A gold-based immunochromatographic strip for the detection of sirolimus in human whole blood

Abstract

Sirolimus is a potent macrolide immunosuppressant, with a long half-life, a narrow therapeutic window, and large individual variations in pharmacokinetics. In this study, an indirect enzyme-linked immunosorbent assay (ic-ELISA) and a colloidal gold-based immunochromatographic strip were developed to establish a rapid and efficient clinical screening of sirolimus. The hapten for sirolimus was synthesized by the oximation reaction and then coupled to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA) to prepare the immunogen and coating antigen. Based on highly specific monoclonal antibodies (mAbs), the 50% inhibitory concentration (IC₅₀) of the optimized ic-ELISA was 1.54 ng mL⁻¹ and the limit of detection (LOD) was 0.19 ng mL⁻¹ in whole blood samples. Good specificity was revealed by its low cross-reactivity (CR) with several analogs of sirolimus. The visual limit of detection (vLOD) and cut-off values of the strip were 20 and 100 ng mL⁻¹ in whole blood samples, as assessed by the naked eye. Therefore, both methods could be used as potentially rapid monitoring approaches for the detection of sirolimus in human whole blood.