Multi-walled carbon nanotube/poly(glycine) modified carbon paste electrode for the determination of dopamine in biological fluids and pharmaceuticals

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2013-10, Vol.110, p.458-465
• Main Authors: Thomas, Tony, Mascarenhas, Ronald J., Swamy, B.E. Kumara, Martis, Praveen, Mekhalif, Zineb, Sherigara, B.S.
• Format: Article
• Language: English
• Subjects: ascorbic acid; Ascorbic Acid - chemistry; blood serum; Body Fluids - chemistry; Carbon; Carbon - chemistry; carbon nanotubes; Carbon paste electrode; colloids; detection limit; Dielectric Spectroscopy; Dispersions; Dopamine; Dopamine - analysis; drugs; electrochemistry; Electrodes; Electropolymerization; energy; energy-dispersive X-ray analysis; Glycine; Glycine - chemistry; humans; Hydrogen-Ion Concentration; impedance; Multi wall carbon nanotubes; Multi-walled carbon nanotube; nitrogen; Particle Size; Pastes; Pharmaceutical Preparations - chemistry; Polymerization; Polymers - chemical synthesis; Polymers - chemistry; Scanning electron microscopy; spectroscopy; Surface Properties; uric acid; Uric Acid - chemistry; X-radiation
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2013.03.056

•MWCNTs/poly(glycine) at CPE improves redox kinetics of dopamine.•Presence of MWCNTs increases the extent of polymerization of glycine.•100% exclusion of AA signal below the concentration of 3.1×10−4M.•Simple, cheap, reproducible and biocompatible.•Successful estimation of dopamine in injection and blood serum. A modified carbon paste electrode (CPE) for the selective detection of dopamine (DA) in presence of large excess of ascorbic acid (AA) and uric acid (UA) at physiological pH has been fabricated by bulk modification of CPE with multi-walled carbon nanotubes (MWCNTs) followed by electropolymerization of glycine (Gly). The surface morphology is compared using SEM images. The presence of nitrogen was confirmed by the energy dispersion X-ray spectroscopy (EDS) indicating the polymerization of Gly on the surface of the modified electrode. The impedance study indicates a better charge transfer kinetics for DA at CPE modified with MWCNT/polyglycine electrode. The presence of MWCNTs in carbon paste matrix triggers the extent of electropolymerization of Gly and imparts more selectivity towards DA by electrochemically not sensing AA below a concentration of 3.1×10−4M. Due to the exclusion of the signal for AA, the interference of AA in the determination of DA is totally ruled out by DPV method which is used for its detection at lower concentrations. Large peak separation, good sensitivity, reproducibility and stability allow this modified electrode to analyze DA individually and simultaneously along with AA and UA. Detection limit of DA was determined from differential pulse voltammetric (DPV) study and found to be 1.2×10−8M with a linear dynamic range of 5.0×10−7M to 4.0×10−5M. The practical analytical application of this electrode was demonstrated by measurement of DA content in dopamine hydrochloride injection and human blood serum.