Photodynamic inactivation of Staphylococcus aureus using low symmetrically substituted phthalocyanines supported on a polystyrene polymer fiber
- Masilela, Nkosiphile, Kleyi, Phumelele, Tshentu, Zenixole R, Priniotakis, Georgios, Westbroek, Philippe, Nyokong, Tebello
- Authors: Masilela, Nkosiphile , Kleyi, Phumelele , Tshentu, Zenixole R , Priniotakis, Georgios , Westbroek, Philippe , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7330 , http://hdl.handle.net/10962/d1020591
- Description: This work reports on the antimicrobial photo-activities of a series of low symmetrically substituted phthalocyanine complexes in solution and in a fiber matrix. Phthalocyanine complexes were successfully electrospun into a polystyrene polymer. The fiber diameter ranged from 240 nm to 390 nm in average. The modified polymer fiber showed successful singlet oxygen production with the Ge monocarboxy phthalocyanine modified fiber giving the highest singlet oxygen quantum yield value of 0.46 due to lack of aggregation when in the polymer. All the unsymmetrically substituted complexes showed antimicrobial activity towards S. Aureus under illumination with visible light. The symmetrical ZnPc and ZnTPCPc showed no activity under illumination with light in the fiber matrix due to low singlet oxygen production. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2012.10.001
- Full Text: false
- Authors: Masilela, Nkosiphile , Kleyi, Phumelele , Tshentu, Zenixole R , Priniotakis, Georgios , Westbroek, Philippe , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7330 , http://hdl.handle.net/10962/d1020591
- Description: This work reports on the antimicrobial photo-activities of a series of low symmetrically substituted phthalocyanine complexes in solution and in a fiber matrix. Phthalocyanine complexes were successfully electrospun into a polystyrene polymer. The fiber diameter ranged from 240 nm to 390 nm in average. The modified polymer fiber showed successful singlet oxygen production with the Ge monocarboxy phthalocyanine modified fiber giving the highest singlet oxygen quantum yield value of 0.46 due to lack of aggregation when in the polymer. All the unsymmetrically substituted complexes showed antimicrobial activity towards S. Aureus under illumination with visible light. The symmetrical ZnPc and ZnTPCPc showed no activity under illumination with light in the fiber matrix due to low singlet oxygen production. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2012.10.001
- Full Text: false
Photodynamic therapy effect of zinc monoamino phthalocyanine–folic acid conjugate adsorbed on single walled carbon nanotubes on melanoma cells
- Ogbodu, Racheal O, Ndhundhuma, Ivy, Karsten, Aletta, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Ndhundhuma, Ivy , Karsten, Aletta , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7273 , http://hdl.handle.net/10962/d1020288
- Description: This work reports on the photodynamic therapy effect of zinc monoamino phthalocyanine linked to folic acid represented as ZnMAPc-FA, which was further immobilized onto single walled carbon nanotube represented as ZnMAPc-FA-SWCNT on melanoma A375 cell line, the effect of SWCNT-FA (without ZnMAPc) was also examined. All the compounds were non-toxic to the melanoma A375 cell line in the absence of light. Upon irradiation of the melanoma A375 cell line with a 676 nm diode laser at a power density of 98 mW/cm2 at 5 J/cm2 about 60% and 63% cell death was observed in the presence of ZnMAPc-FA and ZnMAPc-FA-SWCNT respectively. SWCNT-FA had no significant photodynamic therapy or photothermal effect to the cell, only 23% of cell death was observed after irradiation. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2014.09.033
- Full Text: false
- Authors: Ogbodu, Racheal O , Ndhundhuma, Ivy , Karsten, Aletta , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7273 , http://hdl.handle.net/10962/d1020288
- Description: This work reports on the photodynamic therapy effect of zinc monoamino phthalocyanine linked to folic acid represented as ZnMAPc-FA, which was further immobilized onto single walled carbon nanotube represented as ZnMAPc-FA-SWCNT on melanoma A375 cell line, the effect of SWCNT-FA (without ZnMAPc) was also examined. All the compounds were non-toxic to the melanoma A375 cell line in the absence of light. Upon irradiation of the melanoma A375 cell line with a 676 nm diode laser at a power density of 98 mW/cm2 at 5 J/cm2 about 60% and 63% cell death was observed in the presence of ZnMAPc-FA and ZnMAPc-FA-SWCNT respectively. SWCNT-FA had no significant photodynamic therapy or photothermal effect to the cell, only 23% of cell death was observed after irradiation. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2014.09.033
