Positively charged styryl pyridine substituted Zn (II) Phthalocyanines for Photodynamic Therapy and Photoantimicrobial Chemotherapy
- Magadla, Aviwe, Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Magadla, Aviwe , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190600 , vital:45009 , xlink:href="https://doi.org/10.1039/D1DT01047F"
- Description: Cationic Zn phthalocyanine complexes were synthesized using Knoevenagel reaction starting from a Zn(II) tetrakis(2-formylphenoxy)phthalocyanine (1) to form Zn(II) tetrakis(1-butyl-4-(4-(tetraphenoxy)styryl)pyridin-1-ium) phthalocyanine (2) and Zn(II) tetrakis(4-(4-(tetraphenoxy)styryl)-1-(4-(triphenylphosphonio)butyl)pyridin-1-ium)phthalocyanine (3). The photophysicochemical behaviours of the Pc complexes were assessed. The cationic complexes display high water-solubility and gave moderate singlet oxygen quantum yield in water. The cationic Pcs demonstrate good cellular uptake and photodynamic activity against MCF-7 cells with IC50 values of 8.2 and 4.9 μM for 2 and 3, respectively. The cationic Pcs also demonstrate high photoantimicrobial activity against Escherichia coli with log reductions of 5.3 and 6.0 for 2 and 3, respectively.
- Full Text:
- Date Issued: 2021
- Authors: Magadla, Aviwe , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190600 , vital:45009 , xlink:href="https://doi.org/10.1039/D1DT01047F"
- Description: Cationic Zn phthalocyanine complexes were synthesized using Knoevenagel reaction starting from a Zn(II) tetrakis(2-formylphenoxy)phthalocyanine (1) to form Zn(II) tetrakis(1-butyl-4-(4-(tetraphenoxy)styryl)pyridin-1-ium) phthalocyanine (2) and Zn(II) tetrakis(4-(4-(tetraphenoxy)styryl)-1-(4-(triphenylphosphonio)butyl)pyridin-1-ium)phthalocyanine (3). The photophysicochemical behaviours of the Pc complexes were assessed. The cationic complexes display high water-solubility and gave moderate singlet oxygen quantum yield in water. The cationic Pcs demonstrate good cellular uptake and photodynamic activity against MCF-7 cells with IC50 values of 8.2 and 4.9 μM for 2 and 3, respectively. The cationic Pcs also demonstrate high photoantimicrobial activity against Escherichia coli with log reductions of 5.3 and 6.0 for 2 and 3, respectively.
- Full Text:
- Date Issued: 2021
A Sn (iv) porphyrin with mitochondria targeting properties for enhanced photodynamic activity against MCF-7 cells
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
- Date Issued: 2022
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230897 , vital:49829 , xlink:href="https://doi.org/10.1039/D2NJ00350C"
- Description: Two readily synthesized Sn(IV) porphyrins (SnP, SnPH) have been prepared with and without the cationic triphenylphosphonium moiety (TPP+), which have high singlet oxygen quantum yields (ca. 0.72) and long triplet state lifetimes. The Sn(IV) porphyrin with a TPP+ moiety (SnPH) exhibits favorable photodynamic activity against MCF-7 cells with IC50 values of 2.9 μM. SnPH exhibits higher cellular uptake than SnP in MCF-7 cells. A Rhodamine 123 (Rh123) assay showed that SnPH targets mitochondria and induces apoptosis by generating reactive oxygen species. The results demonstrate that this structural modification strategy merits further in-depth study.
- Full Text:
- Date Issued: 2022
Structural modification of RhIIItriarylcorroles for enhanced electrocatalyzed hydrogen evolution reactions
- Zhu, Weihua, Li, Lihua, Wang, Yu, Mack, John, Dingiswayo, Somila, Nyokong, Tebello, Liang, Xu
- Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
- Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
- Full Text:
- Date Issued: 2022
- Authors: Zhu, Weihua , Li, Lihua , Wang, Yu , Mack, John , Dingiswayo, Somila , Nyokong, Tebello , Liang, Xu
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229933 , vital:49724 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.110046"
- Description: A series of A3 type RhIIItriarylcorroles 2a-c with different meso-substituents with differing electron-donating and withdrawing properties and two A2B type RhIIItriarylcorroles 4a-b with meso-methylthiophenyls at the B position have been prepared and characterized. An analysis of structure-property relationships of 2a-c and 4a-b has been carried out by comparing the optical spectroscopy and electrochemistry of the dyes to trends predicted in DFT and TD-DFT calculations. Rational structural modification strategies that enhance the suitability of 2a-c for use as highly efficient catalysts for hydrogen evolution reactions on glassy carbon electrodes coated with 2a-c/reduced graphene oxide composites and of 4a-b in surface-modified Au electrodes are explored.
- Full Text:
- Date Issued: 2022
Interaction of CdTe quantum dots with 2, 2-diphenyl-1-picrylhydrazyl free radical
- Adegoke, Oluwasesan, Chidawanyika, Wadzanai J U, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245751 , vital:51402 , xlink:href="https://doi.org/10.1007/s10895-011-1012-2"
- Description: The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH● is proposed.
