Inhibitory effects of selected cannabinoids against dipeptidyl peptidase IV, an enzyme linked to type 2 diabetes
- Mkabayi, Lithalethu, Viljoen, Zenobia, Krause, Rui W M, Lobb, Kevin A, Pletschke, Brett I, Frost, Carminita L
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Krause, Rui W M , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452760 , vital:75168 , xlink:href="https://doi.org/10.1016/j.heliyon.2023.e23289"
- Description: Ethnopharmacological relevance: In recent times the decriminalisation of cannabis globally has increased its use as an alternative medication. Where it has been used in modern medicinal practises since the 1800s, there is limited scientific investigation to understand the biological activities of this plant. Aim of the study: Dipeptidyl peptidase IV (DPP-IV) plays a key role in regulating glucose homeostasis, and inhibition of this enzyme has been used as a therapeutic approach to treat type 2 diabetes. However, some of the synthetic inhibitors for this enzyme available on the market may cause undesirable side effects. Therefore, it is important to identify new inhibitors of DPP-IV and to understand their interaction with this enzyme.
- Full Text:
- Authors: Mkabayi, Lithalethu , Viljoen, Zenobia , Krause, Rui W M , Lobb, Kevin A , Pletschke, Brett I , Frost, Carminita L
- Date: 2024
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452760 , vital:75168 , xlink:href="https://doi.org/10.1016/j.heliyon.2023.e23289"
- Description: Ethnopharmacological relevance: In recent times the decriminalisation of cannabis globally has increased its use as an alternative medication. Where it has been used in modern medicinal practises since the 1800s, there is limited scientific investigation to understand the biological activities of this plant. Aim of the study: Dipeptidyl peptidase IV (DPP-IV) plays a key role in regulating glucose homeostasis, and inhibition of this enzyme has been used as a therapeutic approach to treat type 2 diabetes. However, some of the synthetic inhibitors for this enzyme available on the market may cause undesirable side effects. Therefore, it is important to identify new inhibitors of DPP-IV and to understand their interaction with this enzyme.
- Full Text:
Activated carbon-decorated polyacrylonitrile fibers and their porphyrin-immobilized composites for removal of methylene blue dye and Ciprofloxacin in water
- Oyim, James, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Oyim, James , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:65077 , xlink:href="https://doi.org/10.1080/10601325.2023.2183868"
- Description: Photocatalyst adsorbents are an appealing group of materials for environmental applications. Herein, we study a new simple, inexpensive, yet very effective adsorbent photocatalyst based on porphyrin immobilized activated carbon-decorated polyacrylonitrile, InP(PAN/AC), for removal of methylene blue dye and Ciprofloxacin in water under Xe-lamp and sunlight irradiation (the latter for Ciprofloxacin only). Our results shed light on developing the most effective and sustainable adsorbent photocatalysts that can easily be industrialized due to the ease of preparation through electrospinning coupled with the readily available preparation materials. After five cycles, the InP(PAN/AC) maintained high methylene dye removal efficiency and structural integrity. Significantly, we propose the coordinated contribution of singlet oxygen and hydroxyl radical in the photodegradation process and highlight the importance of such an integrated system with adsorption and photodegradation capabilities for water treatment.
- Full Text:
- Authors: Oyim, James , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:65077 , xlink:href="https://doi.org/10.1080/10601325.2023.2183868"
- Description: Photocatalyst adsorbents are an appealing group of materials for environmental applications. Herein, we study a new simple, inexpensive, yet very effective adsorbent photocatalyst based on porphyrin immobilized activated carbon-decorated polyacrylonitrile, InP(PAN/AC), for removal of methylene blue dye and Ciprofloxacin in water under Xe-lamp and sunlight irradiation (the latter for Ciprofloxacin only). Our results shed light on developing the most effective and sustainable adsorbent photocatalysts that can easily be industrialized due to the ease of preparation through electrospinning coupled with the readily available preparation materials. After five cycles, the InP(PAN/AC) maintained high methylene dye removal efficiency and structural integrity. Significantly, we propose the coordinated contribution of singlet oxygen and hydroxyl radical in the photodegradation process and highlight the importance of such an integrated system with adsorption and photodegradation capabilities for water treatment.
- Full Text:
Electrocatalytic Behavior of Manganese and Cobalt Porphyrins Attached to Graphene Quantum Dots: Applied in the Oxidation of Hydrazine
- Jokazi, Mbulelo, Mpeta, Lekhetho S, Nyokong, Tebello
- Authors: Jokazi, Mbulelo , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360411 , vital:65086 , xlink:href="https://doi.org/10.1002/elan.202200222"
- Description: Manganese and cobalt metalated 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins (ClMnTA3CPP and CoTA3CPP) were synthesized and attached to graphene quantum dots (GQDs) via π-π interaction and electrostatic interaction. The electrochemical oxidation of hydrazine was performed via cyclic voltammetry and chronoamperometry. The CoTA3CPP showed good electrocatalytic activity towards the oxidation of hydrazine in terms of catalytic rate constants and limits of detection (LoD). ClMnTA3CPP showed lower overpotential 0.60 V. The introduction of GQDs improved the electrocatalytic ability when combined with CoTA3CPP and ClMnTA3CPP with the lowest LoD (0.0025 mM CoTA3CPP–GQDs) followed by ClMnTA3CPP–GQDs with 0.0033 mM.
