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.

Elucidation of one step synthesis of PEGylated CuFe bimetallic nanoparticles. Antimicrobial activity of CuFe@PEG vs Cu@PEG.

There is a growing field of research on the physicochemical properties of bimetallic nanoparticles (BMNPs) and their potential use in different applications. Meanwhile, their antimicrobial activity is scarcely reported, although BMNPs can potentially achieve unique chemical transformations and synergetic effects can be presented. Towards this direction a reproducible simple hybrid polyol process under moderate temperature solvothermal conditions has been applied for the isolation of non-oxide contaminated bimetallic CuFe nanoparticles (NPs). 1,2-propylene glycol (PG), tetraethylene glycol (TEG) and polyethylene glycol (PEG 8000), that exhibit different physicochemical properties, have been utilized to regulate the size, structure, composition and the surface chemistry of NPs. The BMNPs were found to be of small crystalline size, 30-45nm, and high hydrophilicity, different wt% percentage of organic coating and variable hydrodynamic size and surface charge. The antimicrobial activity of the BMNPs was evaluated against the bacterial strains B. subtilis, E. coli and fungus S. cerevisiae. The IC50 values for CuFe NPs were found significantly lower compared with Cu NPs of the same size, revealing an enhancement in the antimicrobial activity when iron and copper coexist in the crystal structure. The reactive oxygen species (ROS) production was measured intracellularly and extracellularly by the nitroblue tetrazolium assay in the fungal cultures. No extracellular ROS were measured suggesting that both CuFe and Cu NPs enter the fungal cells during the incubation, also verified by optical imaging of the fungal cells in the presence of NPs. Higher ROS concentrations were generated intracellularly for CuFe NPs supporting different red/ox reaction mechanisms.

Synthesis and biological evaluation of PEGylated CuO nanoparticles.

There is a growing field of research into the physicochemical properties of metal oxide nanoparticles (NPs) and their potential use against tumor formation, development and progression. Coated NPs with biocompatible surfactants can be incorporated into the natural metabolic pathway of the body and specifically favor delivery to the targeted cancerous cells versus normal cells. Polyethylene glycol (PEG) is an FDA approved, biocompatible synthetic polymer and PEGylated NPs are regarded as "stealth" nanoparticles, which are not recognized by the immune system. Herein, PEGylated cupric oxide nanoparticles (CuO NPs) with either PEG 1000 or PEG 8000 were hydrothermally prepared upon properly adjusting the reaction conditions. Depending on the reaction time CuO NPs in the range of core sizes 11-20nm were formed, while hydrodynamic sizes substantially varied (330-1120nm) with improved colloidal stability in PBS. The anticancer activity of the NPs was evaluated on human cervical carcinoma HeLa cells by using human immortalized embryonic kidney 293 FT cells as a control. Viability assays (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT) revealed that CuO NPs could selectively reduce viability of tumor cells (IC50 values 11.91-25.78µg/mL). Reactive oxygen species (ROS) production, cell membrane damage and apoptotic DNA laddering were also evident by nitroblue tetrazolium (NBT) reduction, lactate dehydrogenase (LDH) release assays and DNA electrophoresis, respectively. CuO NPs strongly inhibited lipoxygenase (LOX) enzymatic activity with IC50 values 4-5.9µg/mL, highlighting in that manner their anti-inflammatory activity.

Selective synthesis of Cu2O and Cu/Cu2O NPs: antifungal activity to yeast Saccharomyces cerevisiae and DNA interaction.

A facile selective synthesis of Cu2O and heterogeneous Cu/Cu2O nanoparticles (NPs) was achieved through a solvothermal approach by Cu(NO3)2 in proportion of three different surfactants, namely, tetraethylene glycol (TEG), oleylamine (OAm) and polyoxyethylene (20) sorbitan laurate (Tween 20). Formation aspects for the spherical Cu2O@OAm (30 nm) and Cu2O@Tween (12 nm) as well as for the core-shell and semishell Cu/Cu2O@TEG NPs (7 nm) and the Cu/Cu2O@OAm (170 nm) nanorods have been proposed. The fungistatic and fungicidal activity of the newly synthesized NPs was studied in vitro against the yeast Saccharomyces cerevisiae, which constitutes a unicellular eukaryotic model microorganism in molecular and cell biology. The antifungal results, based on optical density and fluorescence measurements, clearly indicate that the composition, size, and amount of surfactant are of key importance in the antifungal properties of the NPs. Cu2O@OAm NPs exhibited the most prominent antifungal activity with 3.73 µg/mL IC(50viability) value. The isolated DNA of S. cerevisiae cells after exposure to the NPs was investigated, and binding and/or degradation phenomena were recorded that are correlated to the size and concentration of the NPs. Their activity pathway was further explored, and reactive oxygen species production and lipid peroxidation were verified mainly for Cu2O NPs.

The effect of composition and structural ordering on the magnetism of FePt nanoparticles.

Spherical 4 nm FePt nanoparticles were synthesized by the simultaneous decomposition of Fe(CO)5 and the polyol reduction of Pt(acac)2. The final Fe-to-Pt composition was tuned between 15-55 at.% by varying the ingredient precursor ratios. The effect of composition and structural ordering on the macroscopic magnetic features of final FePt nanoparticles was examined via post-synthetic annealing stages at different conditions. Structural ordering is promoted in all cases, though samples approximating equiatomic Fe/Pt ratios eventually transform to fct-FePt phase while the FePt3-phase is favored for the Pt-richer samples. Consequently, the magnetic features of the annealed nanoparticles may be categorized; the hard magnetic FePt region dominating for Fe content between 40-55 at.% and the soft magnetic FePt3 region dominating in the region 20-30 at.% while Fe content less than 20 at.% results in Pt-richer phases with diminishing ferromagnetic behavior.

Size-induced effects in wet-chemically synthesized CoPt3 nanoparticles.

CoPt3 alloy spherical nanoparticles with sizes tuned between 3-7 nm were produced by the simultaneous thermal treatment of proper platinum and cobalt precursors in the presence of surfactants. The final size and composition of the particles are determined by the precursors' ratio, the chemical behavior of Co precursors and the stabilizing efficiency of the surfactants. By employing higher reaction temperatures (approximately 350 degrees C) better alloying is achieved leading to enhancement of macroscopic magnetic features and decrease of the superparamagnetic limit down to 7 nm.