Ultrasensitive detection of prostate-specific antigen using glucose-encapsulated nanoliposomes anti-PSA polyclonal antibody as detection nanobioprobes
- Authors: Mwanza, Daniel , Mfamela, Nololo , Adeniyi, Omotayo , Nyokong, Tebello , Mashazi, Philani N
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300268 , vital:57911 , xlink:href="https://doi.org/10.1016/j.talanta.2022.123483"
- Description: In this work, the preparation of glucose encapsulating nanoliposomes was achieved using two different lipid formulations, labelled as F1 and F2. Both formulations contained phosphatidylcholine (PC), oleylamido-4-butanoic acid (OABA) and in addition, F1 had cholesterol (CHO) while F2 contained cholesteroyl hemisussinate (CHEMS). These formulations were studied for their pH sensitivity and controlled release of encapsulated glucose for indirect detection of prostate-specific antigen (PSA) using sandwich immunoassay. As a signal generator, encapsulated glucose in nanoliposomes was quantified directly using the personal glucose meter (PGM) and colorimetrically using peroxidase property of horseradish peroxidase (HRP) enzyme and Pd|PdO as nanozymes. Controlled release of the encapsulated glucose was achieved using the pH effect or Triton-X 100 as a surfactant to destabilize the liposomal structure. The F2 formulation showed maximum controlled release at acidic phosphate buffer saline (PBS, pH 5.0). The concentration of encapsulated glucose was found to be high in F2 formulation and these were applied for the indirect detection of PSA. The limit of detection (LOD) values for PSA were found to be 53 fg mL−1, 64 fg mL−1 and 10 fg mL−1 when HRP, Pd|PdO and PGM were respectively used. The detection signal was linear over a wide concentration range for PSA including the clinical range of 4–10 ng mL−1. The HRP system showed low LOD value when compared with Pd|PdO nanozymes. PGM system gave lowest LOD values owing to the sensitivity of the system towards glucose. Pd|PdO nanozyme system showed good stability over a wide temperature up to 80 °C. PGM system required less reaction time (2 min), low reagents and results were readily generated in digital format.
- Full Text:
- Date Issued: 2022
Nanohybrid electrocatalyst based on cobalt phthalocyanine-carbon nanotube-reduced graphene oxide for ultrasensitive detection of glucose in human saliva
- Authors: Adeniyi, Omotayo , Nwahara, Nnamdi , Mwanza, Daniel , Nyokong, Tebello , Mashazi, Philani N
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231356 , vital:49880 , xlink:href="https://doi.org/10.1016/j.snb.2021.130723"
- Description: The current diabetes management systems require collecting blood samples via an invasive and painful finger pricking leading to the formation of callus, scarring and loss of sensibility to patients due to continuous monitoring. Therefore, a non-invasive and painless method of determining glucose levels would be desirable to diabetes patients who need constant monitoring. Saliva glucose measurement is a non-invasive alternative for diabetes management. A highly sensitive, stable, and selective non-enzymatic electrochemical sensor that can accurately quantify saliva glucose is required. A single-walled carbon nanotube/reduced graphene oxide/cobalt phthalocyanines nanohybrid modified glassy carbon electrode (GCE-SWCNT/rGO/CoPc) has been fabricated for the non-enzymatic determination of glucose in human saliva. The SWCNT/rGO/CoPc was characterized using various spectroscopic, microscopic, and electrochemical techniques. The synergistic effect between SWCNT, rGO, and CoPc facilitated excellent electron transfer process that improved the sensor sensitivity. The GCE-SWCNT/rGO/CoPc sensor exhibited two linear responses in the 0.30 μM to 0.50 mM and 0.50–5.0 mM glucose concentration ranges, and the detection limit was 0.12 μM. The sensor had an excellent saliva glucose detection sensitivity of 992.4 μA·mM−1·cm−2 and high specificity for glucose in the presence of other coexisting analytes. In addition, it showed good storage stability, reusability, and a fast response time of about 1.2 s. The GCE-SWCNT/rGO/CoPc nanohybrid electrode showed excellent potential for developing accurate, non-invasive, and painless glucose sensing.
- Full Text:
- Date Issued: 2021
Visible light responsive TiO2-graphene oxide nanosheets-Zn phthalocyanine ternary heterojunction assisted photoelectrocatalytic degradation of Orange G
- Authors: Nwahara, Nnamdi , Adeniyi, Omotayo , Mashazi, Philani N , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185446 , vital:44387 , xlink:href="https://doi.org/10.1016/j.jphotochem.2021.113291"
- Description: Herein, we report on the successful fabrication of a visible light-responsive TiO2 - graphene oxide nanosheets – Zn phthalocyanine (TiO2@GONS@ZnPc) ternary structure for the photoelectrochemical degradation of Orange G azo dye. The characterization of TiO2@GONS@ZnPc composite was achieved using various spectroscopic and microscopic techniques. Our results show that the TiO2@GONS@ZnPc surface hybrid heterojunction promotes charge separation and electron migration, significantly improving the degradation efficiency with an applied potential. For the first time, we show the existence of a non-radical activation route for persulfate (PS) using such π electron-rich ZnPc-GONS catalysts. The degradation kinetics were found to follow pseudo first order kinetics. Electron spin resonance analyses suggested that neither hydroxyl radicals nor sulfate radicals were produced therein, and therefore were not responsible for the persulfate-driven oxidation of the OG dye. These findings suggest that both which GONS and ZnPc play a critical role in mediating the eventual charge transfer mediated PS activation. The results illustrate the remarkable capacity of the TiO2@GONS@ZnPc composite to rapidly degrade Orange G by a coupled TiO2@GONS@ZnPc-persulfate system.
- Full Text:
- Date Issued: 2021