Colorimetric sensor array for protein discrimination based on different DNA chain length-dependent gold nanoparticles aggregation

A facile colorimetric sensor array for detection of proteins was demonstrated using DNA as nonspecific receptors. We found that different proteins could trigger the DNA-protected gold nanoparticles (AuNPs) to show different aggregation behaviors in the presence of salt with high concentrations along with various color changes. As a proof-of-concept application, a multi-protein discrimination array was fabricated with two ssDNA strands (15A and 30A bases) as a receptor array. The combinatorial colorimetric response of this sensor array can be analyzed by linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA). 12 proteins have been well distinguished with the naked eye at the 50 nM level. The proteins in human serum have also been discriminated. Furthermore, the accuracies of discrimination of the similar mixtures of proteins and unknown samples were all 100%.