Synthesis and characterization of lanthanum-doped curcumin-functionalized antimicrobial copper oxide nanoparticles

Flavonoid-based nanomaterials have extensive potential in antimicrobial research because of their non-toxicity, large-scale producibility, and chemical stability. An efficient combination of flavonoids and rare earth metals can have excellent antimicrobial properties owing to their robust medicinal and physicochemical properties. In this study, we synthesized copper oxide (CuO) nanoparticles (NPs) using a reflux reaction and repeated doping with the rare earth element lanthanum to prepare La–CuO NPs. Next, these La–CuO NPs were functionalized with the flavonoid curcumin, and the modified NPs were termed Cu–La–CuO NPs. These NPs were chemically characterized via microscopic and spectroscopic techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) adsorption, Fourier transform infrared spectroscopy (FT-IR) spectroscopy, and powder X-ray diffraction (XRD) analysis. The SEM-EDX analysis reveals the elements doped into the native CuO NPs. The TEM and XRD characterization results show, in detail, the distinct morphology and phase composition of the prepared CuO, La–CuO, and Cu–La–CuO NPs. The antimicrobial activity of the Cu–La–CuO NPs was investigated on bacteria, such as Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and fungi, including Aspergillus niger (A. niger). The Cu–La–CuO NPs delivers excellent antimicrobial effects due to the incorporation of lanthanum and curcumin into the CuO NPs. The Cu–La–CuO NPs show excellent antimicrobial potentials with an adequate zone of inhibition values around 2.2 and 2.9 mm in E. coli and A. niger, respectively. Live and dead analysis studies suggest the antimicrobial effects of lanthanum and curcumin moieties over native CuO NPs. The obtained results are significant in developing of rare earth metal-based flavonoid-conjugated nanocomposites against typical microbes.