Synthesis and photophysicochemical properties of novel axially di-substituted silicon (IV) phthalocyanines and their photodynamic antimicrobial chemotherapy (PACT) activity against Staphylococcus aureus
- Sen, Pinar, Sindelo, Azole, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Sen, Pinar , Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186757 , vital:44531 , xlink:href="https://doi.org/10.1016/j.synthmet.2019.116203"
- Description: In this study, novel silicon (IV) phthalocyanine axially di-substituted with benzimidazole moieties (3) and its quaternized derivative (4) have been synthesized and fully characterized. The photophysical and photochemical properties of both phthalocyanines such as absorption, fluorescence and, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. These new silicon phthalocyanines exhibited low fluorescence but produced high singlet oxygen yields in both DMSO (compound 3 and 4) and aqueous media (compound 4). The quaternization of Si(IV)Pc (3) improved the triplet state quantum yield (ΦT) 0.61 to 0.83, consequently singlet oxygen generation (ΦΔ) increased to 0.69 from 0.42. Photodynamic antimicrobial chemotherapy activities (PACT) of Si(IV)Pc photosensitizers were determined towards Staphylococcus aureus. The higher efficiency was obtained with cationic derivative (4) giving reduction percentage value of 99.75%.
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186757 , vital:44531 , xlink:href="https://doi.org/10.1016/j.synthmet.2019.116203"
- Description: In this study, novel silicon (IV) phthalocyanine axially di-substituted with benzimidazole moieties (3) and its quaternized derivative (4) have been synthesized and fully characterized. The photophysical and photochemical properties of both phthalocyanines such as absorption, fluorescence and, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. These new silicon phthalocyanines exhibited low fluorescence but produced high singlet oxygen yields in both DMSO (compound 3 and 4) and aqueous media (compound 4). The quaternization of Si(IV)Pc (3) improved the triplet state quantum yield (ΦT) 0.61 to 0.83, consequently singlet oxygen generation (ΦΔ) increased to 0.69 from 0.42. Photodynamic antimicrobial chemotherapy activities (PACT) of Si(IV)Pc photosensitizers were determined towards Staphylococcus aureus. The higher efficiency was obtained with cationic derivative (4) giving reduction percentage value of 99.75%.
- Full Text:
- Date Issued: 2019
A comparative study of the singlet oxygen generation capability of a zinc phthalocyanine linked to graphene quantum dots through π-π stacking and covalent conjugation when embedded in asymmetric polymer membranes
- Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187461 , vital:44655 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.11.096"
- Description: Following the establishment of graphene quantum dots as potential phthalocyanine supports in photoactive membrane preparation for phthalocyanines lacking linkage functional groups, the practical efficiency of p-p stacking versus covalent linkage was investigated. Synthesized materials were characterized using FT-IR, Raman, powder X-ray diffraction, and UVeVis spectroscopies and also by transmission electron and scanning electron microscopies. Phthalocyanine loadings onto graphene quantum dots of 0.40 mg/mg and 0.14 mg/mg (Pc mass/conjugate mass) for the p-p stacked and covalent linked conjugates respectively were observed. Covalent linkage to graphene quantum dots proved to be functionally superior to p-p linkage, where singlet oxygen quantum yield value of the phthalocyanine in the membrane for the covalent linked conjugate was approximately twice that of the p-p stacked membrane.
- Full Text:
- Date Issued: 2019
- Authors: Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187461 , vital:44655 , xlink:href="https://doi.org/10.1016/j.molstruc.2018.11.096"
- Description: Following the establishment of graphene quantum dots as potential phthalocyanine supports in photoactive membrane preparation for phthalocyanines lacking linkage functional groups, the practical efficiency of p-p stacking versus covalent linkage was investigated. Synthesized materials were characterized using FT-IR, Raman, powder X-ray diffraction, and UVeVis spectroscopies and also by transmission electron and scanning electron microscopies. Phthalocyanine loadings onto graphene quantum dots of 0.40 mg/mg and 0.14 mg/mg (Pc mass/conjugate mass) for the p-p stacked and covalent linked conjugates respectively were observed. Covalent linkage to graphene quantum dots proved to be functionally superior to p-p linkage, where singlet oxygen quantum yield value of the phthalocyanine in the membrane for the covalent linked conjugate was approximately twice that of the p-p stacked membrane.