- Full Text:
- Date Issued: 2012
- Authors: Adegoke, Oluwasesan , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245751 , vital:51402 , xlink:href="https://doi.org/10.1007/s10895-011-1012-2"
- Description: The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH● is proposed.
- Full Text:
- Date Issued: 2012
Optical Limiting Properties of 3, 5-Dithienylenevinylene BODIPY Dyes at 532 nm
- Harris, Jessica, Gai, Lizhi, Kubheka, Gugu, Mack, John, Nyokong, Tebello, Shen, Zhen
- Authors: Harris, Jessica , Gai, Lizhi , Kubheka, Gugu , Mack, John , Nyokong, Tebello , Shen, Zhen
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189274 , vital:44833 , xlink:href="https://doi.org/10.1002/chem.201702503"
- Description: The optical limiting properties of a series of near infrared absorbing 3,5-dithienylenevinylene BODIPY (borondipyrromethene) dyes (1–3) that contain donor and acceptor moieties in their p-conjugation systems were studied by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed when the compounds are embedded into poly(bisphenol carbonate A) polymer thin films, which demonstrates that BODIPY dyes with this type of structure are suitable for use in optical limiting applications.
- Full Text:
- Date Issued: 2017
- Authors: Harris, Jessica , Gai, Lizhi , Kubheka, Gugu , Mack, John , Nyokong, Tebello , Shen, Zhen
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189274 , vital:44833 , xlink:href="https://doi.org/10.1002/chem.201702503"
- Description: The optical limiting properties of a series of near infrared absorbing 3,5-dithienylenevinylene BODIPY (borondipyrromethene) dyes (1–3) that contain donor and acceptor moieties in their p-conjugation systems were studied by using the z-scan technique at 532 nm in the nanosecond pulse range. A strong reverse saturable absorption response was observed when the compounds are embedded into poly(bisphenol carbonate A) polymer thin films, which demonstrates that BODIPY dyes with this type of structure are suitable for use in optical limiting applications.
- Full Text:
- Date Issued: 2017
Synthesis, characterization and electrochemistry of rhodium (iii) complexes of meso-substituted [14] tribenzotriphyrin (2.1. 1)
- Xue, Zhaoli, Wang, Yemei, Mack, John, Mkhize, Scebi, Nyokong, Tebello, Fang, Yuanyuan, Ou, Zhongping, Kadish, Karl M
- Authors: Xue, Zhaoli , Wang, Yemei , Mack, John , Mkhize, Scebi , Nyokong, Tebello , Fang, Yuanyuan , Ou, Zhongping , Kadish, Karl M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241043 , vital:50899 , xlink:href="https://doi.org/10.1039/C6RA03028A"
- Description: A thermal reaction using a series of [14]tribenzotriphyrins(2.1.1) (TriPs, 1a–d) with Rh2(C8H12)Cl2 provides RhIII–TriP complexes (2a–d) in 40−52% yields. The complexes were characterized by mass spectrometry, UV-visible absorption and 1H NMR spectroscopy. Single crystal X-ray analysis reveals that 2b adopts a dome-shaped conformation. The rhodium(III) ion is coordinated by the three pyrrole nitrogen atoms, two chloride ions and the nitrogen atom of an acetonitrile (CH3CN) solvent molecule. The optical spectra can be assigned using Michl's perimeter model. The L and B bands of the 2a–d complexes lie at ca. 600 and 500 nm, respectively, and are markedly red shifted relative to those of 1a–d. A reversible one-electron oxidation and two reversible one-electron reductions are observed in the cyclic voltammograms of 2a–d in CH2Cl2. The redox potentials are consistent with the optical data and the relatively narrow HOMO–LUMO gaps that are predicted in DFT calculations. TD-DFT calculations have been used to assign a third intense spectral band at 375 nm to a higher energy π → π* transition of the [14]tribenzotriphyrin(2.1.1) π-system.
- Full Text:
- Date Issued: 2016
- Authors: Xue, Zhaoli , Wang, Yemei , Mack, John , Mkhize, Scebi , Nyokong, Tebello , Fang, Yuanyuan , Ou, Zhongping , Kadish, Karl M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241043 , vital:50899 , xlink:href="https://doi.org/10.1039/C6RA03028A"
- Description: A thermal reaction using a series of [14]tribenzotriphyrins(2.1.1) (TriPs, 1a–d) with Rh2(C8H12)Cl2 provides RhIII–TriP complexes (2a–d) in 40−52% yields. The complexes were characterized by mass spectrometry, UV-visible absorption and 1H NMR spectroscopy. Single crystal X-ray analysis reveals that 2b adopts a dome-shaped conformation. The rhodium(III) ion is coordinated by the three pyrrole nitrogen atoms, two chloride ions and the nitrogen atom of an acetonitrile (CH3CN) solvent molecule. The optical spectra can be assigned using Michl's perimeter model. The L and B bands of the 2a–d complexes lie at ca. 600 and 500 nm, respectively, and are markedly red shifted relative to those of 1a–d. A reversible one-electron oxidation and two reversible one-electron reductions are observed in the cyclic voltammograms of 2a–d in CH2Cl2. The redox potentials are consistent with the optical data and the relatively narrow HOMO–LUMO gaps that are predicted in DFT calculations. TD-DFT calculations have been used to assign a third intense spectral band at 375 nm to a higher energy π → π* transition of the [14]tribenzotriphyrin(2.1.1) π-system.
