Effects of axial ligands on the photophysical properties of silicon octaphenoxyphthalocyanine
- Maree, M David, Nyokong, Tebello, Suhling, Klaus, Phillips, David
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
- Authors: Maree, M David , Nyokong, Tebello , Suhling, Klaus , Phillips, David
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289582 , vital:56651 , xlink:href="https://doi.org/10.1142/S1088424602000452"
- Description: The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
- Full Text:
- Date Issued: 2002
Determination of 2′, 3′-Dideoxyinosine Using Iron (II) Phthalocyanine Modified Carbon Paste Electrode
- Ozoemena, Kenneth I, Stefan, Raluca-Ioana, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Stefan, Raluca-Ioana , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300298 , vital:57914 , xlink:href="https://doi.org/10.1081/AL-200031940"
- Description: An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine complex (FePc), has been constructed for the assay of anti‐HIV agent dideoxyinosine (didanosine, DDI). Using chronoamperometry (E = +1.04 V versus Ag/AgCl) technique, the amperometric sensor can be used reliably for dideoxyinosine assay at pH 7.4 phosphate buffer in the 1.5–9.5 nmol/L concentration range with a detection limit of 5.7 × 10−10 mol/L. The surface of the electrode can easily be regenerated by simple polishing, obtaining a fresh surface ready for use in a new assay. The new amperometric sensor proved to be highly reliable for the assay of dideoxyinosine purity in raw material as well as for the uniformity content test of Videx® tablets.
- Full Text:
- Date Issued: 2004
- Authors: Ozoemena, Kenneth I , Stefan, Raluca-Ioana , Nyokong, Tebello
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300298 , vital:57914 , xlink:href="https://doi.org/10.1081/AL-200031940"
- Description: An amperometric sensor, based on carbon paste impregnated with iron (II) phthalocyanine complex (FePc), has been constructed for the assay of anti‐HIV agent dideoxyinosine (didanosine, DDI). Using chronoamperometry (E = +1.04 V versus Ag/AgCl) technique, the amperometric sensor can be used reliably for dideoxyinosine assay at pH 7.4 phosphate buffer in the 1.5–9.5 nmol/L concentration range with a detection limit of 5.7 × 10−10 mol/L. The surface of the electrode can easily be regenerated by simple polishing, obtaining a fresh surface ready for use in a new assay. The new amperometric sensor proved to be highly reliable for the assay of dideoxyinosine purity in raw material as well as for the uniformity content test of Videx® tablets.
- Full Text:
- Date Issued: 2004
A comparative physicochemical study of unsymmetrical indium phthalocyanines in the presence of magnetic nanoparticles or quantum dots
- Osifeko, Olawale L, Nyokong, Tebello
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
- Authors: Osifeko, Olawale L , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188743 , vital:44781 , xlink:href="https://doi.org/10.1080/00958972.2016.1152628"
- Description: Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.
- Full Text:
- Date Issued: 2016
Photophysical and photochemical studies of sulfur containing phthalocyanine derivatives in the presence of folic acid
- Nombona, Nolwazi, Nyokong, Tebello
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/243180 , vital:51124 , xlink:href="https://doi.org/10.1016/j.ica.2012.03.051"
- Description: The syntheses of zinc and magnesium 9,16,23-tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyaninato complexes are described for the first time. The photophysical and photochemical parameters of these molecules in the absence or presence of folic acid are compared to the corresponding oxygen bridged complexes and to 2,9,17,23-tetrakis-[(1,6-hexanedithiol)phthalocyaninato]zinc(II), [8,15,22-tris-(naptho)-2-(amidoethanethiol)phthalocyaninato]zinc(II) and zinc phthalocyanine tetrasulfonate. In the absence of folic acid, the complexes show relatively good triplet quantum yields (ranging from 0.52 to 0.88) in DMSO with reasonable triplet lifetime between 140 and 470 μs. The complexes showed high singlet oxygen quantum yield values ranging from 0.27 to 0.66 in the absence of folic acid. In the presence of folic acid, the triplet quantum yield values were between 0.37 and 0.75 and the lifetimes were significantly reduced (70–320 μs).
