Washing-free centrifugal microchip fluorescence immunoassay for rapid and point-of-care detection of protein.

Simplifying the procedure of immunoassay is still a challenge due to problems such as multiple washing processes, complicated chemical modification and expensive cost. In this study, we developed a portable centrifugal microchip fluorescence immunoassay for washing-free, rapid, quantitative and point-of-care (POC) detection of protein. The designed microchip was fabricated by polycarbonate and assembled by double-sided adhesive tape using injecting molding with high scalability and low cost. The centrifugal strategy is capable of washing-out the bio-fluid and improving signal-to-noise ratio. Matrix nano-spotting method was employed to facilitate satisfactory immunological binding sites with the advantage of high capture efficiency and reproducibility. The proposed approach was capable of sensitively detecting procalcitonin (PCT) with a wide dynamic ranging from 0.10 ng/mL to 70.00 ng/mL within 10 min. Furthermore, this novel integrated diagnostic tool was successfully applied to detect PCT in 101 clinical samples with good consistency with Roche's method, indicating its attractive practical application capability. With favorable simplicity, rapidity, low cost and excellent analytical performance, our method holds great promise for POC diagnostics of proteins.