- Full Text:
- Date Issued: 2016
Push–pull type manganese (III) corroles
- Liang, Xu, Fang, Junjia, Li, Minzhi, Chen, Qiuyun, Mack, John, Molupe, Nthabeleng, Nyokong, Tebello, Zhu, Weihua
- Authors: Liang, Xu , Fang, Junjia , Li, Minzhi , Chen, Qiuyun , Mack, John , Molupe, Nthabeleng , Nyokong, Tebello , Zhu, Weihua
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189201 , vital:44826 , xlink:href="https://doi.org/10.1142/S1088424617500778"
- Description: The synthesis of three low symmetry A2B type Mn(III)triarylcorroles with meso-aryl substituents that provide push–pull electron-donating and -withdrawing properties is reported. An analysis of the structure-property relationships for the optical and redox properties has been carried out through a comparison with the results of theoretical calculations. The results demonstrate that A2B type Mn(III)triarylcorroles interact strongly with cell-free circulating tumor deoxyribonucleic acid (ctDNA) in solution, and that the interaction constants are enhanced when a stronger electron-donating substituent is introduced at the 10-position of the meso-triarylcorrole ligand.
- Full Text:
- Date Issued: 2017
- Authors: Liang, Xu , Fang, Junjia , Li, Minzhi , Chen, Qiuyun , Mack, John , Molupe, Nthabeleng , Nyokong, Tebello , Zhu, Weihua
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189201 , vital:44826 , xlink:href="https://doi.org/10.1142/S1088424617500778"
- Description: The synthesis of three low symmetry A2B type Mn(III)triarylcorroles with meso-aryl substituents that provide push–pull electron-donating and -withdrawing properties is reported. An analysis of the structure-property relationships for the optical and redox properties has been carried out through a comparison with the results of theoretical calculations. The results demonstrate that A2B type Mn(III)triarylcorroles interact strongly with cell-free circulating tumor deoxyribonucleic acid (ctDNA) in solution, and that the interaction constants are enhanced when a stronger electron-donating substituent is introduced at the 10-position of the meso-triarylcorrole ligand.
- Full Text:
- Date Issued: 2017
Photophysical studies of 2, 6-dibrominated BODIPY dyes substituted with 4-benzyloxystyryl substituents
- Ngoy, Bokolombe Pitchou, Molupe, Nthabeleng, Harris, Jessica, Fomo, Gertrude, Mack, John, Nyokong, Tebello
- Authors: Ngoy, Bokolombe Pitchou , Molupe, Nthabeleng , Harris, Jessica , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233068 , vital:50053 , xlink:href="https://doi.org/10.1142/S1088424617500420"
- Description: A series of novel 2,6-dibrominated BODIPY dyes with styryl groups at the 3,5-positions has been prepared, and their photophysical properties have been analyzed to assess their potential utility for use as photosensitizers in photodynamic therapy and in bioimaging.
- Full Text:
- Date Issued: 2017
- Authors: Ngoy, Bokolombe Pitchou , Molupe, Nthabeleng , Harris, Jessica , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233068 , vital:50053 , xlink:href="https://doi.org/10.1142/S1088424617500420"
- Description: A series of novel 2,6-dibrominated BODIPY dyes with styryl groups at the 3,5-positions has been prepared, and their photophysical properties have been analyzed to assess their potential utility for use as photosensitizers in photodynamic therapy and in bioimaging.
- Full Text:
- Date Issued: 2017
The extent and perceptions of vandalism as a cause of street tree damage in small towns in the Eastern Cape, South Africa
- Richardson, Emma, Shackleton, Charlie M
- Authors: Richardson, Emma , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180954 , vital:43676 , xlink:href="https://doi.org/10.1016/j.ufug.2014.04.003"
- Description: Street trees are important foundations of urban sustainability due to the ecosystem services that they provide society and the environment. However, street trees are vulnerable to vandalism and damage, especially when small, which constraints the flow of benefits they provide and also increases the costs of planting programmes. Despite being a common phenomenon, there is limited knowledge regarding the extent of vandalism and the reasons for it. Here we seek to understand the causes and extent of street tree damage in eleven small Eastern Cape (South Africa) towns and to assess the perceptions of residents and officials. The condition of newly planted street trees was assessed in each town and residents were interviewed in the two towns with the highest number of newly planted street trees. Almost half (42%) of recently planted street trees were totally snapped, ranging between 0% and 63% per town. There was no difference in the prevalence of trees being snapped between those with protective structures and those without. Each town used different structures around newly planted street trees, but in only two towns were all the structures intact. The prevalence of damage declined with increasing trunk thickness and increasing town size. According to residents, boredom, misbehaviour, lack of appreciation of trees and collection for wood were the main factors for tree vandalism by people along with damage by livestock. Ward councillors recognised the presence of vandalism, but indicated that it was not a priority topic in their ward meetings. Suggestions by residents to prevent vandalism included: planting in sensible areas, re-designing the protective structures, re-locating livestock and engendering community participation and ownership in all aspects of street tree planting.
