Cytotoxicity, Antioxidant, Antibacterial, and Photocatalytic Activities of ZnO-CdS Powders

Photocatalytic-Driven Antiviral Activities of Heterostructured BiOCl0.2Br0.8 - BiOBr Semiconductors

Numerous methods for eliminating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being extensively examined in recent years as a result of the COVID-19 pandemic and its adverse effects on society. Photocatalysis is among the most encouraging solutions since it has the capacity to fully annihilate pathogens, surpassing conventional disinfecting methods. A heterostructured photocatalytic composite of (70%W BiOCl0.2Br0.8 with 30%W BiOBr) was prepared via a simple synthetic route that yielded microspheres ∼3-4 μm in diameter. The composite was evidenced to inactivate stubborn enveloped viruses. By utilizing scanning electron microscopy, transmission electron microscopy, N2 sorption, and X-ray diffraction, the morphology and the chemical composition of the heterostructured composite was revealed. Full elimination of SARS-CoV-2 occurred 5 min following the light-activation of the photocatalytic mixture. Illumination absence bared a slower yet effective result of full viral decomposition at a time span of 25 min. A comparable efficacious outcome was observed in the study case of vesicular stomatitis virus with complete diminishing within 30 min of visible light exposure.

CdS nanocrystallites sensitized ZnO nanosheets for visible light induced sonophotocatalytic/photocatalytic degradation of tetracycline: From experimental results to a generalized model based on machine learning methods

CdS/ZnO nanosheets heterostructures ((x)CdS/ZNs) with different mole ratios of Cd/Zn ((x) = 0.2, 0.4, and 0.6) were synthesized by the impregnation-calcination method. PXRD patterns showed that the (100) diffraction of ZNs was the most significant in the (x)CdS/ZNs heterostructures, and it confirmed that CdS nanoparticles (in cubic phase) occupied the (101) and (002) crystal facets of ZNs with hexagonal wurtzite crystal phase. UV-Vis DRS results indicated that CdS nanoparticles decreased the band gap energy of ZNs (2.80-2.11 eV) and extended the photoactivity of ZNs to the visible light region. The vibrations of ZNs were not observed clearly in the Raman spectra of (x)CdS/ZNs due to the extensive coverage of CdS nanoparticles shielding the deeper-laying ZNs from Raman response. The photocurrent of (0.4) CdS/ZNs photoelectrode reached 33 μA, about 82 times higher than that for ZNs (0.4 μA, 0.1 V vs Ag/AgCl). The formation of an n-n junction at the (0.4) CdS/ZNs reduced the recombination of electron-hole pairs and increased the degradation performance of the as-prepared (0.4) CdS/ZNs heterostructure. The highest percentage removal of tetracycline (TC) in the sonophotocatalytic/photocatalytic processes was obtained by (0.4) CdS/ZNs under visible light. The quenching tests showed that O₂^•-, h⁺, and OH^• were the main active species in the degradation process. The degradation percentage decreased negligibly in the sonophotocatalytic (84%-79%) compared to the photocatalytic (90%-72%) process after four re-using runs due to the presence of ultrasonic waves. For the estimation of degradation behavior, two machine learning methods were applied. The comparison between the ANN and GBRT models evidenced that both models had high prediction accuracy and could be used for predicting and fitting the experimental data of the %removal of TC. The excellent sonophotocatalytic/photocatalytic performance and stability of the fabricated (x)CdS/ZNs catalysts made them promising candidates for wastewater purification.

