Advancements in the Synthesis and Functionalization of Zinc Oxide-Based Nanomaterials for Enhanced Oral Cancer Therapy.

The fabrication of zinc oxide-based nanomaterials (including natural and synthetic polymers like sulfated polysaccharide, chitosan, and polymethyl methacrylate) has potential to improve oral cancer treatment strategies. This comprehensive review explores the diverse synthesis methods employed to fabricate zinc oxide nanomaterials tailored for oral cancer applications. Several synthesis processes, particularly sol-gel, hydrothermal, and chemical vapor deposition approaches, are thoroughly studied, highlighting their advantages and limitations. The review also examines how synthesis parameters, such as precursor selection, the reaction temperature, and growth conditions, influence both the physicochemical attributes and biological efficacy of the resulting nanomaterials. Furthermore, recent advancements in surface functionalization and modification strategies targeted at improving the targeting specificity and pharmaceutical effectiveness of zinc oxide-based nanomaterials in oral cancer therapy are elucidated. Additionally, the review provides insights into the existing issues and prospective views in the field, emphasizing the need for further research to optimize synthesis methodologies and elucidate the mechanisms underlying the efficacy of zinc oxide-based nanoparticles in oral cancer therapy.

Improving ultraviolet protection properties of cotton textiles using Zinc oxide (ZnO) nanomaterials: an approach for controlling occupational and environmental exposures.

Ultraviolet (UV) radiation exposure is one of the most important risk factor among workers. it may stimulate health outcomes such as multiple skin injuries and blinding eye diseases. So, UV protection is mainly important for people who expose to it. Modification of cotton textiles by nanomaterials is a new approach to overcome this problem. So, the aim of this study is to review studies conducted on using ZnO nanoparticles for improving ultraviolet protection of cotton textiles. The search strategy was provided by cochrane guideline. 45 studies were regarded as appropriate. The results show that UPF for textiles has improved by coated ZnO. However, UPF was depended on the physicochemical characteristics of ZnO and textiles such as yarn structure, effect of woven fabric construction, fabric porosity, and impurity of textiles and laundering conditions. Also, plasma technology has improved UPF, it is recommended that more studies be done to achieve better results.

Reshapable Osteogenic Biomaterials Combining Flexible Melt Electrowritten Organic Fibers with Inorganic Bioceramics.

Ever-growing various applications, especially for tissue regeneration, cause a pressing need for novel methods to functionalize melt electrowritten (MEW) microfibrous scaffolds with unique nanomaterials. Here, two novel strategies are proposed to modify MEW polycaprolactone (PCL) grids with ZnO nanoparticles (ZP) or ZnO nanoflakes (ZF) to enhance osteogenic differentiation. The calcium mineralization levels of MC3T3 osteoblasts cultured on PCL/ZP 0.1 scaffolds are ∼3.91-fold higher than those cultured on nonmodified PCL scaffolds, respectively. Due to the nanotopography mimicking bone anatomy, the PCL/ZF scaffolds (∼2.60 times higher in ALP activity compared to PCL/ZP 1 and ∼2.17 times higher in mineralization compared to PCL/ZP 0.1) achieved superior results. Moreover, the flexible feature inherited from PCL grids makes it possible for them to act as a reshapable osteogenic bioscaffold. This study provides new strategies for synthesizing nanomaterials on microscale surfaces, opening up a new route for functionalizing MEW scaffolds to fulfill the growing demand of tissue engineering.

Palmitate enhanced the cytotoxicity of ZnO nanomaterials possibly by promoting endoplasmic reticulum stress.

We recently synthesized ZnO nanomaterials (denoted as ZnO nanorods [NRs] and Mini-NRs) and suggested that their cytotoxicity could be related with the activation of endoplasmic reticulum (ER) stress apoptosis. However, in a complex biological microenvironment, the ER stress-apoptosis pathway could also be modulated by biological molecules, such as free fatty acids, leading to unpredicted biological effects. In this study, we investigated the combined toxicity of ZnO NRs/Mini-NRs and palmitate (PA) to THP-1 macrophages. PA influenced the zeta potential and solubility of ZnO NRs and ZnO Mini-NRs in water, which indicated a change of colloidal stability. Exposure to ZnO NRs and Mini-NRs dose-dependent decreased cellular viability and release of soluble monocyte chemotactic protein 1 (sMCP-1), and these effects were significantly promoted with the presence of PA. However, ZnO NR- and Mini-NR-induced intracellular Zn ions or reactive oxygen species were not significantly affected by PA. ZnO NRs and ZnO Mini-NRs significantly promoted the expression of ER stress genes HSPA5, DDIT3, XBP-1s and apoptotic gene CASP3, whereas PA also modestly promoted the expression of HSPA5, DDIT3 and CASP3. Interestingly, the ER stress inducer thapsigargin showed a similar effect as PA to promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs. It is suggested that PA might promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs possibly by promoting ER stress.

The toxicity of ZnO nanomaterials to HepG2 cells: the influence of size and shape of particles.

