection of cysteine by a donor-acceptor type quinoline fluorophore: Exploring the sensing strategy and performance in bioimaging
- Muthusamy, Selvaraj, Zhao, Long, Rajalakshmi, Kanagaraj, Zhu, Dongwei, Soy, Rodah, Mack, John, Nyokong, Tebello, Wang, Shengjun, Lee, Kang-Bong, Zhu, Weihua
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
- Authors: Muthusamy, Selvaraj , Zhao, Long , Rajalakshmi, Kanagaraj , Zhu, Dongwei , Soy, Rodah , Mack, John , Nyokong, Tebello , Wang, Shengjun , Lee, Kang-Bong , Zhu, Weihua
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185644 , vital:44406 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109556"
- Description: Tracking the biothiol cysteine (Cys) in living systems is a significant responsibility to balance the redox environment and oxidative stress. A quinoline-7-nitro-1,2,3-benzoxadiazole (Q-NBD) fluorophore has been synthesized and characterized towards examination of Cys. The probe forms a quinoline-substituted phenol (Q-Ph-OH) after thiolysis of the NBD ether bond, leading to an increase of fluorescence at green channel. The turn-on sensing mechanism originates from the change in intramolecular charge transfer (ICT-OFF) along with an aggregation-induced emission (AIE) as suggested by spectroscopy measurements in solutions, time-dependent density-functional theory (TD-DFT) calculations and 1H NMR titration examination. Importantly, Q-NBD exhibited great sensitivity with a low limit of detection value of 89.5 nM and remarkable selectivity in various biothiols towards Cys. The sensor probe was successfully used for detecting both endogenous and exogenous Cys in PC3 living cells and spiked Cys in human urine samples.
- Full Text:
- Date Issued: 2021
Ultrasound-Triggered Release of 5-Fluorouracil from Soy Lecithin Echogenic Liposomes
- Ezekiel, Charles I, Bapolisi, Alain M, Walker, Roderick B, Krause, Rui W M
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
- Authors: Ezekiel, Charles I , Bapolisi, Alain M , Walker, Roderick B , Krause, Rui W M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183115 , vital:43913 , xlink:href="https://doi.org/10.3390/pharmaceutics13060821"
- Description: Colorectal cancer is the third most diagnosed cancer and the second leading cause of death. The use of 5-fluorouracil (5-FU) has been the major chemotherapeutic treatment for colorectal cancer patients. However, the efficacy of 5-FU is limited by drug resistance, and bone marrow toxicity through high-level expression of thymidylate synthase, justifying the need for improvement of the therapeutic index. In this study, the effects of ultrasound on echogenic 5-FU encapsulated crude soy liposomes were investigated for their potential to address these challenges. Liposomes were prepared by thin-film hydration using crude soy lecithin and cholesterol. Argon gas was entrapped in the liposomes for sonosensitivity (that is, responsiveness to ultrasound). The nanoparticles were characterized for particle size and morphology. The physicochemical properties were also evaluated using differential scanning calorimetry, Fourier transform infrared and X-ray diffraction. The release profile of 5-FU was assessed with and without 20 kHz low-frequency ultrasound waves at various amplitudes and exposure times. The result reveal that 5-FU-loaded liposomes were spherical with an encapsulation efficiency of approximately 60%. Approximately 65% of 5-FU was released at the highest amplitude and exposure time was investigated. The results are encouraging for the stimulated and controlled release of 5-FU for the management of colorectal cancer.
- Full Text:
- Date Issued: 2021
Unlocking the Diversity of Pyrroloiminoquinones Produced by Latrunculid Sponge Species
- Kalinski, Jarmo-Charles J, Krause, Rui W M, Parker-Nance, Shirley, Waterworth, Samantha C, Dorrington, Rosemary A
- Authors: Kalinski, Jarmo-Charles J , Krause, Rui W M , Parker-Nance, Shirley , Waterworth, Samantha C , Dorrington, Rosemary A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191802 , vital:45165 , xlink:href="https://doi.org/10.3390/md19020068"
- Description: Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are Tsitsikamma favus, Tsitsikamma pedunculata, Cyclacanthia bellae, and Latrunculia apicalis as well as the recently discovered species, Tsitsikamma nguni and Tsitsikamma michaeli. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species T. nguni closely resembled those of the known T. favus (chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins. T. michaeli sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as T. favus (chemotype I) or non- or monobrominated, hydroxylated discorhabdins. C. bellae and L. apicalis produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
- Full Text:
- Date Issued: 2021
- Authors: Kalinski, Jarmo-Charles J , Krause, Rui W M , Parker-Nance, Shirley , Waterworth, Samantha C , Dorrington, Rosemary A
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191802 , vital:45165 , xlink:href="https://doi.org/10.3390/md19020068"
- Description: Sponges of the Latrunculiidae family produce bioactive pyrroloiminoquinone alkaloids including makaluvamines, discorhabdins, and tsitsikammamines. The aim of this study was to use LC-ESI-MS/MS-driven molecular networking to characterize the pyrroloiminoquinone secondary metabolites produced by six latrunculid species. These are Tsitsikamma favus, Tsitsikamma pedunculata, Cyclacanthia bellae, and Latrunculia apicalis as well as the recently discovered species, Tsitsikamma nguni and Tsitsikamma michaeli. Organic extracts of 43 sponges were analyzed, revealing distinct species-specific chemical profiles. More than 200 known and unknown putative pyrroloiminoquinones and related compounds were detected, including unprecedented makaluvamine-discorhabdin adducts and hydroxylated discorhabdin I derivatives. The chemical profiles of the new species T. nguni closely resembled those of the known T. favus (chemotype I), but with a higher abundance of tsitsikammamines vs. discorhabdins. T. michaeli sponges displayed two distinct chemical profiles, either producing mostly the same discorhabdins as T. favus (chemotype I) or non- or monobrominated, hydroxylated discorhabdins. C. bellae and L. apicalis produced similar pyrroloiminoquinone chemistry to one another, characterized by sulfur-containing discorhabdins and related adducts and oligomers. This study highlights the variability of pyrroloiminoquinone production by latrunculid species, identifies novel isolation targets, and offers fundamental insights into the collision-induced dissociation of pyrroloiminoquinones.
- Full Text:
- Date Issued: 2021