- Full Text:
- Authors: Jokazi, Mbulelo , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360411 , vital:65086 , xlink:href="https://doi.org/10.1002/elan.202200222"
- Description: Manganese and cobalt metalated 5, 10, 15-tris(aminophenyl)-20-(4-carboxyphenyl) porphyrins (ClMnTA3CPP and CoTA3CPP) were synthesized and attached to graphene quantum dots (GQDs) via π-π interaction and electrostatic interaction. The electrochemical oxidation of hydrazine was performed via cyclic voltammetry and chronoamperometry. The CoTA3CPP showed good electrocatalytic activity towards the oxidation of hydrazine in terms of catalytic rate constants and limits of detection (LoD). ClMnTA3CPP showed lower overpotential 0.60 V. The introduction of GQDs improved the electrocatalytic ability when combined with CoTA3CPP and ClMnTA3CPP with the lowest LoD (0.0025 mM CoTA3CPP–GQDs) followed by ClMnTA3CPP–GQDs with 0.0033 mM.
- Full Text:
Fruits of the city: The nature, nurture and future of urban foraging
- Sardeshpande, Mallika, Shackleton, Charlie M
- Authors: Sardeshpande, Mallika , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402259 , vital:69835 , xlink:href="https://doi.org/10.1002/pan3.10428"
- Description: Urban foraging is a global informal phenomenon which has been investigated in the Global North more than oth-er parts of the world. Characterising the nature of urban foraging in the Global South is imperative given the rapid urbanisation and sustainable development priorities in the region. In this study, we interviewed 80 urban forag-ers in four cities in the eastern coastal region of South Af-rica, with an aim to understand the nature of urban forag-ing in a developing nation context. We asked foragers about their initiation to and motivations for foraging, their logistics, yields and associated activities, descriptions of their foraging grounds, and if and how they had changed, and what they envisage as an ideal future for foraging.
- Full Text:
- Authors: Sardeshpande, Mallika , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402259 , vital:69835 , xlink:href="https://doi.org/10.1002/pan3.10428"
- Description: Urban foraging is a global informal phenomenon which has been investigated in the Global North more than oth-er parts of the world. Characterising the nature of urban foraging in the Global South is imperative given the rapid urbanisation and sustainable development priorities in the region. In this study, we interviewed 80 urban forag-ers in four cities in the eastern coastal region of South Af-rica, with an aim to understand the nature of urban forag-ing in a developing nation context. We asked foragers about their initiation to and motivations for foraging, their logistics, yields and associated activities, descriptions of their foraging grounds, and if and how they had changed, and what they envisage as an ideal future for foraging.
- Full Text:
Governing pregnancy in the Global South: the case of post-apartheid South Africa
- du Plessis, Ulandi, Macleod, Catriona I
- Authors: du Plessis, Ulandi , Macleod, Catriona I
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441212 , vital:73867 , xlink:href="https://doi.org/10.1080/13698575.2023.2249943"
- Description: Women who sell sex (WSS) are vulnerable to violence. We present a scoping review of the last decade of research on the prevalence and incidence of, factors associated with, and services regarding violence against WSS in Eastern and Southern African (ESA). A systematic search of various databases resulted in 20 papers being reviewed. Inclusion criteria, applied by the first two authors, were as follows: empirical papers, key research problem is violence against WSS, and conducted in ESA countries. The lifetime prevalence of violence revealed in the studies ranged from 21% to 82%. A pattern of generalized violence against WSS from paying clients, male partners, strangers, family members, friends/acquaintances, and the authorities emerged. Factors associated with violence included the context within which the sex work occurs, alcohol use, type of sex exchange interactions, and personal factors (low education, low income, marriage, youth, high client volume, time in sex work, forced sexual debut, and internalized sex work stigma). WSS seldom access services after violence. Evaluations of two programs, a woman-focused HIV intervention, and the Diagonal Interventions to Fast-Forward Reproductive Health project, showed improvements in gender-based violence services. Findings suggest that targeted programmes should be paired with improving general health services and focus on promoting collective agency among WSS.
- Full Text:
- Authors: du Plessis, Ulandi , Macleod, Catriona I
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441212 , vital:73867 , xlink:href="https://doi.org/10.1080/13698575.2023.2249943"
- Description: Women who sell sex (WSS) are vulnerable to violence. We present a scoping review of the last decade of research on the prevalence and incidence of, factors associated with, and services regarding violence against WSS in Eastern and Southern African (ESA). A systematic search of various databases resulted in 20 papers being reviewed. Inclusion criteria, applied by the first two authors, were as follows: empirical papers, key research problem is violence against WSS, and conducted in ESA countries. The lifetime prevalence of violence revealed in the studies ranged from 21% to 82%. A pattern of generalized violence against WSS from paying clients, male partners, strangers, family members, friends/acquaintances, and the authorities emerged. Factors associated with violence included the context within which the sex work occurs, alcohol use, type of sex exchange interactions, and personal factors (low education, low income, marriage, youth, high client volume, time in sex work, forced sexual debut, and internalized sex work stigma). WSS seldom access services after violence. Evaluations of two programs, a woman-focused HIV intervention, and the Diagonal Interventions to Fast-Forward Reproductive Health project, showed improvements in gender-based violence services. Findings suggest that targeted programmes should be paired with improving general health services and focus on promoting collective agency among WSS.