- Full Text:
- Date Issued: 2019
New type of metal-free and Zinc (II), In (III), Ga (III) phthalocyanines carrying biologically active substituents: Synthesis and photophysicochemical properties and photodynamic therapy activity
- Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186971 , vital:44552 , xlink:href="https://doi.org/10.1016/j.ica.2019.03.010"
- Description: This study reports on novel phthalocyanines having benzimidazole units which are known to have biological properties. 4-(4-(5-chloro-1H-benzo[d]imidazol-2-yl) substituted metal-free, Zn(II), In(III) and Ga(III) phthalocyanines were synthesized, these newly synthesized molecules that were substituted by oxygen bridges were fully characterized. For the purpose of determining their potency for photodynamic therapy, the photophysicochemical properties were investigated in DMSO. The H2Pc (4) showed higher fluorescence quantum yield and fluorescence lifetime as compared to metallated phthalocyanines derivatives. However, the highest singlet oxygen (ΦΔ) and triplet state quantum yields (ΦT) values were obtained with the In(III)Pc (5).
- Full Text:
- Date Issued: 2019
A novel axially palladium (II)-Schiff base complex substituted silicon (IV) phthalocyanine
- Sen, Pinar, Nyokong, Tebello
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
- Authors: Sen, Pinar , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186813 , vital:44536 , xlink:href="https://doi.org/10.1016/j.poly.2019.114135"
- Description: In this study, a novel silicon(IV) phthalocyanine is reported for the first time as a phthalocyanine derivative bearing axially a palladium(II)-Schiff base complex. The photophysical and photochemical properties of the new Si(IV)Pc, such as absorption, fluorescence, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were measured in DMSO. The new silicon phthalocyanine displayed very low fluorescence, showing efficient intersystem crossing resulting in high triplet and high singlet oxygen quantum yields in DMSO. When compared with the unsubstituted SiPcCl2, the singlet oxygen quantum yield value (UD = 0.47) in relation to the triplet quantum yield (UT = 0.82), which is an important determinant for PDT applications, increased. The photodynamic antimicrobial chemotherapy activity (PACT) of new Si(IV)Pc towards Staphylococcus aureus was determined in comparison to the unsubstituted SiPcCl2. The results of the photodynamic antimicrobial effect study demonstrated that the Pd(II) complex substituted SiPc (5) possesses excellent photodynamic activity with a reduction percentage value of 99.94% and a log red value of 3.26.
- Full Text:
- Date Issued: 2019
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
Spectroscopic and nonlinear optical properties of alkyl thio substituted binuclear phthalocyanines
- Makinde, Zainab O, Louzada, Marcel S, Britton, Jonathan, Nyokong, Tebello, Khene, Samson M
- Authors: Makinde, Zainab O , Louzada, Marcel S , Britton, Jonathan , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187485 , vital:44661 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.10.022"
- Description: This work presents the spectroscopic and nonlinear optical properties of metal free binuclear and monomeric 4- (pentylthio)phthalocyanine and cobalt 4,5-(bipentylthio)phthalocyanine. Second order nonlinear absorption coefficient (β) values for the complexes were determined and compared.
- Full Text:
- Date Issued: 2019
- Authors: Makinde, Zainab O , Louzada, Marcel S , Britton, Jonathan , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187485 , vital:44661 , xlink:href="https://doi.org/10.1016/j.dyepig.2018.10.022"
- Description: This work presents the spectroscopic and nonlinear optical properties of metal free binuclear and monomeric 4- (pentylthio)phthalocyanine and cobalt 4,5-(bipentylthio)phthalocyanine. Second order nonlinear absorption coefficient (β) values for the complexes were determined and compared.
