Electronic and vibrational spectroscopic study complemented with the computational evaluation of hydroxychloroquine mixed with silver nanoparticles

Synthesized silver nanoparticles via laser liquid ablation were characterized using XRD, TEM, EDS, UV–Vis, and Raman spectroscopy. The AgNPs were then conjugated with HCQ at different concentrations. The study aimed to explore the effectiveness of HCQ against malaria and autoimmune diseases as well as how conjugating AgNPs with HCQ would broaden its activity against various infections and diseases, owing to the antimicrobial activity of AgNPs. The electronic and vibrational study of HCQ and its mixture showed a successful conjugation of the two, which would increase the potent of HCQ against SARS Coronavirus (SARS-COV-2) infection. Steady-state absorption measurements revealed a broadband peak at around 337.4 nm (3.68 eV), corresponding to a π to π* transition in the quinoline ring of the HCQ molecule. In addition, the AgNPs Localized Surface Plasmon Resonance (LSPR) band centred around 408 nm exhibited an intensity decrease with an increase in the concentration of HCQ. The experimental Raman spectra exhibited bands similar to the density function theory (DFT) calculated spectra centred at 392 cm−1, 768 cm−1, 1392 cm−1, 2928 cm−1, 3224 cm−1, 3656 cm−1, and 3808 cm−1. TEM, EDS, and XRD analysis confirmed the formation of 8.75 nm AgNPs. Understanding the electronic and vibrational spectroscopic properties of the interaction between HCQ and AgNPs, as deduced from the spectroscopic results supported by DFT, can significantly benefit researchers in the pharmaceutical industry. Researchers could apply this knowledge to overcome drug resistance, repurpose existing drugs, and reduce the side effects of conventional clinically approved drugs.