Surface enhanced Raman spectroscopy-based biosensor using nano-sculptured thin film to detect glial fibrillary acidic protein (GFAP) in blast-exposed moderately injured rat serum.

To prevent neurological damage and enable effective treatment, especially for military personnel, there is a clinical requirement for rapid, accurate, and early diagnosis of blast-exposed traumatic brain injury (TBI). A silver nano-sculptured thin film (nSTF) based surface-enhanced Raman spectroscopy (SERS) biosensor is developed to detect TBI biomarker GFAP. The biosensor chip is prepared by immobilizing an anti-GFAP antibody onto the 4-aminothiophenol (4ATP) adsorbed over Ag-nSTF deposited over Si substrate. The GFAP biosensor is based on the enhancement in the intensity of SERS signal of 4ATP. SERS signals are recorded for varying concentrations of GFAP over the sensor chip. The limit of detection (LOD) of the sensor for GFAP in PBS, and in spiked control serum is achieved to be 1 pg/ml. The concentrations of GFAP in three blast-exposed moderately injured rat sera, validated with ELISA, are diluted 1000 times and found to be 15, 24, and 37 pg/ml. The sensor's performance is further validated in blind-fold tests of 1000 times diluted rat sera to predict blast or no-blast cases, in accordance with ELISA. The fabricated sensor offers specificity, repeatability, and reusability, along with a compact size, minimal analyte requirement (3 μl), and a rapid Raman readout (500 ms) with a total response time <15 min in comparison to ELISA.