Carbon-Based Enzyme Mimetics for Electrochemical Biosensing

Abstract

Natural enzymes are used as special reagents for the preparation of electrochemical (bio)sensors due to their ability to catalyze processes, improving the selectivity of detection. However, some drawbacks, such as denaturation in harsh experimental conditions and their rapid de- gradation, as well as the high cost and difficulties in recycling them, restrict their practical applications. Nowadays, the use of artificial enzymes, mostly based on nanomaterials, mimicking the functions of natural products, has been growing. These so-called nanozymes present several advantages over natural enzymes, such as enhanced stability, low cost, easy production, and rapid activity. These outstanding features are responsible for their widespread use in areas such as catalysis, energy, imaging, sensing, or biomedicine. These materials can be divided into two main groups: metal and carbon-based nanozymes. The latter provides additional advantages compared to metal nanozymes, i.e., stable and tuneable activity and good biocompatibility, mimicking enzyme activities such as those of peroxidase, catalase, oxidase, superoxide dismutase, nuclease, or phosphatase. In this review article, we have focused on the use of carbon-based nanozymes for the preparation of electrochemical (bio)sensors. The main features of the most recent applications have been revised and illustrated with examples selected from the literature over the last four years (since 2020).

Keywords: artificial enzyme; carbon nanozyme; electrochemical biosensor; enzyme mimicking.

Figure 1

Schematic principle of the preparation of a GPC3 electrochemical nanobiosensor involving the H-rGO-Pd NPs nanozyme. Reproduced from [32] with permission.

Figure 2

Illustration of the preparation procedure and sensing mechanism of AuNP/N-GQDs-PEI-MOF/GCE- and GOx/AuNP/N-GQDs-PEI-MOF/GCE-based amperometric sensors for (A) H₂O₂ and (B) glucose. Reproduced from [45] with permission.

Figure 3

(A) Schematic display of the preparation of Ag@Ag@CDs; (B) Au@Ag@CDs nanoenzymes-driven multifunctional signal amplification combined with Ti₂C/Ag₂S composites for photoelectrochemical biosensing. Reprinted and adapted from [48] with permission.

Figure 4

(A) Schematic illustration of the preparation of Co₉S₈/CDs and (B) cyclic voltammograms obtained at Co₉S₈/CDs/GCE with different concentrations of H₂O₂. Reprinted and adapted from [53] with permission.

Figure 5

Schemes of (A) MNPs/CS/CDH/gC₃N₄ and (B) the electrotransfer mechanism during lactose oxidation. Reprinted and adapted from [76] with permission.

Figure 6

Amplified signal strategy based on the ECL-based nanozyme. Reprinted from [77] with permission.

Figure 7

Schematic illustration of the photoelectrochemical biosensor developed for the determination of the telomerase activity. Reprinted from [81] with permission.