Effect of bovine serum albumin and single walled carbon nanotube on the photophysical properties of zinc octacarboxy phthalocyanine
- Ogbodu, Racheal O, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189806 , vital:44933 , xlink:href="https://doi.org/10.1016/j.saa.2013.10.064"
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased.
- Full Text:
- Date Issued: 2014
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189806 , vital:44933 , xlink:href="https://doi.org/10.1016/j.saa.2013.10.064"
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased.
- Full Text:
- Date Issued: 2014
Effect of bovine serum albumin and single walled carbon nanotube on the photophysical properties of zinc octacarboxy phthalocyanine
- Ogbodu, Racheal O, Nyokong, Tebello
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7321 , http://hdl.handle.net/10962/d1020566
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2013.10.064
- Full Text: false
- Authors: Ogbodu, Racheal O , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7321 , http://hdl.handle.net/10962/d1020566
- Description: This work reports on the photophysical parameters of the conjugate between zinc octacarboxy phthalocyanine (ZnOCPc) and bovine serum albumin (BSA) represented as ZnOCPc–BSA (1) which was further adsorbed onto single walled carbon nanotubes (SWCNT) represented as (ZnOCPc–BSA–SWCNT 2). ZnOCPc (without BSA) was also adsorbed on SWCNT represented as ZnOCPc–SWCNT (3). The presence of BSA resulted in the increase in singlet oxygen quantum yield (ΦΔ) for 1 (at ΦΔ = 0.44) and 2 (at ΦΔ = 0.41) compared to ΦΔ = 0.21 for ZnOCPc alone. For complex 3 which did not contain BSA singlet oxygen quantum yield decreased. , Original publication is available at http://dx.doi.org/10.1016/j.saa.2013.10.064
- Full Text: false
Effect of bromination on the optical limiting properties at 532 nm of BODIPY dyes with p-benzyloxystyryl groups at the 3, 5-positions
- Ngoy, Bokolombe P, May, Aviwe K, Mack, John, Nyokong, Tebello
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187507 , vital:44665 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.08.012"
- Description: The optical limiting (OL) properties of 3,5-di-p-benzyloxystyrylBODIPY dyes that contain both protons and bromine atoms at the 2,6-positions have been investigated by using the Z-scan technique at 532 nm on the nanosecond timescale. There is relatively weak absorbance at 532 nm under ambient light conditions, because the incorporation of p-benzyloxystyryl groups at the 3,5-positions results in a ca. 140 nm red shift of the main BODIPY spectral band to the 640–670 nm range. Reverse saturable absorbance (RSA) profiles that are consistent with an excited state absorption (ESA) mechanism involving the T1 and/or S1 states are observed in CH2Cl2 solution. Second order hyperpolarizability values of ca. 8 × 10−30 esu are obtained and this demonstrates that the dyes are potentially suitable for use in OL applications at 532 nm. There is a slight enhancement of the OL properties upon bromination, due to increased intersystem crossing to the triplet manifold, but the enhancement of the OL properties is less significant than has been observed with metal phthalocyanine complexes.
- Full Text:
- Date Issued: 2019
- Authors: Ngoy, Bokolombe P , May, Aviwe K , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187507 , vital:44665 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.08.012"
- Description: The optical limiting (OL) properties of 3,5-di-p-benzyloxystyrylBODIPY dyes that contain both protons and bromine atoms at the 2,6-positions have been investigated by using the Z-scan technique at 532 nm on the nanosecond timescale. There is relatively weak absorbance at 532 nm under ambient light conditions, because the incorporation of p-benzyloxystyryl groups at the 3,5-positions results in a ca. 140 nm red shift of the main BODIPY spectral band to the 640–670 nm range. Reverse saturable absorbance (RSA) profiles that are consistent with an excited state absorption (ESA) mechanism involving the T1 and/or S1 states are observed in CH2Cl2 solution. Second order hyperpolarizability values of ca. 8 × 10−30 esu are obtained and this demonstrates that the dyes are potentially suitable for use in OL applications at 532 nm. There is a slight enhancement of the OL properties upon bromination, due to increased intersystem crossing to the triplet manifold, but the enhancement of the OL properties is less significant than has been observed with metal phthalocyanine complexes.
