Design and evaluation of an electrochemical immunosensor for measles serodiagnosis using measles-specific Immunoglobulin G antibodies
- Mashazi, Philani N, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
Electrocatalytic behavior of cobalt phthalocyanine complexes immobilized on glassy carbon electrode towards the reduction of dicrotophos pesticide
- Vilakazi, Sibulelo, Nyokong, Tebello, Fukuda, Takamitsu, Kobayashi, Nagao
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245832 , vital:51409 , xlink:href="https://doi.org/10.1142/S1088424612501040"
- Description: Electrocatalytic properties of cobalt phthalocyanine (CoPc), cobalt tetra-carboxy phthalocyanine (CoTCPc) and cobalt octa-carboxy (CoOCPc), towards the detection of dicrotophos have been studied. Catalytic behavior towards the reduction of dicrotophos was found to be dependent on the pH, as well as the substitution on the phthalocyanine ring. Strong electron withdrawing groups on the phthalocyanine ring yielded best catalysis as evidenced by the enhancement of the reduction peak current, (~5 fold) compared to the bare glassy carbon electrode. The analysis gave a good detection limit of 1.25 × 10-7 M, and good linearity for the studied concentration range. A high Tafel slope value was obtained, indicating a strong interaction between dicrotophos and the cobalt phthalocyanine complex.
- Full Text:
- Date Issued: 2012
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello , Fukuda, Takamitsu , Kobayashi, Nagao
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245832 , vital:51409 , xlink:href="https://doi.org/10.1142/S1088424612501040"
- Description: Electrocatalytic properties of cobalt phthalocyanine (CoPc), cobalt tetra-carboxy phthalocyanine (CoTCPc) and cobalt octa-carboxy (CoOCPc), towards the detection of dicrotophos have been studied. Catalytic behavior towards the reduction of dicrotophos was found to be dependent on the pH, as well as the substitution on the phthalocyanine ring. Strong electron withdrawing groups on the phthalocyanine ring yielded best catalysis as evidenced by the enhancement of the reduction peak current, (~5 fold) compared to the bare glassy carbon electrode. The analysis gave a good detection limit of 1.25 × 10-7 M, and good linearity for the studied concentration range. A high Tafel slope value was obtained, indicating a strong interaction between dicrotophos and the cobalt phthalocyanine complex.
- Full Text:
- Date Issued: 2012
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7325 , http://hdl.handle.net/10962/d1020575
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner. , Original publication is available at http://dx.doi.org/10.1016/j.bios.2013.04.028
- Full Text: false
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Language: English
- Type: Article
- Identifier: vital:7325 , http://hdl.handle.net/10962/d1020575
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner. , Original publication is available at http://dx.doi.org/10.1016/j.bios.2013.04.028
- Full Text: false
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
Facile deposition of gold nanoparticle thin films on semi-permeable cellulose substrate
- Sosibo, Ndabenhle, Mdluli, Phumlani, Mashazi, Philani N, Tshikhudo, Robert, Skepu, Amanda, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Sosibo, Ndabenhle , Mdluli, Phumlani , Mashazi, Philani N , Tshikhudo, Robert , Skepu, Amanda , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242638 , vital:51063 , xlink:href="https://doi.org/10.1016/j.matlet.2012.08.043"
- Description: This study reports the facile method for the deposition of gold nanoparticle thin film onto a monoporous semi-permeable cellulose membrane through the diffusion of borohydride ions leading to the reduction of AuCl4− ions. The synthesis of gold nanoparticle thin film was deposited on one side of the membrane that was exposed to AuCl4− ions while the other side containing a reducing agent remained clear. The gold nanoparticle thin film exhibited a broad surface plasmon resonance (SPR) peak at 529 nm. Various characterization techniques were employed and all demonstrated the presence of gold thin film. The reported method represents a simplistic method for the deposition of gold nanoparticle thin films and various other metal nanoparticles may be deposited following this method.
- Full Text:
- Date Issued: 2012
- Authors: Sosibo, Ndabenhle , Mdluli, Phumlani , Mashazi, Philani N , Tshikhudo, Robert , Skepu, Amanda , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242638 , vital:51063 , xlink:href="https://doi.org/10.1016/j.matlet.2012.08.043"
- Description: This study reports the facile method for the deposition of gold nanoparticle thin film onto a monoporous semi-permeable cellulose membrane through the diffusion of borohydride ions leading to the reduction of AuCl4− ions. The synthesis of gold nanoparticle thin film was deposited on one side of the membrane that was exposed to AuCl4− ions while the other side containing a reducing agent remained clear. The gold nanoparticle thin film exhibited a broad surface plasmon resonance (SPR) peak at 529 nm. Various characterization techniques were employed and all demonstrated the presence of gold thin film. The reported method represents a simplistic method for the deposition of gold nanoparticle thin films and various other metal nanoparticles may be deposited following this method.
