Plasmonic Ag Nanocube Enhanced SERS Biosensor for Sensitive Detection of Oral Cancer DNA Based on Nicking Endonuclease Signal Amplification and Heated Electrode

Abstract Surface-enhanced Raman scattering (SERS) biosensing has attracted great attention due to its multiplexed capability, high sensitivity, and rapid readout. In this study, plasmonic Ag Nanocube (AgNC) enhanced SERS biosensing platform was proposed by coupling nicking endonuclease-assisted target recycling signal amplification with heated electrode for sensitive detection of DNA species related to oral cancer. SERS tags were manufactured by signal DNA (sDNA) conjugating onto the surfaces of AgNCs, and 4-mercaptobenzoic acid (4-MBA) assembled on the surfaces of AgNC/sDNA as a Raman reporter. The sharp feature of edges and corners of AgNCs with high electromagnetic field provided SER hot spots with high quality, and stronger SERS signal could be achieved. In addition, the activity of nicking endonuclease Nt.BstNBI could be greatly enhanced by elevating the temperature of the surface of the heated Au electrode (HAuE) during Nt.BstNBI-assisted target recycling amplification process, resulting in dramatic amplification of target DNA detection. All of these contributed to the high sensitivity of the developed SERS biosensor. A limit of detection (LOD) of 3.1 fM (S/N = 3) could be obtained with an electrode temperature of 45 °C. This proposed SERS biosensor was anticipated to act as a promising biosensing platform for early clinical diagnosis of oral cancer.