- Full Text:
- Date Issued: 2019
Effect of doping vs covalent linking of a low symmetry zinc phthalocyanine to silica nanoparticles on singlet oxygen production
- Peteni, Siwaphiwe, Nyokong, Tebello
- Authors: Peteni, Siwaphiwe , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187873 , vital:44705 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.029"
- Description: Tris[(4-(pyridin-4-ylthio)-2-thio-4-methylthiazol-5-yl)acetic acid phthalocyaninato] zinc (II) (3) was covalently linked to and doped onto SiNPs. An increase in triplet quantum yields for 3-SiNPs (linked) with decreasing lifetimes was observed. For 3-SiNPs (doped) there was a decrease in both the triplet quantum yield and lifetimes when compared to 3 alone. There was an increase in singlet oxygen quantum yields for 3-SiNPs (linked) compared to 3 from 0.67 to 0.80, while there was a decrease for 3-SiNPs (doped) to 0.25.
- Full Text:
- Date Issued: 2018
- Authors: Peteni, Siwaphiwe , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187873 , vital:44705 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.029"
- Description: Tris[(4-(pyridin-4-ylthio)-2-thio-4-methylthiazol-5-yl)acetic acid phthalocyaninato] zinc (II) (3) was covalently linked to and doped onto SiNPs. An increase in triplet quantum yields for 3-SiNPs (linked) with decreasing lifetimes was observed. For 3-SiNPs (doped) there was a decrease in both the triplet quantum yield and lifetimes when compared to 3 alone. There was an increase in singlet oxygen quantum yields for 3-SiNPs (linked) compared to 3 from 0.67 to 0.80, while there was a decrease for 3-SiNPs (doped) to 0.25.
- Full Text:
- Date Issued: 2018
Effect of gold nanoparticle shape on the photophysicochemical properties of sulphur containing metallophthalocyanines
- Dube, Edith, Nyokong, Tebello
- Authors: Dube, Edith , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187048 , vital:44559 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.12.091"
- Description: In this work tetrakise[(thiopheneethoxy) phthalocyaninato] zinc(II) (1), tetrakise[(thiopheneethoxy) phthalocyaninato] indium (II) chloride (2), tetrakis [(benzo [d]thiazol-2-yl phenoxy) phthalocyaninato] zinc(II) (3), and tetrakis [(benzo [d]thiazol-2-yl phenoxy)phthalocyaninato] indium (II) chloride (4) were linked to both gold nanospheres (AuNSs) and gold nanotriangles (AuNTs) via Au-S and Au-N (the latter for complexes 3 and 4 only) self assembly. The photophysicochemical behaviour of complexes and their conjugates were studied. The conjugates yielded improved triplet and singlet quantum yields, with nanospheres displaying better properties than nanotriangles. The conjugates with a benzothiazole phenoxy substituent also yielded better properties than their thiophene ethoxy counterpart. These conjugates especially those with a benzothiazole phenoxy substituent have potential as photosensitisers for photodynamic therapy applications.
- Full Text:
- Date Issued: 2019
- Authors: Dube, Edith , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187048 , vital:44559 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.12.091"
- Description: In this work tetrakise[(thiopheneethoxy) phthalocyaninato] zinc(II) (1), tetrakise[(thiopheneethoxy) phthalocyaninato] indium (II) chloride (2), tetrakis [(benzo [d]thiazol-2-yl phenoxy) phthalocyaninato] zinc(II) (3), and tetrakis [(benzo [d]thiazol-2-yl phenoxy)phthalocyaninato] indium (II) chloride (4) were linked to both gold nanospheres (AuNSs) and gold nanotriangles (AuNTs) via Au-S and Au-N (the latter for complexes 3 and 4 only) self assembly. The photophysicochemical behaviour of complexes and their conjugates were studied. The conjugates yielded improved triplet and singlet quantum yields, with nanospheres displaying better properties than nanotriangles. The conjugates with a benzothiazole phenoxy substituent also yielded better properties than their thiophene ethoxy counterpart. These conjugates especially those with a benzothiazole phenoxy substituent have potential as photosensitisers for photodynamic therapy applications.
