Highly stable, love-mode surface acoustic wave biosensor using Au nanoparticle-MoS2-rGO nano-cluster doped polyimide nanocomposite for the selective detection of carcinoembryonic antigen

Herein, presents a novel method for the preparation of a Love mode SAW biosensor for the selective detection of carcinoembryonic antigen (CEA) using a transuding polymer nanocomposite thin film based bioreceptor. Graphene oxide (GO) was synthesized using modified Hummers' method and flower-like MoS2 nanoparticles were allowed to grow on the 2D layers GO. The rGO-MoS2 was further used as a host for the synthesis of Au nanoparticles (AuNP) and the final three-component nano-cluster was introduced to the previously synthesized polyamic acid diethyl ethanolamine salt precursor. The uniform mixture was coated on the delay line area of SAW device and conducted thermal imidization process to obtain polyimide nanocomposite. The thickness of the thin film was optimized based on the insertion loss and centre frequency response of the SAW device. Further, anti-CEA self-assembled monolayer (SAM) based bioreceptor was prepared on the polyimide nanocomposite thin film through thioglycolic acid - EDC/NHS immobilization mechanism. The bioreceptor was tested for immunoassay analysis with CEA solution with varying concentrations. The LOD of the biosensor was estimated at 0.084 ng/ml. The real-time applicability of the biosensor was validated using clinical serum sample analysis and the selectivity was evaluated through the affinity test towards other common tumour marking proteins. The biosensor also showed excellent stability, only 10% reduction activity was observed till 80th day of storage. The antigen-antibody adsorption parameters were also evaluated through Langmuir and Freundlich adsorption isotherms.