N protein

To detect for N-protein using our nanozyme signal enhanced LFA, a 25 μL human serum sample (#50–203-6415, Fisher Scientific, Waltham, MA) spiked with varying concentrations of N-protein (#40588, Sino Biological, Wayne, PA) was added to the sample well on the LFA (above the biotinylated capture antibody pad). As in the case of typical LFAs for serum samples, this was immediately followed by a chase buffer. In our system, we used 75 μL of chase buffer composed of 2% (w/v) polyvinylpyrrolidone 10kDa, 0.2% (w/v) BSA, 0.2% (w/v) Tween 20, and 0.2% (w/v) casein in 0.1 M potassium phosphate at pH 7.2. After 20 min, the user pressed the button to move down the middle piece of the casing (Fig. 4B). The movement of the middle casing piece resulted in the rupture of the mylar seal to release the enhancement buffer and also served to lower the connector pads to provide a continuous flow path for the enhancement reagents to flow through the LFA strip. Final results were observed after 20 min of enhancement. Results were photographed before and after the signal enhancement reaction with a Nikon D3400 digital camera (Nikon, Tokyo, Japan) in a controlled lighting environment. To quantify the relative test line intensities, the resulting images were processed by a MATLAB script developed by our lab.^{24 (link)}