- Full Text:
- Date Issued: 2019
Effect of gold nanoparticles shape and size on the photophysicochemical behaviour of symmetric and asymmetric zinc phthalocyanines
- Dube, Edith, Nyokong, Tebello
- Authors: Dube, Edith , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187569 , vital:44672 , xlink:href="https://doi.org/10.1016/j.jlumin.2018.09.063"
- Description: Glutathione (GSH) capped Au nanotriangles (AuNTs–GSH) and nanospheres (AuNSs–GSH) are covalently linked to symmetric Zn phthalocyanine (ZnPc) substituted with phenoxy propanoic acid substituents only (complex 1) and two asymmetric ZnPc, each containing one phenoxy propanoic acid and three benzothiazole phenoxy moieties (complex 2), and one phenoxy propanoic acid and no other ligands (complex 3). The photophysicochemical behaviour of Pc complexes and their conjugates were studied. All conjugates displayed improved triplet and singlet oxygen quantum yields with decreases in fluorescence quantum yields compared to their respective Pc complexes. The conjugates of asymmetric complexes 2 and 3, afforded much higher triplet and singlet oxygen quantum yields compared to the symmetric complex 1, and could serve as good candidates for photodynamic therapy
- Full Text:
- Date Issued: 2019
- Authors: Dube, Edith , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187569 , vital:44672 , xlink:href="https://doi.org/10.1016/j.jlumin.2018.09.063"
- Description: Glutathione (GSH) capped Au nanotriangles (AuNTs–GSH) and nanospheres (AuNSs–GSH) are covalently linked to symmetric Zn phthalocyanine (ZnPc) substituted with phenoxy propanoic acid substituents only (complex 1) and two asymmetric ZnPc, each containing one phenoxy propanoic acid and three benzothiazole phenoxy moieties (complex 2), and one phenoxy propanoic acid and no other ligands (complex 3). The photophysicochemical behaviour of Pc complexes and their conjugates were studied. All conjugates displayed improved triplet and singlet oxygen quantum yields with decreases in fluorescence quantum yields compared to their respective Pc complexes. The conjugates of asymmetric complexes 2 and 3, afforded much higher triplet and singlet oxygen quantum yields compared to the symmetric complex 1, and could serve as good candidates for photodynamic therapy
- Full Text:
- Date Issued: 2019
Effect of nature of nanoparticles on the photophysicochemical properties of asymmetrically substituted Zn phthalocyanines
- Magadla, Aviwe, Oluwole, David O, Britton, Jonathan, Nyokong, Tebello
- Authors: Magadla, Aviwe , Oluwole, David O , Britton, Jonathan , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234539 , vital:50206 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.043"
- Description: In this work, low symmetry Zn mono caffeic acid tri-tert butyl (1) and Zn monocarboxyphenoxy tri-(tert-butylphenoxyl) (2) phthalocyanines (Pcs) were covalently linked to amino (using glutathione, GSH, or 3-aminopropyl)triethoxysilane, APTES) functionalised nanoparticles. The nanoparticles are represented as: AgNPs-GSH, SiNPs-APTES, Fe3O4-Ag-SiNPs-APTES and Fe3O4-AgNPs-GSH). The photophysical and photochemical behaviour of the complexes 1 and 2 and their conjugates with nanoparticles were investigated in dimethyl sulfoxide. The conjugates of the Pc complexes with the NPs afforded increase in triplet quantum yields with corresponding decrease in fluorescence quantum yield compared to the Pc complexes alone. The conjugates of 1-AgNPs-GSH, 2-SiNPs-APTES and 2-Fe3O4-Ag-SiNPs-APTES showed higher singlet oxygen quantum yield values as compared to the Pc complexes alone.
