Abstract

There are limited data on amperometric biosensors (ABSs) for L-arginine (Arg) determination based on oxidases that produce hydrogen peroxide (H2O2) as a byproduct of enzymatic reaction, and artificial peroxidases (POs) for decomposition of H2O2. The most frequently proposed Arg-sensitive oxidase-based ABSs contain at least two enzymes in the bioselective layer; this complicates the procedure and increases the cost of analysis. Therefore, the construction of a one-enzyme ABS for Arg analysis is a practical problem. In the current work, fabrication, and characterization of three ABS types for the direct measurement of Arg were proposed. L-arginine oxidase (ArgO) isolated from the mushroom Amanita phalloides was co-immobilized with PO-like nanozymes (NZs) on the surface of graphite electrodes. As PO mimetics, chemically synthesized NZs of CeCu (nCeCU) and NiPtPd (nNiPtPd), as well as green-synthesized hexacyanoferrate of copper (gCuHCF), were used. The novel ABSs exhibited high sensitivity and selectivity to Arg, broad linear ranges and good storage stabilities. Two ABSs were tested on real samples of products containing Arg, including the pharmaceutical preparation “Tivortine”, juices, and wine. A high correlation (R = 0.995) was demonstrated between the results of testing “Tivortine” and juice using nCeCU/GE and nNiPtPd/GE. It is worth mentioning that only a slight difference (less than 1%) was observed for “Tivortin” between the experimentally determined content of Arg and its value declared by the producer. The proposed ArgO-NZ-based ABSs may be promising for Arg analysis in different branches of science, medicine, and industry.

Highlights

  • L-arginine (Arg) concentration is an important indicator of food and food-supplement quality, as well as an important biomarker in clinical diagnostics and nutritional status assessment [1,2,3,4,5,6]

  • Enzyme-based biosensors for Arg determination rely on the measurement of reactants consumed or products generated from enzymatic cascade reactions, including ammonium ions or H2O2 [13,18]

  • Substitution of PO with PO-like mimetics in a biosensing layer improved the electrochemical properties of the electrodes and the detection of Arg in wider ranges of linear responses

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Summary

Introduction

L-arginine (Arg) concentration is an important indicator of food and food-supplement quality, as well as an important biomarker in clinical diagnostics and nutritional status assessment [1,2,3,4,5,6]. A variety of optical and electrochemical methods for Arg determination have been developed to date [7,8,9,10,11,12,13,14,15]. To improve their selectivity, enzymatic approaches have been developed, including electrochemical biosensors [10,11,12,13,14,15,16]. For Arg analysis, arginine decarboxylase, L-arginase, with urease [12,14,19,20,21,22,23,24,25], arginine deiminase (ADI) [26,27,28], and L-arginine oxidase (ArgO) with peroxidase [29,30,31,32,33]

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