Cobalt Phthalocyanine Molecular Electrode for the Electrochemical Investigation of the Release of Glutathione upon Copper-Catalyzed Decomposition of S-Nitrosoglutathione
- Sehlotho, Nthapo, Griveau, Sophie, Nyokong, Tebello, Bedioui, Fethi
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281201 , vital:55701 , xlink:href="https://doi.org/10.1002/elan.200603656"
- Description: Decomposition of S-nitrosoglutathione (GSNO) in phosphate buffer solution at physiological pH 7.4 in the presence of cuprous ion as a catalyst and sodium borohydride as a reducing agent is analyzed by observing the transient apparition of reduced glutathione GSH through its electrooxidation. Transient formation of GSH, upon decomposition of 1 mM GSNO in presence of 0.025 mM Cu(NO3)2 and 1 mM NaBH4 was detected by using an ordinary pyrolytic graphite electrode modified with an adsorbed monolayer of cobalt phthalocyanine at 0 V vs. SCE.
- Full Text:
- Date Issued: 2007
- Authors: Sehlotho, Nthapo , Griveau, Sophie , Nyokong, Tebello , Bedioui, Fethi
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281201 , vital:55701 , xlink:href="https://doi.org/10.1002/elan.200603656"
- Description: Decomposition of S-nitrosoglutathione (GSNO) in phosphate buffer solution at physiological pH 7.4 in the presence of cuprous ion as a catalyst and sodium borohydride as a reducing agent is analyzed by observing the transient apparition of reduced glutathione GSH through its electrooxidation. Transient formation of GSH, upon decomposition of 1 mM GSNO in presence of 0.025 mM Cu(NO3)2 and 1 mM NaBH4 was detected by using an ordinary pyrolytic graphite electrode modified with an adsorbed monolayer of cobalt phthalocyanine at 0 V vs. SCE.
- Full Text:
- Date Issued: 2007
Photodynamic antimicrobial action of asymmetrical porphyrins functionalized silver-detonation nanodiamonds nanoplatforms for the suppression of Staphylococcus aureus planktonic cells and biofilms
- Openda, Yolande I, Ngoy, Bokolombe P, Nyokong, Tebello
- Authors: Openda, Yolande I , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190544 , vital:45004 , xlink:href="https://doi.org/10.3389/fchem.2021.628316"
- Description: New asymmetrical porphyrin derivatives containing a p-hydroxyphenyl moiety and p-acetylphenyl moieties along with their functionalized silver-detonation nanodiamonds nanohybrids were characterized and their photophysicochemical properties were established. The study provides evidence that the metalated porphyrin derivatives were red-shifted in absorption wavelength and possessed high singlet oxygen quantum yield comparative to the unmetalated core, thus making them suitable agents for photodynamic antimicrobial chemotherapy. As a result of conjugation to detonation nanodiamonds and silver nanoparticles, these compounds proved to be more effective as they exhibited stronger antibacterial and anti-biofilm activities on the multi-drug resistant S. aureus strain due to synergetic effect, compared to Ps alone. This suggests that the newly prepared nanohybrids could be used as a potential antimicrobial agent in the treatment of biofilms caused by S. aureus strain.
- Full Text:
- Date Issued: 2021
- Authors: Openda, Yolande I , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190544 , vital:45004 , xlink:href="https://doi.org/10.3389/fchem.2021.628316"
- Description: New asymmetrical porphyrin derivatives containing a p-hydroxyphenyl moiety and p-acetylphenyl moieties along with their functionalized silver-detonation nanodiamonds nanohybrids were characterized and their photophysicochemical properties were established. The study provides evidence that the metalated porphyrin derivatives were red-shifted in absorption wavelength and possessed high singlet oxygen quantum yield comparative to the unmetalated core, thus making them suitable agents for photodynamic antimicrobial chemotherapy. As a result of conjugation to detonation nanodiamonds and silver nanoparticles, these compounds proved to be more effective as they exhibited stronger antibacterial and anti-biofilm activities on the multi-drug resistant S. aureus strain due to synergetic effect, compared to Ps alone. This suggests that the newly prepared nanohybrids could be used as a potential antimicrobial agent in the treatment of biofilms caused by S. aureus strain.