- Full Text: false
Photoinactivation of Candida albicans and Escherichia coli using aluminium phthalocyanine on gold nanoparticles
- Mthethwa, Thandekile, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7298 , http://hdl.handle.net/10962/d1020364
- Description: The conjugates of aluminium phthalocyanine (complex 1) with gold nanorods (complex 1–AuNRs) and bipyramids (complex 1–AuBPs) showed improved singlet oxygen quantum yields of 0.23 and 0.24, respectively, compared to that of complex 1 alone at 0.12. Complex 1 and its conjugates were used for the photoinactivation of fungi (C. albicans) and bacteria cells (E. coli). The Q band absorbances were the same for the Pc alone and when conjugated to AuNPs. The efficiency of these conjugates was evaluated by measuring the log reduction of the microorganisms (C. albicans and E. coli) after irradiation with visible light in the presence of photosensitizers. Aluminium phthalocyanine alone showed log 1.78 and log 2.51 reductions for C. albicans and E. coli respectively. However, the conjugates showed higher photosensitization with log 2.08 and log 3.34 for C. albicans and E. coli, respectively using 1–AuBPs. For complex 1–AuNRs log 2.53 and log 3.71 were achieved for C. albicans and E. coli respectively. The statistical analysis of the results showed that the enhanced photoinactivation observed in both microorganisms was irrespective of the shape of the nanoparticles conjugated. Photoinactivation of C. albicans was less than that of E. coli even though a higher concentration of complex 1 or its conjugates was used in C. albicans. , Original publication is available at http://dx.doi.org/10.1039/C4PP00315B , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iTextSharp 5.5.1 �2000-2014 iText Group NV (AGPL-version); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
- Full Text:
- Authors: Mthethwa, Thandekile , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7298 , http://hdl.handle.net/10962/d1020364
- Description: The conjugates of aluminium phthalocyanine (complex 1) with gold nanorods (complex 1–AuNRs) and bipyramids (complex 1–AuBPs) showed improved singlet oxygen quantum yields of 0.23 and 0.24, respectively, compared to that of complex 1 alone at 0.12. Complex 1 and its conjugates were used for the photoinactivation of fungi (C. albicans) and bacteria cells (E. coli). The Q band absorbances were the same for the Pc alone and when conjugated to AuNPs. The efficiency of these conjugates was evaluated by measuring the log reduction of the microorganisms (C. albicans and E. coli) after irradiation with visible light in the presence of photosensitizers. Aluminium phthalocyanine alone showed log 1.78 and log 2.51 reductions for C. albicans and E. coli respectively. However, the conjugates showed higher photosensitization with log 2.08 and log 3.34 for C. albicans and E. coli, respectively using 1–AuBPs. For complex 1–AuNRs log 2.53 and log 3.71 were achieved for C. albicans and E. coli respectively. The statistical analysis of the results showed that the enhanced photoinactivation observed in both microorganisms was irrespective of the shape of the nanoparticles conjugated. Photoinactivation of C. albicans was less than that of E. coli even though a higher concentration of complex 1 or its conjugates was used in C. albicans. , Original publication is available at http://dx.doi.org/10.1039/C4PP00315B , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iTextSharp 5.5.1 �2000-2014 iText Group NV (AGPL-version); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
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Photophysical and non-linear optical behavior of novel tetra alkynyl terminated indium phthalocyanines: Effects of the carbon chain length
- Bankole, Owolabi M, Britton, Jonathan, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7262 , http://hdl.handle.net/10962/d1020271