- Full Text:
- Date Issued: 2012
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
Nonlinear optical response and electrocatalytic activity of cobalt phthalocyanine clicked zinc oxide nanoparticles
- Mpeta, Lekhetho S, Sekhosana, Kutloano E, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
- Date Issued: 2020
- Authors: Mpeta, Lekhetho S , Sekhosana, Kutloano E , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186179 , vital:44471 , xlink:href="https://doi.org/10.1016/j.ica.2020.119661"
- Description: In this article, we report on the linking of cobalt tetrakis (4-pentyn-oxy) phthalocyanine (CoTPPc) to ZnO nanoparticles via click chemistry. Subsequently, electrocatalytic activity and nonlinear optical properties were investigated (the latter using an open Z-scan technique at 532 nm). The linking of CoTPPc with ZnO resulted in the lowest limiting intensity value of 0.27 J.Cm−2, the βeff (cmW−1) values were found to be 1.51 × 10-8 and 7.10 × 104 for ZnO and CoTPPc-ZnO respectively. The catalytic rate constants (M−1s−1) (and limits of detection) were 4.1 × 104 (12.87 µM), 5.7 × 104 (8.62 µM) and 7.36 × 104 (4.35 µM) for ZnO, CoTPPc and CoTPPc-ZnO. Hence linking ZnO nanoparticles to CoTPPc result in the enhancement of both nonlinear optical behaviour and catalytic activity.
- Full Text:
- Date Issued: 2020
Phthalocyanine based fabricated exfoliated graphite photoanode for electrodegradation of 4-acetamidophenol under visible light irradiation
- Mpeta, Lekhetho S, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295809 , vital:57380 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114115"
- Description: In this study exfoliated graphite (EG) was prepared from natural graphite flakes and incorporated with zinc phthalocyanine for fabrication of photoanode. The electron transfer capabilities of fabricated photoanode were examined by using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy. Electrophotocatalytic degradation of 4-acetamidophenol in 0.1 M Na2SO4 electrolyte was performed. The photoanode with zinc phthalocyanine (EG-ZnPc) displayed better degradation compared to when only exfoliated graphite was used (EG). Furthermore, electrophotocatalytic degradation gave better performance (removal efficiency of 47.76%) than when individual electrochemical degradation and photodegradation techniques were used.
- Full Text:
- Date Issued: 2022
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295809 , vital:57380 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114115"
- Description: In this study exfoliated graphite (EG) was prepared from natural graphite flakes and incorporated with zinc phthalocyanine for fabrication of photoanode. The electron transfer capabilities of fabricated photoanode were examined by using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy. Electrophotocatalytic degradation of 4-acetamidophenol in 0.1 M Na2SO4 electrolyte was performed. The photoanode with zinc phthalocyanine (EG-ZnPc) displayed better degradation compared to when only exfoliated graphite was used (EG). Furthermore, electrophotocatalytic degradation gave better performance (removal efficiency of 47.76%) than when individual electrochemical degradation and photodegradation techniques were used.
- Full Text:
- Date Issued: 2022
Enhanced Light-Driven Antimicrobial Activity of Cationic Poly (oxanorbornene) s by Phthalocyanine Incorporation into Polymer as Pendants
- Ahmetali, Erem, Sen, Pinar, Süer, N Ceren, Aksu, Burak, Nyokong, Tebello, Eren, Tarik, Sener, Kasim M
- Authors: Ahmetali, Erem , Sen, Pinar , Süer, N Ceren , Aksu, Burak , Nyokong, Tebello , Eren, Tarik , Sener, Kasim M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185976 , vital:44453 , xlink:href=" https://doi.org/10.1002/macp.202000386"
- Description: Amphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring-opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium-containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram-positive and gram-negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.
