Smartphone-aided paper imprinted aptasensor for the ultrasensitive detection of lead in aquatic products

A fluorescent biosensor was synthesized for sensitive detection of lead ions by integrating aptamer with ion imprinted polymer. ZnSe@ZnS quantum dots served as the fluorescence indicator and aptamers served as recognition elements. Specific and rapid detection of lead ions was achieved through imprinting cavities containing aptamers with specific conformations. The resulting biosensor, after optimization via the multi-factor response surface methodology, can detect lead with a detection limit as low as 0.56 nmol·L −1 (the detection limit in aquatic products is 47.73 μg/kg). Furthermore, a paper-based biosensor was developed using glass cellulose paper as the carrier material for the portable and rapid determination of lead ions in aquatic products. The proposed paper-based biosensor significantly reduces the detection time from ten minutes to one minute, and the recoveries ranged from 88.06% to 107.29%, which were validated using the ICP-MS method. These findings demonstrate that the biosensor provides a sensitive and rapid method for detecting heavy metals in complex food matrices.