- Description: We report on the synthesis, photophysical and nonlinear optical behavior of tetra-substituted alkynyl indium phthalocyanine complexes (3a and 3b). Both complexes showed large triplet quantum yields. Nonlinear optical properties were also evaluated for the two complexes at a wavelength of 532 nm using nanosecond Z-scan technique in dimethylsulfoxide. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The underlining 2PA and observed RSA were subjected to further scrutiny by comparing the analytical absorption model to the transmittance optical absorption theory. The theoretical results were in good agreement to the observed RSA and the 2PA mechanism. Large two-photon absorption cross-section (1.29 × 10−42 and 1.15 × 10−42 cm4 s/photon), third-order susceptibility (2.10 × 10−14 and 2.15 × 10−14 esu) and hyperpolarizability (2.70 × 10−32 and 3.19 × 10−32 esu) were estimated for complex 3a and 3b, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.12.020
- Full Text: false
- Authors: Bankole, Owolabi M , Britton, Jonathan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7262 , http://hdl.handle.net/10962/d1020271
- Description: We report on the synthesis, photophysical and nonlinear optical behavior of tetra-substituted alkynyl indium phthalocyanine complexes (3a and 3b). Both complexes showed large triplet quantum yields. Nonlinear optical properties were also evaluated for the two complexes at a wavelength of 532 nm using nanosecond Z-scan technique in dimethylsulfoxide. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The underlining 2PA and observed RSA were subjected to further scrutiny by comparing the analytical absorption model to the transmittance optical absorption theory. The theoretical results were in good agreement to the observed RSA and the 2PA mechanism. Large two-photon absorption cross-section (1.29 × 10−42 and 1.15 × 10−42 cm4 s/photon), third-order susceptibility (2.10 × 10−14 and 2.15 × 10−14 esu) and hyperpolarizability (2.70 × 10−32 and 3.19 × 10−32 esu) were estimated for complex 3a and 3b, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2014.12.020
- Full Text: false
Photophysical and nonlinear optical studies of tetraakynyl zincphthalocyanine and its “clicked” analogue
- Bankole, Owolabi M, Nyokong, Tebello
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7251 , http://hdl.handle.net/10962/d1020259
- Description: We report here for the first time on the photophysical and nonlinear optical behavior of tetra-substituted alkynyl zinc phthalocyanine and its “clicked” analogue (4 and 5). The compounds exhibited high triplet quantum yields in dimethylsulphoxide (DMSO). Nonlinear optical (NLO) properties were also evaluated for the two compounds at 532 nm and 10 ns in DMSO. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The presence of electron acceptor groups fused with triazole linkers in the peripheral positions of 4 provide excellent coexistent features, such as enhanced triplet quantum yields and lifetimes compared to 5. Large third-order susceptibility (2.09 × 10−11 and 3.53 × 10−9 esu) and hyperpolarizability (1.09 × 10−30 and 9.13 × 10−29 esu) were estimated for complexs 4 and 5, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.molstruc.2015.01.048
- Full Text: false
- Authors: Bankole, Owolabi M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7251 , http://hdl.handle.net/10962/d1020259
- Description: We report here for the first time on the photophysical and nonlinear optical behavior of tetra-substituted alkynyl zinc phthalocyanine and its “clicked” analogue (4 and 5). The compounds exhibited high triplet quantum yields in dimethylsulphoxide (DMSO). Nonlinear optical (NLO) properties were also evaluated for the two compounds at 532 nm and 10 ns in DMSO. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The presence of electron acceptor groups fused with triazole linkers in the peripheral positions of 4 provide excellent coexistent features, such as enhanced triplet quantum yields and lifetimes compared to 5. Large third-order susceptibility (2.09 × 10−11 and 3.53 × 10−9 esu) and hyperpolarizability (1.09 × 10−30 and 9.13 × 10−29 esu) were estimated for complexs 4 and 5, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.molstruc.2015.01.048
- Full Text: false
Photophysical and photochemical properties of a novel thiol terminated low symmetry zinc phthalocyanine complex and its gold nanoparticles conjugate
- Mthethwa, Thandekile P., Tuncel, Sinem, Durmuş, Mahmut, Nyokong, Tebello
- Authors: Mthethwa, Thandekile P. , Tuncel, Sinem , Durmuş, Mahmut , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7329 , http://hdl.handle.net/10962/d1020590
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone. , Original publication is available at http://dx.doi.org/10.1039/C3DT32698E
- Full Text:
- Authors: Mthethwa, Thandekile P. , Tuncel, Sinem , Durmuş, Mahmut , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7329 , http://hdl.handle.net/10962/d1020590