- Full Text:
- Date Issued: 2020
- Authors: Ahmetali, Erem , Sen, Pinar , Süer, N Ceren , Aksu, Burak , Nyokong, Tebello , Eren, Tarik , Sener, Kasim M
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185976 , vital:44453 , xlink:href=" https://doi.org/10.1002/macp.202000386"
- Description: Amphiphilic poly(oxanorbornene)s are promising synthetic polymers that mimic the structural properties and antimicrobial functions of naturally occurring antimicrobial peptides. Here, poly(oxanorbornene)s bearing pendant zinc(II) phthalocyanine and triphenyl(ethyl) phosphonium functionalities are synthesized by ring-opening metathesis polymerization (ROMP). Fluorescence, singlet oxygen and triplet quantum yields of polymers are measured in dimethyl sulfoxide and aqueous medium. The singlet oxygen quantum yields of copolymers with the highest triphenyl and triethyl phosphonium content are found to be 0.29 and 0.41, respectively. Then, antimicrobial activities of polymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are investigated under both dark and light conditions. Synergistic effect of zinc(II) phthalocyanine and phosphonium-containing poly(oxanorbornene) is observed that the conjugate possessing the most triphenyl phosphonium side chains has the highest activity under light against both gram-positive and gram-negative bacterial strains after 80 min irradiation, reducing the survival of E. coli or S. aureus by 99.9999%. Hemolytic concentrations of the copolymers are found between 8 and 512 µg mL−1. Scanning electron microscopy (SEM) proves that the bacteria membrane deforms after contacting with the biocidal polymer.
- Full Text:
- Date Issued: 2020
Asymmetrical zinc (II) phthalocyanines cobalt tungstate nanomaterial conjugates for photodegradation of methylene blue
- Mgidlana, Sithi, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184991 , vital:44314 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113421"
- Description: Herein, we present syntheses of three asymmetrical zinc(II) phthalocyanine (ZnPc) complexes and hydrothermal synthesis of cobalt tungstate nanoparticles. The ZnPc derivatives were covalently linked to cobalt tungstate nanoparticles. Photophysical and photochemical behaviour of Pcs and nanoconjugates were investigated. The nanoconjugates generated higher triplet quantum yield and singlet oxygen quantum yield than the ZnPcs alone. Furthermore, in this paper photocatalytic efficiencies of ZnPc complexes and nanoconjugates were investigated for the degradation of methylene blue and higher photocatalytic behaviour was observed for the conjugates. The kinetic model was used to study photocatalytic behaviour of all the prepared photocatalysts.
- Full Text:
- Date Issued: 2021
- Authors: Mgidlana, Sithi , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184991 , vital:44314 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113421"
- Description: Herein, we present syntheses of three asymmetrical zinc(II) phthalocyanine (ZnPc) complexes and hydrothermal synthesis of cobalt tungstate nanoparticles. The ZnPc derivatives were covalently linked to cobalt tungstate nanoparticles. Photophysical and photochemical behaviour of Pcs and nanoconjugates were investigated. The nanoconjugates generated higher triplet quantum yield and singlet oxygen quantum yield than the ZnPcs alone. Furthermore, in this paper photocatalytic efficiencies of ZnPc complexes and nanoconjugates were investigated for the degradation of methylene blue and higher photocatalytic behaviour was observed for the conjugates. The kinetic model was used to study photocatalytic behaviour of all the prepared photocatalysts.
- Full Text:
- Date Issued: 2021
Effect of ultrasonic frequency and power on the sonodynamic therapy activity of cationic Zn (II) phthalocyanines
- Nene, Lindokuhle C, Sindelo, Azole, Britton, Jonathan, Nyokong, Tebello
- Authors: Nene, Lindokuhle C , Sindelo, Azole , Britton, Jonathan , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185737 , vital:44419 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111397"
- Description: We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (Par I (1 MHz, 1 W cm−2), Par II (1 MHz, 2 W cm−2), Par III (3 MHz, 1 W cm−2) and Par IV (3 MHz, 2 W cm−2)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV–vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.
- Full Text:
- Date Issued: 2021
- Authors: Nene, Lindokuhle C , Sindelo, Azole , Britton, Jonathan , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185737 , vital:44419 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111397"
- Description: We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (Par I (1 MHz, 1 W cm−2), Par II (1 MHz, 2 W cm−2), Par III (3 MHz, 1 W cm−2) and Par IV (3 MHz, 2 W cm−2)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV–vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.