- Full Text:
- Date Issued: 2021
Synthesis and photophysical properties of 1, 1′-binaphthol substituted phthalocyanines
- Canlica, Meylude, Nyokong, Tebello
- Authors: Canlica, Meylude , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249148 , vital:51782 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.034"
- Description: We report on the synthesis, characterization and photophysical properties of a new symmetrically tetra substituted {at non-peripheral positions with tetra(1,1′-bi-binaphtoxy)} phthalocyanines containing H2, Mg(II), Al(III)Cl, Si(IV)Cl2 in the central cavity. The synthesized compounds were characterized by the elemental analyses, UV–Vis, FT-IR and 1H NMR spectroscopies. The fluorescence quantum yields, triplet quantum yields and lifetimes of the newly synthesized H2, Mg, Al, and Si phthalocyanines were explored. Triplet quantum yields ranged from 0.24 to 0.54. The triplet lifetime for the silicon phthalocyanine derivative was the highest ever reported for a phthalocyanine (∼3.5 ms).
- Full Text:
- Date Issued: 2010
- Authors: Canlica, Meylude , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249148 , vital:51782 , xlink:href="https://doi.org/10.1016/j.ica.2010.06.034"
- Description: We report on the synthesis, characterization and photophysical properties of a new symmetrically tetra substituted {at non-peripheral positions with tetra(1,1′-bi-binaphtoxy)} phthalocyanines containing H2, Mg(II), Al(III)Cl, Si(IV)Cl2 in the central cavity. The synthesized compounds were characterized by the elemental analyses, UV–Vis, FT-IR and 1H NMR spectroscopies. The fluorescence quantum yields, triplet quantum yields and lifetimes of the newly synthesized H2, Mg, Al, and Si phthalocyanines were explored. Triplet quantum yields ranged from 0.24 to 0.54. The triplet lifetime for the silicon phthalocyanine derivative was the highest ever reported for a phthalocyanine (∼3.5 ms).
- Full Text:
- Date Issued: 2010
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
Ball-type phthalocyanines and reduced graphene oxide nanoparticles as separate and combined corrosion inhibitors of aluminium in HCl
- Nnaji, Nnaemeka, Nawji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Nawji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185421 , vital:44385 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130279"
- Description: Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron microscopy revealed effective metal surface protection by the inhibitors by formation of protective films.
- Full Text:
- Date Issued: 2021
- Authors: Nnaji, Nnaemeka , Nawji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185421 , vital:44385 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.130279"
- Description: Corrosion inhibition performances and adsorption behaviour at the aluminum-HCl solution interface were investigated for reduced graphene oxide nanosheets (rGONS), tetrakis-[4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)] (diphthalocyaninato gallium (III) chloride) (2) and tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyaninato gallium(III) chloride) (1). Corrosion inhibition effects of rGONS, 1 and 2 were evaluated alone and in combination in 1.0 M hydrochloric acid solution using electrochemical techniques. The mechanism of aluminum corrosion inhibition revealed predominantly anodic character for rGONS and predominantly cathodic character for 1, 2, and conjugates with rGONS . The polarization technique gave inhibition efficiency values of 96.5% and 96.9% respectively for 1 and 2, which increased in the presence of rGONS to 97.4% and 98.1%, respectively, for the highest concentrations of 1 and 2. Scanning electron microscopy revealed effective metal surface protection by the inhibitors by formation of protective films.
- Full Text:
- Date Issued: 2021
Photoelectrochemical characterization of electrodeposited ZnO thin films sensitized by octacarboxymetallophthalocyanine derivatives
- Idowu, Mopelola, Loewenstein, Thomas, Hastall, Andreas, Nyokong, Tebello, Schlettwein, Derck
- Authors: Idowu, Mopelola , Loewenstein, Thomas , Hastall, Andreas , Nyokong, Tebello , Schlettwein, Derck
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262655 , vital:53541 , xlink:href="https://doi.org/10.1142/S1088424610001854"
- Description: Hybrid thin films of crystalline zinc oxide (ZnO) modified by different octacarboxymetallophthalocyanines (MOCPc) were prepared by the readsorption method. Homogeneously blue or green thin films were formed. The photoelectrochemical characteristics of the electrodes were studied by time-resolved photocurrent measurements. Zinc(II) 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine (ZnOCPc) showed considerably large quantum efficiency in sensitization of ZnO, one of the highest quantum efficiencies obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films.
