TargetingtheHIVEpidemicinSouthAfrica:TheNeedforTestingandLinkagetoCareinEmergencyDepartments
- Authors: Nyanisa, Yandisa
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3740 , vital:43941
- Full Text:
- Authors: Nyanisa, Yandisa
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3740 , vital:43941
- Full Text:
The development of catalytic oxovanadium(IV)-containing microspheres for the oxidation of various organosulfur compounds
- Ogunlaja, Adeniyi S, Khene, M Samson, Antunes, Edith M, Nyokong, Tebello, Torto, Nelson, Tshentu, Zenixole R
- Authors: Ogunlaja, Adeniyi S , Khene, M Samson , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Language: English
- Type: Article
- Identifier: vital:7324 , http://hdl.handle.net/10962/d1020574
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil. , Original publication is available at http://dx.doi.org/10.1016/j.apcata.2013.05.004
- Full Text: false
- Authors: Ogunlaja, Adeniyi S , Khene, M Samson , Antunes, Edith M , Nyokong, Tebello , Torto, Nelson , Tshentu, Zenixole R
- Language: English
- Type: Article
- Identifier: vital:7324 , http://hdl.handle.net/10962/d1020574
- Description: The development of poly[allylSB-co-EGDMA] beads containing a tetradentate ligand was achieved via suspension polymerization. The catalyst poly[allylSB-co-EGDMA]-VO was synthesized by reacting VIVOSO4 with poly[allylSB-co-EGDMA]. XPS and EPR were used to confirm the presence of vanadium (V4+) on the beads. The synthesized catalyst (poly[allylSB-co-EGDMA]-VO) was found to have a BET surface area of 22 m2 g−1 and porosity of 135 Å, with the atomic force microscopy (AFM) showing more insight on the porous nature of the beads. Oxidation of thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out using tert-butyl hydroperoxide (t-BuOOH) as oxidant. An overall conversion of 60%, 82%, 98% and 87% was achieved for thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6 dimethyldibenzothiophene (4,6-DMDBT) respectively at higher (t-BuOOH) to substrate ratio and at a temperature of 40 °C. The efficient oxidation of the various organosulfur compounds presents potential for the possible application of this catalyst in oxidative desulfurization (ODS) of crude oil. , Original publication is available at http://dx.doi.org/10.1016/j.apcata.2013.05.004
- Full Text: false
The effect of ascorbic acid on the photophysical properties and photodynamic therapy activities of zinc phthalocyanine-single walled carbon nanotube conjugate on MCF-7 cancer cells
- Ogbodu, Racheal O, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7286 , http://hdl.handle.net/10962/d1020334
- Description: Zinc mono carboxy phenoxy phthalocyanine (1) was chemical modified with ascorbic acid via an ester bond to give ZnMCPPc-AA (2). Complexes 2 and 1 were coordinated to single walled carbon nanotubes via π–π interaction to give ZnMCPPc-AA-SWCNT (3) and ZnMCPPc-SWCNT (4) respectively. Complexes 2, 3 and 4 showed better photophysical properties: with improved triplet lifetimes and quantum yields, and singlet oxygen quantum yields when compared to 1 alone. The photodynamic therapy activities of complexes 1, 2, 3 and 4 were tested in vitro on MCF-7 breast cancer cells. Ascorbic acid suppresses the photodynamic therapy effect of 1, due to its ability to reduce oxidative DNA damage as a result of its potent reducing properties. The highest phototoxicity was observed for 4 which resulted in 77% decrease in cell viability, followed by 3 which resulted in 67% decrease in cell viability. This shows the importance of combination therapy, where the phthalocyanines are the photodynamic therapy agents and single walled carbon nanotubes are the photothermal therapy agents. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2015.06.063
- Full Text: false
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7286 , http://hdl.handle.net/10962/d1020334
- Description: Zinc mono carboxy phenoxy phthalocyanine (1) was chemical modified with ascorbic acid via an ester bond to give ZnMCPPc-AA (2). Complexes 2 and 1 were coordinated to single walled carbon nanotubes via π–π interaction to give ZnMCPPc-AA-SWCNT (3) and ZnMCPPc-SWCNT (4) respectively. Complexes 2, 3 and 4 showed better photophysical properties: with improved triplet lifetimes and quantum yields, and singlet oxygen quantum yields when compared to 1 alone. The photodynamic therapy activities of complexes 1, 2, 3 and 4 were tested in vitro on MCF-7 breast cancer cells. Ascorbic acid suppresses the photodynamic therapy effect of 1, due to its ability to reduce oxidative DNA damage as a result of its potent reducing properties. The highest phototoxicity was observed for 4 which resulted in 77% decrease in cell viability, followed by 3 which resulted in 67% decrease in cell viability. This shows the importance of combination therapy, where the phthalocyanines are the photodynamic therapy agents and single walled carbon nanotubes are the photothermal therapy agents. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2015.06.063
- Full Text: false
The effects of gold coated and uncoated zinc oxide nanohexagons on the photophysicochemical properties of the low symmetry zinc phthalocyanine