- Full Text:
- Date Issued: 2021
The influence of livelihood dependency, local ecological knowledge and market proximity on the ecological impacts of harvesting non-timber forest products
- Steele, Melita Z, Shackleton, Charlie M, Shaanker, Ramanan U, Ganeshaiah, Kotiganahalli N, Radloff, Sarah E
- Authors: Steele, Melita Z , Shackleton, Charlie M , Shaanker, Ramanan U , Ganeshaiah, Kotiganahalli N , Radloff, Sarah E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180908 , vital:43669 , xlink:href="https://doi.org/10.1016/j.forpol.2014.07.011"
- Description: It is well established that non-timber forest products make significant contributions to rural incomes throughout most of the developing world. NTFP use frequently raises concerns about the sustainability of, or ecological impacts associated with, NTFP harvesting, as well as local contextual factors which may limit or reduce the impacts. Here we test the conceptual model first advanced by Uma Shaanker et al. (2004) relating to the factors that may limit or exacerbate the ecological impacts associated with NTFP harvesting. These were the extent of local dependence on NTFPs, the degree of marketing and the level of local ecological knowledge. Data were collected via household questionnaires and ecological surveys of woody plants from eight villages throughout South Africa. We found no significant relationships between measures of ecological impact with local ecological knowledge or market proximity and engagement. There was a strong positive relationship between ecological impacts and NTFP dependency as indexed through mean annual direct-use value for NTFPs. This indicates that the higher the dependency and demand for NTFPs, the greater is the possibility of high impacts to the local environment. However, other contextual drivers not included in the original Uma Shaanker et al. (2004) model may also play a role, particularly the strength of local resource governance institutions.
- Full Text: false
- Date Issued: 2015
- Authors: Steele, Melita Z , Shackleton, Charlie M , Shaanker, Ramanan U , Ganeshaiah, Kotiganahalli N , Radloff, Sarah E
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180908 , vital:43669 , xlink:href="https://doi.org/10.1016/j.forpol.2014.07.011"
- Description: It is well established that non-timber forest products make significant contributions to rural incomes throughout most of the developing world. NTFP use frequently raises concerns about the sustainability of, or ecological impacts associated with, NTFP harvesting, as well as local contextual factors which may limit or reduce the impacts. Here we test the conceptual model first advanced by Uma Shaanker et al. (2004) relating to the factors that may limit or exacerbate the ecological impacts associated with NTFP harvesting. These were the extent of local dependence on NTFPs, the degree of marketing and the level of local ecological knowledge. Data were collected via household questionnaires and ecological surveys of woody plants from eight villages throughout South Africa. We found no significant relationships between measures of ecological impact with local ecological knowledge or market proximity and engagement. There was a strong positive relationship between ecological impacts and NTFP dependency as indexed through mean annual direct-use value for NTFPs. This indicates that the higher the dependency and demand for NTFPs, the greater is the possibility of high impacts to the local environment. However, other contextual drivers not included in the original Uma Shaanker et al. (2004) model may also play a role, particularly the strength of local resource governance institutions.
- Full Text: false
- Date Issued: 2015
Women’s experiences on the use of Implanon as a contraceptive method in a selected primary healthcare facility in KwaZulu-Natal
- Mgobhozi, Lucky N., Mbeje, Pretty N., Mchunu, Gugu G.
- Authors: Mgobhozi, Lucky N. , Mbeje, Pretty N. , Mchunu, Gugu G.
