Hydrothermal Synthesis of Chlorogenic Acid-Functionalized Ag Nanoparticles and Their Antibacterial Activity

In this study, chlorogenic acid (CGA), a natural organic acid, was employed as both a reducing and stabilizing agent to synthesize chlorogenic acid-functionalized silver nanoparticles (CGA-AgNPs). The synthesis conditions of CGA-AgNPs, including reactant ratio, pH, temperature, and reaction time, were optimized. The synthesized CGA-functionalized AgNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). TEM imaging results indicated that CGA-AgNPs were spherical nanoparticles with an average diameter of 36.70 ± 0.65 nm. FTIR spectroscopy results confirmed that CGA was covered on the surface of AgNPs. XPS results indicated that the surface of nanoparticles was made up of Ag atoms. The inhibitory activity of CGA-AgNPs against Candida albicans (C. albicans), Acinetobacter baumanniiand (A. baumannii), and Staphylococcus aureus (S. aureus) was measured and evaluated by the inhibition circle method and the minimum inhibitory concentration. The synthesized CGA-AgNPs under optimal conditions indicated good antibacterial activity against C. albicans, A. baumannii, and S. aureus with MIC values of 36.95 ± 0.22 μg/mL and MBC values of 73.90 ± 0.22 μg/mL. In summary, this study provides a facile and green synthesis method to prepare CGA-AgNPs with excellent antibacterial activities.