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Two different synthetic routes were employed to modify surface of graphitic carbon nitride (g- CN) with copper nanoparticles (CuNPs). Structure, morphology and CuNPs distribution on presynthesized g-CN surface are characterized by FT-IR, XRD and TEM. Results suggested that the simpler method based on mixing of precursors in inert atmosphere and room temperature, resulted in better CuNPs distribution compared to method which used refluxing as a step in synthesis.

A novel and effective antibacterial agent based on a combination of copper nanoparticles (CuNPs) and polypyrrole (PPy) is presented. By using a straightforward in situ polymerization method in water, a copper/polypyrrole (Cu/PPy) nanocomposite with spherical CuNPs, around 25 nm in diameter, uniformly dispersed throughout a granular PPy matrix, was characterized and subjected to determination of antibacterial activity toward E. coli, and S. aureus. In this survey, the synergistic engagement of various features of CuNPs and PPy against bacteria was somewhat expected. After a 24 h interaction with S. aureus, already 2 ppm of Cu/PPy with only 9.45 wt% content of Cu is acting almost completely cidal, with 99.17 % bacterial growth inhibition, while 10 ppm has a cidal value of 99.99 % at the same time. Safe and environmentally acceptable concentrations of Cu/PPy indicate that it is convenient as an antibacterial agent for wider use.

Despite having a very similar electrocaloric (EC) coefficient, i.e., the EC temperature change divided by the applied electric field, the 0.9Pb(Mg1/3Nb2/3)O3–0.1PbTiO3 (PMN-10PT) ceramic prepared by mechanochemical synthesis exhibits a much higher EC temperature change than the columbite-derived version, i.e., 2.37 °C at 107 °C and 115 kV/cm. The difference is due to the almost two-times-higher breakdown field of the former material, 115 kV/cm, as opposed to 57 kV/cm in the latter. While both ceramic materials have similarly high relative densities and grain sizes (>96%, ≈5 µm) and an almost correct perovskite stoichiometry, the mechanochemical synthesis contributes to a lower level of compositional deviation. The peak permittivity and saturated polarization are slightly higher and the domain structure is finer in the mechanochemically derived ceramic. The secondary phases that result from each synthesis are identified and related to different interactions of the individual materials with the electric field: an intergranular lead-silicate-based phase in the columbite-derived PMN-10PT and MgO inclusions in the mechanochemically derived ceramic

Despite the challenges of practical implementation, electrocaloric (EC) cooling remains a promising technology because of its good scalability and high efficiency. Here, we investigate the feasibility of an EC cooling device that couples the EC and electromechanical (EM) responses of a highly functionally, efficient, lead magnesium niobate ceramic material. We fabricated multifunctional cantilevers from this material and characterized their electrical, EM and EC properties. Two active cantilevers were stacked in a cascade structure, forming a proof-of-concept device, which was then analyzed in detail. The cooling effect was lower than the EC effect of the material itself, mainly due to the poor solid-to-solid heat transfer. However, we show that the use of ethylene glycol in the thermal contact area can significantly reduce the contact resistance, thereby improving the heat transfer. Although this solution is most likely impractical from the design point of view, the results clearly show that in this and similar cooling devices, a non-destructive, surface-modification method, with the same effectiveness as that of ethylene glycol, will have to be developed to reduce the thermal contact resistance. We hope this study will motivate the further development of multifunctional cooling devices.

A novel and favorable antibacterial agent as a combination of copper nanoparticles (CuNPs) and polypyrrole (PPy) is presented. By simple in situ polymerization method, copper/polypyrrole (Cu/PPy) nanocomposite with spherical CuNPs, around 25 nm in diameter, uniformly dispersed throughout PPy matrix with granular morphology, was characterized and subjected to determination of antibacterial activity toward bacteria Escherichia coli and Staphylococcus aureus. Knowing that when acting alone, CuNPs and PPy have already shown antimicrobial responce, their mutual and synergetic engagement against bacteria in this survey is somewhat expected. After a twenty-four-hour interaction with S. aureus, already 2 ppm of Cu/PPy with only 9.45 wt% content of Cu is acting almost completely cidal, with 99.17% of bacterial growth inhibition. Such nanocomposite could easily find application in water disinfection, soil sterilization and food preservation.

Soy isoflavone genistein (Gen) exerts beneficial effects against prostate cancer cells in vitro and in vivo. However, its use as a chemoprevention/therapeutic agent is largely limited due to its low bioavailability. In this study we synthesized two variants of a new delivery system, genistein–gold nanoparticles conjugates Gen@AuNPs1 and Gen@AuNPs2, by an environmentally friendly method, using a dual role of Gen to reduce Au3+ and stabilize the formed AuNPs, with no additional component. The formation of Gen@AuNPs was confirmed via UV–Vis spectroscopy, FTIR, and Raman spectra measurements. The spherical shape and uniform size of Gen@AuNPs1 and Gen@AuNPs2 (10 ± 2 and 23 ± 3 nm, respectively), were determined by transmission electron microscopy. The nano-conjugates also varied in hydrodynamic diameter (65.0 ± 1.7 and 153.0 ± 2.2 nm) but had similar negative zeta potential (−35.0 ± 2.5 and −37.0 ± 1.6 mV), as measured by dynamic light scattering. The Gen loading was estimated to be 46 and 48%, for Gen@AuNPs1 and Gen@AuNPs2, respectively. The antiproliferative activities of GenAuNPs were confirmed by MTT test in vitro on three malignant prostate carcinoma cell lines (PC3, DU 145, and LNCaP), while selectivity toward malignant phenotype was confirmed using non-cancerous MRC-5 cells. Flow cytometric analysis showed that the inhibition on cell proliferation of more potent Gen@AuNPs1 nano-conjugate is comparable with the effects of free Gen. In conclusion, the obtained results, including physicochemical characterization of newly synthesized AuNPs loaded with Gen, cytotoxicity, and IC50 assessments, indicate their stability and bioactivity as an antioxidant and anti-prostate cancer agent, with low toxicity against human primary cells. © 2021 Elsevier B.V.

We report a simple and green procedure for the preparation of magnetic iron oxide nanocrystals via solvothermal synthesis. The nanocrystal synthesis was carried out under mild conditions in the water–ethanol–oleic acid solvent system with the use of the oleate anion as a surface modifier of nanocrystals and glucose as a reducing agent. Specific conditions for homogenous precipitation achieved in such a reaction system lead to the formation of uniform high-quality nanocrystals down to 5 nm in diameter. The obtained hydrophobic nanocrystals can easily be converted to hydrophilic magnetic nanoparticles by being immobilized in a poly(l-lactide)–polyethyleneimine polymeric matrix. These hybrid nano-constructs may find various biomedical applications, such as magnetic separation, gene transfection and/or magnetic resonance imaging.

Magnetic iron oxide nanoparticles ranging from 5 to 20 nm were synthesized using hydrothermal approach. Syntheses were carried out starting from non toxic chemicals at mild reaction temperatures. Different surfactants such as sodium oleate, oleic acid/oleyl amine and PEG are used as in situ surface modifiers for nanoparticles. Also, by varying the type and concentration of precursors and surfactants the size and habitus of the obtained nanocrystals was adjusted. Furthermore, prepared particles are used for fabrication of hydrophilic nano and micro composite particles using biodegradable poly(L-lactide). The qualitative analysis of the synthesized magnetic particles and composites were carried out by XRD. The particle morphology, size and structure were determined TEM, while size distribution was measured by laser diffraction. The phase composition of composite particles, in particular, surface modification was investigated by FT−IR spectroscopy. Morphology of composite particles was observed by SEM.