- Date: 2021
- Subjects: Contraception Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7159 , vital:53073 , xlink:href=" https://doi.org/10.4102/curationis.v44i1.2187"
- Description: Background: The South African department of health recently introduced subdermal Implanon contraceptive implant with the aim to reduce teenage pregnancy and maternal mortality. First used in all public healthcare facilities across the country since early 2014, this method of contraception has been described as highly effective. However, some women have reported unbearable side effects, forcing them to remove the contraceptive implant early before its expiry date. Negligible emphasis has been placed on staff training and development to equip the nurses with new protocol and policies on Implanon. Objectives: The objective of this study was to explore experiences of women using Implanon as method of contraception at a selected primary healthcare facility in KwaZulu-Natal province of South Africa. Methods: A qualitative, descriptive and exploratory study design was used. A purposive sampling technique was used and a sample of seven women aged between 15 and 50 years was selected for this study. Semi-structured interviews were used in the data collection process. The Tesch’s method for data coding and data analysis was utilised. Necessary ethical measures were taken to ensure that the study is trustworthy. The study was conducted at Community Health Centre, KwaZulu-Natal between June 2017 and December 2018. Results: The findings showed that some participants were still willing to continue using this method of contraception regardless of the unwanted side effects. Major side effects reported were heavy menstrual bleeding, pain and discomfort, weight loss, insomnia and decreased sexual interest, which resulted in most participants stopping the use of Implanon. Conclusion: Most of the participants’ experience unwanted side effects because of poor screening, counselling and support. There is a clear demand to develop a screening tool and facilitate training of healthcare workers when initiating the use of Implanon. Keywords: Implanon; Implanon users; experiences; perceptions; primary healthcare
- Full Text:
- Date Issued: 2021
- Authors: Mgobhozi, Lucky N. , Mbeje, Pretty N. , Mchunu, Gugu G.
- Date: 2021
- Subjects: Contraception Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7159 , vital:53073 , xlink:href=" https://doi.org/10.4102/curationis.v44i1.2187"
- Description: Background: The South African department of health recently introduced subdermal Implanon contraceptive implant with the aim to reduce teenage pregnancy and maternal mortality. First used in all public healthcare facilities across the country since early 2014, this method of contraception has been described as highly effective. However, some women have reported unbearable side effects, forcing them to remove the contraceptive implant early before its expiry date. Negligible emphasis has been placed on staff training and development to equip the nurses with new protocol and policies on Implanon. Objectives: The objective of this study was to explore experiences of women using Implanon as method of contraception at a selected primary healthcare facility in KwaZulu-Natal province of South Africa. Methods: A qualitative, descriptive and exploratory study design was used. A purposive sampling technique was used and a sample of seven women aged between 15 and 50 years was selected for this study. Semi-structured interviews were used in the data collection process. The Tesch’s method for data coding and data analysis was utilised. Necessary ethical measures were taken to ensure that the study is trustworthy. The study was conducted at Community Health Centre, KwaZulu-Natal between June 2017 and December 2018. Results: The findings showed that some participants were still willing to continue using this method of contraception regardless of the unwanted side effects. Major side effects reported were heavy menstrual bleeding, pain and discomfort, weight loss, insomnia and decreased sexual interest, which resulted in most participants stopping the use of Implanon. Conclusion: Most of the participants’ experience unwanted side effects because of poor screening, counselling and support. There is a clear demand to develop a screening tool and facilitate training of healthcare workers when initiating the use of Implanon. Keywords: Implanon; Implanon users; experiences; perceptions; primary healthcare
- Full Text:
- Date Issued: 2021
Synthesis and photophysical properties of nanocomposites of aluminum tetrasulfonated phthalocyanine covalently linked to glutathione capped CdTe/CdS/ZnS quantum dots
- Oluwole, David O, Britton, Jonathan, Mashazi, Philani N, Nyokong, Tebello
- Authors: Oluwole, David O , Britton, Jonathan , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241379 , vital:50934 , xlink:href="https://doi.org/10.1016/j.synthmet.2015.04.015"
- Description: Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was covalently linked with different sizes of glutathione capped CdTe/CdS/ZnS quantum dots (QDs). The photophysical and Förster resonance energy transfer (FRET) properties of the nanoconjugates were investigated. The CdTe/CdS/ZnS(6.3) nanocomposite showed the highest enhancement in its photophysical properties while (CdTe/CdS/ZnS(3.2) nanocomposite showed the least. Highest FRET efficiency was observed in the linked CdTe/CdS/ZnS(6.3) nanocomposites at 93%. Hence, the combination of CdTe/CdS/ZnS with ClAlTSPc exhibited excellent photophysical properties.
