Aptamer-driven limited-domain imprinted fluorescent sensor for ultra-sensitive and highly selective detection of Cr(VI).

A limited-domain ion-imprinted fluorescence sensor (LDIFS) was developed by integrating aptamers with ion-imprinted polymers, achieving exceptional sensitivity and selectivity. Aptamers were immobilized on silanized ZnS quantum dots, after which pre-polymerized potassium dichromate and functional monomers were introduced. The polymerization process generated selective imprinted cavities and stabilized the active conformation of aptamer. LDIFS achieves the detection within 15 min by leveraging the inner filter effect. A dual-recognition mechanism, which integrates conformational locking and imprinted cavity memory, synergistically improves the analytical performance of the sensor. The sensor achieves an ultralow detection limit of 0.43 nmol/L, exhibiting 1-3 orders of magnitude higher sensitivity than conventional approaches. A high selectivity factor of 17.9 was attained, ensuring excellent anti-interference capability. The method was successfully applied to the analysis of real squid samples, yielding recoveries ranging from 85.39% to 102.5% with RSD < 3%. This work presents a highly sensitive and selective strategy for chromium ion detection, showcasing its promising applications in environmental monitoring and food safety analysis.