A combined experimental and computational analysis of dexamethasone-conjugated silver nanoparticles for improved surface-enhanced Raman substrate detection. 

Abstract

Computations based on density functional theory (DFT) and experimental analysis on spectral vibrations have been performed on the dexamethasone molecule. The computer simulations have been analyzed using DFT-B3LYP functional at 6-311 + + G(d,p) basis. UV-Vis and Raman spectra have been recorded and reported. High-purity silver granules (99.99%) were immersed in 5 ml of distilled water in a 25 ml glass beaker. A Q-Switched Nd: YAG laser (1064 nm, max energy of 250 mJ, 8 ns) was focused on the silver sample target by a convex lens whose focal length was 30mm. The ablation time varied from 2 to 8 hours leading to the formation of yellow to dark brown AgNPs colloids. Raman spectroscopy, UV-Vis spectroscopy, and Scanning Electron Microscopy techniques were used for the sample characterization. At 8 hours, the synthesized AgNPs were most chemically stable and had spherical colloids with a diameter of 6.3 nm. Conjugating dexamethasone with AgNPs led to the enhancement of the Raman signals by a factor of 1.4. A position shift in the plasmon resonance peak attributed to the newly formed complex with unique optical characteristics was noted. The findings support the possibility of enhancing the functionality of dexamethasone by developing new-drug-like candidates after conjugation with AgNPs.