Ultra-sensitive label-free biosensor for doxorubicin detection by doxorubicin optimized aptamer

Doxorubicin (DOX), an anthracycline antibiotic used in cancer treatment, engenders health and environmental hazards owing to its adverse effects and subsequent discharge into wastewater, necessitating meticulous surveillance. Aptamer-based fluorescence biosensors (AFBs) have emerged as highly sensitive and cost-effective tools for this purpose. This study developed a label-free AFB by exploiting structural alterations in the DOX’s aptamer, induced by DOX and simulated by Thioflavin T (ThT). Binding affinities between DOX and its aptamer were scrutinized by molecular docking, circular dichroism, and UV–visible spectroscopy aimed at mimicking the interaction between aptamer and DOX and refining the DOX aptamer. One of the optimized aptamers (DOX-5) exhibited a detection limit of 3.15 nmol/L within a 5–100 nmol/L range. It proficiently detected DOX in milk and serum samples, with recovery rates of 98.1 %-102.6 % and 101.1 %-103.8 %, respectively. This methodology exemplifies a straightforward, economically viable, and productive strategy for DOX detection, significantly advancing antibiotic surveillance, food safety, and environmental vigilance measures.