Biological relevance of CuFeO2 nanoparticles: Antibacterial and anti-inflammatory activity, genotoxicity, DNA and protein interactions.

Heterometal oxide nanoparticles of bioessential metals are shedding new light to nanoparticle-inspired bioapplications. Pairing bioreactive elements like copper and iron can affect the redox dynamic and biological profile of the nanomaterial. Given the complexity of physicochemical properties, biological activity and toxicity concerns, extensive exploration is demanded, especially when active and less active oxidation states participate as in case of cuprous-ferric delafossite CuFeO2 (copper(I)-iron(III)), a less widespread nanomaterial. In that vein, CuFeO2 nanoparticles were synthesized and biological profile was evaluated in comparison with cuprous oxide (Cu2O NPs) counterpart, an already established antimicrobial agent. Interactions with bacteria, proteins and DNA were examined. Cu2O NPs exhibited stronger antibacterial activity (IC50 < 25 µg/ml) than CuFeO2 NPs (IC50 > 100 µg/ml). In vitro exposure of nanoparticles on plasmid DNA unveiled toxicity in the form of DNA damage for Cu2O and enhanced biocompatibility for CuFeO2 NPs. Genotoxicity estimated by the frequency of sister chromatid exchanges, cytostaticity based on the proliferating rate indices and cytotoxicity based on the mitotic indices at human peripheral lymphocyte cultures were all significantly lower in the case of CuFeO2 NPs. Furthermore, through in vitro albumin denaturation assay, CuFeO2 NPs showed better performance in protein denaturation protection, correlating in superior anti-inflammatory activity than Cu2O and similar to acetylsalicylic acid. Synergy of copper(I)-iron(III) in nanoscale is apparent and gives rise to fruitful bioapplications and perspectives.

Hydrothermal synthesis of copper based nanoparticles: antimicrobial screening and interaction with DNA.

Copper based nanoparticles (Cu-based NPs) of different compositions and sizes have been hydrothermally synthesized by varying the reaction time in the presence of the biocompatible surfactants polyoxyethylene (20) sorbitan laurate (Tween 20) and polyethylene glycol 8000 (PEG 8000). Effective control of the above synthetic parameters gave rise to Cu, Cu2O and Cu/Cu2O NPs of 10-44 nm. The antibacterial activity of the NPs was screened against Gram-positive (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus) and Gram-negative (Xanthomonas campestris, Escherichia coli) bacteria. The Cu-based NPs induce pDNA degradation in a dose-dependent manner as well as extensive ds CT-DNA degradation. Cu2O NPs of 16 nm and 12 nm exhibit the lowest IC50 values (2.13 µg/mL and 3.7 µg/mL) against B. cereus and B. subtilis, respectively. The agarose gel electrophoresis of ds CT-DNA treated with Cu2O NPs demonstrated degradation at high concentration. In lower concentrations, viscosity measurements indicated groove binding. In regard to the enhanced antibacterial effect and specificity of Cu2O NPs against the Gram-positive strains, the activity pathway was further explored and ROS production and lipid peroxidation verified. The released copper ions 5.15 mg/L in distilled water and 16.32 mg/L in nutrient medium, found below the critical value to inhibit bacterial growth and thus nanosized composition effect is predominant.