Highly responsive signal-on biosensor based on autocatalytic and antifouling cell membrane gel interface for ultrasensitive immunoassay.

In sensing analysis, controlling signal switch through targets is a key method to ensure detection sensitivity. To improve the control effect, an antifouling sensor based on controlled-release and co-reaction catalytic strategies was designed. Concretely, the gel interface with the biocompatible red cell membrane as the skeleton was developed to resist the non-specific adsorption of interfering proteins in the serum environment. Secondly, due to the strong specific binding of antigens and antibodies, S QDs were released from the cavity of mesoporous SiO2, thereby achieving target-induced signal self-on. At the same time, Pd NCs encapsulated in the antifouling hydrogel were used for autocatalysis of luminescence signals to achieve highly responsive signal-on. The integration of interface antifouling and controlled release effectively avoided the adverse interferences from external environment and background signals, improving the reliability of target-induced responses, and the highly responsive signal-on mode endowed the biosensor with high sensitivity. Based on this, the constructed biosensor realized trace detection of squamous cell carcinoma antigen in a wide detection range of 100 fg/mL ∼1 μg/mL, with a detection limit of 27.7 fg/mL, meeting the needs of early clinical diagnosis of related cancers. The proposed biosensing platform based on cell membrane antifouling and highly responsive signal-on provides a powerful tool for the applications in clinical diagnose and other biological detection scenarios.