- Full Text:
Sense of Community: Perceptions of "Inter-Intra" Collaborations in an Academic Environment through the Lenses of Botho Principles and the Field of industrial Psychology
- Authors: Diale, Dineo
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450715 , vital:74976 , xlink:href="https://www.sciedupress.com/journal/index.php/ijhe/article/download/21745/13462"
- Description: In the current study, I explored the concept of collaboration from Botho principles and the industrial psychology perspective in the specific higher learning institution. Using a qualitative approach, 13 participants performing academic and nonacademic roles formed part of the study. Overall, the participants experience regarding collaboration in an academic environment are reported to be in the form of shared goals, sense of unity, diversity, and solution-driven teams. Further participants experience in relation to collaboration is African culture [Botho principles]. The latter were perceived   contributors to collaboration within departments (intra); and few barriers to collaboration were discovered, such as criteria, lack of shared leadership, lack of collaboration champions or ambassadors. The concept of Botho is defined as a social contract of mutual respect, humanity, and responsibility that members have with one another often referred to as bringing in humanity onto a set environment. Although there are commonalities between Botho and Ubuntu, they however have dissimilarities and are underpinned by different cultures and traditions. Ubuntu is seen often used by a slogan, "I am because you are". Botho is Setswana or Sesotho concept while Ubuntu forms part of Nguni languages.  I then further conceptualize collaboration through the lens of industrial psychology from the results and offer future research recommendations in the current paper.
- Full Text:
- Authors: Diale, Dineo
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/450715 , vital:74976 , xlink:href="https://www.sciedupress.com/journal/index.php/ijhe/article/download/21745/13462"
- Description: In the current study, I explored the concept of collaboration from Botho principles and the industrial psychology perspective in the specific higher learning institution. Using a qualitative approach, 13 participants performing academic and nonacademic roles formed part of the study. Overall, the participants experience regarding collaboration in an academic environment are reported to be in the form of shared goals, sense of unity, diversity, and solution-driven teams. Further participants experience in relation to collaboration is African culture [Botho principles]. The latter were perceived   contributors to collaboration within departments (intra); and few barriers to collaboration were discovered, such as criteria, lack of shared leadership, lack of collaboration champions or ambassadors. The concept of Botho is defined as a social contract of mutual respect, humanity, and responsibility that members have with one another often referred to as bringing in humanity onto a set environment. Although there are commonalities between Botho and Ubuntu, they however have dissimilarities and are underpinned by different cultures and traditions. Ubuntu is seen often used by a slogan, "I am because you are". Botho is Setswana or Sesotho concept while Ubuntu forms part of Nguni languages.  I then further conceptualize collaboration through the lens of industrial psychology from the results and offer future research recommendations in the current paper.
- Full Text:
Asymmetrical zinc (II) phthalocyanines conjugated to metal tungstate nanoparticles for photoinactivation of Staphylococcus aureus
- Mgidlana, Sithi, Managa, Muthumuni, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Managa, Muthumuni , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295718 , vital:57372 , xlink:href="https://doi.org/10.1080/00958972.2022.2090837"
- Description: In this study, we report for the first time on the photodynamic antimicrobial chemotherapy (PACT) of asymmetrical zinc(II) phthalocyanines and their conjugates with nickel tungstate (NiWO4), cobalt tungstate (CoWO4) and bismuth tungstate (Bi2WO6) nanoparticles. CoWO4, NiWO4 and Bi2WO6 were capped with glutathione and covalently linked to three asymmetrical zinc(II) phthalocyanines for PACT. The plate count method was used to investigate the effect of covalently linking asymmetrical zinc(II) phthalocyanines to nanoparticles under light (for PACT against Staphylococcus aureus) and in the dark. Both Pc complexes and the conjugates indicated minimum dark-toxicity. The conjugates showed greater antimicrobial activity against a gram-positive and drug resistant bacteria, Staphylococcus aureus, than Pc complexes alone.
- Full Text:
- Authors: Mgidlana, Sithi , Managa, Muthumuni , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295718 , vital:57372 , xlink:href="https://doi.org/10.1080/00958972.2022.2090837"
- Description: In this study, we report for the first time on the photodynamic antimicrobial chemotherapy (PACT) of asymmetrical zinc(II) phthalocyanines and their conjugates with nickel tungstate (NiWO4), cobalt tungstate (CoWO4) and bismuth tungstate (Bi2WO6) nanoparticles. CoWO4, NiWO4 and Bi2WO6 were capped with glutathione and covalently linked to three asymmetrical zinc(II) phthalocyanines for PACT. The plate count method was used to investigate the effect of covalently linking asymmetrical zinc(II) phthalocyanines to nanoparticles under light (for PACT against Staphylococcus aureus) and in the dark. Both Pc complexes and the conjugates indicated minimum dark-toxicity. The conjugates showed greater antimicrobial activity against a gram-positive and drug resistant bacteria, Staphylococcus aureus, than Pc complexes alone.
- Full Text:
Hybrid approaches to teaching: Re-imagining the teaching of a foundational science course during a global pandemic
- Parker, Daniel M, Vorster, Jo-Anne E, Quinn, Lynn, Blackie, Margaret A L
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
Neoliberalism’s conditioning effects on the university and the example of proctoring during COVID-19 and since
- Authors: McKenna, Sioux
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426929 , vital:72401 , xlink:href="https://doi.org/10.1080/14767430.2022.2100612"
- Description: Neoliberalism has shaped the academy in ways that constrain its potential as a public good. Neoliberalism is based on the assumption that, by submitting to the so-called neutral forces of the market, wealth can be created alongside the achievement of equality and efficiency. Although this assumption is demonstrably false, neoliberalism remains politically powerful. As an example, this article discusses how neoliberalism has enabled the rapid uptake of proctoring software during the covid pandemic and since. ‘Proctoring' is the online monitoring of students’ behaviour as they sit for exams. Many within the academy consider proctoring software to be dehumanizing – essentially legalized spyware. They argue that the software invades privacy and is inherently racist and ableist, amongst other things. It is hoped that by understanding how structural forces such as neoliberalism affect both our agency and university activities, frequently against the common good, strategies can be developed to change these structures.
