Synthesis and bactericidal action of Fe3O4/AgO bifunctional magnetic-bactericidal nanocomposite

CuO improved energy band of AgO/fibrous SiO2-ZrO2 for optimized simultaneous photocatalytic redox of chromium (VI) and p-cresol using response surface methodology

Ternary CuO/AgO/FSZr photocatalysts were fabricated via the hydrothermal and electrochemical methods with three different CuO loading (1, 3 and 5 wt%), indicated as 1CuO/AgO/FSZr, 3CuO/AgO/FSZr and 5CuO/AgO/FSZr. The photocatalytic reaction was tested towards simultaneous chromium (VI) photoreduction and p-cresol photooxidation and the performance in order as follow: 3CuO/AgO/FSZr > 5CuO/AgO/FSZr > 1CuO/AgO/FSZr > AgO/FSZr > FSZr. CuO/AgO/FSZr photocatalysts showed an improvement in photocatalytic activity compared to AgO/FSZr and FSZr due to the reduction potential of chromium (VI) aligned closer to the conduction band of CuO and provided abundant free active electrons (e^-) and holes (h⁺) with efficient transportation and migration. Interestingly, the 3CuO/AgO/FSZr was established as the best photocatalyst with 98% reduction of chromium (VI) and 83% oxidation of p-cresol simultaneously, owing to its strong corporation between the metal oxides and support and higher total pore volume. The Langmuir-Hinshelwood model were employed for kinetics which followed the pseudo-first-order kinetics model well. Based on the simultaneous photocatalytic mechanism, chromium (VI) and p-cresol were directly reduced and oxidized by e^- and h⁺, respectively. The response surface methodology (RSM) discovered that the quadratic term initial concentration of chromium (VI) is the main significant factor in photocatalytic performance. The optimum parameters for simultaneous photoredox of chromium (VI) and p-cresol predicted from RSM are 9.6 mg L^-1 of chromium (VI) concentration, 9.8 mg L^-1 of p-cresol concentration and 0.32 g L^-1 of catalyst dosage. Under these conditions the error between the predicted and experimental values is only 3.7%. The 3CuO/AgO/FSZr sustained the photocatalytic performance after reused for five cycles and could oxidized various organic pollutants as well as reduced chromium (VI) simultaneously.

Cellulose nanofibers aerogels functionalized with AgO: Preparation, characterization and antibacterial activity

In the experiment, a chemical oxidation method was used to prepare nano-divalent silver oxide powder with a particle size of about 10 nm. Compared with silver nanoparticles and monovalent silver compounds, nano‑silver oxide has better antibacterial properties. The cellulose antibacterial aerogel was prepared by combining it with cellulose nanofibrils and using freeze-thaw cycles and freeze-drying methods. The microscopic morphology, mechanical properties, in vitro release of silver ions, antibacterial properties and biodegradability of composite aerogels were studied. The porosity of the cellulose antibacterial aerogel can reach 94%, the swelling rate was greater than 1000%, and the pore size was between 13 and 15 nm, which showed a larger storage space and attachment site for the aerogel. The diameter of the inhibition zone of the aerogel against Escherichia coli and Staphylococcus aureus was 23 mm and 20 mm respectively, and the aerogels still exhibited significant antibacterial activities with more than 99.5% reductions in Escherichia coli and Staphylococcus aureus, which shows highly effective antibacterial properties. This research proposes an economical and novel preparation method of antibacterial cellulose aerogel, making it a candidate material with high efficiency, broad-spectrum antibacterial and more suitable for life needs.

Electrodecoration and Characterization of Superparamagnetic Iron Oxide Nanoparticles with Bioactive Synergistic Nanocopper: Magnetic Hyperthermia-Induced Ionic Release for Anti-Biofilm Action

The urgency for the availability of new antibacterial/disinfectant agents has become a worldwide priority. At the same time, along with the extensive use of other metal nanoparticles (NPs), the investigation of magnetic NPs (MNPs) in antibacterial studies has turned out to be an increasingly attractive research field. In this context, we present the preparation and characterization of superparamagnetic iron oxide NPs, electrodecorated with antimicrobial copper NPs, able to modulate the release of bioactive species not only by the NP’s stabilizer, but also through the application of a suitable magnetic field. Antimicrobial synergistic CuNPs stabilized by benzalkonium chloride have been used in the current study. We demonstrate the successful preparation of Cu@Fe₃O₄ MNPs composites through morphological and spectroscopic results. Additionally, an extensive magnetic characterization is reported, along with hyperthermia-induced copper ionic release. On the basis of our results, we propose a new generation of antimicrobial magnetic nanomaterials, whose bioactivity can be also tuned by the application of a magnetic field.