Nonenzymatic Lactic Acid Detection Using Cobalt Polyphthalocyanine/Carboxylated Multiwalled Carbon Nanotube Nanocomposites Modified Sensor

Abstract

In this study, a novel cobalt polyphthalocyanine/carboxylic acid functionalized multiwalled carbon nanotube nanocomposite (CoPPc/MWCNTs-COOH) to detect lactic acid was successfully fabricated. The nanocomposite was systematically characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible absorption spectroscopy, and X-ray photoelectron spectroscopy. The nanocomposite provided excellent conductivity for effective charge transfer and avoided the agglomeration of MWCNTs-COOH. The electrochemical surface area, diffusion coefficient and electron transfer resistance of the CoPPc/MWCNTs-COOH glassy carbon electrode (CoPPc/MWCNTs-COOH/GCE) were calculated as A = 0.49 cm2, D = 9.22 × 10−5 cm2/s, and Rct = 200 Ω, respectively. The lactic acid sensing performance of the CoPPc/MWCNTs-COOH was evaluated using cyclic voltammetry in 0.1 M PBS (pH 4). The results demonstrated that the novel electrode exhibited excellent electrochemical performance toward lactic acid reduction over a wide concentration range (10 to 240 μM), with a low detection limit (2 μM (S/N = 3)), and a reasonable selectivity against various interferents (ascorbic acid, uric acid, dopamine, sodium chloride, glucose, and hydrogen peroxide). Additionally, the electrode was also successfully applied to quantify lactic acid in rice wine samples, showing great promise for rapid monitoring applications.

Recent Advances in the Use of CoPc-MWCNTs Nanocomposites as Electrochemical Sensing Materials

“…In an attempt to detect lactic acid, Shao and group [ 19 ] fabricated a novel sensor by modifying GCE with cobalt polyphthalocyanine (CoPPc) nanocomposite and MWCNTs-COOH. The reduction mechanism of lactic acid on the CoPPc/MWCNTs-COOH/GCE surface is illustrated in Scheme 6 below.…”

“… The reduction mechanism of lactic acid reduction on the CoPPc/MWCNTs-COOH/GCE surface, adapted from [ 19 ] with permission. …”

“…Thus, MWCNTs have better redox activity than single-walled carbon nanotubes (SWCNTs) [ 7 ]. Importantly, CNTs (SWCNTs and MWCNTs) have been extensively used as a sensing material to fabricate various nanocomposites which have been successfully employed to determine a wide range of analytes, such as uric acid, ascorbic acid, dopamine [ 8 , 9 ], styrene, epinephrine [ 7 , 10 ], glutathione, cysteine, acetaminophen [ 11 , 12 ], carbaryl, thiols, bisphenols [ 13 , 14 , 15 ], bromate, nitrite [ 16 ], hydrogen peroxide, paracetamol [ 17 , 18 ], lactic acid, hydrazine, glucose [ 19 , 20 , 21 ], and others.…”

“…CoPc has been widely used as a mediator in electronic devices and in constructing electrochemical sensors due to its electronic, catalytic, and semi-conductor proprieties; besides, it can be anchored in cationic substrates by simple adsorption processes [ 31 , 32 ]. Additionally, the rich redox chemistry of CoPc and its high ability to transport electrons leading to its outstanding electrocatalytic activity for various chemicals, has given it a wider usage in sensor fabrication [ 19 ].…”

Enzyme-Mimics for Sensitive and Selective Steroid Metabolite Detection

“…In early research, cobalt phthalocyanine (CoPc) was recognized for O 2 reduction for low-cost fuel cell applications . Phthalocyanines with different metal centers (e.g., iron, cobalt, copper, nickel, and ruthenium) have been reported to exhibit electrocatalytic activity for electrochemical oxidation or reduction of various biomarkers, molecules, and ions, including glucose, uric acid, lactic acid, paracetamol, creatinine, CO 2 , oxygen evolution reaction, dopamine, ascorbic acid, H 2 O 2 , nitrite, Cd 2+ and Pb 2+ ions, cysteine, and pyridoxine . In this work, we employed copper phthalocyanine tetrasulfonate (CuPcTS) to catalyze cortisol reduction.…”