Abstract

A novel sensitive electrochemical immunosensor has been designed for determination of tacrolimus (Tac) based on spherical carrier amplification strategy. In this work, a spherical signal carrier was prepared by conjugating gold nanorods (AuNRs) functionalized L-cysteine ( [email protected] ) onto polystyrene nanoparticles (PS) to form a nanostructure, greatly increasing the amount of loaded capture antibodies. The PS was a stable spherical functional polymer with large specific surface area and was labeled with [email protected] via coupling reagent to increase active groups, biocompatibility and conductivity . The capture antibodies could be attached on the PS- [email protected] via linkage reagent glutaraldehyde (GA). Furthermore, single-layer molybdenum disulfide (MoS 2 ) fixed by chitosan were utilized to construct the base of this immunosensor, increasing the carrying capacity and stability of the electrode. After electrochemical reduction , the conductivity and electron transfer rate of MoS 2 were obviously improved, which offered a platform for this immunosensor and further amplified the signal. Under the optimized conditions, the proposed immunosensor revealed a linear Tac-concentration behavior from 1.0 to 30 ng mL −1 with a detection limit of 0.17 ng mL −1  (S/N = 3). The immunoassay was successfully applied to the quantification of Tac in serum samples with acceptable precision. The results indicated that a potentially analytical platform may be used to recognize the concentration of other drugs.