Chemical memory in nanostructured transducers for scalable biosensing: from synthesis to device-ready interfaces.

Scalable biosensing is limited less by isolated detection limits than by whether a nanostructured interface remains chemically accessible, reproducible and stable after fabrication. In this review, we develop the concept of chemical memory to describe how residual ligands, defect density, terminal groups, oxidation history, colloidal ageing and formulation additives introduced during nanomaterial synthesis persist into device interfaces. Unlike a descriptive list of synthesis variables, chemical memory is defined by a causally traceable link between a retained materials state and a measurable device consequence. Using DNAzyme interfaces, rolling circle amplification (RCA) chemistries and printed/electrodeposited electrochemical transducers as stress tests, and extending the comparison to metal-organic frameworks (MOFs), covalent organic frameworks (COFs), nanozymes and single-atom catalysts, we analyse which failure modes each material class solves. We further introduce a semi-quantitative evidence chain connecting XPS/Raman spectroscopy/ligand-coverage, resistance and catalytic-site measurements to probe accessibility, blank current, matrix recovery, device RSD and storage retention. The resulting design rules emphasise when a nanostructure should be introduced, when a bare or post-modified printed electrode is preferable, and which batch, matrix, shelf-life and fabrication evidence is needed before translational claims are credible.