Colorimetric sensor array for proteins discrimination based on the tunable peroxidase-like activity of AuNPs-DNA conjugates

We proposed a colorimetric sensor array for proteins discrimination based on the tunable catalytic activity of AuNPs-DNA conjugates. The peroxidase-like activity of AuNPs could be enhanced by the attachment of single-stranded oligonucleotides on its surface, resulting in highly sensitive colorimetric signal by catalyzing the oxidization of TMB. In the presence of different proteins, the AuNPs-DNA conjugates showed tunable catalytic activity, inducing differential colorimetric response. At the same time, the same protein could tune the catalytic activity of AuNPs decorated by different DNA with different degree. The fingerprint response generated from the sensor array was used for proteins discrimination. Compared to the colorimetric sensor array based on salt-induced AuNPs aggregation, this strategy exhibited much improved discrimination power for proteins at the low concentration. Seven proteins at the concentration of 10 nM could be successfully identified and proteins spiked in human urine at the final concentration of 100 nM could also be well distinguished. The discrimination accuracy of unknown samples was all 100% for these experiments. The current colorimetric array demonstrated its potential for highly sensitive diagnostic applications.