Nanozymes in Point-of-Care Diagnosis: An Emerging Futuristic Approach for Biosensing

Abstract

Nanomaterial-based artificial enzymes (or nanozymes) have attracted great attention in the past few years owing to their capability not only to mimic functionality but also to overcome the inherent drawbacks of the natural enzymes. Numerous advantages of nanozymes such as diverse enzyme-mimicking activities, low cost, high stability, robustness, unique surface chemistry, and ease of surface tunability and biocompatibility have allowed their integration in a wide range of biosensing applications. Several metal, metal oxide, metal–organic framework-based nanozymes have been exploited for the development of biosensing systems, which present the potential for point-of-care analysis. To highlight recent progress in the field, in this review, more than 260 research articles are discussed systematically with suitable recent examples, elucidating the role of nanozymes to reinforce, miniaturize, and improve the performance of point-of-care diagnostics addressing the ASSURED (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to the end user) criteria formulated by World Health Organization. The review reveals that many biosensing strategies such as electrochemical, colorimetric, fluorescent, and immunological sensors required to achieve the ASSURED standards can be implemented by using enzyme-mimicking activities of nanomaterials as signal producing components. However, basic system functionality is still lacking. Since the enzyme-mimicking properties of the nanomaterials are dictated by their size, shape, composition, surface charge, surface chemistry as well as external parameters such as pH or temperature, these factors play a crucial role in the design and function of nanozyme-based point-of-care diagnostics. Therefore, it requires a deliberate exertion to integrate various parameters for truly ASSURED solutions to be realized. This review also discusses possible limitations and research gaps to provide readers a brief scenario of the emerging role of nanozymes in state-of-the-art POC diagnosis system development for futuristic biosensing applications.

A Sub-Nanostructural Transformable Nanozyme for Tumor Photocatalytic Therapy

“…Though promising, the difficulties in storage and recycling, low chemical durability, and high cost of natural enzymes have limited their broad applications [ 3 ]. In recent years, artificial nanozymes with natural enzyme-mimetic activities have been developed [ 4 – 10 ], which attracted remarkable attention for various biomedical applications including biosensing, cytoprotection, tumor therapy, etc. [ 11 – 14 ].…”

Sensitive detection of the okadaic acid marine toxin in shellfish by Au@Pt NPs/horseradish peroxidase dual catalysis immunoassay

“…Currently, signal amplification strategies based on active nanoparticle catalysis have been proposed and intensively used for sensitivity enhancement. 23 Attributed to the high loading of signal labels and their inherent catalytic activity, special functional nanomaterials such as Au nanospheres, 24 carbon nanotubes 25 and platinum nanoparticles (Pt NPs) 26 were often adopted for signal reinforcement and are widely used for bioassays of proteins, drug residues and biological toxins. Attributed to the special change of surface atomic arrangement and electronic structure, 27 Au@Pt bimetallic nanoparticles displayed higher catalytic activity than the single Au or Pt atoms, and have been employed for the sensitive colorimetric immunoassay of mycotoxins and phycotoxins.…”

Prussian Blue Nanozymes with Enhanced Catalytic Activity: Size Tuning and Application in ELISA-like Immunoassay

“…In this type of assay, enzymes and their artificial analogs are responsible for the conversion of colorless substrate to colored product [ 4 ]. Nowadays, colorimetric immunoassays are one of the key analytical instruments in medicine, food quality control, and biotechnology [ 5 , 6 ]. Despite nanozymes not being mature enough and numerous challenges present [ 6 ], they emerge as prospective alternatives to natural enzymes in the field of biosensing [ 7 , 8 ].…”