- Full Text:
- Date Issued: 2014
- Authors: Richardson, Emma , Shackleton, Charlie M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180954 , vital:43676 , xlink:href="https://doi.org/10.1016/j.ufug.2014.04.003"
- Description: Street trees are important foundations of urban sustainability due to the ecosystem services that they provide society and the environment. However, street trees are vulnerable to vandalism and damage, especially when small, which constraints the flow of benefits they provide and also increases the costs of planting programmes. Despite being a common phenomenon, there is limited knowledge regarding the extent of vandalism and the reasons for it. Here we seek to understand the causes and extent of street tree damage in eleven small Eastern Cape (South Africa) towns and to assess the perceptions of residents and officials. The condition of newly planted street trees was assessed in each town and residents were interviewed in the two towns with the highest number of newly planted street trees. Almost half (42%) of recently planted street trees were totally snapped, ranging between 0% and 63% per town. There was no difference in the prevalence of trees being snapped between those with protective structures and those without. Each town used different structures around newly planted street trees, but in only two towns were all the structures intact. The prevalence of damage declined with increasing trunk thickness and increasing town size. According to residents, boredom, misbehaviour, lack of appreciation of trees and collection for wood were the main factors for tree vandalism by people along with damage by livestock. Ward councillors recognised the presence of vandalism, but indicated that it was not a priority topic in their ward meetings. Suggestions by residents to prevent vandalism included: planting in sensible areas, re-designing the protective structures, re-locating livestock and engendering community participation and ownership in all aspects of street tree planting.
- Full Text:
- Date Issued: 2014
Food insecurity in South Africa: To what extent can social grants and consumption of wild foods eradicate hunger?
- Chakona, Gamuchirai, Shackleton, Charlie M
- Authors: Chakona, Gamuchirai , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179541 , vital:43081 , xlink:href="https://doi.org/10.1016/j.wdp.2019.02.001"
- Description: As the world continues to face widespread food insecurity, achieving food security for all at all times is increasingly complicated. In South Africa, social grants and the use of wild foods have been reported as some ways to improve household food insecurity and reduce poverty. The study examined if social grants and consumption of wild foods alleviate food insecurity in South Africa. Household surveys and focus group discussions were conducted along the rural-urban continuum in three South African towns situated along an agro-ecological gradient. We explored the differences in household food security indicators, mean monthly food expenditure and wealth index between households receiving social grants, households consuming wild foods, and those who did not. Households receiving social grants were more food insecure with lower mean monthly food expenditure and wealth index than those who did not. Overall all towns, the use of wild foods improved household food security which was not true within towns where wild foods were mostly consumed by low income and more food insecure households. Social grants alone cannot eradicate food insecurity as the money is not enough to cater for all household needs whilst wild foods can potentially alleviate household food insecurity. As food prices continue to increase gradually and worsening household food insecurity, ways to shift ‘income circumstances’ of households and promote the use and consumption of wild foods which may increase dietary diversity and diversifying food access. Focus should be placed on capacity building, employment creation and promoting awareness on own food production which is one way to improve food security of poor households rather than depending on purchases from the grant money alone.
- Full Text:
- Date Issued: 2019
- Authors: Chakona, Gamuchirai , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179541 , vital:43081 , xlink:href="https://doi.org/10.1016/j.wdp.2019.02.001"
- Description: As the world continues to face widespread food insecurity, achieving food security for all at all times is increasingly complicated. In South Africa, social grants and the use of wild foods have been reported as some ways to improve household food insecurity and reduce poverty. The study examined if social grants and consumption of wild foods alleviate food insecurity in South Africa. Household surveys and focus group discussions were conducted along the rural-urban continuum in three South African towns situated along an agro-ecological gradient. We explored the differences in household food security indicators, mean monthly food expenditure and wealth index between households receiving social grants, households consuming wild foods, and those who did not. Households receiving social grants were more food insecure with lower mean monthly food expenditure and wealth index than those who did not. Overall all towns, the use of wild foods improved household food security which was not true within towns where wild foods were mostly consumed by low income and more food insecure households. Social grants alone cannot eradicate food insecurity as the money is not enough to cater for all household needs whilst wild foods can potentially alleviate household food insecurity. As food prices continue to increase gradually and worsening household food insecurity, ways to shift ‘income circumstances’ of households and promote the use and consumption of wild foods which may increase dietary diversity and diversifying food access. Focus should be placed on capacity building, employment creation and promoting awareness on own food production which is one way to improve food security of poor households rather than depending on purchases from the grant money alone.