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone. , Original publication is available at http://dx.doi.org/10.1039/C3DT32698E
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Photophysical properties gallium octacarboxy phthalocyanines conjugated to CdSe@ZnS quantum dots
- Tshangana, Charmaine, Nyokong, Tebello
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7287 , http://hdl.handle.net/10962/d1020335
- Description: l-Glutathione (GSH) capped core CdSe (2.3 nm) and core shell CdSe@ZnS quantum dots (QDs) (3.0 nm and 3.5 nm) were coordinated to gallium octacarboxy phthalocyanine (ClGaPc(COOH)8) to form ClGaPc(COOH)8–QDs conjugates. An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer (FRET), the FRET efficiencies in all cases was above 50%. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were also determined for the conjugates. There was a decrease in the fluorescence lifetimes of ClGaPc(COOH)8 in the presence of all the QDs, due to the heavy atom effect. The triplet quantum yields increased in the conjugates. The lifetimes also became longer for the conjugates compared to Pc alone. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2015.06.086
- Full Text: false
- Authors: Tshangana, Charmaine , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7287 , http://hdl.handle.net/10962/d1020335
- Description: l-Glutathione (GSH) capped core CdSe (2.3 nm) and core shell CdSe@ZnS quantum dots (QDs) (3.0 nm and 3.5 nm) were coordinated to gallium octacarboxy phthalocyanine (ClGaPc(COOH)8) to form ClGaPc(COOH)8–QDs conjugates. An efficient transfer of energy from the QDs to the Pcs was demonstrated through Förster resonance energy transfer (FRET), the FRET efficiencies in all cases was above 50%. The photophysical parameters (triplet state and fluorescence quantum yields and lifetimes) were also determined for the conjugates. There was a decrease in the fluorescence lifetimes of ClGaPc(COOH)8 in the presence of all the QDs, due to the heavy atom effect. The triplet quantum yields increased in the conjugates. The lifetimes also became longer for the conjugates compared to Pc alone. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2015.06.086
- Full Text: false
Photophysical properties of a new water soluble tetra thiamine substituted zinc phthalocyanine conjugated to gold nanorods of different aspect ratios
- Mthethwa, Thandekile, Antunes, Edith M, Nyokong, Tebello
- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7302 , http://hdl.handle.net/10962/d1020379
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods. , Original publication is available at http://dx.doi.org/10.1039/C4DT00197D , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
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- Authors: Mthethwa, Thandekile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7302 , http://hdl.handle.net/10962/d1020379
- Description: A water soluble zinc phthalocyanine substituted with thiamine is reported in this work. The aggregation of this compound in aqueous solutions causes quenching of the fluorescence quantum yields. Gold nanospheres and nanorods were linked to the phthalocyanine. X-ray photoelectron spectroscopy showed that both the amine and the sulphur groups on the thiamine substituent of the zinc phthalocyanine were involved in the linking to gold nanoparticles. The Pc showed an increase in the fluorescence quantum yields in the presence of the nanoparticles. The singlet oxygen quantum yield increased when the Pc was conjugated to the nanoparticles and even higher for larger aspect ratio gold nanorods. , Original publication is available at http://dx.doi.org/10.1039/C4DT00197D , Arbortext Advanced Print Publisher 9.1.520/W Unicode , Acrobat Distiller 10.0.0 (Windows); modified using iText� 5.3.3 �2000-2012 1T3XT BVBA (AGPL-version)
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Photophysical Properties of Zinc Tetracarboxy Phthalocyanines Conjugated to Magnetic Nanoparticles
- Modisha, Phillimon, Antunes, Edith M, Nyokong, Tebello
- Authors: Modisha, Phillimon , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7254 , http://hdl.handle.net/10962/d1020263
- Description: Magnetite nanoparticles (MNPs) were synthesised by the co-precipitation method and coated with amino functional groups which allowed for amide bond formation with the carboxylic acid groups on zinc tetra- or octa-carboxyphthalocyanine (ZnTCPc or ZnOCPc respectively). The absorption spectra of ZnTCPc linked to MNPs showed a reduction in aggregation, while the photophysical parameters (Φ T , τ T and ΦΔ) of ZnTCPc or ZnOCPc increased upon linking with the MNPs. , Original publication is available at http://dx.doi.org/10.1166/jnn.2015.9247
