KLK3 and cancer: Furthermore, in this study, the combination of nanochains and surface-enhanced Raman scattering technology enabled the quantification of a panel of cancer protein biomarkers [prostate-specific antigen (PSA), α-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen 125, and carbohydrate antigen 199] and bacterial species (Escherichia coli O157:H7) in 1 μl of body fluids within 8 min.