- Full Text:
- Date Issued: 2018
- Authors: Magadla, Aviwe , Oluwole, David O , Britton, Jonathan , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234539 , vital:50206 , xlink:href="https://doi.org/10.1016/j.ica.2018.06.043"
- Description: In this work, low symmetry Zn mono caffeic acid tri-tert butyl (1) and Zn monocarboxyphenoxy tri-(tert-butylphenoxyl) (2) phthalocyanines (Pcs) were covalently linked to amino (using glutathione, GSH, or 3-aminopropyl)triethoxysilane, APTES) functionalised nanoparticles. The nanoparticles are represented as: AgNPs-GSH, SiNPs-APTES, Fe3O4-Ag-SiNPs-APTES and Fe3O4-AgNPs-GSH). The photophysical and photochemical behaviour of the complexes 1 and 2 and their conjugates with nanoparticles were investigated in dimethyl sulfoxide. The conjugates of the Pc complexes with the NPs afforded increase in triplet quantum yields with corresponding decrease in fluorescence quantum yield compared to the Pc complexes alone. The conjugates of 1-AgNPs-GSH, 2-SiNPs-APTES and 2-Fe3O4-Ag-SiNPs-APTES showed higher singlet oxygen quantum yield values as compared to the Pc complexes alone.
- Full Text:
- Date Issued: 2018
Effect of number of positive charges on the photophysical and photodynamic therapy activities of quarternary benzothiazole substituted zinc phthalocyanine
- Matshitse, Refilwe, Nwaji, Njemuwa, Mananga, Muthumuni, Prinsloo, Earl, Nyokong, Tebello
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Mananga, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187819 , vital:44700 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.08.033"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activity of quaternary benzothiazole substituted zinc phthalocyanine (2, containing two charges, and 3, containing four charges) are reported in this work. Furthermore, the activity of the synthesized complex was compared to non-quaternary derivative (1). Higher triplet and singlet oxygen quantum yields of 0.92 and 0.85, respectively, for quaternized complexes 2 and 3 compared to complex 1 alone. Complexes 1, 2 and 3 showed relatively no dark toxicity against the epithelial breast cancer cells with cell survival of above 90 ± 3%. The quaternary derivatives (2 and 3) showed superior PDT activity with 30% or less of viable cells at concentration of 50.0 μg/mL in comparison to complex 1 alone which further lay credence to the importance of quaternization in the enhancement of PDT activity.
- Full Text:
- Date Issued: 2018
- Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Mananga, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187819 , vital:44700 , xlink:href="https://doi.org/10.1016/j.jphotochem.2018.08.033"
- Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activity of quaternary benzothiazole substituted zinc phthalocyanine (2, containing two charges, and 3, containing four charges) are reported in this work. Furthermore, the activity of the synthesized complex was compared to non-quaternary derivative (1). Higher triplet and singlet oxygen quantum yields of 0.92 and 0.85, respectively, for quaternized complexes 2 and 3 compared to complex 1 alone. Complexes 1, 2 and 3 showed relatively no dark toxicity against the epithelial breast cancer cells with cell survival of above 90 ± 3%. The quaternary derivatives (2 and 3) showed superior PDT activity with 30% or less of viable cells at concentration of 50.0 μg/mL in comparison to complex 1 alone which further lay credence to the importance of quaternization in the enhancement of PDT activity.
- Full Text:
- Date Issued: 2018
Effect of oligomerization on the photochemical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
- Authors: Maree, M David , Nyokong, Tebello
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/291542 , vital:56885 , xlink:href="https://doi.org/10.1016/S1010-6030(01)00485-3"
- Description: The photochemical properties of silicon octaphenoxyphthalocyanines (SiOPPc) oligomerized were studied in dimethylsulfoxide (DMSO) solutions. Oligomers containing 2–5 and 9 SiOPPc rings linked with terephthalate linkages were synthesized. Singlet oxygen quantum yields were found to be in the range 0.11–0.34, and increased with the number of rings up to five rings, a decrease in the quantum yield was observed for nine rings. This is explained in terms of the high aggregation of the oligomer containing nine rings.