- Full Text:
- Date Issued: 2019
The photo-physicochemical properties and in vitro photodynamic therapy activity of differently substituted-zinc (II)-phthalocyanines and graphene quantum dots conjugates on MCF7 breast cancer cell line
- Nene, Lindokuhle C, Managa, Muthumuni E, Oluwole, David O, Mafukidze, Donovan M, Sindelo, Azole, Nyokong, Tebello
- Authors: Nene, Lindokuhle C , Managa, Muthumuni E , Oluwole, David O , Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187449 , vital:44653 , xlink:href="https://doi.org/10.1016/j.ica.2019.01.012"
- Description: Several differently substituted Zn(II) phthalocyanines (ZnPcs) were prepared and conjugated to GQDs. The photophysical properties were determined for both the Pcs and their respective conjugates including the fluorescence/triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pcs decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields, this is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of the reduced actual number of Pcs units provided in the conjugate for therapy. Upon introduction of cationic charges, the photodynamic therapy activity of the complexes increased.
- Full Text:
- Date Issued: 2019
- Authors: Nene, Lindokuhle C , Managa, Muthumuni E , Oluwole, David O , Mafukidze, Donovan M , Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187449 , vital:44653 , xlink:href="https://doi.org/10.1016/j.ica.2019.01.012"
- Description: Several differently substituted Zn(II) phthalocyanines (ZnPcs) were prepared and conjugated to GQDs. The photophysical properties were determined for both the Pcs and their respective conjugates including the fluorescence/triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pcs decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields, this is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of the reduced actual number of Pcs units provided in the conjugate for therapy. Upon introduction of cationic charges, the photodynamic therapy activity of the complexes increased.
- Full Text:
- Date Issued: 2019
Nonlinear optical properties of metal free and nickel binuclear phthalocyanines
- Kabwe, Kapambwe P, Louzada, Marcel, Britton, Jonathan, Olomola,Temitope O, Nyokong, Tebello, Khene, Samson M
- Authors: Kabwe, Kapambwe P , Louzada, Marcel , Britton, Jonathan , Olomola,Temitope O , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186846 , vital:44539 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.05.003"
- Description: This work employs the open and closed Z-scan aperture technique to comparatively study the nonlinear optical (NLO) properties of nickel and metal free 4-tert-butylphenoxy phthalocyanine, biphenyl bridged bis-4-tert-butylphenoxy phthalocyanine and naphthalene bridged bis-4-tert-butylphenoxy phthalocyanine. Density functional theory (DFT) calculations of dipolar and octupolar ( J=1 and J=3) contribution were determined theoretically from hyper-Rayleigh scattering (HRS) response ( HRS) values.
- Full Text:
- Date Issued: 2019
- Authors: Kabwe, Kapambwe P , Louzada, Marcel , Britton, Jonathan , Olomola,Temitope O , Nyokong, Tebello , Khene, Samson M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186846 , vital:44539 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.05.003"
- Description: This work employs the open and closed Z-scan aperture technique to comparatively study the nonlinear optical (NLO) properties of nickel and metal free 4-tert-butylphenoxy phthalocyanine, biphenyl bridged bis-4-tert-butylphenoxy phthalocyanine and naphthalene bridged bis-4-tert-butylphenoxy phthalocyanine. Density functional theory (DFT) calculations of dipolar and octupolar ( J=1 and J=3) contribution were determined theoretically from hyper-Rayleigh scattering (HRS) response ( HRS) values.
