LSPR biosensing for the early-stage prostate cancer detection using hydrogen bonds between PSA and antibody: Molecular dynamic and experimental study

Abstract

Prostate specific antigen (PSA) as a prostate cancer marker has a significant role in screening the tumor in the initial stages. The LSPR is a versatile and robust technique among the PSA detection methods. In this study an ultra-sensitive label-free nanobiosensor was designed for determination of PSA at low concentration level in serum samples using antibody conjugated‑gold nanoparticle (GNP) and the high affinity binding mechanism of antibody/GNP probe with PSA protein was investigated by computational modeling. The first crystal structure of the complex between human PSA and monoclonal antibody (mAb) 8G8F5 were studied using molecular dynamics (MD) simulations. MD simulation also supports the formation of the antibody–PSA complex. The sensing principle is based on the LSPR peak shift produced by small changes in the refractive index of the dielectric medium around the probe upon binding to the antigen. The GNPs were synthesized by the citric acid reduction method and characterized by the UV–Vis spectrophotometry and dynamic light scattering. The 10 nm gold nanoparticles were covalently conjugated to the anti-PSA antibody and the affecting factors such as the concentration ratio of the antibody to Au NPs, pH and temperature were optimized. A detection limit of 0.2 ng mL−1, and calibration sensitivity of 43.75 nm/(ng mL−1) were obtained.