- Full Text:
- Date Issued: 2001
Effect of peripheral fused ring substitution on the optical spectroscopy and electronic structure of metal phthalocyanine complexes
- Chidawanyika, Wadzanai, Mack, John, Shimizu, Soji, Kobayashi, Nagao, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai , Mack, John , Shimizu, Soji , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263353 , vital:53620 , xlink:href="https://doi.org/10.1142/S1088424609001339"
- Description: In this paper the impact of peripheral substitution with a strongly withdrawing fused ring group on the optical spectroscopy of a metal phthalocyanine complex is analyzed. We report the synthesis of [9 (or 10), 16 (or 17), 23 (or 24)-tri-tert-butylimidophthalocyaninato]zinc(II) (ZnttbIPc), which should eventually prove to be a useful precursor for forming dimeric compounds. The electronic structure is analyzed through a detailed analysis of the UV-visible absorption and magnetic circular dichroism spectra and time-dependent density functional theory calculations. Other than a marked splitting of the Q band, the spectrum is broadly similar to that of ZnPc in terms of the main π → π* electronic bands. The vibrational bands differ markedly in the Q band region when an imido group is added to ligand periphery, relative to what is observed in the case of zinc mononaphthotribenzotetraazaporphyrin (Zn3B1N) with an additional fused benzene ring. The absorption and emission spectra lack mirror symmetry as is the case with ZnPc and thus provide possible evidence for a second set of electronic origins in the Q band region arising from n → π* rather then π → π* transitions.
- Full Text:
- Date Issued: 2009
- Authors: Chidawanyika, Wadzanai , Mack, John , Shimizu, Soji , Kobayashi, Nagao , Nyokong, Tebello
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/263353 , vital:53620 , xlink:href="https://doi.org/10.1142/S1088424609001339"
- Description: In this paper the impact of peripheral substitution with a strongly withdrawing fused ring group on the optical spectroscopy of a metal phthalocyanine complex is analyzed. We report the synthesis of [9 (or 10), 16 (or 17), 23 (or 24)-tri-tert-butylimidophthalocyaninato]zinc(II) (ZnttbIPc), which should eventually prove to be a useful precursor for forming dimeric compounds. The electronic structure is analyzed through a detailed analysis of the UV-visible absorption and magnetic circular dichroism spectra and time-dependent density functional theory calculations. Other than a marked splitting of the Q band, the spectrum is broadly similar to that of ZnPc in terms of the main π → π* electronic bands. The vibrational bands differ markedly in the Q band region when an imido group is added to ligand periphery, relative to what is observed in the case of zinc mononaphthotribenzotetraazaporphyrin (Zn3B1N) with an additional fused benzene ring. The absorption and emission spectra lack mirror symmetry as is the case with ZnPc and thus provide possible evidence for a second set of electronic origins in the Q band region arising from n → π* rather then π → π* transitions.
- Full Text:
- Date Issued: 2009
Effect of symmetry and metal nanoparticles on the photophysicochemical and photodynamic therapy properties of cinnamic acid zinc phthalocyanine
- Matlou, Gauta G, Managa, Muthumuni, Nyokong, Tebello
- Authors: Matlou, Gauta G , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187026 , vital:44557 , xlink:href="https://doi.org/10.1016/j.saa.2019.02.005"
- Description: In this study, a novel asymmetric cinnamic acid zinc phthalocyanine (ZnPc, 1) containing three tert-butyl substituents is reported. The asymmetric ZnPc (1) is further linked to amino functionalized magnetic nanoparticles (AMNPs) (1-AMNPs) and to cysteine functionalized silver nanoparticles (cys-AgNPs) (1-cys-AgNPs) through an amide bond. 1-AMNPs and 1-cys-AgNPs improved the triplet and singlet oxygen quantum yields of complex 1, this was also observed with the previously reported 2-AMNPs when compared to 2 while 3-AMNPs yielded an unexpected decrease in triplet quantum yield as compared to 3. The silver nanoparticles (1-cys-AgNPs) had a better effect on improving the singlet oxygen quantum yield of complex 1 than the magnetic nanoparticles (1- AMNPs). The Pcs and conjugates recorded low cell cytotoxicity in the dark and high photocytotoxicity against MCF-7 cells in-vitro. MCF-7 cell viabilities of less than 50% were recorded at 80 μg/mL making the Pcs and conjugates under study potential candidates for use as photosensitizers in cancer therapy.