- Full Text:
- Date Issued: 2019
Fabrication of efficient nonlinear optical absorber using Zn phthalocyanine-semiconductor quantum dots conjugates
- Mgidlana, Sithi, Oluwole, David O, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
Characterization of electrodes modified with nanocomposites of cobalt tetraaminophenoxyphthalocyanine, reduced graphene and multi-walled carbon nanotubes
- Shumba, Munyaradz, Nyoni, Stephen, Britton, Jonathan, Nyokong, Tebello
- Authors: Shumba, Munyaradz , Nyoni, Stephen , Britton, Jonathan , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187003 , vital:44555 , xlink:href="https://doi.org/10.1080/00958972.2019.1621299"
- Description: Glassy carbon electrodes or plates were modified with nanocomposites consisting of cobalt tetraaminophenoxyphthalocyanine (CoTAPhPc), reduced graphene oxide nanosheets (rGONs) and multi-walled carbon nanotubes (MWCNTs). The modified electrodes were characterized using cyclic voltammetry, scanning electrochemical microscopy (SECM) and time-of-flight-secondary ion mass spectrometer (TOF-SIMS). The electrocatalytic activity of the modified electrode was tested for detection of L-cysteine. The presence of CoTAPhPc on sequential layers of MWCNT and rGONs resulted in improved detection currents compared to CoTAPhPc alone or when MWCNT/rGONs are mixed in CoTAPhPc–MWCNT/ rGONs (mix)–glassy carbon electrode (GCE). CoTAPhPc–MWCNT–GCE (without rGONS) showed higher sensitivity toward L-cysteine as compared to the probes incorporating rGONs with a catalytic rate constant of 4.62x104 M-1 s-1 and a detection limit of 30 nM. The presence of rGONs improved the stability of the electrode.
- Full Text:
- Date Issued: 2019
- Authors: Shumba, Munyaradz , Nyoni, Stephen , Britton, Jonathan , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187003 , vital:44555 , xlink:href="https://doi.org/10.1080/00958972.2019.1621299"
- Description: Glassy carbon electrodes or plates were modified with nanocomposites consisting of cobalt tetraaminophenoxyphthalocyanine (CoTAPhPc), reduced graphene oxide nanosheets (rGONs) and multi-walled carbon nanotubes (MWCNTs). The modified electrodes were characterized using cyclic voltammetry, scanning electrochemical microscopy (SECM) and time-of-flight-secondary ion mass spectrometer (TOF-SIMS). The electrocatalytic activity of the modified electrode was tested for detection of L-cysteine. The presence of CoTAPhPc on sequential layers of MWCNT and rGONs resulted in improved detection currents compared to CoTAPhPc alone or when MWCNT/rGONs are mixed in CoTAPhPc–MWCNT/ rGONs (mix)–glassy carbon electrode (GCE). CoTAPhPc–MWCNT–GCE (without rGONS) showed higher sensitivity toward L-cysteine as compared to the probes incorporating rGONs with a catalytic rate constant of 4.62x104 M-1 s-1 and a detection limit of 30 nM. The presence of rGONs improved the stability of the electrode.
- Full Text:
- Date Issued: 2019
Electrocatalytic Activity of Asymmetrical Cobalt Phthalocyanines in the Presence of N Doped Graphene Quantum Dots: The Push-pull Effects of Substituents
- Nkhahle, Reitumetse, Sekhosana, Kutloano E, Centane, Sixolile, Nyokong, Tebello
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
Investigation of novel substituted zinc and aluminium phthalocyanines for photodynamic therapy of epithelial breast cancer
- Mohammed, Imadalulla, Oluwole, David O, Nemakal, Majunatha, Sannegowda, Lokesh K, Nyokong, Tebello
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
- Date Issued: 2019
- Authors: Mohammed, Imadalulla , Oluwole, David O , Nemakal, Majunatha , Sannegowda, Lokesh K , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186824 , vital:44537 , xlink:href="https://doi.org/10.1016/j.dyepig.2019.107592"
- Description: A series of phthalonitrile ligands were synthesized by nucleophilic substitution reaction using the hydroxyl or sulfanyl group precursors and the nitro moiety of the nitrophthalonitrile to yield corresponding oxy or sulfanyl bridged ligands. These ligands were subsequently subjected to cyclocondensation reaction with diamagnetic metal ions like zinc and aluminium to afford symmetrically substituted zinc and aluminium phthalocyanine (Pc) complexes and polymers. The ligands and Pc complexes were characterized by 1 H nuclear magnetic resonance, fourier transform infrared, ultraviolet visible and mass spectrometric techniques. Additionally, thermal gravimetric, and elemental analyzer were used for characterization of the Pc complexes. The photophysical and photochemical behaviour of the Pc complexes were investigated in dimethyl sulfoxide. Additionally, the complexes were tested against epithelial breast cancer cells for photodynamic therapy (PDT) effect. The substituted ZnPc complexes afforded higher singlet oxygen quantum yields as compared to the AlPc analogue. All the complexes showed innocuous invitro dark cytotoxicity and moderate PDT effect.