- Full Text:
- Authors: McKenna, Sioux
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426929 , vital:72401 , xlink:href="https://doi.org/10.1080/14767430.2022.2100612"
- Description: Neoliberalism has shaped the academy in ways that constrain its potential as a public good. Neoliberalism is based on the assumption that, by submitting to the so-called neutral forces of the market, wealth can be created alongside the achievement of equality and efficiency. Although this assumption is demonstrably false, neoliberalism remains politically powerful. As an example, this article discusses how neoliberalism has enabled the rapid uptake of proctoring software during the covid pandemic and since. ‘Proctoring' is the online monitoring of students’ behaviour as they sit for exams. Many within the academy consider proctoring software to be dehumanizing – essentially legalized spyware. They argue that the software invades privacy and is inherently racist and ableist, amongst other things. It is hoped that by understanding how structural forces such as neoliberalism affect both our agency and university activities, frequently against the common good, strategies can be developed to change these structures.
- Full Text:
One and done, or a bundle and stumble? an exploration of assessment methods in undergraduate science curricula
- Authors: Edwards, Shelley
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/461539 , vital:76211 , xlink:href="https://doi.org/10.2478/atd-2022-0023"
- Description: Assessment, historically, has been done in a summative manner in post-secondary education (HE). Whilst useful for the purposes of grading and assessment of competency, there is also increasing pressure from post-secondary education institutions to meet certain standards in terms of education quality and graduate numbers, putting pressure on teachers to produce evidence of students’ level of understanding and thus putting a greater emphasis on the use of summative assessments. The formative assessment approach for student learning is preferable in some fields, but how useful is this format for the science subjects?
- Full Text:
- Authors: Edwards, Shelley
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/461539 , vital:76211 , xlink:href="https://doi.org/10.2478/atd-2022-0023"
- Description: Assessment, historically, has been done in a summative manner in post-secondary education (HE). Whilst useful for the purposes of grading and assessment of competency, there is also increasing pressure from post-secondary education institutions to meet certain standards in terms of education quality and graduate numbers, putting pressure on teachers to produce evidence of students’ level of understanding and thus putting a greater emphasis on the use of summative assessments. The formative assessment approach for student learning is preferable in some fields, but how useful is this format for the science subjects?
- Full Text:
Photodegradation of tetracycline by asymmetrical zinc (II) phthalocyanines conjugated to cobalt tungstate nanoparticles
- Mgidlana, Sithi, Sen, Pinar, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300233 , vital:57908 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.132938"
- Description: This work focused on syntheses of novel asymmetrically tetra substituted Zn phthalocyanines (ZnPc) each containing a single carboxyl group, with the other substituents bearing alkynyl (complex 1) and fluorine containing groups (complexes 2 and 3). The complexes were conjugated to cobalt tungstate nanoparticles and employed as efficient photocatalysts for degradation of tetracycline in water. ZnPc complexes and their conjugates showed good photophysical and photochemical properties behaviour with complex 1 giving higher triplet and singlet oxygen quantum yields compared to 2 and 3. Complex 1 showed higher activity towards the photodegradation of tetracycline compared to complexes 2 and 3, with higher kobs and initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model.
- Full Text:
- Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300233 , vital:57908 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.132938"
- Description: This work focused on syntheses of novel asymmetrically tetra substituted Zn phthalocyanines (ZnPc) each containing a single carboxyl group, with the other substituents bearing alkynyl (complex 1) and fluorine containing groups (complexes 2 and 3). The complexes were conjugated to cobalt tungstate nanoparticles and employed as efficient photocatalysts for degradation of tetracycline in water. ZnPc complexes and their conjugates showed good photophysical and photochemical properties behaviour with complex 1 giving higher triplet and singlet oxygen quantum yields compared to 2 and 3. Complex 1 showed higher activity towards the photodegradation of tetracycline compared to complexes 2 and 3, with higher kobs and initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model.
- Full Text:
The effect of charge on Zn tetra morpholine porphyrin conjugated to folic acid-nitrogen doped graphene quantum dots for photodynamic therapy studies
- Magaela, N Bridged, Matshitse, Refilwe, Nyokong, Tebello
- Authors: Magaela, N Bridged , Matshitse, Refilwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295840 , vital:57383 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102898"
- Description: Zinc tetra morpholine porphyrin (complex 2), and its quaternized derivative (complex 3) were synthesized and conjugated to folic acid decorated nitrogen doped graphene quantum dots (FA-NGQDs) through π−π stacking to study their photodynamic therapy (PDT) efficacy. Photophysiochemical properties of complexes 2, 3, and their conjugates (2-FA-NGQDs, 3-FA-NGQDs) were studied. It was found that complex 3 had higher ϕΔ of 0.56 compared to complex 2 with ϕΔ of 0.24, and respective composites: 3-FA-NGQDs had higher ϕΔ compared to 2-FA-NGQDs. The PDT studies were conducted for nanoparticles (FA-NGQDs), complexes (2, 3), and respective composites (2-FA-NGQDs, and 3-FA-NGQDs) using MCF-7 breast cancer cell. Dark toxicity of all compounds was above 90% which is negligible. At a highest concentration of 40 µg/mL, 3-FA-NGQDs gave the lowest cell viability of 28% compared to all other conjugates and porphyrins alone.