- Full Text:
- Date Issued: 2015
- Authors: Oluwole, David O , Britton, Jonathan , Mashazi, Philani N , Nyokong, Tebello
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241379 , vital:50934 , xlink:href="https://doi.org/10.1016/j.synthmet.2015.04.015"
- Description: Aluminum tetrasulfonated phthalocyanine (ClAlTSPc) was covalently linked with different sizes of glutathione capped CdTe/CdS/ZnS quantum dots (QDs). The photophysical and Förster resonance energy transfer (FRET) properties of the nanoconjugates were investigated. The CdTe/CdS/ZnS(6.3) nanocomposite showed the highest enhancement in its photophysical properties while (CdTe/CdS/ZnS(3.2) nanocomposite showed the least. Highest FRET efficiency was observed in the linked CdTe/CdS/ZnS(6.3) nanocomposites at 93%. Hence, the combination of CdTe/CdS/ZnS with ClAlTSPc exhibited excellent photophysical properties.
- Full Text:
- Date Issued: 2015
Comparative efficiency of immobilized non-transition metal phthalocyanine photosensitizers for the visible light transformation of chlorophenols
- Agboola, Bolade, Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
- Authors: Agboola, Bolade , Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/286043 , vital:56233 , xlink:href="https://doi.org/10.1016/j.molcata.2005.12.009"
- Description: Photolysis of aqueous solutions of chlorophenols (4-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol) in the presence of immobilized non-transition metal phthalocyanine photosensitizers onto Amberlite® is presented. The photosensitizers studied are: Al (AlOCPc) and Zn (ZnOCPc) octacarboxyphthalocyanines; Al (AlPcS4) and Zn (ZnPcS4) tetrasulfophthalocyanines; sulfonated phthalocyanine complexes (containing mixtures of differently substituted derivatives) of Al (AlPcSmix), Zn (ZnPcSmix), Ge (GePcSmix), Si (SiPcSmix) and Sn (SnPcSmix). Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The complexes showed order of activity towards the transformation of pentachlorophenol as follows: ZnOCPc > SiPcSmix > SnPcSmix > ZnPcSmix > GePcSmix > ZnPcS4 > AlPcSmix > AlOCPc > AlPcS4. The generation of singlet oxygen (1O2) by these immobilized MPc photosensitizers was found to play a major role in their photoactivities towards the transformation of these chlorophenols. Langmuir–Hinshelwood (L–H) kinetic model studies showed that the ZnOCPc, GePcSmix and ZnPcSmix photocatalysis occurred on the catalysts surface. © 2005 Elsevier B.V. All rights reserved.
- Full Text:
- Date Issued: 2006
A Critical Review of Environmental Governance, Land Restitution, and Tourism in Protected Areas
- Authors: Ramukumba, Takalani
- Date: 2021
- Subjects: Tourism Land use Environmental protection Wildlife conservation Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7029 , vital:52756 , xlink:href=":https://doi.org/10.46222/ajhtl.19770720.200"
- Description: Natural areas, when protected, conserve the natural environment and function as social spaces in which tourism brings increased income, employment, and financial support for conservation. The inclusion of local community members in the planning and management of protected areas has been on the rise since the early 1900s. Tourism has been advocated as a strategy that can help in achieving economic development, especially in rural areas. However, governance issues and potential negative impacts of tourism development have been under inspection. Conservation efforts in Southern Africa especially in the late 1800s and early 1900s had negative impacts on the local communities since this led to many communities being displaced or having limited access to these protected areas. This has seen the need for ways and efforts to get local community members' despondency and attitudes towards protected areas change such that in the 20th century, there were efforts to use conservation models that included community members in the decision-making and benefit-sharing process to garner their support for protected areas. This paper reviews literature on environmental governance, land restitution in protected areas, tourism in protected areas, co-management, and the importance of community participation. These concepts are reviewed using Manyeleti Game Reserve as a case study. Keywords: Tourism, land restitution, environmental governance, wildlife resources, and stakeholder participation
- Full Text:
- Date Issued: 2021
- Authors: Ramukumba, Takalani
- Date: 2021
- Subjects: Tourism Land use Environmental protection Wildlife conservation Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7029 , vital:52756 , xlink:href=":https://doi.org/10.46222/ajhtl.19770720.200"
