Small Peptide for the selective Capture of a Protein Biomarker and Its Use for Sensitive Detection Scheme by Surface Enhanced Raman Scattering Using a Gold Nanoparticle

Abstract

In stead of using conventional antibody to selectively bind a protein biomarker, we have used small peptides (16mers) for the same purpose. The advantages of using peptide for nano-bio detection are higher bio-stability (much less chance of denaturing) and smaller size compared to the use of antibody. Additionally, it can be easily synthesized for required amino acid sequence. The synthesized peptides were used to detect Anthrax biomarker protein (Protective Antigen, PA) in ultra low concentration range using surface enhanced Raman scattering (SERS). Based on our previous study, the binding affinities of these peptide probes were comparable to that of conventional antibody. Peptide conjugated gold nano-probes were prepared to introduce SERS to increase Raman signal for low concentration detection. Additionally, we have attempted to increase Raman intensity by utilizing regularly patterned Au-AAO (gold coated anodized aluminum oxide) substrate. Simultaneously, bare gold coated substrate was also used for comparison. The overall results demonstrate the feasibility of peptide as a novel selective binder to detect of PA along with the use of antibody. Additionally, we have found that the sensitivity and reproducibility of the proposed analytical scheme could be significantly improved with the use of regularly patterned Au-AAO substrate.