Fluorescent microsphere-based strip for sensitive and quantitative detection of 3-quinuclidinyl benzilate and clidinium bromide in biological samples

Abstract

In this study, a sensitive monoclonal antibody (mAb) was firstly developed through a novel hapten synthesis route, targeting both 3-quinuclidinyl benzilate (QNB) and clidinium bromide (CB). An immunochromatographic assay (ICA) integrated with fluorescent microsphere sensors was established, enabling the qualitative and quantitative detection of QNB and CB within 10 minutes. Under the optimized conditions, the calculated limits of detection (LOD) for QNB and CB in urine samples were all found to be 2.5 ng mL⁻¹, with quantitative detection ranges of 10 to 100 ng mL⁻¹, while for QNB and CB in plasma samples they were about 10 ng mL⁻¹, with quantitative detection ranges of 30 to 100 ng mL⁻¹. These LOD values could meet the requirements of immediate clinical diagnosis for exposure or metabolic monitoring of QNB and CB in vivo. Recovery tests and detection were also conducted in water, urine and serum samples, validating the reliability of this method in clinical diagnosis, consistent with the results obtained from LC-MS/MS. Collectively, the ICA provides a promising choice for rapid on-site diagnosis of QNB and CB exposure.