- Full Text:
- Date Issued: 2019
Use of public urban green spaces for spiritual services in Bulawayo, Zimbabwe
- Ngulani, T, Shackleton, Charlie M
- Authors: Ngulani, T , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179710 , vital:43163 , xlink:href="https://doi.org/10.1016/j.ufug.2018.11.009"
- Description: Urban green spaces provide an array of ecosystem services. Spiritual services provided by urban green spaces are widely used, but are often overlooked and rarely quantified. These services are accessed at sites of specific religious or sacred significance or more general urban green spaces used for religious practices that require natural or semi-natural, outdoor settings. We sampled twelve public green spaces in Bulawayo, Zimbabwe, to determine their use as sites for religious gatherings, interviewed visitors to green spaces and religious congregants about such and used the travel cost method to assign a value to the green spaces for spiritual benefits. Religious gatherings were observed in all twelve sampled green spaces, and 7% of a random sample of visitors to the urban green spaces said that they participated in such. Amongst the worshippers, 71% said worshipping outdoors was part of their religious practices and 29% said they did so because they had no building in which to worship. Most (79%) worshipped in public green spaces 1–4 times per week. Many felt that it would be easier if the city council designated specific and quiet areas in public green spaces for their religious observances, which they could then help maintain. The mean value of spiritual services was determined to be US$93 ± 79 /ha/yr, and tended to be highest in the high density, poorer suburbs. These results reveal the significance of urban green spaces for spiritual purposes and indicate the need for greater recognition amongst researchers and city planners and authorities to secure and maintain such benefit flows.
- Full Text:
- Date Issued: 2019
- Authors: Ngulani, T , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/179710 , vital:43163 , xlink:href="https://doi.org/10.1016/j.ufug.2018.11.009"
- Description: Urban green spaces provide an array of ecosystem services. Spiritual services provided by urban green spaces are widely used, but are often overlooked and rarely quantified. These services are accessed at sites of specific religious or sacred significance or more general urban green spaces used for religious practices that require natural or semi-natural, outdoor settings. We sampled twelve public green spaces in Bulawayo, Zimbabwe, to determine their use as sites for religious gatherings, interviewed visitors to green spaces and religious congregants about such and used the travel cost method to assign a value to the green spaces for spiritual benefits. Religious gatherings were observed in all twelve sampled green spaces, and 7% of a random sample of visitors to the urban green spaces said that they participated in such. Amongst the worshippers, 71% said worshipping outdoors was part of their religious practices and 29% said they did so because they had no building in which to worship. Most (79%) worshipped in public green spaces 1–4 times per week. Many felt that it would be easier if the city council designated specific and quiet areas in public green spaces for their religious observances, which they could then help maintain. The mean value of spiritual services was determined to be US$93 ± 79 /ha/yr, and tended to be highest in the high density, poorer suburbs. These results reveal the significance of urban green spaces for spiritual purposes and indicate the need for greater recognition amongst researchers and city planners and authorities to secure and maintain such benefit flows.
- Full Text:
- Date Issued: 2019
Beyond just research: Experiences from Southern Africa in developing social learning partnerships for resource conservation initiatives
- Shackleton, Charlie M, Cundill, Georgina, Knight, Andrew T
- Authors: Shackleton, Charlie M , Cundill, Georgina , Knight, Andrew T
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181157 , vital:43703 , xlink:href="https://doi.org/10.1111/j.1744-7429.2009.00559.x"
- Description: There is a well-acknowledged communication or knowledge gap between scientists and decision-makers. Many scientists who take on the challenge of narrowing this gap operate on the understanding that their role is to communicate their findings in a one-way flow of information: from science to decision-makers. However, to be effective scientists must engage in an ongoing social learning process with decision-makers, and regard themselves as facilitators, and also as one among many stakeholders who have valid and important ecological knowledge. The developing world poses some particular challenges in this regard, specifically in terms of the large number of local level subsistence resources users who are important de facto decision-makers. We examine four natural resource management case studies from South Africa that differ in spatial scale and complexity, ranging from a single village to a whole biome. We distil seven lessons to help guide development of social learning processes and organizations in similar situations relating to natural resource planning and management. The lessons pertain to: maintaining ‘key individuals’ within social learning processes; the role of researchers; the formulation of research questions that social learning processes require adaptive long-term funding and capacity support; that local resource users are key decision-makers in developing countries; some perspectives on knowledge; and the need to measure research success.
- Full Text:
- Date Issued: 2009
- Authors: Shackleton, Charlie M , Cundill, Georgina , Knight, Andrew T
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181157 , vital:43703 , xlink:href="https://doi.org/10.1111/j.1744-7429.2009.00559.x"
- Description: There is a well-acknowledged communication or knowledge gap between scientists and decision-makers. Many scientists who take on the challenge of narrowing this gap operate on the understanding that their role is to communicate their findings in a one-way flow of information: from science to decision-makers. However, to be effective scientists must engage in an ongoing social learning process with decision-makers, and regard themselves as facilitators, and also as one among many stakeholders who have valid and important ecological knowledge. The developing world poses some particular challenges in this regard, specifically in terms of the large number of local level subsistence resources users who are important de facto decision-makers. We examine four natural resource management case studies from South Africa that differ in spatial scale and complexity, ranging from a single village to a whole biome. We distil seven lessons to help guide development of social learning processes and organizations in similar situations relating to natural resource planning and management. The lessons pertain to: maintaining ‘key individuals’ within social learning processes; the role of researchers; the formulation of research questions that social learning processes require adaptive long-term funding and capacity support; that local resource users are key decision-makers in developing countries; some perspectives on knowledge; and the need to measure research success.