- Full Text:
- Date Issued: 2019
- Authors: Matlou, Gauta G , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187026 , vital:44557 , xlink:href="https://doi.org/10.1016/j.saa.2019.02.005"
- Description: In this study, a novel asymmetric cinnamic acid zinc phthalocyanine (ZnPc, 1) containing three tert-butyl substituents is reported. The asymmetric ZnPc (1) is further linked to amino functionalized magnetic nanoparticles (AMNPs) (1-AMNPs) and to cysteine functionalized silver nanoparticles (cys-AgNPs) (1-cys-AgNPs) through an amide bond. 1-AMNPs and 1-cys-AgNPs improved the triplet and singlet oxygen quantum yields of complex 1, this was also observed with the previously reported 2-AMNPs when compared to 2 while 3-AMNPs yielded an unexpected decrease in triplet quantum yield as compared to 3. The silver nanoparticles (1-cys-AgNPs) had a better effect on improving the singlet oxygen quantum yield of complex 1 than the magnetic nanoparticles (1- AMNPs). The Pcs and conjugates recorded low cell cytotoxicity in the dark and high photocytotoxicity against MCF-7 cells in-vitro. MCF-7 cell viabilities of less than 50% were recorded at 80 μg/mL making the Pcs and conjugates under study potential candidates for use as photosensitizers in cancer therapy.
- Full Text:
- Date Issued: 2019
Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres
- De Schoenmaker, Bert, Van de Schueren, Lien, Zugle, Ruphino, Goethals, Annelies, Westbroek, Philippe, Kiekens, Paul, Nyokong, Tebello, De Clerck, Karen
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
Effect of ultrasonic frequency and power on the sonodynamic therapy activity of cationic Zn (II) phthalocyanines
- Nene, Lindokuhle C, Sindelo, Azole, Britton, Jonathan, Nyokong, Tebello
- Authors: Nene, Lindokuhle C , Sindelo, Azole , Britton, Jonathan , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185737 , vital:44419 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111397"
- Description: We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (Par I (1 MHz, 1 W cm−2), Par II (1 MHz, 2 W cm−2), Par III (3 MHz, 1 W cm−2) and Par IV (3 MHz, 2 W cm−2)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV–vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.
- Full Text:
- Date Issued: 2021
- Authors: Nene, Lindokuhle C , Sindelo, Azole , Britton, Jonathan , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185737 , vital:44419 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111397"
- Description: We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (Par I (1 MHz, 1 W cm−2), Par II (1 MHz, 2 W cm−2), Par III (3 MHz, 1 W cm−2) and Par IV (3 MHz, 2 W cm−2)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV–vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.
- Full Text:
- Date Issued: 2021
Effects of analytes on the fluorescence properties of CdTe@ ZnS quantum dots decorated with cobalt tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
- Date Issued: 2014
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189829 , vital:44935 , xlink:href="https://doi.org/10.1016/j.jlumin.2013.09.079"
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe.
