Development of a Quantum Dot-Based Immunochromatographic Assay for Rapid and Sensitive Detection of Non-Medical...

Etomidate is an ultrashort-acting imidazole-derived intravenous anesthetic. The non-medical abuse of etomidate as a new psychoactive substance has emerged as a critical public health challenge globally, particularly among adolescents, necessitating sensitive, rapid detection methods for forensic analysis. This study developed a quantum dot-based immunochromatographic test strip and a corresponding rapid detection method for the sensitive detection of etomidate acid in urine. CdSe/ZnS fluorescent quantum dot microspheres were used as labeling probes combined with specific monoclonal antibodies, and the detection protocol utilized a portable fluorescence reader. The method's validation demonstrated a linear range of 10-2000 ng/mL (y = -0.231lnx + 0.5241, r = -0.991), with intra-batch and inter-batch coefficients of variation below 12%. The spike recovery rates ranged from 88.24% to 95.69%. Cross-reactivity testing against 12 common drugs and structural analogs showed no interference. The detection limit of 10 ng/mL represents a substantial improvement over conventional colloidal gold strips and approaches LC-MS/MS sensitivity. Assays of real urine specimens confirmed that the immunochromatographic test strip and detection method possess favorable accuracy and reliability. This fluorescent quantum dot-based immunochromatographic assay provides rapid, quantitative, and highly specific etomidate screening suitable for on-site forensic applications, effectively bridging front-end rapid testing with confirmatory laboratory analysis.