- Full Text:
- Date Issued: 2019
Electrocatalytic activity of ethynylbenzyl phthalocyanines when linked to quantum dots via click chemistry: Towards efficient oxygen reduction reaction and H2O2 oxidation
- Mpeta, Lekhetho S, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187037 , vital:44558 , xlink:href="https://doi.org/10.1016/j.jelechem.2019.03.064"
- Description: This work describes the conjugation of Co, Mn and Fe tetra ethynyl benzyl phthalocyanines to CdTe/ZnS quantum dots via click chemistry. The synthesized conjugates were then immobilised on glassy carbon electrode and their electrocatalytic activity towards hydrogen peroxide oxidation and oxygen reduction investigated. CoPc (1)-QDs showed superior electrocatalytic behaviour towards hydrogen peroxide catalysis with sensitivity of 2.8 × 105 μA/mM and limit of detection of 0.023 μM. On the other hand, FePc(3)-QDs showed the best oxygen reduction activity involving a direct 4-electron mechanism.
- Full Text:
- Date Issued: 2019
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187037 , vital:44558 , xlink:href="https://doi.org/10.1016/j.jelechem.2019.03.064"
- Description: This work describes the conjugation of Co, Mn and Fe tetra ethynyl benzyl phthalocyanines to CdTe/ZnS quantum dots via click chemistry. The synthesized conjugates were then immobilised on glassy carbon electrode and their electrocatalytic activity towards hydrogen peroxide oxidation and oxygen reduction investigated. CoPc (1)-QDs showed superior electrocatalytic behaviour towards hydrogen peroxide catalysis with sensitivity of 2.8 × 105 μA/mM and limit of detection of 0.023 μM. On the other hand, FePc(3)-QDs showed the best oxygen reduction activity involving a direct 4-electron mechanism.
- Full Text:
- Date Issued: 2019
Physicochemical and photodynamic antimicrobial chemotherapy activity of morpholine-substituted phthalocyanines: Effect of point of substitution and central metal
- Sindelo, Azole, Kobayashi, Nagao, Kimura, Mutsumi, Nyokong, Tebello
- Authors: Sindelo, Azole , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187438 , vital:44652 , xlink:href="https://doi.org/10.1016/j.jphotochem.2019.01.025"
- Description: In this study, novel metal-free, zinc and indium 1(4),8(11),15(18),22(25)-tetramorpholine (1a, 2a, 3a respectively) and 2(3), 9(10), 16(17),23(24)-tetramorpholine (1b, 2b, 3b respectively) phthalocyanines were synthesized and complexes 2 and 3 were quaternized. The photophysical and photochemical properties were investigated in dimethylsulfoxide. The non-peripherally substituted phthalocyanines generated higher singlet oxygen than the peripherally substituted phthalocyanines. Photodynamic antimicrobial chemotherapy activities towards inactivation of Escherichia coli, Staphylococcus aureus and Candida albican were evaluated, where all the quaternized Pcs showed total elimination of the micro-organism with log reductions greater than 9. Though the neutral Pcs had log reductions less than 2, for C. albican the percentage reduction was 68.5% for 2b showing the antifungal properties of the morpholine group.
- Full Text:
- Date Issued: 2019
- Authors: Sindelo, Azole , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187438 , vital:44652 , xlink:href="https://doi.org/10.1016/j.jphotochem.2019.01.025"
- Description: In this study, novel metal-free, zinc and indium 1(4),8(11),15(18),22(25)-tetramorpholine (1a, 2a, 3a respectively) and 2(3), 9(10), 16(17),23(24)-tetramorpholine (1b, 2b, 3b respectively) phthalocyanines were synthesized and complexes 2 and 3 were quaternized. The photophysical and photochemical properties were investigated in dimethylsulfoxide. The non-peripherally substituted phthalocyanines generated higher singlet oxygen than the peripherally substituted phthalocyanines. Photodynamic antimicrobial chemotherapy activities towards inactivation of Escherichia coli, Staphylococcus aureus and Candida albican were evaluated, where all the quaternized Pcs showed total elimination of the micro-organism with log reductions greater than 9. Though the neutral Pcs had log reductions less than 2, for C. albican the percentage reduction was 68.5% for 2b showing the antifungal properties of the morpholine group.