- Full Text:
- Date Issued: 2014
Effects of analytes on the fluorescence properties of CdTe@ZnS quantum dots decorated with cobalt tetraamino-phthalocyanine
- Adegoke, Oluwasesan, Nyokong, Tebello
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7315 , http://hdl.handle.net/10962/d1020541
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe. , Original publication is available at http://dx.doi.org/10.1016/j.jlumin.2013.09.079
- Full Text: false
- Authors: Adegoke, Oluwasesan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7315 , http://hdl.handle.net/10962/d1020541
- Description: In this work, we have carried out an investigation on the effects of different biologically active analytes on the fluorescence response of glutathione-capped CdTe@ZnS quantum dots (QDs)-colbalt tetraamino-phthalocyanine nanoconjugate system. Firstly, fluorescence quenching occurred. Experimental results showed that some analytes either “turned on”, others further quenched or showed no effect on the fluorescence emission of the nanoprobe. , Original publication is available at http://dx.doi.org/10.1016/j.jlumin.2013.09.079
- Full Text: false
Effects of axial ligands on the photophysical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello, Suhling, Klaus, Phillips, David
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
Effects of central metal on the photophysical and photochemical properties of non-transition metal sulfophthalocyanine
- Ogunsipe, Abimbola, Nyokong, Tebello
- Authors: Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289337 , vital:56623 , xlink:href="https://doi.org/10.1142/S1088424605000186"
- Description: The photophysical and photochemical properties and quenching (by 1,4-benzoquinone) of metallophthalocyanine sulfonates of aluminium (AlPcSmix), zinc (ZnPcSmix), silicon (SiPcSmix), germanium (GePcSmix) and tin (SnPcSmix) are presented. The quantum yield values of fluorescence (ΦF), triplet state (ΦT), singlet oxygen (ΦΔ) and photodegradation (Φd) were determined and the observed trends in their variation among the complexes discussed in terms of aggregation and the heavy atom effect. 1,4-benzoquinone effectively quenched the fluorescence of the complexes. Quenching analyses gave positive deviations from Stern-Volmer behavior, suggesting the existence of static quenching in addition to dynamic quenching. The static and dynamic components of the quenching were separated using a modified Stern-Volmer equation and the “sphere of action quenching model”. The quenching constant was found to be a function of the radius of the central metal ion.
- Full Text:
- Date Issued: 2005
- Authors: Ogunsipe, Abimbola , Nyokong, Tebello
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289337 , vital:56623 , xlink:href="https://doi.org/10.1142/S1088424605000186"
- Description: The photophysical and photochemical properties and quenching (by 1,4-benzoquinone) of metallophthalocyanine sulfonates of aluminium (AlPcSmix), zinc (ZnPcSmix), silicon (SiPcSmix), germanium (GePcSmix) and tin (SnPcSmix) are presented. The quantum yield values of fluorescence (ΦF), triplet state (ΦT), singlet oxygen (ΦΔ) and photodegradation (Φd) were determined and the observed trends in their variation among the complexes discussed in terms of aggregation and the heavy atom effect. 1,4-benzoquinone effectively quenched the fluorescence of the complexes. Quenching analyses gave positive deviations from Stern-Volmer behavior, suggesting the existence of static quenching in addition to dynamic quenching. The static and dynamic components of the quenching were separated using a modified Stern-Volmer equation and the “sphere of action quenching model”. The quenching constant was found to be a function of the radius of the central metal ion.
- Full Text:
- Date Issued: 2005
Effects of charge on the photophysicochemical properties of zinc phthalocyanine derivatives doped onto silica nanoparticles
- Peteni, Siwaphiwe, Sekhosana, Kutloano E, Britton, Jonathan, Nyokong, Tebello
- Authors: Peteni, Siwaphiwe , Sekhosana, Kutloano E , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188159 , vital:44728 , xlink:href="https://doi.org/10.1016/j.poly.2017.09.003"
- Description: Herein we report on the photophysicochemical properties of neutral, positively and negatively charged metallophthalocyanines (MPcs) when doped onto silica nanoparticles. The MPcs are: unsubstituted ZnPc (complex 1, neutral), Zn tetraaminophenoxy phthalocyanine (ZnTAPhPc, complex 2, neutral), tetrakis[4-(iodo-N-methylpyridinium)thio] phthalocyanine (ZnTMPyPc, complex 3, cationic), and Zn tetra sulfophenoxy phthalocyanine (ZnTSPhPc, complex 4, anionic). Following doping onto SiNPs, the triplet quantum yields increased for neutral complex 1 and positively charged complex 3. However, singlet oxygen quantum yields increased for positively charged 3 (in 3-SiNPs) and the negatively charge 4 (in 4-SiNPs) and not for complex 1 (in 1-SiNPs), compared to Pcs alone, due to the screening effect.