- Full Text:
- Authors: Magaela, N Bridged , Matshitse, Refilwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295840 , vital:57383 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102898"
- Description: Zinc tetra morpholine porphyrin (complex 2), and its quaternized derivative (complex 3) were synthesized and conjugated to folic acid decorated nitrogen doped graphene quantum dots (FA-NGQDs) through π−π stacking to study their photodynamic therapy (PDT) efficacy. Photophysiochemical properties of complexes 2, 3, and their conjugates (2-FA-NGQDs, 3-FA-NGQDs) were studied. It was found that complex 3 had higher ϕΔ of 0.56 compared to complex 2 with ϕΔ of 0.24, and respective composites: 3-FA-NGQDs had higher ϕΔ compared to 2-FA-NGQDs. The PDT studies were conducted for nanoparticles (FA-NGQDs), complexes (2, 3), and respective composites (2-FA-NGQDs, and 3-FA-NGQDs) using MCF-7 breast cancer cell. Dark toxicity of all compounds was above 90% which is negligible. At a highest concentration of 40 µg/mL, 3-FA-NGQDs gave the lowest cell viability of 28% compared to all other conjugates and porphyrins alone.
- Full Text:
The use and value of wild harvested provisioning ecosystem services along a landscape heterogeneity gradient in rural South Africa
- Herd-Hoare, Shannon C, Shackleton, Charlie M
- Authors: Herd-Hoare, Shannon C , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401341 , vital:69727 , xlink:href="https://doi.org/10.1080/26395916.2022.2140711"
- Description: Provisioning ecosystem services (PES) are typically crucial to rural livelihoods, especially in developing countries. However, the links between PES and local biodiversity or landscape heterogeneity are poorly explored. Here, we examined the extent of use and value of locally harvested wild, terrestrial and marine PES (such as wild foods, traditional medicines, firewood, building materials and others) in three villages (35–40 households per village) along a gradient of decreasing landscape heterogeneity. Households at the site with the highest landscape heterogeneity used a greater array of PES (9 ± 4) compared to the intermediate (5 ± 3) and least heterogenous (0.9 ± 0.8) sites. This resulted in a significantly greater annual value of PES to local livelihoods at the most diverse site (US$2 656 ± 2 587 per household), compared to US$1 120 ± 1 313 at the intermediate site and only US$105 ± 193 at the least heterogeneous site. This study shows the importance of access to a diversity of landscapes and PES to support rural livelihoods, which is frequently overlooked in PES valuation studies and in situations of land use change where landscape heterogeneity may decline.
- Full Text:
- Authors: Herd-Hoare, Shannon C , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401341 , vital:69727 , xlink:href="https://doi.org/10.1080/26395916.2022.2140711"
- Description: Provisioning ecosystem services (PES) are typically crucial to rural livelihoods, especially in developing countries. However, the links between PES and local biodiversity or landscape heterogeneity are poorly explored. Here, we examined the extent of use and value of locally harvested wild, terrestrial and marine PES (such as wild foods, traditional medicines, firewood, building materials and others) in three villages (35–40 households per village) along a gradient of decreasing landscape heterogeneity. Households at the site with the highest landscape heterogeneity used a greater array of PES (9 ± 4) compared to the intermediate (5 ± 3) and least heterogenous (0.9 ± 0.8) sites. This resulted in a significantly greater annual value of PES to local livelihoods at the most diverse site (US$2 656 ± 2 587 per household), compared to US$1 120 ± 1 313 at the intermediate site and only US$105 ± 193 at the least heterogeneous site. This study shows the importance of access to a diversity of landscapes and PES to support rural livelihoods, which is frequently overlooked in PES valuation studies and in situations of land use change where landscape heterogeneity may decline.
- Full Text:
Amphiphilic axially modified cationic indium-porphyrins linked to hydrophilic magnetic nanoparticles for photodynamic antimicrobial chemotherapy against gram-negative strain; Escherichia coli
- Makolla, Collen L, Mgidlana, Sithi, Nyokong, Tebello
- Authors: Makolla, Collen L , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185024 , vital:44317 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109262"
- Description: In this study, we report on the synthesis, characterization, and application of indium porphyrins linked to silver core-shell magnetic nanoparticles for in vitro photodynamic antimicrobial chemotherapy (PACT) against gram-negative strain, E. coli. This work compares the photophysicochemical and PACT activities of InCl 5-p-carboxyphenyl-10-15-20-(tris-4-methylpyridinium)-triiodide porphyrin (1), InCl 5-p-carboxyphenyl-10-15-20-(tris-4-hexylpyridinium)-triiodide porphyrin (2), In (para-aminophenyl) 5,10,15,20-tetrakis(4-methylpyridinium)-tetraiodide porphyrin (3), and In (para-aminophenyl) 5,10,15,20-tetrakis(4-hexylpyridinium)-tetraiodide porphyrin (4). The comparisons were based on the structure and number of charges. Hydrophilic and hydrophobic characters of the amphiphilic porphyrins were studied by comparing the effect of the different alkyl halides (iodomethane and iodohexane) quaternizing agents. The porphyrin complexes were further linked to magnetic nanoparticles to facilitate antimicrobial synergy and recovery of the complexes after use. High Log reduction values ranging from 7.19 to 9.58 were obtained for the quaternized complexes.
