A smartphone readable colorimetric sensing platform for rapid multiple protein detection

A simple, visible and smartphone readable strategy has been proposed for the sensitive detection and discrimination of multiple proteins. By employing five different concentrations of NaCl salt, AuNP exhibited different aggregation behavior for different proteins because of differential ion strength, leading to diverse color changes. The sensing system could not only discriminate twelve proteins at the concentration of 50 nM in aqueous solution, but it could also discriminate these proteins at 200 nM in the presence of human urine with an accuracy of 100%. More importantly, based on the theory of chromatics, we could directly read out the color value using a smartphone to distinguish twelve proteins, pure Lys and HSA at various concentrations, and the mixture of these two proteins in the presence of human urine with no confusion after a hierarchical clustering analysis (HCA). The inexpensive and convenient colorimetric sensor array using the ubiquitous smartphone for signal readout has great potential for the point-of-care diagnosis without additional devices.