Nanomaterials are materials with dimensions in the 1–100 nm range or containing nanoscale features on their surfaces or within their structures. Their tunable composition, structure, and surface chemistry give rise to unique magnetic, electronic, and optical properties. Based on composition and structural organization, nanomaterials are commonly classified into metal and metal-oxide nanoparticles, carbon-based nanomaterials, metal–organic frameworks, hierarchical nanoflowers, and single-atom nanozymes. These engineered nanomaterials provide versatile platforms for catalytic and biosensing applications.

Nanozyme engineering involves the rational design of nanomaterials that exhibit enzyme-like catalytic activities, enabling them to mimic the functions of natural enzymes while offering superior stability and tunability. According to the type of catalytic reaction, nanozymes are mainly classified into oxidoreductase-like nanozymes (e.g., peroxidase, oxidase, catalase, and superoxide dismutase mimics) and hydrolase-like nanozymes (e.g., phosphatase, phosphodiesterase, esterase, and DNase mimics). These activities are governed by engineered active sites, surface chemistry, and electronic structures at the nanoscale. Such nanozymes provide robust and versatile catalytic platforms for signal amplification, reactive species regulation, and biosensing applications.

Nanozyme–hybrid engineering integrates nanozymes with biological recognition elements, including enzymes, antibodies, and aptamers, to enhance catalytic efficiency, molecular specificity, and operational stability. In nanozyme–enzyme hybrids, such as enzyme-embedded nanoflowers or enzymes confined within mesoporous nanomaterials and metal–organic frameworks, cascade reactions are enabled while the nanostructured matrices protect enzymes from denaturation. In contrast to traditional antibody- or aptamer-based systems relying on unstable natural enzymes, nanozyme–antibody and nanozyme–aptamer hybrids provide selective target recognition with robust and efficient catalytic signal amplification. Through rational interfacial and structural design, these hybrid systems enable highly sensitive, selective, and durable platforms for advanced biosensing and diagnostic applications.

Nano-enabled biosensors leverage engineered nanomaterials and nanozymes to selectively recognize and transduce signals from diverse analytical targets, which are broadly classified into biological molecules, environmental substances, and bacteria. Owing to the distinct chemical and biochemical characteristics of each target, the design of sensing platforms and nanozyme systems must be tailored accordingly. Depending on the target, nanozymes may directly catalyze analyte oxidation or hydrolysis, or operate in conjunction with specific enzymes to enable selective signal generation. Furthermore, different targets can induce either signal enhancement or inhibition, underscoring the importance of understanding target-specific reaction mechanisms. Such mechanistic insights are essential for the rational development of sensitive, selective, and reliable nano-enabled biosensing platforms.

Nano-enabled biosensors are implemented on diverse platforms, including solution-based, paper-based, PDMS-based microfluidic, and cell-based systems, each offering distinct advantages. Solution-based platforms are well suited for rapid assays and mechanistic studies, while paper-based formats enable low-cost, portable, and on-site detection. PDMS-based microfluidic devices provide precise fluid handling, multiplexing capability, and reduced reagent consumption, whereas cell-based platforms allow biosensing in biologically relevant environments.

Signal transduction in these platforms is achieved through various readout modalities, such as colorimetric, fluorometric, electrochemical, and surface-enhanced Raman scattering (SERS) techniques. In some cases, multiple readouts are combined into multimodal sensing systems to improve sensitivity, reliability, and analytical robustness.

Nanozyme-based systems have been extensively explored for functional applications beyond biosensing, including cytoprotection, antibacterial activity, and environmental remediation. In cytoprotection, antioxidant nanozymes mimicking superoxide dismutase and catalase efficiently regulate intracellular reactive oxygen species, thereby protecting cells from oxidative stress–induced damage. For antibacterial applications, nanozymes generate or modulate reactive species to disrupt bacterial membranes and metabolic processes, enabling effective pathogen inactivation. In environmental applications, nanozymes exhibiting laccase- or peroxidase-like activities catalyze the degradation of organic pollutants, such as phenolic dyes, offering sustainable and efficient strategies for contaminant removal. Together, these application-oriented studies highlight the versatility of nanozyme engineering in addressing biomedical and environmental challenges.