- Full Text:
- Date Issued: 2010
- Authors: Idowu, Mopelola , Loewenstein, Thomas , Hastall, Andreas , Nyokong, Tebello , Schlettwein, Derck
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262655 , vital:53541 , xlink:href="https://doi.org/10.1142/S1088424610001854"
- Description: Hybrid thin films of crystalline zinc oxide (ZnO) modified by different octacarboxymetallophthalocyanines (MOCPc) were prepared by the readsorption method. Homogeneously blue or green thin films were formed. The photoelectrochemical characteristics of the electrodes were studied by time-resolved photocurrent measurements. Zinc(II) 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine (ZnOCPc) showed considerably large quantum efficiency in sensitization of ZnO, one of the highest quantum efficiencies obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films.
- Full Text:
- Date Issued: 2010
Asymmetrical zinc phthalocyanine conjugated to various nanomaterials for applications in phototransformation of organic pollutants and photoinactivation of bacteria
- Mgidlana, Sithi, Openda, Yolande Ikala, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360344 , vital:65081 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.134850"
- Description: Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.
- Full Text:
- Date Issued: 2023
- Authors: Mgidlana, Sithi , Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360344 , vital:65081 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.134850"
- Description: Zinc phthalocyanine (ZnPc) complexes are linked to metallic nanoparticles covalently via amide and ester bonds. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, CoWO4 and Ag-Fe3O4 nanoparticles are evaluated for photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the prepared phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria. The results indicate that Ag2WO4 based nanoconjugates exhibit high antimicrobial activity with higher log reduction compared to NiWO4, CoWO4 and Ag-Fe3O4 based materials.
- Full Text:
- Date Issued: 2023
Synthetic pathways to water-soluble phthalocyanines and close analogs
- Dumoulin, Fabienne, Durmus, Mahmut, Ahsen, Vefa, Nyokong, Tebello
- Authors: Dumoulin, Fabienne , Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249082 , vital:51776 , xlink:href="https://doi.org/10.1016/j.ccr.2010.05.002"
- Description: The different types of water-soluble phthalocyanines are presented and their synthesis is reviewed.
- Full Text:
- Date Issued: 2010
- Authors: Dumoulin, Fabienne , Durmus, Mahmut , Ahsen, Vefa , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249082 , vital:51776 , xlink:href="https://doi.org/10.1016/j.ccr.2010.05.002"
- Description: The different types of water-soluble phthalocyanines are presented and their synthesis is reviewed.
- Full Text:
- Date Issued: 2010
The effect of structure on the electrochemical properties of 14 marine pyrroloquinoline metabolites
- Antunes, Edith M, Maree, Suzanne E, Nyokong, Tebello, Davies-Coleman, Mike T, Maree, M David
- Authors: Antunes, Edith M , Maree, Suzanne E , Nyokong, Tebello , Davies-Coleman, Mike T , Maree, M David
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286126 , vital:56242 , xlink:href="https://doi.org/10.3184/030823405775146915"
- Description: The electrochemical properties of 14 structurally related pyrroloquinoline metabolites (compounds 1–14) isolated from marine sponges were studied in pH-varied experiments using cyclic and square wave voltammetry. In general both substitution patterns and pH were observed to influence the reduction potentials of these molecules.
- Full Text:
- Date Issued: 2005
- Authors: Antunes, Edith M , Maree, Suzanne E , Nyokong, Tebello , Davies-Coleman, Mike T , Maree, M David
- Date: 2005
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286126 , vital:56242 , xlink:href="https://doi.org/10.3184/030823405775146915"
- Description: The electrochemical properties of 14 structurally related pyrroloquinoline metabolites (compounds 1–14) isolated from marine sponges were studied in pH-varied experiments using cyclic and square wave voltammetry. In general both substitution patterns and pH were observed to influence the reduction potentials of these molecules.
- Full Text:
- Date Issued: 2005
Fabrication of electrospun fibers from a porphyrin linked to polyacrylonitrile polymer for photocatalytic transformation of phenols
- Jones, Ben, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Jones, Ben , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186196 , vital:44472 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128191"
- Description: A novel mono-porphyrin (2) was employed for the photodegradation of 4-chlorophenol and 4-n-nonylphenol at pH 10.60. A partially modified polyacrylonitrile (PAN) polymer was utilized only as a support system for the photosensitiser to allow the formation of a covalent linkage. Complex 2 showed singlet oxygen values of 0.70 in dimethyl formamide and when conjugated (2-PAN) showed 0.39 in water. When employed against 4-chlorophenol a degradation efficiency (η) of 29.1% was achieved at 0.20 mol L−1 over a period of 10 min. When employed against 4-n-nonylphenol we obtained a η of 26.7% at 0.17 mol L−1 over a period of 10 min.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Ben , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186196 , vital:44472 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128191"
- Description: A novel mono-porphyrin (2) was employed for the photodegradation of 4-chlorophenol and 4-n-nonylphenol at pH 10.60. A partially modified polyacrylonitrile (PAN) polymer was utilized only as a support system for the photosensitiser to allow the formation of a covalent linkage. Complex 2 showed singlet oxygen values of 0.70 in dimethyl formamide and when conjugated (2-PAN) showed 0.39 in water. When employed against 4-chlorophenol a degradation efficiency (η) of 29.1% was achieved at 0.20 mol L−1 over a period of 10 min. When employed against 4-n-nonylphenol we obtained a η of 26.7% at 0.17 mol L−1 over a period of 10 min.
