Enhanced Antimicrobial Activity of Biofunctionalized Zirconia Nanoparticles

[Image: see text] The effective interactions of nanomaterials with biological constituents play a significant role in enhancing their biomedicinal properties. These interactions can be efficiently enhanced by altering the surface properties of nanomaterials. In this study, we demonstrate the method of altering the surface properties of ZrO(2) nanoparticles (NPs) to enhance their antimicrobial properties. To do this, the surfaces of the ZrO(2) NPs prepared using a solvothermal method is functionalized with glutamic acid, which is an α-amino acid containing both COO(–) and NH(4)(+) ions. The binding of glutamic acid (GA) on the surface of ZrO(2) was confirmed by UV–visible and Fourier transform infrared spectroscopies, whereas the phase and morphology of resulting GA-functionalized ZrO(2) (GA-ZrO(2)) was identified by X-ray diffraction and transmission electron microscopy. GA stabilization has altered the surface charges of the ZrO(2), which enhanced the dispersion qualities of NPs in aqueous media. The as-prepared GA-ZrO(2) NPs were evaluated for their antibacterial properties toward four strains of oral bacteria, namely, Rothia mucilaginosa, Rothia dentocariosa, Streptococcus mitis, and Streptococcus mutans. GA-ZrO(2) exhibited increased antimicrobial activities compared with pristine ZrO(2). This improved activity can be attributed to the alteration of surface charges of ZrO(2) with GA. Consequently, the dispersion properties of GA-ZrO(2) in the aqueous solution have increased considerably, which may have enhanced the interactions between the nanomaterial and bacteria.