- Full Text:
- Date Issued: 2019
Evaluation of the photosensitizing properties of zinc and indium tetra cinnamic acid phthalocyanines linked to magnetic nanoparticles on human breast adenocarcinoma cells
- Matlou, Gauta G, Oluwole, David O, Nyokong, Tebello
- Authors: Matlou, Gauta G , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187582 , vital:44673 , xlink:href="https://doi.org/10.1016/j.jlumin.2018.09.054"
- Description: This work reports on the synthesis, photophysico-chemical properties and photodynamic therapy activity of novel zinc (1) and indium (2) tetra substituted cinnamic acid phthalocyanine (Pc) complexes linked to amino functionalized magnetic nanoparticles (AMNPs) through an amide bond. Asymmetric ZnPc complex (3) showed better triplet and singlet oxygen quantum yields as compared to its symmetrical analogues (1 and 2). The AMNPs (1-AMNPs and 2-AMNPs) linked conjugates depicted increased triplet quantum yields in comparison to their unlinked Pcs, while 3-AMNPs showed a decrease compared to 3. The complexes showed increased in-vitro photo-cytotoxic effect against MCF-7 cells with an increase in drug concentration. At 80 µg/mL, 2 and 3, 2-AMNPs and 3-AMNPs with higher singlet oxygen quantum yields caused more cytotoxic effect on the cancer cells in the presence of light as compared to 1 and 1-AMNPs respectively.
- Full Text:
- Date Issued: 2019
- Authors: Matlou, Gauta G , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187582 , vital:44673 , xlink:href="https://doi.org/10.1016/j.jlumin.2018.09.054"
- Description: This work reports on the synthesis, photophysico-chemical properties and photodynamic therapy activity of novel zinc (1) and indium (2) tetra substituted cinnamic acid phthalocyanine (Pc) complexes linked to amino functionalized magnetic nanoparticles (AMNPs) through an amide bond. Asymmetric ZnPc complex (3) showed better triplet and singlet oxygen quantum yields as compared to its symmetrical analogues (1 and 2). The AMNPs (1-AMNPs and 2-AMNPs) linked conjugates depicted increased triplet quantum yields in comparison to their unlinked Pcs, while 3-AMNPs showed a decrease compared to 3. The complexes showed increased in-vitro photo-cytotoxic effect against MCF-7 cells with an increase in drug concentration. At 80 µg/mL, 2 and 3, 2-AMNPs and 3-AMNPs with higher singlet oxygen quantum yields caused more cytotoxic effect on the cancer cells in the presence of light as compared to 1 and 1-AMNPs respectively.
- Full Text:
- Date Issued: 2019
Electrocatalytic activity of a push pull Co (II) phthalocyanine in the presence of graphitic carbon nitride quantum dots
- Nxele, Siphesihle R, Oluwole, David O, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
- Date Issued: 2019
- Authors: Nxele, Siphesihle R , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186746 , vital:44530 , xlink:href="https://doi.org/10.1016/j.electacta.2019.134978"
- Description: This work reports for the first time on the use of a conjugate of graphitic carbon nitride quantum dots (gCNQDs) with a push-pull asymmetrical cobalt phthalocyanine (CoPc) for electrochemical sensing. The nanocomposite is immobilized on a glassy carbon electrode (GCE) surface for the use in l-cysteine electrocatalysis. The nanocomposites were characterized using techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Raman spectroscopy and electrochemical methods. The nanocomposites were immobilized by the drop-dry method, sequentially or when premixed in solution. Good electrocatalytic oxidation of l-cysteine was observed, especially by the sequentially modified electrode surface, with the CoPc on top of gCNQDs. The sensitivity was determined as 3.5 μA.mM-1 and the limit of detection (LoD) as 101.3 μM for GCE-gCNQDs, 0.65 μA.mM-1 and 0.96 μM for GCE-CoPc, 23.41 μA.mM-1 and 0.41 μM for gCNQDs-CoPc (premixed) and 100.5 μA.mM-1 and 0.02 μM for gCNQDs-CoPc (sequential). The electrode surfaces also showed high stability by continuous cyclization.