- Full Text:
- Date Issued: 2020
The effect of the cobalt and manganese central metal ions on the nonlinear optical properties of tetra (4-propargyloxyphenoxy) phthalocyanines
- Mwanza, Daniel, Louzada, Marcel, Britton, Jonathan, Sekhosana, Kutloano E, Khene, Samson M, Nyokong, Tebello, Mashazi, Philani N
- Authors: Mwanza, Daniel , Louzada, Marcel , Britton, Jonathan , Sekhosana, Kutloano E , Khene, Samson M , Nyokong, Tebello , Mashazi, Philani N
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233357 , vital:50083 , xlink:href="https://doi.org/10.1039/C8NJ00748A"
- Description: The metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (Mn(OAc)TPrOPhOPc) tetra propargyloxyphenoxy phthalocyanines were evaluated for their potential as optical limiting materials. The effect of the substituents and the central metal ions on the nonlinear optical properties was evaluated. The metal-free phthalocyanine exhibited better nonlinear optical properties when compared to the cobalt and manganese complexes owing to the metal ions quenching the excited state due to their half-filled d-orbitals. The nonlinear absorption coefficient (βeff, ×10−5 m MW−1) followed the trend of H2TPrOPhOPc > CoTPrOPhOPc > Mn(OAc)TPrOPhOPc. The values βeff (×10−5 m MW−1) using 532 nm Nd:YAG (560 nm monochromatic Ekspla) laser sources were 23.5 > 14.3 > 9.20 (14.4). The second-order nonlinear coefficient obtained using density functional theory calculations, the theoretical hyper-Rayleigh scattering (βHRS, ×10−28 esu), showed the decreasing trend for H2TPrOPhOPc (2.28) > CoTPrOPhOPc (2.10) > Mn(OAc)TPrOPhOPc (1.86). The 4-(propargyloxy)phenoxy substituents enhanced the optical limiting properties of the synthesized phthalocyanines.
- Full Text:
- Date Issued: 2018
- Authors: Mwanza, Daniel , Louzada, Marcel , Britton, Jonathan , Sekhosana, Kutloano E , Khene, Samson M , Nyokong, Tebello , Mashazi, Philani N
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233357 , vital:50083 , xlink:href="https://doi.org/10.1039/C8NJ00748A"
- Description: The metal-free (H2TPrOPhOPc), cobalt (CoTPrOPhOPc) and manganese (Mn(OAc)TPrOPhOPc) tetra propargyloxyphenoxy phthalocyanines were evaluated for their potential as optical limiting materials. The effect of the substituents and the central metal ions on the nonlinear optical properties was evaluated. The metal-free phthalocyanine exhibited better nonlinear optical properties when compared to the cobalt and manganese complexes owing to the metal ions quenching the excited state due to their half-filled d-orbitals. The nonlinear absorption coefficient (βeff, ×10−5 m MW−1) followed the trend of H2TPrOPhOPc > CoTPrOPhOPc > Mn(OAc)TPrOPhOPc. The values βeff (×10−5 m MW−1) using 532 nm Nd:YAG (560 nm monochromatic Ekspla) laser sources were 23.5 > 14.3 > 9.20 (14.4). The second-order nonlinear coefficient obtained using density functional theory calculations, the theoretical hyper-Rayleigh scattering (βHRS, ×10−28 esu), showed the decreasing trend for H2TPrOPhOPc (2.28) > CoTPrOPhOPc (2.10) > Mn(OAc)TPrOPhOPc (1.86). The 4-(propargyloxy)phenoxy substituents enhanced the optical limiting properties of the synthesized phthalocyanines.