- Description: Natural areas, when protected, conserve the natural environment and function as social spaces in which tourism brings increased income, employment, and financial support for conservation. The inclusion of local community members in the planning and management of protected areas has been on the rise since the early 1900s. Tourism has been advocated as a strategy that can help in achieving economic development, especially in rural areas. However, governance issues and potential negative impacts of tourism development have been under inspection. Conservation efforts in Southern Africa especially in the late 1800s and early 1900s had negative impacts on the local communities since this led to many communities being displaced or having limited access to these protected areas. This has seen the need for ways and efforts to get local community members' despondency and attitudes towards protected areas change such that in the 20th century, there were efforts to use conservation models that included community members in the decision-making and benefit-sharing process to garner their support for protected areas. This paper reviews literature on environmental governance, land restitution in protected areas, tourism in protected areas, co-management, and the importance of community participation. These concepts are reviewed using Manyeleti Game Reserve as a case study. Keywords: Tourism, land restitution, environmental governance, wildlife resources, and stakeholder participation
- Full Text:
- Date Issued: 2021
Book Review Growing the next generation of researchers: A handbook for emerging researchers and their mentors, Holness, L
- Motshoane, Puleng, Muthama, Evelyn, McKenna, Sioux
- Authors: Motshoane, Puleng , Muthama, Evelyn , McKenna, Sioux
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187205 , vital:44579 , xlink:href="https://doi.org/10.14426/cristal.v3i2.56"
- Description: South Africa urgently needs more researchers (NRF, 2008; NDP, 2011). We also need a transformation in the demographics of our researchers. One indicator of this is that currently only 14% of university professors are black African, and only 2% are black African females (DHET, 2012). The Staffing South Africa's Universities Framework includes a number of initiatives to drive the process of growing the next generation of academics. For example, the nGAP project has inserted 125 new posts into the higher education system in 2015, with more to follow. This project allows for new academics to undertake postgraduate study and develop as teachers and researchers through mentorship, a reduced teaching load and so on.
- Full Text:
- Date Issued: 2015
- Authors: Motshoane, Puleng , Muthama, Evelyn , McKenna, Sioux
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187205 , vital:44579 , xlink:href="https://doi.org/10.14426/cristal.v3i2.56"
- Description: South Africa urgently needs more researchers (NRF, 2008; NDP, 2011). We also need a transformation in the demographics of our researchers. One indicator of this is that currently only 14% of university professors are black African, and only 2% are black African females (DHET, 2012). The Staffing South Africa's Universities Framework includes a number of initiatives to drive the process of growing the next generation of academics. For example, the nGAP project has inserted 125 new posts into the higher education system in 2015, with more to follow. This project allows for new academics to undertake postgraduate study and develop as teachers and researchers through mentorship, a reduced teaching load and so on.
- Full Text:
- Date Issued: 2015
Glumlazi
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229829 , vital:49715 , xlink:href="https://hdl.handle.net/10520/EJC47808"
- Full Text:
- Date Issued: 2009
- Authors: Krueger, Anton
- Date: 2009
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229829 , vital:49715 , xlink:href="https://hdl.handle.net/10520/EJC47808"
- Full Text:
- Date Issued: 2009
Handspring Puppet Company, Jane Taylor (Ed.)
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229658 , vital:49697 , xlink:href="https://0hdl.handle.net.wam.seals.ac.za/10520/EJC31088"
- Description: Handspring Puppet Company recently won three prestigious London awards (including the Olivier) for their design of the production War Horse, which is still running to great acclaim in the West End. This beautiful book has been released at exactly the right time, at a highpoint of an extraordinary company which has been producing astonishing work for 28 years already. It is an appropriate celebration of their many marvellous designs for 11 plays and two operas.