Burdock-Derived Composites Based on Biogenic Gold, Silver Chloride and Zinc Oxide Particles as Green Multifunctional Platforms for Biomedical Applications and Environmental Protection

Green nanotechnology is a rapidly growing field linked to using the principles of green chemistry to design novel nanomaterials with great potential in environmental and health protection. In this work, metal and semiconducting particles (AuNPs, AgClNPs, ZnO, AuZnO, AgClZnO, and AuAgClZnO) were phytosynthesized through a "green" bottom-up approach, using burdock (Arctium lappa L.) aqueous extract. The morphological (SEM/TEM), structural (XRD, SAED), compositional (EDS), optical (UV-Vis absorption and FTIR spectroscopy), photocatalytic, and bio-properties of the prepared composites were analyzed. The particle size was determined by SEM/TEM and by DLS measurements. The phytoparticles presented high and moderate physical stability, evaluated by zeta potential measurements. The investigation of photocatalytic activity of these composites, using Rhodamine B solutions' degradation under solar light irradiation in the presence of prepared powders, showed different degradation efficiencies. Bioevaluation of the obtained composites revealed the antioxidant and antibacterial properties. The tricomponent system AuAgClZnO showed the best antioxidant activity for capturing ROS and ABTS•+ radicals, and the best biocidal action against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The "green" developed composites can be considered potential adjuvants in biomedical (antioxidant or biocidal agents) or environmental (as antimicrobial agents and catalysts for degradation of water pollutants) applications.

Prokaryotic and eukaryotic toxicity of halloysite decorated with photoactive nanoparticles

The development of new approaches to treat the growing antibiotic resistance of pathogenic bacterial species is an important task to ensure the future safety of society. Utilization of irradiation of different wavelengths together with nanostructured materials based on metal containing nanoparticles may result in synergetic antibacterial effects. In this paper we aim to show the main conceptions of light-assisted bacteria deactivation techniques and prospects of application of natural clay nanotubes as a carrier for scalable photoactive antibacterial nanomaterials. Halloysite aluminosilicate nanotubes (ca 50 nm diameter, ca. 1.0 μm length) are safe and biocompatible natural materials produced in tons. Their application as a template or a carrier for metal nanoparticles, QDs and organic compounds has already found application in biomedical research, cosmetics, polymers, coatings, catalysis and related applications. Here, we show the toxicity of halloysite decorated with photoactive nanoparticles on prokaryotic and eukaryotic cells. The formation of light active nanostructured materials with this clay as the base is a promising tool for solving the problem of the antibiotic resistance of microorganisms.

Functionalized zinc oxide microparticles for improving the antimicrobial effects of skin-care products and wound-care medicines

ZnO is an important component in skin-protection products and wound-care medicines. However, ZnO's antibacterial activity is moderate. We developed two types of ZnO microparticles loading with phthalocyanine-type photosensitizers (ZnO/PSs) introducing the photodynamic effects. These photosensitive ZnO microparticles exhibited long-term while moderate antimicrobial effects by continuously releasing Zn²⁺ ions. The antimicrobial efficacies were remarkably enhanced by triggering the photodynamic antimicrobial effects. Compared to the sole ZnO which showed non-measurable antimicrobial activity at a concentration of 10 mg/L, both ZnO/PSs demonstrated antimicrobial rates ranged 99%-99.99% against Escherichia coli, normal and drug-resistant Staphylococcus aureus. In a dorsal wound infection mouse model, treatment with ZnO/PSs significantly accelerated the wound recovery rates. ZnO/PSs promoted wound healing by a dual effect: 1) the release of Zn²⁺ ions from ZnO facilitating tissue remodeling; 2) the photodynamic effect efficiently eliminates pathogens avoiding infection. Notably, ZnO/PSs inherited the high biosafety of ZnO without causing noticeable toxicity against erythrocyte and endothelial cells. This study not only provides a highly safe and efficient antimicrobial ZnO material for skin cares and wound modulations, but also proposes a strategy to functionalize ZnO materials.

Correction: Zgura et al. Cytotoxicity, Antioxidant, Antibacterial, and Photocatalytic Activities of ZnO-CdS Powders. Materials 2020, 13, 182

In the original publication [...].

