A portable near-infrared aptasensor platform for derivatization-assisted on-site analysis of acrylamide in food...

Rapid and reliable on-site analysis remains a central challenge in food safety monitoring, particularly for small-molecule contaminants that are difficult to detect using portable analytical platforms. Acrylamide (AM), a typical low-epitope processing contaminant widely present in thermally treated foods, exhibits weak molecular recognition and inefficient optical signal transduction, which severely limits its direct detection by aptamer-based fluorescence methods. In this work, a portable near-infrared (NIR) fluorescence point-of-care testing (POCT) platform is developed for derivatization-assisted analysis of acrylamide by integrating covalent target conversion, aptamer-based molecular recognition, and twisted intramolecular charge transfer (TICT) signal modulation. Acrylamide is first converted into a structurally enhanced xanthydrol-acrylamide adduct (XAA), enabling effective aptamer binding and reliable optical transduction. Through molecular library screening, a TICT-active fluorophore with robust NIR emission was identified, whose fluorescence is reversibly regulated by aptamer binding and competitive target interaction. The resulting aptasensor achieves selective and quantitative detection of acrylamide in complex food matrices with a low detection limit of 0.48 µM, yielding recoveries of 91.78-110.67%. Moreover, the platform maintains consistent analytical performance upon integration with a compact fluorometer, overcoming the limitations of smartphone-based RGB analysis. More importantly, this strategy provides a generalizable framework for portable and quantitative fluorescence sensing of low-epitope targets, offering a practical blueprint for on-site food safety analysis.