Interfacial Assembly of Signal Amplified Multienzymes and Biorecognized Antibody into Proteinosome for an Ultrasensitive Immunoassay.

Enzyme as signal tag has been widely employed in colorimetric immunoassays for decades. Nevertheless, it remains a great challenge to substantially improve the detection sensitivity of enzyme-based immunoassays, which inhibits further critical applications. To circumvent this confinement, a multifunctional self-assembled proteinosome based on the integration of signal amplification elements (enzyme) and biorecognition unit (antibody) is proposed for fabricating an immunoassay strategy with significantly enhanced sensitivity. Owing to the self-assembly technique, this proteinosome not only efficiently loads abundant enzymes to possess high catalytic activity, but also enhances enzymatic stability and maintains recognition ability of antibody. Using imidacloprid as a model target, the proteinosome-based immunoassay reaches a limit of detection down to the picogram mL level, which is 150-fold lower than that of conventional enzyme-linked immunosorbent assay. This method provides a versatile approach for constructing spherical proteinosome as a recognizer and amplifier for profiling a broad range of target antigen.