- Full Text:
- Date Issued: 2009
“Turn on” fluorescence enhancement of Zn octacarboxyphthaloyanine-graphene oxide conjugates by hydrogen peroxide
- Shumba, Munyaradzi, Mashazi, Philani N, Nyokong, Tebello
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240875 , vital:50881 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
- Authors: Shumba, Munyaradzi , Mashazi, Philani N , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240875 , vital:50881 , xlink:href="https://doi.org/10.1016/j.jlumin.2015.11.001"
- Description: Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates were characterized by absorption spectroscopy, transmission electron microscopy, fluorescence spectroscopy, X-ray diffraction, thermo gravimetric analysis and X-ray photon spectroscopy. The presence of reduced graphene oxide or graphene oxide resulted in the quenching (turn on) of Zn octacarboxy phthalocyanine fluorescence which can be explained by photoinduced electron transfer. Zn octacarboxy phthalocyanine-reduced graphene oxide or graphene oxide conjugates “turned on” fluorescence showed a linear response to hydrogen peroxide hence their potential to be used as sensors. The nanoprobe developed showed high selectivity towards hydrogen peroxide in the presence of physiological interferences.
- Full Text:
- Date Issued: 2016
Characterization of electrodes modified by one pot or step by step electro-click reaction and axial ligation of iron tetracarboxyphthalocyanine
- Maringa, Audacity, Mashazi, Philani N, Nyokong, Tebello
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193892 , vital:45403 , xlink:href="https://doi.org/10.1016/j.electacta.2014.09.011"
- Description: The modification of the glassy carbon electrode (GCE) was carried out using two methods. The first method is simultaneous electropolymerization and electro-click followed by immersion into a solution of dimethyl formamide (DMF) containing FeTCPc. The second method is step by step whereby electropolymerization is carried out first followed by electro-click and then immersion into a DMF solution containing FeTCPc. From the electrochemical characterization, it was observed that the second route (step by step method) was the best as indicated by the ferricyanide studies (cyclic voltammetry and scanning electrochemical microscopy). In the electrooxidation of hydrazine, we obtained a potential of 0.26 V. Of interest were the detection limit of 6.4 μM and the catalytic rate constant of 2.1 × 109 cm3 mol−1 s−1. This shows that the sensor can be used for the electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Mashazi, Philani N , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193892 , vital:45403 , xlink:href="https://doi.org/10.1016/j.electacta.2014.09.011"
- Description: The modification of the glassy carbon electrode (GCE) was carried out using two methods. The first method is simultaneous electropolymerization and electro-click followed by immersion into a solution of dimethyl formamide (DMF) containing FeTCPc. The second method is step by step whereby electropolymerization is carried out first followed by electro-click and then immersion into a DMF solution containing FeTCPc. From the electrochemical characterization, it was observed that the second route (step by step method) was the best as indicated by the ferricyanide studies (cyclic voltammetry and scanning electrochemical microscopy). In the electrooxidation of hydrazine, we obtained a potential of 0.26 V. Of interest were the detection limit of 6.4 μM and the catalytic rate constant of 2.1 × 109 cm3 mol−1 s−1. This shows that the sensor can be used for the electrooxidation of hydrazine.
- Full Text:
- Date Issued: 2014
Design and evaluation of an electrochemical immunosensor for measles serodiagnosis using measles-specific Immunoglobulin G antibodies
- Mashazi, Philani N, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
Synthesis, density functional theory, molecular dynamics and electrochemical studies of 3-thiopheneacetic acid-capped gold nanoparticles
- Sosibo, Ndabenhle M, Mdluli, Phumlane S, Mashazi, Philani N, Dyan, Busiswa, Revaprasadu, Neerish, Nyokong, Tebello, Tshikhudo, Robert T, Skepu, Amanda, Van Der Lingen, Elma
- Authors: Sosibo, Ndabenhle M , Mdluli, Phumlane S , Mashazi, Philani N , Dyan, Busiswa , Revaprasadu, Neerish , Nyokong, Tebello , Tshikhudo, Robert T , Skepu, Amanda , Van Der Lingen, Elma
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246446 , vital:51477 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.09.057"
- Description: Gold nanoparticles capped with a bifunctional ligand, 3-thiopheneacetic acid (3-TAA) were synthesised by borohydride reduction at room temperature. The transmission electron microscopy (TEM) analysis showed that the particle aggregates and had semi-linear partial linkages that could be attributed to multi-modal binding of the ligand with various gold nanoparticles through the terminal thiolether (–S–) group and oxygen of the carboxylic (–COOH) group. This bimodal interaction led to limited stability of the resultant nanoparticles when tested using highly electrolytic media. To investigate further, density functional theory (DFT) quantum chemical and molecular dynamic calculations were conducted. The energetically favorable binding modes of the ligand to gold nanoparticle surfaces using the Gaussian program were studied. The DFT results showed kinetic stability of Au–3-TAA–Au interactions leading to inter-particle coupling or aggregation. Electrochemical analysis of the resultant nature of the capping agent revealed that 3-thiopheneacetic acid did not form a polymer during the preparation of Au–3-TAA. The cyclic voltammograms of Au–3-TAA nanoparticles coated glassy carbon electrode showed a typical gold character with the oxidation and reduction peaks at 1.4 V and 0.9 V, respectively.
