Staining Traditional Colloidal Gold Test Strips with Pt Nanoshell Enables Quantitative Point-of Care Testing with Simple and Portable Pressure Meter Readout

Traditional immunochromatographic test strips based on colloidal gold are effective devices for portable and low-cost point-of-care (POC) testing. Nevertheless, they still suffer from the limitation of qualitative or semiquantitative tests via naked-eye detection. Replacement of gold with other signal entities, such as magnetic particles or fluorescent particles, requires professional instrumentation to obtain quantitative results. A pressure-based assay with platinum nanoparticles (PtNPs) can provide quantitative results using a portable pressure meter but is also hampered by the long-term instability of PtNPs. Consequently, we developed a Pt-staining method based on test strips to create platinum nanoshells on the surface of colloidal gold. This method not only preserves the original advantages of colloidal gold with easy synthesis and decoration but also introduces PtNPs with excellent catalytic activity as signal labels to achieve sensitive quantitative detection. Myoglobin was tested as a model targe...