Ultrasensitive and rapid detection of methamphetamine in forensic biological fluids using fluorescent apta-nanobiosensors based on CdTe quantum dots

Rapid and sensitive detection of illegal and addictive drugs in biological samples is essential in various organizations such as forensic medicine, diagnostic clinics, and anti-narcotics headquarters. Methamphetamine (MA) is the second most addictive psychoactive substance, which poses a major threat to global health. This study aimed to propose a novel apta-nano biosensor for ultrasensitive and fast detection of MA in biological fluids. The water-soluble apta-nano biosensor was prepared with the ligand-exchange method using the replacement of thioglycolic acid (TGA) molecules at the surface of QDs with thiolated MA aptamer. The fluorescence intensity of QDs was increased after modification with aptamer and then decreased by the addition of the target molecule (MA) due to the formation of the aptamer-MA complex. The apta-nano biosensor was used as an ultrasensitive and selective fluorescent sensor for the determination of MA with a linear range of 1.34 ± 0.25 × 10−10– 1.24 ± 0.07 × 10−7 mol L−1, and the detection limit 40.34 ± 1.05 × 10−12 mol L−1. The fabricated apta-nano biosensor can be successfully applied for the determination of MA in forensic biological fluids (blood plasma and urine) with satisfactory analytical results. Also, obtained results were evaluated with liquid chromatography-tandem mass spectrometry (LC-MS-MS).