- Full Text:
- Date Issued: 2018
Electrochemical, spectroscopic and microscopic studies of new manganese phthalocyanine complexes in solution and as self-assembled monolayers on gold
- Coates, Megan, Antunes, Edith M, Nyokong, Tebello
- Authors: Coates, Megan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261144 , vital:53363 , xlink:href="https://doi.org/10.1142/S1088424610002471"
- Description: Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
- Full Text:
- Date Issued: 2010
- Authors: Coates, Megan , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261144 , vital:53363 , xlink:href="https://doi.org/10.1142/S1088424610002471"
- Description: Four new manganese(III) phthalocyanines (3a–d), octasubstituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups, respectively, were synthesized. Their specific electrochemical, spectroscopic and microscopic properties in solution and as self-assembled monolayers on gold were characterized. The UV-vis spectra confirmed red-shifted Q bands for all the complexes, due to the effect of the central metal and the electron-donating substituents. Three redox couples were visible during cyclic voltammetry studies for the four complexes, and spectroelectrochemistry confirmed the couples as corresponding to MnIIIPc-2/MnIIPc-2 (II) (metal reduction), MnIIPc-2/MnIIPc-3 (III) (ring reduction) and MnIIIPc-1/MnIIIPc-2 (I) (ring oxidation). Electrochemistry was also used to determine the blocking characteristics of the MnPc self-assembled monolayers on gold, which proved to be highly dependent on the type of substituent. Other methods of characterization included Raman spectroscopy, atomic force and scanning electrochemical microscopy analyses of the SAMs.
- Full Text:
- Date Issued: 2010
Photophysical behavior and photodynamic therapy activity of conjugates of zinc monocarboxyphenoxy phthalocyanine with human serum albumin and chitosan
- Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188497 , vital:44759 , xlink:href="https://doi.org/10.1016/j.saa.2016.09.032"
- Description: Zincmonocarboxyphenoxy phthalocyanine (ZnMCPPc) was linked to human serum albumin (HSA) and chitosan via amide bond formation. The photophysical behavior and photodynamic therapy (PDT) activity (against human breast adenocarcinoma cell line (MCF-7 cells) of ZnMCPPc alone and its conjugates were investigated. The conjugates showed improved fluorescence, triplet and singlet oxygen quantum yields when compared to ZnMCPPc alone. The in vitro dark cytotoxicity and PDT studies were carried out at a dose of 3.6 μg/mL to 57.1 μg/mL. The in vitro dark cytotoxicity studies of ZnMCPPc showed cell viability more than 50% at 28.6 μg/mL and 57.1 μg/mL, while the conjugates showed > 50% in all their tested concentrations (3.6 to 57.1) μg/mL. Thus, conjugation of ZnMCPPc to HSA and chitosan improves its dark cytotoxicity, an important criteria for molecules meant for photodynamic therapy. Complex 1 showed the most efficacious PDT activity with cell viability more than 50% at concentration range of (14.3 to 57.1) μg/mL in comparison to the conjugates which only showed more than 50% cell viability at 28.6 μg/mL and 57.1 μg/mL for 1-HSA and 57.1 μg/mL for 1-Chitosan.
- Full Text:
- Date Issued: 2017
Adsorption and separation of platinum and palladium by polyamine functionalized polystyrene-based beads and nanofibers
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Kempgens, Pierre F M, Antunes, Edith M, Torto, Nelson, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Kempgens, Pierre F M , Antunes, Edith M , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241694 , vital:50961 , xlink:href="https://doi.org/10.1016/j.mineng.2013.06.006"
- Description: Adsorption and separation of platinum and palladium chlorido species (PtCl62- and PdCl42-) on polystyrene beads as well as nanofibers functionalized with ammonium centres based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tris-(2-aminoethyl)amine (TAEA) are described. The functionalized sorbent materials were characterized by microanalysis, SEM, XPS, BET and FTIR. The surface area of the functionalized fibers was in the range 69–241 m2/g while it was 73–107 m2/g for the beads. The adsorption and loading capacities of the sorption materials were investigated using both the batch and column studies at 1 M HCl concentration. The adsorption studies for both PtCl62- and PdCl42- on the different sorbent materials fit the Langmuir isotherm with R2 values >0.99. The highest loading capacity of Pt and Pd were 7.4 mg/g and 4.3 mg/g respectively for the nanofiber sorbent material based on ethylenediamine (EDA) while the beads with ethylenediamine (EDA) gave 1.0 mg/g and 0.2 mg/g for Pt and Pd respectively. Metals loaded on the sorbent materials were recovered by using 3% m/v thiourea solution as the eluting agent with quantitative desorption efficiency under the selected experimental conditions. Separation of platinum from palladium was partially achieved by selective stripping of PtCl62- with 0.5 M of NaClO4 in 1.0 M HCl while PdCl42- was eluted with 0.5 M thiourea in 1.0 M HCl. Separation of platinum from iridium and rhodium under 1 M HCl concentration was successful on triethylenetriamine (TETA)-functionalized Merrifield beads. This material (M-TETA) showed selectivity for platinum albeit the low loading capacity.