- Full Text:
- Date Issued: 2017
- Authors: Peteni, Siwaphiwe , Sekhosana, Kutloano E , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188159 , vital:44728 , xlink:href="https://doi.org/10.1016/j.poly.2017.09.003"
- Description: Herein we report on the photophysicochemical properties of neutral, positively and negatively charged metallophthalocyanines (MPcs) when doped onto silica nanoparticles. The MPcs are: unsubstituted ZnPc (complex 1, neutral), Zn tetraaminophenoxy phthalocyanine (ZnTAPhPc, complex 2, neutral), tetrakis[4-(iodo-N-methylpyridinium)thio] phthalocyanine (ZnTMPyPc, complex 3, cationic), and Zn tetra sulfophenoxy phthalocyanine (ZnTSPhPc, complex 4, anionic). Following doping onto SiNPs, the triplet quantum yields increased for neutral complex 1 and positively charged complex 3. However, singlet oxygen quantum yields increased for positively charged 3 (in 3-SiNPs) and the negatively charge 4 (in 4-SiNPs) and not for complex 1 (in 1-SiNPs), compared to Pcs alone, due to the screening effect.
- Full Text:
- Date Issued: 2017
Effects of covalent versus non-covalent interactions on the electrocatalytic behavior of tetracarboxyphenoxyphthalocyanine in the presence of multi-walled carbon nanotubes
- Shumba, Munyaradzi S, Nyokong, Tebello
- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188271 , vital:44740 , xlink:href="https://doi.org/10.1080/00958972.2017.1303679"
- Description: Tetracarboxyphenoxy phthalocyanine was covalently linked to multi-walled carbon nanotubes and the conjugate was used for modification of glassy carbon electrodes for the detection of hydrogen peroxide. The electrocatalytic behavior was examined by cyclic voltammetry, square wave voltammetry, and rotating disk electrode. The results show that covalent linking is attractive in terms of high detecting currents, low overpotential, and high catalytic rate constants. Very low detection limits were observed with CoTCPhPc-DAMN-MWCNT(linked)-GCE at 0.33 nM. The resulting catalytic rate constant was 1.1 × 103 M−1s−1.
- Full Text:
- Date Issued: 2017
- Authors: Shumba, Munyaradzi S , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188271 , vital:44740 , xlink:href="https://doi.org/10.1080/00958972.2017.1303679"
- Description: Tetracarboxyphenoxy phthalocyanine was covalently linked to multi-walled carbon nanotubes and the conjugate was used for modification of glassy carbon electrodes for the detection of hydrogen peroxide. The electrocatalytic behavior was examined by cyclic voltammetry, square wave voltammetry, and rotating disk electrode. The results show that covalent linking is attractive in terms of high detecting currents, low overpotential, and high catalytic rate constants. Very low detection limits were observed with CoTCPhPc-DAMN-MWCNT(linked)-GCE at 0.33 nM. The resulting catalytic rate constant was 1.1 × 103 M−1s−1.
- Full Text:
- Date Issued: 2017
Effects of differently shaped silver nanoparticles on the photophysics of pyridylsulfanyl-substituted phthalocyanines
- D’Souza, Sarah, Mashazi, Philani N, Britton, Jonathan, Nyokong, Tebello
- Authors: D’Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7290 , http://hdl.handle.net/10962/d1020353
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.06.038
- Full Text: false
- Authors: D’Souza, Sarah , Mashazi, Philani N , Britton, Jonathan , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7290 , http://hdl.handle.net/10962/d1020353
- Description: This paper reports on the photophysical behavior of (2-pyridylsulfanyl)phthalocyaninato zinc(II) and 2,9(10),16(17),23(24)-tetra-(2-pyridylsulfanyl)phthalocyaninato zinc(II) in the presence of differently shaped silver nanoparticles (nanospheres, nanotriangles and nanoflowers). The presence of shaped nanoparticles increased both triplet quantum yields and lifetimes of the tetra-substituted mercaptopyridine zinc phthalocyanine in DMSO. It is apparent from this work that the shape of the silver nanoparticle used is of little consequence in influencing photophysical behavior of the phthalocyanines. , Original publication is available at http://dx.doi.org/10.1016/j.poly.2015.06.038
- Full Text: false