- D'Souza, Sarah, Ogbodu, Racheal O, Nyokong, Tebello
- Authors: D'Souza, Sarah , Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7280 , http://hdl.handle.net/10962/d1020317
- Description: A new low symmetry, Zn phthalocyanine monosubstituted with diethylaminoethanethiol (mDEAET ZnPc) was synthesized and characterized. This work reports on its photophysical and photochemical properties of mDEAET ZnPc alone and when conjugated to gold coated and uncoated zinc oxide nanohexagons (ZnO NHXs). The photophysicochemical properties generally improved in the presence of the ZnO NHXs. These complexes were also tested for their photodynamic antimicrobial activity against Staphylococcus aureus (S. aureus). The Pc alone showed remarkable growth inhibition even at concentrations as low as 0.05 mg/mL. The conjugates showed a high photoinactivation of S. aureus after 30 min at a fluence of 90 mW cm−2 at a concentration of 0.05 mg/mL. The ZnPc-ZnO NHX conjugates produced the best antimicrobial results. , Original publication is available at http://dx.doi.org/10.1016/j.molstruc.2015.06.088
- Full Text: false
- Authors: D'Souza, Sarah , Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7280 , http://hdl.handle.net/10962/d1020317
- Description: A new low symmetry, Zn phthalocyanine monosubstituted with diethylaminoethanethiol (mDEAET ZnPc) was synthesized and characterized. This work reports on its photophysical and photochemical properties of mDEAET ZnPc alone and when conjugated to gold coated and uncoated zinc oxide nanohexagons (ZnO NHXs). The photophysicochemical properties generally improved in the presence of the ZnO NHXs. These complexes were also tested for their photodynamic antimicrobial activity against Staphylococcus aureus (S. aureus). The Pc alone showed remarkable growth inhibition even at concentrations as low as 0.05 mg/mL. The conjugates showed a high photoinactivation of S. aureus after 30 min at a fluence of 90 mW cm−2 at a concentration of 0.05 mg/mL. The ZnPc-ZnO NHX conjugates produced the best antimicrobial results. , Original publication is available at http://dx.doi.org/10.1016/j.molstruc.2015.06.088
- Full Text: false
The nonlinear absorption in new lanthanide double decker pyridine-based phthalocyanines in solution and thin films
- Sekhosana, Kutloano Edward, Nyokong, Tebello
- Authors: Sekhosana, Kutloano Edward , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7299 , http://hdl.handle.net/10962/d1020366
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.022
- Full Text: false
- Authors: Sekhosana, Kutloano Edward , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7299 , http://hdl.handle.net/10962/d1020366
- Description: The optical behavior of bis-{2(3), 9(10), 16(17), 23(24)-(tetrapyridin-4-yloxy phthalocyaninato)} lanthanum (III) (2) and its ytterbium (3) counterpart in dimethyl sulfoxide are presented and compared to bis-{1(4), 8(11), 15(18), 22(25)-(tetrapyridin-4-yloxy phthalocyaninato)} ytterbium (III) (4). We report on the third-order susceptibility, second-order hyperpolarizability and the limiting threshold values. The nonlinear optical limiting threshold values of complexes 2, 3 and 4 showed improvement in the solid state (thin films), with complex 4 giving the best value at 0.033 J cm−2. , Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.022
- Full Text: false
Tuning the physico-electrochemical properties of novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs
- Agboola, Bolade Oyeyinka, Ozoemena, Kenneth I., Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Agboola, Bolade Oyeyinka , Ozoemena, Kenneth I. , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Language: English
- Type: Article
- Identifier: vital:7238 , http://hdl.handle.net/10962/d1019689
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode. , Original publication is available at http://dx.doi.org/doi:10.1016/j.carbon.2009.10.023
- Full Text: false
- Authors: Agboola, Bolade Oyeyinka , Ozoemena, Kenneth I. , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Language: English
- Type: Article
- Identifier: vital:7238 , http://hdl.handle.net/10962/d1019689
- Description: The integration of phenylamine-functionalised SWCNTs (SWCNT-phenylamine) with a novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine (CoOBPPc) complex has been described. The physical and electrochemical properties of the CoOBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical transformation of the CoOBCPPc from the usually bluish colour of cobalt phthalocyanine complexes to a beautiful bright green colour. In addition, the heterogeneous electron transfer kinetics and electrocatalytic properties of the CoOBCPPc were greatly enhanced following the attachment of the SWCNT-phenylamine. The potential electrocatalytic application of the hybrid was tested using β-nicotinamide adenine dinucleotide (NADH) as a model biological analyte. Interestingly, the onset oxidation potential of this analyte was significantly reduced (300 mV) by this hybrid compared to the bare electrode. , Original publication is available at http://dx.doi.org/doi:10.1016/j.carbon.2009.10.023
- Full Text: false