Photo induced mechanistic activity of GO/Zn(Cu)O nanocomposite against infectious pathogens: Potential application in wound healing

Treating infection causing microorganisms is one of the major challenges in wound healing. These may gain resistance due to the overuse of conventional antibiotics. A promising technique is antimicrobial photodynamic therapy (aPDT) used to selectively cause damage to infectious pathogenic cells via generation of reactive oxygen species (ROS). We report on biocompatable nanomaterials that can serve as potential photosensitizers for aPDT. GO/Zn(Cu)O nanocomposite was synthesized by co-precipitation method. Graphene Oxide (GO) is known for its high surface to volume ratio, excellent surface functionality and enhanced antimicrobial property. ZnO nanoparticle induces the generation of reactive oxygen species (ROS) under light irradiation and it leads to recombination of electron-hole pair. Nanocomposites of GO and Cu doped ZnO increases visible light absorption and enhances the photocatalytic property. It generates more ROS and increases the bacterial inhibition. GO/Zn(Cu)O nanocomposite was tested against Staphylococcus aureus (S. aureus), Enterococcus faecium (E. faecium), Escherichia coli (E. coli), Salmonella typhi (S. typhi), Shigella flexneri (S. flexneri) and Pseudomonas aeruginosa (P. aeruginosa) by well diffusion method, growth curve, colony count, biofilm formation under both dark and visible light condition. Reactive Oxygen Species assay (ROS), Lactate dehydrogenase leakage (LDH) assay, Protein estimation assay and membrane integrity study proves the mechanism of inhibition of bacteria. Inhibition kinetics shows the sensitivity between bacteria and GO/Zn(Cu)O nanocomposite.

Improved Bacteriostatic and Anticorrosion Effects of Polycaprolactone/Chitosan Coated Magnesium via Incorporation of Zinc Oxide

Magnesium has been recognized as a groundbreaking biodegradable biomaterial for implant applications, but its use is limited because it degrades too quickly in physiological solutions. This paper describes the research on the influence of polycaprolactone (PCL)/chitosan (CS)/zinc oxide (ZnO) composite coating (PCL/CS/ZnO) on the corrosion resistance and antibacterial activity of magnesium. The PCL/CS film presented a porous structure with thickness of about 40-50 μm, while after incorporation of ZnO into the PCL/CS, a homogenous film without pores and defects was attained. The ZnO embedded in PCL/CS enhanced corrosion resistance by preventing corrosive ions diffusion in the magnesium substrate. The corrosion, antibacterial, and cell interaction mechanism of the PCL/CS/ZnO composite coating is discussed in this study. In vitro cell culture revealed that the PCL/CS coating with low loaded ZnO significantly improved cytocompatibility, but coatings with high loaded ZnO were able to induce some cytotoxicity osteoblastic cells. It was also found that enhanced antibacterial activity of the PCL/CS/ZnO coating against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, while less significant antibacterial activity was detected for uncoated Mg and PCL/CS coating. Based on the results, the PCL/CS coatings loaded with low ZnO content may be recommended as a candidate material for biodegradable Mg-based orthopedic implant applications.

Enhanced photocatalytic degradation of Rhodamine B, antibacterial and antioxidant activities of green synthesised ZnO/N doped carbon quantum dot nanocomposites

In order to explore an alternative photocatalyst for environmental remediation, we report a two-step process for the synthesis of zinc oxide/nitrogen doped carbon quantum dot nanocomposites (ZnO@NCQD NCs).

Facile Use of ZnO Nanopowders to Protect Old Manual Paper Documents

One of the main problems faced by libraries, archives and collectors is the mold degradation of the paper-based documents, books, artworks etc. Microfungi (molds) emerge in regular storage conditions of such items (humidity, usually over 50%, and temperatures under 21 °C). If the removal of the visible mycelium is relatively easy, there is always the problem of the subsequent appearance of mold as the spores remain trapped in the cellulosic, fibrillary texture, which acts as a net. Moreover, due to improper hand hygiene bacteria contamination, old books could represent a source of biohazard, being colonized with human pathogens. An easy and accessible method of decontamination, which could offer long term protection is therefore needed. Here, we present a facile use of the ZnO nanopowders as antimicrobial agents, suitable for cellulose-based products, conferring an extended antibacterial and anti-microfungal effect. The proposed method does not adversely impact on the quality of the cellulose documents and could be efficiently used for biodegradation protection.