- Full Text:
- Date Issued: 2019
Magnetic nanoparticle-indium phthalocyanine conjugate embedded in electrospun fiber for photodynamic antimicrobial chemotherapy and photodegradation of methyl red
- Sindelo, Azole, Nyokong, Tebello
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186857 , vital:44540 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e02352"
- Description: ClIn(III) octacarboxy phthalocyanine (ClInOCPc) when alone or conjugated to magnetic nanoparticles (MNPClInOCPc) was employed for both photodynamic antimicrobial chemotherapy of an unknown water sample and Staphylococcus aureus, and for photo-degradation of methyl red (MR). The singlet oxygen quantum yields (ΦΔ) in water using ClInOCPc and MNP-ClInOCPc embedded in polyacrylonitrile (PAN) electrospun fibers were 0.36 and 0.22, respectively. When in solution, MNP-ClInOCPc gave 90.6% photoinactivation of microbes in a water sample from the stream and of ClInOCPc resulted in 84.8 % photoinactivation. When embedded to the polymer, there was 48.0% clearance for ClInOCPc and 63.7% clearance for MNP-ClInOCPc for the microbes in the water sample from the stream. For the photo-degradation of MR, the rate of degradation increased with decrease of the MR concentration with the MNP-ClInOCPc having the fastest rate.
- Full Text:
- Date Issued: 2019
- Authors: Sindelo, Azole , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186857 , vital:44540 , xlink:href="https://doi.org/10.1016/j.heliyon.2019.e02352"
- Description: ClIn(III) octacarboxy phthalocyanine (ClInOCPc) when alone or conjugated to magnetic nanoparticles (MNPClInOCPc) was employed for both photodynamic antimicrobial chemotherapy of an unknown water sample and Staphylococcus aureus, and for photo-degradation of methyl red (MR). The singlet oxygen quantum yields (ΦΔ) in water using ClInOCPc and MNP-ClInOCPc embedded in polyacrylonitrile (PAN) electrospun fibers were 0.36 and 0.22, respectively. When in solution, MNP-ClInOCPc gave 90.6% photoinactivation of microbes in a water sample from the stream and of ClInOCPc resulted in 84.8 % photoinactivation. When embedded to the polymer, there was 48.0% clearance for ClInOCPc and 63.7% clearance for MNP-ClInOCPc for the microbes in the water sample from the stream. For the photo-degradation of MR, the rate of degradation increased with decrease of the MR concentration with the MNP-ClInOCPc having the fastest rate.
