Gold nano disks arrays for localized surface plasmon resonance based detection of PSA cancer marker

Here in, we report prostate specific antigen (PSA) detection method using DNA aptamer functionalized gold nano disks array. The approach is based on DNA aptamer–PSA specific interaction and the localized surface plasmon resonance (LSPR) extinction λ max shifts of the transmitted light (UV–vis). The specific interaction results in a stable dynamic equilibrium. The concentration effect on equilibrium time has been described. We also describe the relationship between the aptamer concentration and the plasmon response. Using 2 nM DNA aptamer on gold nano arrays, a detectable linear range from 1.7 ng/mL to 20.4 ng/mL was obtained with the R² value > 0.99. The limit of detection (LOD) value was found 1.49 ng/mL. Finite difference time domain (FDTD) simulations were plotted for the gold substrate in air and water. Great agreement was found between the experimental and simulated shifts in both the cases. The refractive index sensitivities (S) of experimental spectra (113 nm/RIU) and simulated spectra (116 nm/RIU) were also found in good agreement. These results indicate that this NanoPlasmonic Sensing (NPS) detection platform is most suitable for the pre-biopsy test of prostate cancer patients. The DNA aptamers have been used as specific receptors for biomarkers for the first time; it provided the method with great potential for monitoring other biological interaction due to its great versatility and resistance to denaturation. Furthermore, substrate is recoverable which gives it clear advantage over most of the prevalent methods.