Zinc oxide nanorods-based immuno-field-effect transistor for human serum albumin detection

Physiological roles in human body system substantially supported by human serum albumin (HSA). Frequent monitoring of HSA level is vital in early diagnosis of HSA-related diseases. This work focuses on demonstrating field-effect transistor (FET)-based immunosensor utilizing high aspect ratio zinc oxide nanorods (ZnO NRs) as a transducer in quantifying HSA. The acetylacetonate-assisted hydrothermal method was used to synthesize ZnO NRs, and a standard photolithography process was applied to fabricate the FET device. The morphology and electrical evaluations of the ZnO NRs were performed using field emission scanning electron microscopy and current-voltage measurement system, respectively. The surface modification of the ZnO NRs was confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The detection mechanism is based on the covalent binding interactions between an antibody and HSA target that induced a change in the drain current (I_D) of the fabricated biosensor. The biosensor exhibited a high sensitivity of 0.826 mA (g/ml)^-1 with a LOD value of 9.81 ng/ml in a linear range between 10 ng/ml and 100 µg/ml. HSA was also successfully detected in the interference by other biomolecules in a real serum, indicating the capability of ZnO NRs-FET immunosensor for quantifying HSA in complex biological matrix. This biosensor also exhibits good stability after stored for 360 days.