Lactoferrin functionalized concave cube Au nanoparticles as biocompatible antibacterial agent

Gold nanoparticles (AuNPs) are one of the most extensively studied nanomaterials and their distinct physicochemical properties make them suitable for versatile applications. Herein, we synthesized concave cube-shaped gold nanoparticles (CCAuNPs) and functionalized them with lactoferrin (Lf), a natural antimicrobial protein, through electrostatic interaction as well as weak covalent formation. The functionalization of CCAuNPs was confirmed through UV–Visible (i.e., bathochromic shift of the surface plasmon resonance peak by 7 nm), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopy, and their surface zeta potential. The concave cusp of CCAuNPs was confirmed through atomic force microscopy (AFM). The Lf-functionalized CCAuNPs (Lf-CCAuNPs) exhibited superior antibacterial propensity against a series of bacteria when compared to that of CCAuNPs. However, they didn't demonstrate any antibacterial activity against Lactobacillus plantarum, one of the key beneficial gut bacteria. The lipid peroxidation (LPO) assay confirmed the oxidation of fatty acids in the bacterial membrane upon interaction with AuNPs, which made the bacterial membrane porous. The resultant membrane-impaired dead bacteria were visualized through CellTox™ Green assay as well as the Trypan Blue dye exclusion assay. Both the nanoparticles demonstrated excellent hemocompatibility as well as biocompatibility (both in vitro and in vivo) as confirmed by MTT assay and the levels of important functional biomarkers of liver (e.g., ALT, AST, and ALP) and kidney (e.g., creatinine, uric acid, and BUN) in the serum. Overall, Lf-CCAuNPs with excellent hemocompatibility, and biocompatibility can be deployed as potential antibacterial agents to tackle the menace of pathogenic bacteria.