- Full Text:
- Date Issued: 2012
Interaction of nitric oxide with cobalt (II) tetrasulfophthalocyanine
- Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
- Full Text:
- Date Issued: 2000
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
- Full Text:
- Date Issued: 2000
Phthalocyanines and related complexes as electrocatalysts for the detection of nitric oxide
- Nyokong, Tebello, Vilakazi, Sibulelo
- Authors: Nyokong, Tebello , Vilakazi, Sibulelo
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290346 , vital:56741 , xlink:href="https://doi.org/10.1016/S0039-9140(03)00356-4"
- Description: Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals such as CoPc and FePc generally show better catalytic activity towards the detection of NO than complexes containing electroinacive central metals. However, the involvement of ring based redox processes was confirmed for the homogenous NO catalysis using CoPc.
- Full Text:
- Date Issued: 2003
- Authors: Nyokong, Tebello , Vilakazi, Sibulelo
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290346 , vital:56741 , xlink:href="https://doi.org/10.1016/S0039-9140(03)00356-4"
- Description: Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals such as CoPc and FePc generally show better catalytic activity towards the detection of NO than complexes containing electroinacive central metals. However, the involvement of ring based redox processes was confirmed for the homogenous NO catalysis using CoPc.
- Full Text:
- Date Issued: 2003
The effects of carbon nanotubes on the electrocatalysis of hydrogen peroxide by metallo-phthalocyanines
- Mashazi, Philani N, Mugadza, Tawanda, Sosibo, Ndabenhle, Mdluli, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Mugadza, Tawanda , Sosibo, Ndabenhle , Mdluli, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247174 , vital:51553 , xlink:href="https://doi.org/10.1016/j.talanta.2011.07.069"
- Description: The pre-grafted screen-printed gold electrode modified with phenyl-amino monolayer was investigated for covalent immobilization of phenyl-amine functionalized single-walled carbon nanotubes (PA-SWCNT) and metal tetra-amino phthalocyanine (MTAPc) using Schiff-base reactions with benzene-1,4-dicarbaldehyde (BDCA) as cross-linker. The PA-SWCNT and MTAPc modified electrodes were applied as hybrids for electrochemical sensing of H2O2. The step-by-step fabrication of the electrode was followed using electrochemistry, impedance spectroscopy, scanning electron microscopy and Raman spectroscopy and all these techniques confirmed the fabrication and the immobilization of PA-SWCNT, MnTAPc and CoTAPc onto gold surfaces. The apparent electron transfer constant (kapp) showed that the carbon nanotubes and metallo-phthalocyanines hybrids possess good electron transfer properties compared to the bare, pre-grafted and the MTAPc modified gold electrode surfaces without PA-SWCNT. The electrochemical sensing of hydrogen peroxide was successful with PA-SWCNT–MTAPc hybrid systems showing higher electrocatalytic currents compared to the other electrodes. The analytical parameters obtained using chronoamperometry gave good linearity at H2O2 concentrations ranging from 1.0 to 30.0 μmol L−1. The values for the limit of detection (LoD) were found to be of the orders of 10−7 M using the 3δ for all the electrodes. The PA-SWCNT–MTAPc modified SPAuEs were much more sensitive compared to PA–MTAPc modified SPAuEs.
- Full Text:
- Date Issued: 2011
- Authors: Mashazi, Philani N , Mugadza, Tawanda , Sosibo, Ndabenhle , Mdluli, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247174 , vital:51553 , xlink:href="https://doi.org/10.1016/j.talanta.2011.07.069"
- Description: The pre-grafted screen-printed gold electrode modified with phenyl-amino monolayer was investigated for covalent immobilization of phenyl-amine functionalized single-walled carbon nanotubes (PA-SWCNT) and metal tetra-amino phthalocyanine (MTAPc) using Schiff-base reactions with benzene-1,4-dicarbaldehyde (BDCA) as cross-linker. The PA-SWCNT and MTAPc modified electrodes were applied as hybrids for electrochemical sensing of H2O2. The step-by-step fabrication of the electrode was followed using electrochemistry, impedance spectroscopy, scanning electron microscopy and Raman spectroscopy and all these techniques confirmed the fabrication and the immobilization of PA-SWCNT, MnTAPc and CoTAPc onto gold surfaces. The apparent electron transfer constant (kapp) showed that the carbon nanotubes and metallo-phthalocyanines hybrids possess good electron transfer properties compared to the bare, pre-grafted and the MTAPc modified gold electrode surfaces without PA-SWCNT. The electrochemical sensing of hydrogen peroxide was successful with PA-SWCNT–MTAPc hybrid systems showing higher electrocatalytic currents compared to the other electrodes. The analytical parameters obtained using chronoamperometry gave good linearity at H2O2 concentrations ranging from 1.0 to 30.0 μmol L−1. The values for the limit of detection (LoD) were found to be of the orders of 10−7 M using the 3δ for all the electrodes. The PA-SWCNT–MTAPc modified SPAuEs were much more sensitive compared to PA–MTAPc modified SPAuEs.
- Full Text:
- Date Issued: 2011
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