Immunosuppressive drug sensor based on MoS2-polycarboxyindole modified electrodes

Azathioprine (Azp) is the principal immunosuppressive drug used in organ transplantation autoimmune diseases by improving therapeutic management and suppressing the immune system. Any discrepancy of Azp in human blood may lead to some serious side effects that obligate its quantitative estimation. In this work, the molybdenum disulfide (MoS2) nanosheets modified with poly(5-carboxyindole) (CPIn) is reported for quantitative estimation of Azp. The synthesis of MoS2 nanosheets is reported through single-step one-pot hydrothermal reaction and exfoliation of sheets is obtained in an aqueous dispersion of 5-carboxyindole (5CIn) through probe ultra-sonication. The nanosheets are further utilized as a template for the growth of the poly(5-carboxyindole) to obtain CPIn stabilized MoS2 nanosheets (MoS2-CPIn). The synthesis of MoS2-CPIn nanohybrid is further validated via different characterization techniques including FTIR, XRD, SEM, TEM, and XPS. MoS2-CPIn with magnificent electrocatalytic property is further exploited for the electroanalytical sensing of Azp via Differential Pulse Voltammetry (DPV) in phosphate buffer solution at biological pH (pH = 7.4) as well as human blood serum at room temperature. The proposed sensor shows a linear dependence of current with Azp concentration. The developed sensor demonstrates an extensively wide linear range of 3.49-284.44 mu M possessing a low limit of detection of 74.65 nM (S/N = 3). The developed sensor shows excellent stability, sensitivity, and good selectivity in physiological pH. The achieved analytical parameters of the proposed sensor for easy quantification of Azp are found to be comparable or better than the previously reported Azp sensors and it is proved to be an excellent contestant for the trace level estimation of Azp in human blood serum.