- Full Text:
- Date Issued: 2012
- Authors: Sosibo, Ndabenhle M , Mdluli, Phumlane S , Mashazi, Philani N , Dyan, Busiswa , Revaprasadu, Neerish , Nyokong, Tebello , Tshikhudo, Robert T , Skepu, Amanda , Van Der Lingen, Elma
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246446 , vital:51477 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.09.057"
- Description: Gold nanoparticles capped with a bifunctional ligand, 3-thiopheneacetic acid (3-TAA) were synthesised by borohydride reduction at room temperature. The transmission electron microscopy (TEM) analysis showed that the particle aggregates and had semi-linear partial linkages that could be attributed to multi-modal binding of the ligand with various gold nanoparticles through the terminal thiolether (–S–) group and oxygen of the carboxylic (–COOH) group. This bimodal interaction led to limited stability of the resultant nanoparticles when tested using highly electrolytic media. To investigate further, density functional theory (DFT) quantum chemical and molecular dynamic calculations were conducted. The energetically favorable binding modes of the ligand to gold nanoparticle surfaces using the Gaussian program were studied. The DFT results showed kinetic stability of Au–3-TAA–Au interactions leading to inter-particle coupling or aggregation. Electrochemical analysis of the resultant nature of the capping agent revealed that 3-thiopheneacetic acid did not form a polymer during the preparation of Au–3-TAA. The cyclic voltammograms of Au–3-TAA nanoparticles coated glassy carbon electrode showed a typical gold character with the oxidation and reduction peaks at 1.4 V and 0.9 V, respectively.
- Full Text:
- Date Issued: 2012
Conjugates of platinum nanoparticles with gallium tetra–(4-Carboxyphenyl) porphyrin and their use in photodynamic antimicrobial chemotherapy when in solution or embedded in electrospun fiber
- Managa, Muthumuni, Antunes, Edith M, Nyokong, Tebello
- Authors: Managa, Muthumuni , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193791 , vital:45396 , xlink:href="https://doi.org/10.1016/j.poly.2014.03.050"
- Description: The conjugation of Pt nanoparticles with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP) showed greater antimicrobial activity against a gram positive and drug resistant bacteria Staphylococcus aureus, than when the porphyrin was used alone. ClGaTCPP and its conjugate with platinum nanoparticle was successfully electrospun into a polystyrene polymer where the diameter ranged from 10 to 22 μm. The conjugates within the fiber still showed activity towards S. aureus.
- Full Text:
- Date Issued: 2014
- Authors: Managa, Muthumuni , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193791 , vital:45396 , xlink:href="https://doi.org/10.1016/j.poly.2014.03.050"
- Description: The conjugation of Pt nanoparticles with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (ClGaTCPP) showed greater antimicrobial activity against a gram positive and drug resistant bacteria Staphylococcus aureus, than when the porphyrin was used alone. ClGaTCPP and its conjugate with platinum nanoparticle was successfully electrospun into a polystyrene polymer where the diameter ranged from 10 to 22 μm. The conjugates within the fiber still showed activity towards S. aureus.
- Full Text:
- Date Issued: 2014
Morphological influence of deposition routes on lead sulfide thin films
- Mlowe, Sixberth, Shombe, Ginena B, Akerman, Matthew P, Mubofu, Egid B, O'Brien, Paul, Mashazi, Philani N, Nyokong, Tebello, Revaprasadu, Neerish
- Authors: Mlowe, Sixberth , Shombe, Ginena B , Akerman, Matthew P , Mubofu, Egid B , O'Brien, Paul , Mashazi, Philani N , Nyokong, Tebello , Revaprasadu, Neerish
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186780 , vital:44533 , xlink:href="https://doi.org/10.1016/j.ica.2019.119116"
- Description: A distorted single crystal structure of bis(piperidinedithiocarbamato)lead(II) complex and its subsequent use to deposit thin films is reported. Two deposition routes namely, aerosol-assisted chemical vapour deposition (AACVD) and spin coating deposition have been employed to obtain anisotropic lead sulfide (PbS) nanostructures. The thin films displayed rod to cubic shaped crystals for AACVD, and a range of cubes, star and dendritic morphologies with variation of temperatures were displayed for spin coated films. Optical band gaps between 1.32 and 1.55 eV as controlled by the change in temperature were observed for thin films deposited by AACVD. Powder X-ray diffraction (P-XRD) studies show that the films formed are composed of cubic crystalline PbS. The X-ray photoelectron spectroscopy (XPS) was used to investigate the effect of activation temperatures (350, 400 and 450 °C) on the chemical composition and oxidation states of PbS samples.