- Full Text:
- Authors: Makolla, Collen L , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185024 , vital:44317 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109262"
- Description: In this study, we report on the synthesis, characterization, and application of indium porphyrins linked to silver core-shell magnetic nanoparticles for in vitro photodynamic antimicrobial chemotherapy (PACT) against gram-negative strain, E. coli. This work compares the photophysicochemical and PACT activities of InCl 5-p-carboxyphenyl-10-15-20-(tris-4-methylpyridinium)-triiodide porphyrin (1), InCl 5-p-carboxyphenyl-10-15-20-(tris-4-hexylpyridinium)-triiodide porphyrin (2), In (para-aminophenyl) 5,10,15,20-tetrakis(4-methylpyridinium)-tetraiodide porphyrin (3), and In (para-aminophenyl) 5,10,15,20-tetrakis(4-hexylpyridinium)-tetraiodide porphyrin (4). The comparisons were based on the structure and number of charges. Hydrophilic and hydrophobic characters of the amphiphilic porphyrins were studied by comparing the effect of the different alkyl halides (iodomethane and iodohexane) quaternizing agents. The porphyrin complexes were further linked to magnetic nanoparticles to facilitate antimicrobial synergy and recovery of the complexes after use. High Log reduction values ranging from 7.19 to 9.58 were obtained for the quaternized complexes.
- Full Text:
Efforts towards engaging communities to promote the benefits of biological control research and implementation in South Africa
- Weaver, Kim N, Hill, Martin P, Byrne, Marcus J, Ivey, Philip J
- Authors: Weaver, Kim N , Hill, Martin P , Byrne, Marcus J , Ivey, Philip J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414428 , vital:71146 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a23"
- Description: In the last decade, biological control in South Africa has evolved from a classical applied science, allied to an extension service, to a more community engagement-based activity. Therefore, capacity building is important for the sustainability of biological control research and its implementation. In South Africa, a broad approach has been taken to build capacity in weed biological control, starting at grass-roots level with primary and secondary school learner programmes, through to developing research capacity at the tertiary level and enhancing technical capacity through adult education. Non-specialists are empowered through access to knowledge. The dissemination of accurate information through the most appropriate outlets has become increasingly important, including non-traditional science communication through the internet and, more importantly, social media, which has the potential to reach a far wider audience. Public understanding of biological control has the potential to contribute significantly to the green and knowledge economies of South Africa, but relies on government support for the sustainability of this discipline.
- Full Text:
- Authors: Weaver, Kim N , Hill, Martin P , Byrne, Marcus J , Ivey, Philip J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414428 , vital:71146 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a23"
- Description: In the last decade, biological control in South Africa has evolved from a classical applied science, allied to an extension service, to a more community engagement-based activity. Therefore, capacity building is important for the sustainability of biological control research and its implementation. In South Africa, a broad approach has been taken to build capacity in weed biological control, starting at grass-roots level with primary and secondary school learner programmes, through to developing research capacity at the tertiary level and enhancing technical capacity through adult education. Non-specialists are empowered through access to knowledge. The dissemination of accurate information through the most appropriate outlets has become increasingly important, including non-traditional science communication through the internet and, more importantly, social media, which has the potential to reach a far wider audience. Public understanding of biological control has the potential to contribute significantly to the green and knowledge economies of South Africa, but relies on government support for the sustainability of this discipline.
- Full Text:
Evaluating and reflecting on coproduction of protected area management plans
- Roux, Dirk J, Nel, Jeanne L, Freitag, Stefanie, Novellie, Peter, Rosenberg, Eureta
- Authors: Roux, Dirk J , Nel, Jeanne L , Freitag, Stefanie , Novellie, Peter , Rosenberg, Eureta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370550 , vital:66353 , xlink:href="https://doi.org/10.1111/csp2.542"
- Description: Protected areas are complex social-ecological systems, hence their management should be guided by engagement and co-learning with diverse stakeholders. The challenge of effective stakeholder participation has generated a body of literature on the design and facilitation of coproduction processes. In this study, we used this literature to develop a principle-based framework for assessing coproduction. We then applied this framework to evaluate how well “adaptive planning” (a sub-process of adaptive management used for visioning and objective setting with stakeholders), as applied to the Garden Route National Park in South Africa, aligned with the ideals of coproduction. Our analysis revealed shortcomings in the adaptive planning process, which could be improved through broadening the agenda beyond the mandate and control of national parks, empowering collective agency among a wider stakeholder network, and embedding co-learning with stakeholders as an ongoing journey. A significant finding was that adaptive management does not align well with the ideals of coproduction, which may be better supported by an adaptive comanagement approach. The latter is particularly necessary in complex national parks that are diverse in terms of both ecosystems and stakeholders, and where governance may be contested.
