Immobilized gold nanoparticle based plasmonic assay platform for biomolecule and microorganism detection

Abstract

Plasmonic sensors are suitable tools for study of molecular interactions. Localized Surface Plasmon Resonance (LSPR) based sensors detect spectral changes associated with intramolecular interactions between analyte molecules and recognition elements. Due to its label­free and highly sensitive features, LSPR based methods have high potential for biosensing applications. In this study, we aim to develop a sensitive, label­free, rapid and simple biosensing platform. For this purpose, a novel refractive index (RI) sensitivity enhancement methodology is proposed by immobilizing gold nanoparticles (GNPs) for platform­based LSPR. Fabrication of platform was carried out by GNP synthesis, immobilization of GNPs on polystyrene solid support, and growth of GNPs. Validation of response to RI changes of developed sensor platform was carried out by tests with varying concentrations of sucrose and ethanol. Then as a proof­of­concept, detection ability and detection limit determination of E.coli BL21 (DE3) and protein Bovine Serum Albumin (BSA) was carried out. Adsorption of E.coli BL21 (DE3) via bulk interactions showed that the developed LSPR platform exhibit high enough binding affinity for bacteria detection, and was able to detect down to concentrations as low as 102 CFU/ml. Immune capturing of BSA via anti­BSA antibody showed that the developed LSPR platform was able to detect BSA protein–antibody interaction down to 10 µM concentration range.