- Full Text:
- Date Issued: 2013
The renaissance in optical spectroscopy of phthalocyanines and other tetraazaporphyrins
- Nyokong, Tebello, Isago, Hiroaki
- Authors: Nyokong, Tebello , Isago, Hiroaki
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
- Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
- Full Text:
- Date Issued: 2004
- Authors: Nyokong, Tebello , Isago, Hiroaki
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289388 , vital:56628 , xlink:href="https://doi.org/10.1142/S1088424604000453"
- Description: Spectral properties of metallophthalocyanines and other tetraazaporphyrins are governed mainly by the Q band which originates from the π-π* transitions within the ring. The position and intensity of the Q band is important in tailoring new phthalocyanine derivatives for particular applications. Aggregation, the nature of the central metal, π conjugation, symmetry of the molecules, and axial, peripheral or non-peripheral substitutions affect the spectra and hence the properties of the phthalocyanine molecule. This review gives a brief outline on how optical spectroscopy provides useful informations on molecular and electronic structures, chemistry and physics of phthalocyanines and other tetraazaporphyrins.
- Full Text:
- Date Issued: 2004
Trends in the optical and redox properties of tetraphenyltetraphenanthroporphyrins
- Mack, John, Lobb, Kevin, Nyokong, Tebello, Shen, Zhen, Kobayashi, Nagao
- Authors: Mack, John , Lobb, Kevin , Nyokong, Tebello , Shen, Zhen , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245809 , vital:51407 , xlink:href="https://doi.org/10.1142/S1088424612500885"
- Description: The results of TD-DFT calculations for a series of tetraaryltetraphenanthroporphyrins containing para-substituents with differing electron donating and accepting properties are compared to the observed optical and redox properties and Michl's perimeter model is used as a conceptual framework for analyzing the results.
- Full Text:
- Date Issued: 2012
- Authors: Mack, John , Lobb, Kevin , Nyokong, Tebello , Shen, Zhen , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245809 , vital:51407 , xlink:href="https://doi.org/10.1142/S1088424612500885"
- Description: The results of TD-DFT calculations for a series of tetraaryltetraphenanthroporphyrins containing para-substituents with differing electron donating and accepting properties are compared to the observed optical and redox properties and Michl's perimeter model is used as a conceptual framework for analyzing the results.
- Full Text:
- Date Issued: 2012
A study on the morphology of thin copper films on para-aramid yarns and their influence on the yarn’s electro-conductive and mechanical properties
- Schwarz, Anne, Hakuzimana, Jean, Westbroek, Philippe, Mey, Gilbert De, Priniotakis, Georgios, Nyokong, Tebello, Langenhove, Lieva Van
- Authors: Schwarz, Anne , Hakuzimana, Jean , Westbroek, Philippe , Mey, Gilbert De , Priniotakis, Georgios , Nyokong, Tebello , Langenhove, Lieva Van
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243487 , vital:51157 , xlink:href="https://doi.org/10.1177/0040517511431291"
- Description: The latest technological advances in new materials and devices enabled wearable systems to be created by utilizing textile solutions. These solutions require electro-conductive yarns as a basic component. Although the production of electroconductive yarn is widely reported, research is still necessary to characterize them to advance their electro-conductive and mechanical properties. Hence, we served this need and characterized copper-coated para-aramid yarns produced by an in-house developed electroless deposition method. In this paper we present our investigation on the yarn’s copper layer characteristics after deposition. Furthermore, we looked, in depth, at the yarn’s electro-conductive properties before and after washing as well as their mechanical properties before and after copper deposition. We found a dependency of the copper layer morphology on its deposition time. This is directly correlated to the resulting layer thickness and hence to the yarn’s electro-conductive properties, demonstrating the autocatalytic nature of the coating process. Above that, the electro-conductive properties of the coated yarn linearly decrease with washing cycles. Furthermore, the copper coating impairs the yarn’s mechanical properties decreasing its specific stress at break by 30%.
