Detection of biomolecules from nano to atto-gram through plasmonic Elisa via tuning the catalyst

A simple and affordable plasmonic ELISA platform is demonstrated using silver nanocrystals as chromogens, and nanocatalysts in the place of enzyme. Apart from ultralow detection limitup to 10 molecules of human Immunoglobulin G (2.5 × 10−18 g/1.68 × 10−19 M), we exhibit very broad dynamic range covering 11-log which goes up to 100 × 10−9 g/6.72 × 10−9 M. To achieve this broad dynamic range and highly controlled standard deviation, nanocatalysts were tuned in terms of shape, size, metallic ratio, surface modification and other parameters. A comparative study is also done between traditional chromogen to independently developed new silver chromogen, and among different catalysts. Our results indicate plasmonic ELISA with small size nanocatalysts may become a very powerful detection strategy for biomolecules.