Rapid and Selective Detection of Proteins by Dual Trapping Using Gold Nanoparticles Functionalized with Peptide Aptamers

A colorimetric platform for the fast, simple, and selective detection of proteins of medical interest is presented. Detection is based on the aggregation of two batches of peptide functionalized gold nanoparticles via the dual-trapping of the protein of interest. As proof of concept, we applied our platform to the detection of the oncoprotein Mdm2. The peptide aptamers used for the functionalization are based on the reported binding sequences of proteins p53 and p14 for the oncoprotein. Rapid aggregation, and a color change from red to purple, was observed upon addition of Mdm2 with concentrations as low as 20 nM. The selectivity of the system was demonstrated by the lack of response upon addition of bovine serum albumin (in large excess) or of a truncated version of Mdm2, which lacks one of the peptide binding sites. A linear response was observed between 30 and 50 nM of Mdm2. The platform reported here is flexible and can be adapted for the detection of other proteins when two binding peptide aptamers can be identified. Unlike current immunoassay methods, it is a one-step and rapid method with an easy readout signal and low production costs.