- Full Text: false
- Authors: Modisha, Phillimon , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7254 , http://hdl.handle.net/10962/d1020263
- Description: Magnetite nanoparticles (MNPs) were synthesised by the co-precipitation method and coated with amino functional groups which allowed for amide bond formation with the carboxylic acid groups on zinc tetra- or octa-carboxyphthalocyanine (ZnTCPc or ZnOCPc respectively). The absorption spectra of ZnTCPc linked to MNPs showed a reduction in aggregation, while the photophysical parameters (Φ T , τ T and ΦΔ) of ZnTCPc or ZnOCPc increased upon linking with the MNPs. , Original publication is available at http://dx.doi.org/10.1166/jnn.2015.9247
- Full Text: false
Photophysichochemical behavior of carbazole derivatized zinc phthalocyanine in the presence of ZnO microparticles and when embedded in electrospun fibers
- Khoza, Phindile, Antunes, Edith M, Nyokong, Tebello
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7303 , http://hdl.handle.net/10962/d1020380
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2013.12.019
- Full Text: false
- Authors: Khoza, Phindile , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7303 , http://hdl.handle.net/10962/d1020380
- Description: The synthesis of a zinc phthalocyanine complex tetrasubstituted with carbazole functionality at the peripheral position (complex 4) is reported. The singlet oxygen quantum yield of the complex was found to be 0.83 in dimethylformamide (DMF). The complex was subsequently conjugated to zinc oxide microparticles (ZnOMPs), the conjugation (formation of the amide bond) was confirmed by IR spectroscopy. The presence of ZnOMPs was found to reduce the singlet oxygen produced (ΦΔ = 0.63) in DMF. Polystyrene electrospun fibers of complex 4 alone and its conjugate to ZnOMPs were found to be thermally stable. The singlet oxygen quantum yield of the modified electrospun fibers was determined in aqueous media with ADMA as a singlet oxygen quencher and were 0.25 and 0.20 for complex 4 and 4-ZnOMPs embedded in fibers, respectively. , Original publication is available at http://dx.doi.org/10.1016/j.dyepig.2013.12.019
- Full Text: false
Physicochemical properties of a zinc phthalocyanine – pyrene conjugate adsorbed onto single walled carbon nanotubes
- Ogbodu, Racheal O, Antunes, Edith M, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7328 , http://hdl.handle.net/10962/d1020589
- Description: A conjugate between zinc monoamino phthalocyanine (ZnMAPc) and pyrene (Py) represented as ZnMAPc–Py (complex 3) was synthesized and characterized by various spectroscopic techniques and by elemental analysis. This manuscript also reports on the photochemical and photophysical properties of 3. This new compound exhibited higher triplet, fluorescence and singlet oxygen quantum yields in comparison to the phthalocyanine alone, hence showing the advantages of attaching pyrene to the Pc without breaking the conjugation. We also observed a decrease in photophysical parameters upon adsorbing the ZnMAPc–Py complex onto single walled carbon nanotubes (SWCNT). However, ZnMAPc–Py still generated some singlet oxygen when adsorbed onto SWCNT. , Original publication is available at http://dx.doi.org/10.1039/C3DT50335F
- Full Text:
- Authors: Ogbodu, Racheal O , Antunes, Edith M , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7328 , http://hdl.handle.net/10962/d1020589
- Description: A conjugate between zinc monoamino phthalocyanine (ZnMAPc) and pyrene (Py) represented as ZnMAPc–Py (complex 3) was synthesized and characterized by various spectroscopic techniques and by elemental analysis. This manuscript also reports on the photochemical and photophysical properties of 3. This new compound exhibited higher triplet, fluorescence and singlet oxygen quantum yields in comparison to the phthalocyanine alone, hence showing the advantages of attaching pyrene to the Pc without breaking the conjugation. We also observed a decrease in photophysical parameters upon adsorbing the ZnMAPc–Py complex onto single walled carbon nanotubes (SWCNT). However, ZnMAPc–Py still generated some singlet oxygen when adsorbed onto SWCNT. , Original publication is available at http://dx.doi.org/10.1039/C3DT50335F
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Polyamide nanofiber membranes functionalized with zinc phthalocyanines