- Full Text:
- Date Issued: 2010
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229658 , vital:49697 , xlink:href="https://0hdl.handle.net.wam.seals.ac.za/10520/EJC31088"
- Description: Handspring Puppet Company recently won three prestigious London awards (including the Olivier) for their design of the production War Horse, which is still running to great acclaim in the West End. This beautiful book has been released at exactly the right time, at a highpoint of an extraordinary company which has been producing astonishing work for 28 years already. It is an appropriate celebration of their many marvellous designs for 11 plays and two operas.
- Full Text:
- Date Issued: 2010
Photophysical and photochemical properties of a novel thiol terminated low symmetry zinc phthalocyanine complex and its gold nanoparticles conjugate
- Mthethwa, Thandekile P, Durmus, Mahmut, Nyokong, Tebello
- Authors: Mthethwa, Thandekile P , Durmus, Mahmut , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231474 , vital:49891 , xlink:href="https://doi.org/10.1039/C3DT32698E"
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone.
- Full Text:
- Date Issued: 2013
- Authors: Mthethwa, Thandekile P , Durmus, Mahmut , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231474 , vital:49891 , xlink:href="https://doi.org/10.1039/C3DT32698E"
- Description: A novel thiol functionalized zinc phthalocyanine complex (ZnPcSH) is reported in this work. This complex was conjugated to gold nanoparticles. The photophysical and photochemical properties of the complex and the conjugate were investigated. Upon conjugation a blue shift was observed from the UV-Vis spectra. The conjugate showed a decrease in the fluorescence quantum yield and lifetime. An increase in the triplet quantum yield and lifetime was observed for ZnPcSH following conjugation to gold nanoparticles. Both ZnPcSH and its conjugate with gold nanoparticles showed high singlet oxygen quantum yields with the conjugate being higher than the Pc alone.
- Full Text:
- Date Issued: 2013
Voltammetric detection of vitamin B1 at carbon paste electrodes and its determination in tablets
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289692 , vital:56663 , xlink:href="https://doi.org/10.1002/1521-4109(200209)14"
- Description: The voltammetric behavior of vitamin B1 in alkaline medium at carbon paste electrode (CPE) is discussed. A method based on cyclic voltammetry for the determination of vitamin B1 at carbon paste electrode modified with manganese phthalocyanine (MnPc-CPE) is presented. In pH 10 buffer, the modified electrode showed catalytic activity towards the oxidation of vitamin B1 by considerably increasing the oxidation current of one of the observed waves compared to the oxidation current obtained at an unmodified electrode. The modified electrode was stable towards the determination of vitamin B1 compared to the unmodified electrode that is completely poisoned after a few scans. A linear relationship between the oxidation current and the concentration of vitamin B1 in solution was observed. The detection limit for vitamin B1 at the modified electrode was of the order of 10−5 mol dm−3. Commercial vitamin B1 tablets were analyzed using the modified electrodes.
- Full Text:
- Date Issued: 2002
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/289692 , vital:56663 , xlink:href="https://doi.org/10.1002/1521-4109(200209)14"
- Description: The voltammetric behavior of vitamin B1 in alkaline medium at carbon paste electrode (CPE) is discussed. A method based on cyclic voltammetry for the determination of vitamin B1 at carbon paste electrode modified with manganese phthalocyanine (MnPc-CPE) is presented. In pH 10 buffer, the modified electrode showed catalytic activity towards the oxidation of vitamin B1 by considerably increasing the oxidation current of one of the observed waves compared to the oxidation current obtained at an unmodified electrode. The modified electrode was stable towards the determination of vitamin B1 compared to the unmodified electrode that is completely poisoned after a few scans. A linear relationship between the oxidation current and the concentration of vitamin B1 in solution was observed. The detection limit for vitamin B1 at the modified electrode was of the order of 10−5 mol dm−3. Commercial vitamin B1 tablets were analyzed using the modified electrodes.
- Full Text:
- Date Issued: 2002