- Full Text:
- Authors: Roux, Dirk J , Nel, Jeanne L , Freitag, Stefanie , Novellie, Peter , Rosenberg, Eureta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370550 , vital:66353 , xlink:href="https://doi.org/10.1111/csp2.542"
- Description: Protected areas are complex social-ecological systems, hence their management should be guided by engagement and co-learning with diverse stakeholders. The challenge of effective stakeholder participation has generated a body of literature on the design and facilitation of coproduction processes. In this study, we used this literature to develop a principle-based framework for assessing coproduction. We then applied this framework to evaluate how well “adaptive planning” (a sub-process of adaptive management used for visioning and objective setting with stakeholders), as applied to the Garden Route National Park in South Africa, aligned with the ideals of coproduction. Our analysis revealed shortcomings in the adaptive planning process, which could be improved through broadening the agenda beyond the mandate and control of national parks, empowering collective agency among a wider stakeholder network, and embedding co-learning with stakeholders as an ongoing journey. A significant finding was that adaptive management does not align well with the ideals of coproduction, which may be better supported by an adaptive comanagement approach. The latter is particularly necessary in complex national parks that are diverse in terms of both ecosystems and stakeholders, and where governance may be contested.
- Full Text:
Happy without money: Minimally monetized societies can exhibit high subjective well-being
- Miñarro, Sara, Reyes-García V, Aswani, Shankar, Selim, Samiya, Barrington-Leigh, Christopher P, Galbraith, Eric D
- Authors: Miñarro, Sara , Reyes-García V , Aswani, Shankar , Selim, Samiya , Barrington-Leigh, Christopher P , Galbraith, Eric D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403430 , vital:69960 , xlink:href="https://doi.org/10.1371/journal.pone.0244569"
- Description: Economic growth is often assumed to improve happiness for people in low income countries, although the association between monetary income and subjective well-being has been a subject of debate. We test this assumption by comparing three different measures of subjective well-being in very low-income communities with different levels of monetization. Contrary to expectations, all three measures of subjective well-being were very high in the least-monetized sites and comparable to those found among citizens of wealthy nations. The reported drivers of happiness shifted with increasing monetization: from enjoying experiential activities in contact with nature at the less monetized sites, to social and economic factors at the more monetized sites. Our results suggest that high levels of subjective well-being can be achieved with minimal monetization, challenging the perception that economic growth will raise life satisfaction among low income populations.
- Full Text:
- Authors: Miñarro, Sara , Reyes-García V , Aswani, Shankar , Selim, Samiya , Barrington-Leigh, Christopher P , Galbraith, Eric D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403430 , vital:69960 , xlink:href="https://doi.org/10.1371/journal.pone.0244569"
- Description: Economic growth is often assumed to improve happiness for people in low income countries, although the association between monetary income and subjective well-being has been a subject of debate. We test this assumption by comparing three different measures of subjective well-being in very low-income communities with different levels of monetization. Contrary to expectations, all three measures of subjective well-being were very high in the least-monetized sites and comparable to those found among citizens of wealthy nations. The reported drivers of happiness shifted with increasing monetization: from enjoying experiential activities in contact with nature at the less monetized sites, to social and economic factors at the more monetized sites. Our results suggest that high levels of subjective well-being can be achieved with minimal monetization, challenging the perception that economic growth will raise life satisfaction among low income populations.
- Full Text:
Impact of axial ligation on photophysical and photodynamic antimicrobial properties of indium (III) methylsulfanylphenyl porphyrin complexes linked to silver-capped copper ferrite magnetic nanoparticles
- Makola, Collen L, Nyokong, Tebello, Amuhaya, Edith K
- Authors: Makola, Collen L , Nyokong, Tebello , Amuhaya, Edith K
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185942 , vital:44450 , xlink:href="https://doi.org/10.1016/j.poly.2020.114882"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known technique used against bacteria that have developed resistance towards antibiotics. We herein report the synthesis, photophysical properties, and PACT activity of 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (3) and quaternized 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (4). The porphyrin complexes (3 and 4) were further linked to oleyamine (OLM)/oleic acid (OLA) capped Ag/CuFe2O4 and also 6-mercapto-1-hexanol functionalized (MCH-Ag/CuFe2O4) nanoparticles through silver - sulphur (Ag-S) and silver-nitrogen (Ag-N); self-assembly. The PACT studies were carried out using Staphylococcus aureus. While all the synthesized porphyrins demonstrated PACT activity, the quaternized complex and its conjugate showed the highest PACT activity with 0% cell viability after irradiation for 25 min, resulting in a log reduction of 8.31.
- Full Text:
- Authors: Makola, Collen L , Nyokong, Tebello , Amuhaya, Edith K
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185942 , vital:44450 , xlink:href="https://doi.org/10.1016/j.poly.2020.114882"
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known technique used against bacteria that have developed resistance towards antibiotics. We herein report the synthesis, photophysical properties, and PACT activity of 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (3) and quaternized 2-hydroxypyridine axial ligated indium 5,10,15,20-tetrakis-(4-phenylmethylthio) porphyrin (4). The porphyrin complexes (3 and 4) were further linked to oleyamine (OLM)/oleic acid (OLA) capped Ag/CuFe2O4 and also 6-mercapto-1-hexanol functionalized (MCH-Ag/CuFe2O4) nanoparticles through silver - sulphur (Ag-S) and silver-nitrogen (Ag-N); self-assembly. The PACT studies were carried out using Staphylococcus aureus. While all the synthesized porphyrins demonstrated PACT activity, the quaternized complex and its conjugate showed the highest PACT activity with 0% cell viability after irradiation for 25 min, resulting in a log reduction of 8.31.