- Full Text:
- Date Issued: 2019
- Authors: Mlowe, Sixberth , Shombe, Ginena B , Akerman, Matthew P , Mubofu, Egid B , O'Brien, Paul , Mashazi, Philani N , Nyokong, Tebello , Revaprasadu, Neerish
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186780 , vital:44533 , xlink:href="https://doi.org/10.1016/j.ica.2019.119116"
- Description: A distorted single crystal structure of bis(piperidinedithiocarbamato)lead(II) complex and its subsequent use to deposit thin films is reported. Two deposition routes namely, aerosol-assisted chemical vapour deposition (AACVD) and spin coating deposition have been employed to obtain anisotropic lead sulfide (PbS) nanostructures. The thin films displayed rod to cubic shaped crystals for AACVD, and a range of cubes, star and dendritic morphologies with variation of temperatures were displayed for spin coated films. Optical band gaps between 1.32 and 1.55 eV as controlled by the change in temperature were observed for thin films deposited by AACVD. Powder X-ray diffraction (P-XRD) studies show that the films formed are composed of cubic crystalline PbS. The X-ray photoelectron spectroscopy (XPS) was used to investigate the effect of activation temperatures (350, 400 and 450 °C) on the chemical composition and oxidation states of PbS samples.
- Full Text:
- Date Issued: 2019
A study of the photophysicochemical and antimicrobial properties of two zinc phthalocyanine–silver nanoparticle conjugates
- Rapulenyane, Nomasonto, Antunes, Edith M, Nyokong, Tebello
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232522 , vital:49999 , xlink:href="https://doi.org/10.1039/C3NJ41107A"
- Description: This work reports conjugation of two mono carboxy substituted zinc phthalocyanines with glutathione capped silver nanoparticles (GSH-AgNPs). The photophysicochemical behaviour of the novel phthalocyanines–silver nanoparticle conjugates was investigated together with simple mixtures of the silver nanoparticles with low symmetry phthalocyanines (i.e. with no direct chemical bond formation). It was observed that upon conjugation of the phthalocyanines to the silver nanoparticles, a blue shifting of the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines alone. Fluorescence lifetimes and quantum yields decreased for conjugates compared to the phthalocyanines alone due to quenching caused by the silver nanoparticles. The low symmetry phthalocyanines and their conjugates showed antimicrobial activity against Escherichia coli in the presence and absence of light.
- Full Text:
- Date Issued: 2013
- Authors: Rapulenyane, Nomasonto , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232522 , vital:49999 , xlink:href="https://doi.org/10.1039/C3NJ41107A"
- Description: This work reports conjugation of two mono carboxy substituted zinc phthalocyanines with glutathione capped silver nanoparticles (GSH-AgNPs). The photophysicochemical behaviour of the novel phthalocyanines–silver nanoparticle conjugates was investigated together with simple mixtures of the silver nanoparticles with low symmetry phthalocyanines (i.e. with no direct chemical bond formation). It was observed that upon conjugation of the phthalocyanines to the silver nanoparticles, a blue shifting of the Q band was induced. The triplet lifetimes and quantum yields improved upon conjugation as compared to the phthalocyanines alone. Fluorescence lifetimes and quantum yields decreased for conjugates compared to the phthalocyanines alone due to quenching caused by the silver nanoparticles. The low symmetry phthalocyanines and their conjugates showed antimicrobial activity against Escherichia coli in the presence and absence of light.
- Full Text:
- Date Issued: 2013
Characterization and photophysical behavior of phthalocyanines when grafted onto silica nanoparticles
- Fashina, Adedayo, Antunes, Edith M, Nyokong, Tebello
- Authors: Fashina, Adedayo , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241981 , vital:50989 , xlink:href="https://doi.org/10.1016/j.poly.2013.01.037"
- Description: This work reports on the functionalization of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally with 4-carboxyphenoxyl and 3-carboxyphenoxyl groups. The phthalocyanine dyes have a free carboxyl group, facilitating the covalent attachment of the dyes on the silica surface via amide bond formation. The phthalocyanine functionalized silica nanoparticles showed higher fluorescence and triplet quantum yields as well as longer triplet lifetimes compared to the free phthalocyanines.
- Full Text:
- Date Issued: 2013
- Authors: Fashina, Adedayo , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241981 , vital:50989 , xlink:href="https://doi.org/10.1016/j.poly.2013.01.037"
- Description: This work reports on the functionalization of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally with 4-carboxyphenoxyl and 3-carboxyphenoxyl groups. The phthalocyanine dyes have a free carboxyl group, facilitating the covalent attachment of the dyes on the silica surface via amide bond formation. The phthalocyanine functionalized silica nanoparticles showed higher fluorescence and triplet quantum yields as well as longer triplet lifetimes compared to the free phthalocyanines.
- Full Text:
- Date Issued: 2013