- Goethals, Annelies, Mugadza, Tawanda, Arslanoglu, Yasin, Zugle, Ruphino, Antunes, Edith M, Hulle, Stijn W H Van, Nyokong, Tebello, Clerck, Karen De
- Authors: Goethals, Annelies , Mugadza, Tawanda , Arslanoglu, Yasin , Zugle, Ruphino , Antunes, Edith M , Hulle, Stijn W H Van , Nyokong, Tebello , Clerck, Karen De
- Language: English
- Type: Article
- Identifier: vital:7313 , http://hdl.handle.net/10962/d1020539
- Description: Electrospinning is an efficient method for the production of polyamide nanofiber membranes that are suitable for water filtration. Previous studies have shown that nanofiber membranes have high clean water permeability. The pathogen removal efficiency can be improved by functionalization with (organic) biocides. However, these membranes, like other membranes, are vulnerable to fouling which reduces the filtration efficiency. Therefore the present article investigates the potential of zinc phthalocyanines, which can produce singlet oxygen in the presence of visible light, as a functionalizing agent. The polyamide nanofiber membranes were functionalized with phthalocyanines using both a pre-functionalizing and post-functionalizing method. Only the post-functionalization method shows to result in nanofiber membranes capable of producing singlet oxygen. After 30 min 45% of 1,2-diphenylisobenzofuran (DPBF), used as an oxygen quencher, was removed by reaction with singlet oxygen. This resulted in a removal rate of 0.33 mol DBPF mol−1Zn min−1. During short term leaching tests, phthalocyanines could not be detected. , Original publication is available at http://dx.doi.org/10.1002/app.40486
- Full Text: false
- Authors: Goethals, Annelies , Mugadza, Tawanda , Arslanoglu, Yasin , Zugle, Ruphino , Antunes, Edith M , Hulle, Stijn W H Van , Nyokong, Tebello , Clerck, Karen De
- Language: English
- Type: Article
- Identifier: vital:7313 , http://hdl.handle.net/10962/d1020539
- Description: Electrospinning is an efficient method for the production of polyamide nanofiber membranes that are suitable for water filtration. Previous studies have shown that nanofiber membranes have high clean water permeability. The pathogen removal efficiency can be improved by functionalization with (organic) biocides. However, these membranes, like other membranes, are vulnerable to fouling which reduces the filtration efficiency. Therefore the present article investigates the potential of zinc phthalocyanines, which can produce singlet oxygen in the presence of visible light, as a functionalizing agent. The polyamide nanofiber membranes were functionalized with phthalocyanines using both a pre-functionalizing and post-functionalizing method. Only the post-functionalization method shows to result in nanofiber membranes capable of producing singlet oxygen. After 30 min 45% of 1,2-diphenylisobenzofuran (DPBF), used as an oxygen quencher, was removed by reaction with singlet oxygen. This resulted in a removal rate of 0.33 mol DBPF mol−1Zn min−1. During short term leaching tests, phthalocyanines could not be detected. , Original publication is available at http://dx.doi.org/10.1002/app.40486
- Full Text: false
Professor Nyokong growing up
- Authors: Nyokong, Tebello
- Identifier: vital:7164 , http://hdl.handle.net/10962/d1005908
- Description: Professor Nyokong growing up.
- Full Text: false
- Authors: Nyokong, Tebello
- Identifier: vital:7164 , http://hdl.handle.net/10962/d1005908
- Description: Professor Nyokong growing up.
- Full Text: false
Rhodes academic gets A-rating from NRF
- Authors: Nyokong, Tebello
- Identifier: vital:7218 , http://hdl.handle.net/10962/d1005894
- Description: The NRF rating is a national indicator of research excellence at universities and, according to the foundation, an A-rating is only awarded to researchers who are “unequivocally recognised by their peers as leading international scholars in their field for the high quality and impact of their recent research outputs”. Photo's taken at the award celebration at Rhodes University.
- Full Text: false
- Authors: Nyokong, Tebello
- Identifier: vital:7218 , http://hdl.handle.net/10962/d1005894
- Description: The NRF rating is a national indicator of research excellence at universities and, according to the foundation, an A-rating is only awarded to researchers who are “unequivocally recognised by their peers as leading international scholars in their field for the high quality and impact of their recent research outputs”. Photo's taken at the award celebration at Rhodes University.