- Full Text:
Muco-adhesive clarithromycin-loaded nanostructured lipid carriers for ocular delivery: Formulation, characterization, cytotoxicity and stability
- Makoni, Pedzisai A, Khamanga, Sandile M, Walker, Roderick B
- Authors: Makoni, Pedzisai A , Khamanga, Sandile M , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183150 , vital:43916 , xlink:href="https://doi.org/10.1016/j.jddst.2020.102171"
- Description: Topical ophthalmic formulations are the preferred approach to treat the anterior segment of the eye as it is a non-invasive therapeutic approach. The ocular bioavailability of drugs is generally limited, due to the presence of impervious anatomical barriers and low residence time and contact with the target tissue. Optimization of clarithromycin-loaded nanostructured lipid carriers using Design of Experiments was undertaken. Manufacture of nanostructured lipid carriers was achieved using hot emulsification ultrasonication. Formulation and process parameters were successfully identified following screening and subsequently optimized using Tween® 20, as a stabilizer. Muco-adhesive properties that could potentially increase ocular residence time, in vitro clarithromycin release and cytotoxicity against HeLa cells were evaluated. Short term stability studies of the optimized lipidic formulations was assessed at 4 °C and 22 °C. The optimized formulation exhibited muco-adhesive properties under stationary conditions assessed using Laser Doppler Anemometry, sustained release of API over 24 h under in vitro conditions. In vitro cytotoxicity studies revealed that the NLC were less cytotoxic to HeLa cells in comparison to pure API. The results suggest that the optimized carriers may have the potential to enhance precorneal retention, increase ocular availability and permit dose reduction or permit use of a longer dosing frequency.
- Full Text:
- Authors: Makoni, Pedzisai A , Khamanga, Sandile M , Walker, Roderick B
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183150 , vital:43916 , xlink:href="https://doi.org/10.1016/j.jddst.2020.102171"
- Description: Topical ophthalmic formulations are the preferred approach to treat the anterior segment of the eye as it is a non-invasive therapeutic approach. The ocular bioavailability of drugs is generally limited, due to the presence of impervious anatomical barriers and low residence time and contact with the target tissue. Optimization of clarithromycin-loaded nanostructured lipid carriers using Design of Experiments was undertaken. Manufacture of nanostructured lipid carriers was achieved using hot emulsification ultrasonication. Formulation and process parameters were successfully identified following screening and subsequently optimized using Tween® 20, as a stabilizer. Muco-adhesive properties that could potentially increase ocular residence time, in vitro clarithromycin release and cytotoxicity against HeLa cells were evaluated. Short term stability studies of the optimized lipidic formulations was assessed at 4 °C and 22 °C. The optimized formulation exhibited muco-adhesive properties under stationary conditions assessed using Laser Doppler Anemometry, sustained release of API over 24 h under in vitro conditions. In vitro cytotoxicity studies revealed that the NLC were less cytotoxic to HeLa cells in comparison to pure API. The results suggest that the optimized carriers may have the potential to enhance precorneal retention, increase ocular availability and permit dose reduction or permit use of a longer dosing frequency.
- Full Text:
Solar Driven Photocatalytic Activity of Porphyrin Sensitized TiO2
- Otieno, Sebastien, Lanterna, Anabel E, Mack, John, Derese, Solomon, Amuhaya, Edith K, Nyokong, Tebello, Scaiano, Juan C
- Authors: Otieno, Sebastien , Lanterna, Anabel E , Mack, John , Derese, Solomon , Amuhaya, Edith K , Nyokong, Tebello , Scaiano, Juan C
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190612 , vital:45010 , xlink:href="https://doi.org/10.3390/molecules26113131"
- Description: The absence of a secure long-term sustainable energy supply is recognized as a major worldwide technological challenge. The generation of H2 through photocatalysis is an environmentally friendly alternative that can help solve the energy problem. Thus, the development of semiconductor materials that can absorb solar light is an attractive approach. TiO2 has a wide bandgap that suffers from no activity in the visible spectrum, limiting its use of solar radiation. In this research, the semiconductor absorption profile was extended into the visible region of the solar spectrum by preparing porphyrin-TiO2 (P-TiO2 ) composites of meso-tetra(4-bromophenyl)porphyrin (PP1) and meso-tetra(5-bromo-2-thienyl)porphyrin (PP2) and their In(III), Zn(II) and Ga(III) metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed on the porphyrins to gain insight into their electron injection capability. The results demonstrate that P-TiO2 systems merit further in-depth study for applications that require efficient photocatalytic H2 generation.
- Full Text:
- Authors: Otieno, Sebastien , Lanterna, Anabel E , Mack, John , Derese, Solomon , Amuhaya, Edith K , Nyokong, Tebello , Scaiano, Juan C
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190612 , vital:45010 , xlink:href="https://doi.org/10.3390/molecules26113131"
- Description: The absence of a secure long-term sustainable energy supply is recognized as a major worldwide technological challenge. The generation of H2 through photocatalysis is an environmentally friendly alternative that can help solve the energy problem. Thus, the development of semiconductor materials that can absorb solar light is an attractive approach. TiO2 has a wide bandgap that suffers from no activity in the visible spectrum, limiting its use of solar radiation. In this research, the semiconductor absorption profile was extended into the visible region of the solar spectrum by preparing porphyrin-TiO2 (P-TiO2 ) composites of meso-tetra(4-bromophenyl)porphyrin (PP1) and meso-tetra(5-bromo-2-thienyl)porphyrin (PP2) and their In(III), Zn(II) and Ga(III) metal complexes. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed on the porphyrins to gain insight into their electron injection capability. The results demonstrate that P-TiO2 systems merit further in-depth study for applications that require efficient photocatalytic H2 generation.
- Full Text: