Emerging strategies for food contaminant detection via DNAzyme-driven DNA walker platforms: Strategies, applications, and future perspectives.

Abstract

DNA walkers are a type of programmable, dynamic DNA nanomachine composed of synthetic oligonucleotides that move in a controlled manner along specific nucleic acid tracks through strand displacement or catalytic cleavage reactions. Among the various methods used to power them, DNAzyme-driven DNA walkers have attracted increasing interest because they combine enzyme-like catalytic functions with the inherent advantages of DNA materials. DNAzymes are single-stranded DNA molecules capable of catalyzing precise cleavage of DNA or RNA substrates in the presence of metal ion cofactors. They offer benefits such as high stability, reproducibility, low cost, and facile chemical modification. These characteristics make DNAzymes particularly well-suited as driving components in DNA walker-based sensing systems. In recent years, DNAzyme-powered DNA walker sensors have become a highly effective analytical method for monitoring food safety due to their fast response, high sensitivity, strong selectivity, and suitability for use in portable detection devices. This review offers a comprehensive overview of the design principles and mechanisms of DNAzyme-driven DNA walkers, focusing on the structures of the walkers and the configurations of their tracks that are crucial for signal amplification. Special attention is given to their applications in detecting food contaminants, including harmful pathogens such as bacteria and toxin-related markers, as well as toxic chemical pollutants like heavy metal ions, pesticide residues, and antibiotics. The main challenges affecting practical applications, such as signal stability, matrix interference, and suitability for on-site use, are thoroughly examined. Finally, future directions are proposed to develop durable, affordable, and field-ready DNAzyme-powered DNA walker systems for food safety evaluation.