- Full Text: false
SA/Germany Workshop, Rhodes University, Grahamstown
- Authors: Nyokong, Tebello
- Identifier: vital:7227 , http://hdl.handle.net/10962/d1006040
- Description: SA/Germany Workshop, Rhodes University, Grahamstown, 7-8 September 2010
- Full Text: false
- Authors: Nyokong, Tebello
- Identifier: vital:7227 , http://hdl.handle.net/10962/d1006040
- Description: SA/Germany Workshop, Rhodes University, Grahamstown, 7-8 September 2010
- Full Text: false
SABC2 Morning Live Interview
- Authors: Nyokong, Tebello
- Identifier: vital:7165 , http://hdl.handle.net/10962/d1005915
- Description: SABC (TV 2, Morning live) Interview on Photodynamic therapy, 2001
- Full Text: false
- Authors: Nyokong, Tebello
- Identifier: vital:7165 , http://hdl.handle.net/10962/d1005915
- Description: SABC (TV 2, Morning live) Interview on Photodynamic therapy, 2001
- Full Text: false
Spectral properties and photophysical behaviour of water soluble cationic Mg(II) and Al(III) phthalocyanines
- Idowu, Mopelola A I, Arslanoglu, Yasin, Nyokong, Tebello
- Authors: Idowu, Mopelola A I , Arslanoglu, Yasin , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7277 , http://hdl.handle.net/10962/d1020292
- Description: Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA). , Original publication is available at http://dx.doi.org/10.2478/s11532-013-0388-z
- Full Text: false
- Authors: Idowu, Mopelola A I , Arslanoglu, Yasin , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7277 , http://hdl.handle.net/10962/d1020292
- Description: Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA). , Original publication is available at http://dx.doi.org/10.2478/s11532-013-0388-z
- Full Text: false
Surface modification of silica-coated gadolinium oxide nanoparticles with zinc tetracarboxyphenoxy phthalocyanine for the photodegradation of Orange G
- Ledwaba, Mpho, Masilela, Nkosiphile, Nyokong, Tebello, Antunes, Edith M
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7249 , http://hdl.handle.net/10962/d1020255
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics. , Original publication is available at http://dx.doi.org/10.1016/j.molcata.2015.03.023
- Full Text: false
- Authors: Ledwaba, Mpho , Masilela, Nkosiphile , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7249 , http://hdl.handle.net/10962/d1020255
- Description: Zinc tetracarboxyphenoxy phthalocyanine was covalently linked to Gd2O3 nanoparticles for the photocatalytic degradation of Orange G. Characterization of the composite was carried out using XRD, TEM, XPS, UV–vis spectroscopy and FT-IR spectroscopy. The composite showed improved photophysical properties over the phthalocyanine alone and the catalyst was found to be reusable. Analyses of the photodegradation rates of the azo dye indicated pseudo first-order kinetics. , Original publication is available at http://dx.doi.org/10.1016/j.molcata.2015.03.023
- Full Text: false
Surface patterning using scanning electrochemical microscopy to locally trigger a “click” chemistry reaction
- Quinton, Damien, Maringa, Audacity, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Quinton, Damien , Maringa, Audacity , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Language: English
- Type: Article
- Identifier: vital:7331 , http://hdl.handle.net/10962/d1020592
- Description: We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈ 10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈ 75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates. , Original publication is available at http://dx.doi.org/10.1016/j.elecom.2013.03.021
- Full Text: false
- Authors: Quinton, Damien , Maringa, Audacity , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Language: English
- Type: Article
- Identifier: vital:7331 , http://hdl.handle.net/10962/d1020592
- Description: We report on the surface micropatterning of conductive surfaces via the electrochemical triggering of a click reaction, the copper(I) catalyzed azide–alkyne cycloaddition reaction (CuAAC) by SECM via a two-step approach: (i) functionalization on the entire surface with azido-aryl groups by using the diazonium approach followed by (ii) the covalent linkage of alkyne-bearing ferrocene by CuAAC within a local area by SECM. More precisely, the click reaction was triggered by Cu(I) catalyst generation for 30 min at the SECM tip positioned ≈ 10 μm above the azido-aryl modified surface. The dimension of the spot obtained under these conditions was ≈ 75 μm. The electrochemical imaging by SECM of the ultra thin area locally clicked with ferrocene moieties was made thanks to the electrocatalytic properties of the ferrocene modified surface towards ferrocyanide electrooxidation. This local clicking procedure opens the gate to further controlled functionalization of restricted small substrates. , Original publication is available at http://dx.doi.org/10.1016/j.elecom.2013.03.021
- Full Text: false
Synthesis and characterization of Na(Y,Gd)F4 upconversion nanoparticles and an investigation of their effects on the photophysical properties of an unsubstituted tetrathiophenoxy phthalocyanine
- Taylor, Jessica M, Litwinski, Christian, Nyokong, Tebello, Antunes, Edith M
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7253 , http://hdl.handle.net/10962/d1020261
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs. , Original publication is available at http://dx.doi.org/10.1007/s11051-015-2889-5
- Full Text: false
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Language: English
- Type: Article
- Identifier: vital:7253 , http://hdl.handle.net/10962/d1020261
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs. , Original publication is available at http://dx.doi.org/10.1007/s11051-015-2889-5
- Full Text: false