- Full Text:
- Date Issued: 2019
Physicochemical and antimicrobial photodynamic chemotherapy (against E. coli) by indium phthalocyanines in the presence of silver–iron bimetallic nanoparticles
- Magadla, Aviwe, Oluwole, David O, Managa, Muthumuni, Nyokong, Tebello
- Authors: Magadla, Aviwe , Oluwole, David O , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187091 , vital:44564 , xlink:href="https://doi.org/10.1016/j.poly.2019.01.032"
- Description: In this work, Schiff base indium phthalocyanines: In–Cl tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine (complex 1b) and In–Cl tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine (complex 2b) are synthesized from tetra amino and tetra phenoxy amino phthalocyanines, respectively. These complexes were further quartenised with 1,3-propanesultone to form zwitterionic complexes 1 and 2, respectively. Silver–iron dimers (Ag–Fe3O4) and silver-iron core shell (Ag@Fe3O4) nanoparticles (NPs) were linked to the synthesised complexes. The photophysical and photochemical behaviour of the complexes and their conjugates with NPs were investigated in dimethyl sulfoxide. Complexes 2 and 2b and their conjugates were then used for photodynamic antimicrobial chemotherapy on Escherichia coli. The zwitter ionic photosensitiser 2 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- Full Text:
- Date Issued: 2019
- Authors: Magadla, Aviwe , Oluwole, David O , Managa, Muthumuni , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187091 , vital:44564 , xlink:href="https://doi.org/10.1016/j.poly.2019.01.032"
- Description: In this work, Schiff base indium phthalocyanines: In–Cl tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine (complex 1b) and In–Cl tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine (complex 2b) are synthesized from tetra amino and tetra phenoxy amino phthalocyanines, respectively. These complexes were further quartenised with 1,3-propanesultone to form zwitterionic complexes 1 and 2, respectively. Silver–iron dimers (Ag–Fe3O4) and silver-iron core shell (Ag@Fe3O4) nanoparticles (NPs) were linked to the synthesised complexes. The photophysical and photochemical behaviour of the complexes and their conjugates with NPs were investigated in dimethyl sulfoxide. Complexes 2 and 2b and their conjugates were then used for photodynamic antimicrobial chemotherapy on Escherichia coli. The zwitter ionic photosensitiser 2 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.
- 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
The photophysicochemical properties and photodynamic therapy activity of phenyldiazenyl phenoxy substituted phthalocyanines when incorporated into Pluronic® F127 micelles
- Motloung, Banele M, Sekhosana, Kutloano E, Managa, Muthumuni, Prinsloo, Earl, Nyokong, Tebello
- Authors: Motloung, Banele M , Sekhosana, Kutloano E , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186769 , vital:44532 , xlink:href="https://doi.org/10.1016/j.poly.2019.114157"
- Description: The synthesis, photophysicochemical properties and photodynamic activity (PDT) of 4(4-phenyldiazenyl) phenoxy substituted indium (III) (InPc) and zinc (ZnPc) phthalocyanines when alone or incorporated into Pluronic_ F127 micelles are presented in this study. The InPc exhibited higher singlet oxygen (UD) at 0.47 compared to the ZnPc at 0.20 in dimethylsulfoxide. The UD values in the presence of Pluronic_ F127 and in water, were 0.32 for InPc and 0.09 for ZnPc. The triplet quantum yields (UT) were 0.92 for InPc and 0.32 for ZnPc in DMSO. The PDT activity followed the same trend as the singlet oxygen quantum yields. At the highest concentration, InPc in Pluronic_ F127 gave 22% cell viability compared to 34% for complex ZnPc. The partition coefficient Kp values were determined using the water and octanol system. InPc had a larger Kp suggesting that it is more likely to be taken up by the cancer cells, hence it exhibited better PDT activity.
- Full Text:
- Date Issued: 2019
- Authors: Motloung, Banele M , Sekhosana, Kutloano E , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186769 , vital:44532 , xlink:href="https://doi.org/10.1016/j.poly.2019.114157"
- Description: The synthesis, photophysicochemical properties and photodynamic activity (PDT) of 4(4-phenyldiazenyl) phenoxy substituted indium (III) (InPc) and zinc (ZnPc) phthalocyanines when alone or incorporated into Pluronic_ F127 micelles are presented in this study. The InPc exhibited higher singlet oxygen (UD) at 0.47 compared to the ZnPc at 0.20 in dimethylsulfoxide. The UD values in the presence of Pluronic_ F127 and in water, were 0.32 for InPc and 0.09 for ZnPc. The triplet quantum yields (UT) were 0.92 for InPc and 0.32 for ZnPc in DMSO. The PDT activity followed the same trend as the singlet oxygen quantum yields. At the highest concentration, InPc in Pluronic_ F127 gave 22% cell viability compared to 34% for complex ZnPc. The partition coefficient Kp values were determined using the water and octanol system. InPc had a larger Kp suggesting that it is more likely to be taken up by the cancer cells, hence it exhibited better PDT activity.
- Full Text:
- Date Issued: 2019