Nano Rolling-Circle Amplification for Enhanced SERS Hot Spots in Protein Microarray Analysis

Abstract

Although "hot spots" have been proved to contribute to surface enhanced Raman scattering (SERS), less attention was paid to increase the number of the "hot spot" to directly enhance the Raman signals in bioanalytical systems. Here we report a new strategy based on nano rolling-circle amplification (nanoRCA) and nano hyperbranched rolling-circle amplification (nanoHRCA) to increase "hot spot" groups for protein microarrays. First, protein and ssDNA are coassembled on gold nanoparticles, making the assembled probe have both binding ability and hybridization ability. Second, the ssDNAs act as primers to initiate in situ RCA reaction to produced long ssDNAs. Third, a large number of SERS probes are loaded on the long ssDNA templetes, allowing thousands of SERS probes involved in each biomolecular recognition event. The strategy offered high-efficiency Raman enhancement and could detect less than 10 zeptomolar protein molecules in protein microarray analysis.