- Full Text:
- Date Issued: 2012
- Authors: Schwarz, Anne , Hakuzimana, Jean , Westbroek, Philippe , Mey, Gilbert De , Priniotakis, Georgios , Nyokong, Tebello , Langenhove, Lieva Van
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243487 , vital:51157 , xlink:href="https://doi.org/10.1177/0040517511431291"
- Description: The latest technological advances in new materials and devices enabled wearable systems to be created by utilizing textile solutions. These solutions require electro-conductive yarns as a basic component. Although the production of electroconductive yarn is widely reported, research is still necessary to characterize them to advance their electro-conductive and mechanical properties. Hence, we served this need and characterized copper-coated para-aramid yarns produced by an in-house developed electroless deposition method. In this paper we present our investigation on the yarn’s copper layer characteristics after deposition. Furthermore, we looked, in depth, at the yarn’s electro-conductive properties before and after washing as well as their mechanical properties before and after copper deposition. We found a dependency of the copper layer morphology on its deposition time. This is directly correlated to the resulting layer thickness and hence to the yarn’s electro-conductive properties, demonstrating the autocatalytic nature of the coating process. Above that, the electro-conductive properties of the coated yarn linearly decrease with washing cycles. Furthermore, the copper coating impairs the yarn’s mechanical properties decreasing its specific stress at break by 30%.
- Full Text:
- Date Issued: 2012
Reverse saturation absorption spectra and optical limiting properties of chlorinated tetrasubstituted phthalocyanines containing different metals
- Tuhl, Ahmad, Manaa, Hacene, Makhseed, Saad, Al-Awadi, Nouria, Matthew, Jacob, Ibrahim, Hamada Mohamed, Nyokong, Tebello, Behbehani, Haider
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
- Authors: Tuhl, Ahmad , Manaa, Hacene , Makhseed, Saad , Al-Awadi, Nouria , Matthew, Jacob , Ibrahim, Hamada Mohamed , Nyokong, Tebello , Behbehani, Haider
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243498 , vital:51158 , xlink:href="https://doi.org/10.1016/j.optmat.2012.05.018"
- Description: A highly non-aggregated series of peripherally tetra(2,6-diisopropylphenoxy) substituted phthalocyanines (Pcs) containing different metals (Al, Ga, In and Zn) were prepared and their nonlinear optical properties (NLO), including the optical limiting behavior were investigated. This study explores the effect of the implanted metals along with the peripheral chlorine atoms on the NLO of the prepared complexes, thereby improving their optical limiting performance. The best wavelength at which the Pc complex exhibits the strongest nonlinear effect was determined over the low absorption window region (420–590 nm) comprised between the Q and B bands using a nanosecond pulsed laser with the aid of a Z-scan technique. The excited state absorption cross sections (σeff) have been found to be wavelength dependent with common double peaks at 505 nm and around 485 nm and the highest value was calculated for Pc1–In (1.1 × 10−16 cm2). The figure of merit spectra show different spectral structure when compared to the excited state absorption spectra and the largest figure of merit value was found to be around 107 for Pc1–In derivative. In full agreement with reverse saturation results, the optical limiting measurements, carried out at 485 nm and 532 nm for each derivative, show very low optical limiting thresholds at the former wavelength. In the continuous wave excitation regime, the Z-scan measurements, which were carried out at 632.8 and 532 nm, showed strong refractive and absorptive nonlinear effects.
- Full Text:
- Date Issued: 2012
In vitro toxicity testing of zinc tetrasulfophthalocyanines in fibroblast and keratinocyte cells for the treatment of melanoma cancer by photodynamic therapy
- Maduray, Kaminee, Karsten, Alta, Odhay, Bharti, Nyokong, Tebello
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
- Authors: Maduray, Kaminee , Karsten, Alta , Odhay, Bharti , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247588 , vital:51597 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2011.01.020"
- Description: A series of water-soluble tetrasulfonated metallophthalocyanines (MPcs) dyes have been studied to be used as a drug or photosensitizer (PS) in photodynamic therapy (PDT) for the treatment of cancers. During PDT the PS is administrated intravenously or topically to the patient before laser light at an appropriate wavelength is applied to the cancerous area to activate the PS. The activated PS will react with oxygen typically present in the cancerous tissue to generate reactive oxygen species for the destruction of the cancerous tissue. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of zinc tetrasulfophthalocyanines (ZnTSPc) activated with a diode laser (λ = 672 nm) on melanoma, keratinocyte and fibroblast cells. To perform this study 3 × 104 cells/ml were seeded in 24-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnTSPc. After 2 h, cells were irradiated with a constant light dose of 4.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Data indicated high concentrations of ZnTSPc (60–100 μg/ml) in its inactive state are cytotoxic to the melanoma cancer cells. Also, results showed that photoactivated ZnTSPc (50 μg/ml) was able to reduce the cell viability of melanoma, fibroblast and keratinocyte cells to 61%, 81% and 83% respectively. At this photosensitizing concentration the efficacy the treatment light dose of 4.5 J/cm2 against other light doses of 2.5 J/cm2, 7.5 J/cm2 and 10 J/cm2 on the different cell lines were analyzed. ZnTSPc at a concentration of 50 μg/ml activated with a light dose of 4.5 J/cm2 was the most efficient for the killing of melanoma cancer cells with reduced killing effects on healthy normal skin cells in comparison to the other treatment light doses. Melanoma cancer cells after PDT with a photosensitizing concentration of 50 μg/ml and a treatment light dose of 4.5 J/cm2 showed certain apoptosis characteristics such as chromatin condensation and fragmentation of the nucleus. This concludes that low concentrations of ZnTSPc activated with the appropriate light dose can be used to induce cell death in melanoma cells with the occurrence of minimal damage to surrounding healthy tissue.
