Several examples deal with different arrangements employing AuNPs to enhance sensitivity towards low molecular weight molecules: Jung and coworkers developed an SPR biosensor for the detection of prostate-specific antigen (PSA), a cancer biomarker, by immobilizing AuNPs onto a SiO2 layer on a gold electrode and the results were compared with those obtained with both an unmodified gold surface and a SiO2 layer on a gold surface. This evidence concerns the gene KLK3 and cancer.