A catalytic—regulated gold nanorods etching process as a receptor with multiple readouts for protein detection

A multidimensional colorimetric sensor array was produced based on a catalytic – regulated gold nanorod (Au NR) etching process as a receptor for protein detection. With the peroxidase-like property of gold nanosphere (Au NP) and H 2 O 2 , 3,3′,5,5′-tetramethylbenzidine (TMB) (colorless) is oxidized into TMB 2+ (yellow). Different concentrations of TMB 2+ promote different degrees of Au NR etching, and the localized surface plasmon resonance band of the Au NR is blueshifted. The blueshift results in color displays (gray, purple, blue and pink), which can be clearly distinguished by the naked eye. When the surfaces of the Au NP are covered by proteins, the catalytic activity is influenced. On this basis, the dynamically tunable system obtains triple channel information including the plasma resonance effect, the catalytic activity of Au NP and the etching of Au NR by TMB 2+ (catalytic products of TMB in the Au NP-H 2 O 2 reaction system), which can be adjusted using different proteins. The array can correctly identify native and thermally denatured proteins. This may provide a new method for studying conformational changes in biological macromolecules. Furthermore, pure protein (different concentrations) and binary protein mixtures can be efficiently differentiated in the urine sample.