- Full Text:
- Date Issued: 2011
Photophysicochemical and photodynamic therapy properties of metallophthalocyanines linked to gold speckled silica nanoparticles
- Dube, Edith, Oluwole, David O, Niemuwa, Nwaji, Prinsloo, Earl, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Niemuwa, Nwaji , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187472 , vital:44657 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.01.019"
- Description: This work reports on the linkage of 2(3),9(10),16(17),23(24) tetrakis [(benzo[d]thiazol-2-yl phenoxy) phthalocyaninato] zinc(II) (1) and indium(III) chloride (2) to gold speckled silica (GSS) nanoparticles via gold to sulphur (Au-S) and gold to nitrogen (Au-N) self-assembly to form the conjugates: 1-GSS and 2-GSS. The formed conjugates were characterized using microscopic and spectroscopic techniques, and the photophysicochemical properties and photodynamic therapy (PDT) activity against human breast adenocarcinoma cell line (MCF-7 cells) were studied. The conjugates afforded decrease in fluorescence quantum yields with corresponding increase in triplet and singlet oxygen quantum yields when compared to phthalocyanines alone. Singlet oxygen is cytotoxic to cancer cells hence it is important for PDT. The in vitro dark toxicity of complex 2 and 2-GSS against MCF–7 cells showed ≥93% viable cells within concentration ranges of 10–160 μg/mL. 2–GSS showed enhanced PDT activity with less than 50% viable cells at 80 μg/mL as compared to 2 and GSS alone which showed > 60% viable cells within 10–160 μg/mL. The observed improvements in the PDT activity of 2-GSS could be attributed to the high singlet oxygen generation of 2-GSS compared to 2 alone in addition to the phototoxicity of GSS.
- Full Text:
- Date Issued: 2019
- Authors: Dube, Edith , Oluwole, David O , Niemuwa, Nwaji , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187472 , vital:44657 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.01.019"
- Description: This work reports on the linkage of 2(3),9(10),16(17),23(24) tetrakis [(benzo[d]thiazol-2-yl phenoxy) phthalocyaninato] zinc(II) (1) and indium(III) chloride (2) to gold speckled silica (GSS) nanoparticles via gold to sulphur (Au-S) and gold to nitrogen (Au-N) self-assembly to form the conjugates: 1-GSS and 2-GSS. The formed conjugates were characterized using microscopic and spectroscopic techniques, and the photophysicochemical properties and photodynamic therapy (PDT) activity against human breast adenocarcinoma cell line (MCF-7 cells) were studied. The conjugates afforded decrease in fluorescence quantum yields with corresponding increase in triplet and singlet oxygen quantum yields when compared to phthalocyanines alone. Singlet oxygen is cytotoxic to cancer cells hence it is important for PDT. The in vitro dark toxicity of complex 2 and 2-GSS against MCF–7 cells showed ≥93% viable cells within concentration ranges of 10–160 μg/mL. 2–GSS showed enhanced PDT activity with less than 50% viable cells at 80 μg/mL as compared to 2 and GSS alone which showed > 60% viable cells within 10–160 μg/mL. The observed improvements in the PDT activity of 2-GSS could be attributed to the high singlet oxygen generation of 2-GSS compared to 2 alone in addition to the phototoxicity of GSS.
- Full Text:
- Date Issued: 2019