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A prototype device of microliter volume voltammetric pH sensor based on carbazole–quinone redox-probe tethered MWCNT modified three-in-one screen-printed electrode

Authors :
Sakthivel Srinivas
Krishnan Ashokkumar
Kamaraj Sriraghavan
Annamalai Senthil Kumar
Source :
Scientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)
Publication Year :
2021
Publisher :
Nature Portfolio, 2021.

Abstract

Abstract As an alternate for the conventional glass-based pH sensor which is associated with problems like fragile nature, alkaline error, and potential drift, the development of a new redox-sensitive pH probe-modified electrode that could show potential, current-drift and surface-fouling free voltammetric pH sensing is a demanding research interest, recently. Herein, we report a substituted carbazole-quinone (Car-HQ) based new redox-active pH-sensitive probe that contains benzyl and bromo-substituents, immobilized multiwalled carbon nanotube modified glassy carbon (GCE/MWCNT@Car-HQ) and screen-printed three-in-one (SPE/MWCNT@Car-HQ) electrodes for selective, surface-fouling free pH sensor application. This new system showed a well-defined surface-confined redox peak at an apparent standard electrode potential, E o′ = − 0.160 V versus Ag/AgCl with surface-excess value, Γ = 47 n mol cm−2 in pH 7 phosphate buffer solution. When tested with various electroactive chemicals and biochemicals such as cysteine, hydrazine, NADH, uric acid, and ascorbic acid, MWCNT@Car-HQ showed an unaltered redox-peak potential and current values without mediated oxidation/reduction behavior unlike the conventional hydroquinone, anthraquinone and other redox mediators based voltammetry sensors with serious electrocatalytic effects and in turn potential and current drifts. A strong π–π interaction, nitrogen-atom assisted surface orientation and C–C bond formation on the graphitic structure of MWCNT are the plausible reasons for stable and selective voltammetric pH sensing application of MWCNT@Car-HQ system. Using a programed/in-built three-in-one screen printed compatible potentiostat system, voltammetric pH sensing of 3 μL sample of urine, saliva, and orange juice samples with pH values comparable to that of milliliter volume-based pH-glass electrode measurements has been demonstrated.

Subjects

Subjects :
Medicine
Science

Details

Language :
English
ISSN :
20452322
Volume :
11
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Scientific Reports
Publication Type :
Academic Journal
Accession number :
edsdoj.f397a541fd36477dae278f12c2d59b1c
Document Type :
article
Full Text :
https://doi.org/10.1038/s41598-021-93368-5