Understanding the possible role of physicochemical properties in determining the toxicity of ZnO nanomaterials (NMs) is crucial for the safe use of ZnO-based materials. In this study, we synthesized four types of ZnO NMs, and characterized them as ZnO nanorods (NRs; length 400-500 nm, diameter 150-200 nm), ZnO Mini-NRs (length 50-100 nm, diameter 15-20 nm), amorphous ZnO microspheres (a-ZnO MS) and crystalline ZnO MS (c-ZnO MS; the a/c-ZnO MS are nanoflowers with an extensive growth of sheet-like structures). ZnO NMs and ZnO Mini-NRs were significantly more cytotoxic than a/c-ZnO MS, and this trend was similar in both HepG2 cells and human umbilical vein endothelial cells. Intracellular reactive oxygen species was only modestly induced by c-ZnO MS, whereas intracellular Zn ions were dose-dependently increased in HepG2 cells by the exposure of all types of ZnO NMs. The expression of endoplasmic reticulum stress marker DDIT3 was induced following an order of ZnO NRs > a-ZnO MS > c-ZnO MS > ZnO Mini-NRs, and the apoptosis gene CASP12 was induced following an order of a-ZnO MS > ZnO NRs > c-ZnO MS > ZnO Mini-NRs. Combined, these results suggested that ZnO NM-induced cytotoxicity and expression of endoplasmic reticulum stress-apoptosis genes could be influenced by the size and shape of ZnO NMs.

Construction of Immobilized Laccase System Based on ZnO and Degradation of Mesotrione.

Mesotrione (MES) is a new environmental pollutant. Some reports have indicated that microbial enzymes could be utilized for MES degradation. Laccase is a green biocatalyst whose potential use in environmental pollutant detoxification has been considered limited due to its poor stability and reusability. However, these issues may be addressed using enzyme immobilization. In the present study, we sought to optimize conditions for laccase immobilization, to analyze and characterize the characteristics of the immobilized laccase, and to compare its enzymatic properties to those of free laccase. In addition, we studied the ability of laccase to degrade MES, and analyzed the metabolic pathway of MES degradation by immobilized laccase. The results demonstrated that granular zinc oxide material (G-ZnO) was successfully used as the carrier for immobilization. G-ZnO@Lac demonstrated the highest recovery of enzyme activity and exhibited significantly improved stability compared with free laccase. Storage stability was also significantly improved, with the relative enzyme activity of G-ZnO@Lac remaining at about 54% after 28 days of storage (compared with only 12% for free laccase). The optimal conditions for the degradation of MES by G-ZnO@Lac were found to be 10 mg, 6 h, 30 °C, and pH 4; under these conditions, a degradation rate of 73.25% was attained. The findings of this study provide a theoretical reference for the laccase treatment of 4-hy-droxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide contamination.

Banana Peel Extract-Derived ZnO Nanopowder: Transforming Solar Water Purification for Safer Agri-Food Production.

Pure water scarcity is the most significant emerging challenge of the modern society. Various organics such as pesticides (clomazone, quinmerac), pharmaceuticals (ciprofloxacin, 17α-ethynilestradiol), and mycotoxins (deoxynivalenol) can be found in the aquatic environment. The aim of this study was to fabricate ZnO nanomaterial on the basis of banana peel extract (ZnO/BPE) and investigate its efficiency in the photocatalytic degradation of selected organics under various experimental conditions. Newly synthesized ZnO/BPE nanomaterials were fully characterized by the XRD, FTIR, SEM-EPS, XPS, and BET techniques, which confirmed the successful formation of ZnO nanomaterials. The photocatalytic experiments showed that the optimal catalyst loading of ZnO/BPE was 0.5 mg/cm3, while the initial pH did not influence the degradation efficiency. The reusability of the ZnO/BPE nanomaterial was also tested, and minimal activity loss was found after three photocatalytic cycles. The photocatalytic efficiency of pure banana peel extract (BPE) was also studied, and the obtained data showed high removal of ciprofloxacin and 17α-ethynilestradiol. Finally, the influence of water from Danube River was also examined based on the degradation efficiency of selected pollutants. These results showed an enhanced removal of ciprofloxacin in water from the Danube River, while in the case of other pollutants, the treatment was less effective.

Toward Understanding the Environmental Risks of Combined Microplastics/Nanomaterials Exposures: Unveiling ZnO Transformations after Adsorption onto Polystyrene Microplastics in Environmental Solutions.

Over recent decades, there has been a dramatic increase in the manufacture of engineered nanomaterials, which has inevitably led to their environmental release. Zinc oxide (ZnO) is among the more abundant nanomaterial manufactured due to its advantageous properties, used for piezoelectric, semiconducting, and antibacterial purposes. Plastic waste is ubiquitous and may break down or delaminate into smaller microplastics, leaving open the question of whether these small polymers may alter the fate of ZnO through adsorption within aquatic media (tap-water and seawater). Here, scanning electron microscopy analysis confirms the effective Zn nano/microstructures adsorption onto polystyrene surfaces after only 24-h incubation in the aquatic media. After pre-aging the nanomaterials for 7-days in different environmental media, nanoprobe X-ray absorption near-edge spectroscopy analysis reveals significant ZnO transformation toward Zn-sulfide and Zn-phosphate. The interaction between a commercial ZnO-based sunscreen with polystyrene and a cleanser consumer containing microbeads with ZnO nanomaterials is also studied, revealing the adsorption of transformed Zn-species in the microplastics surfaces, highlighting the environmental relevancy of this work. Understanding the structural and functional impacts of the microplastics/ZnO complexes, and how they evolve, will provide insights into their chemical nature, stability, transformations, and fate, which is key to predicting their bioreactivity in the environment.

Effective Antibacterial/Photocatalytic Activity of ZnO Nanomaterials Synthesized under Low Temperature and Alkaline Conditions.

The purpose of this study was to evaluate the surface properties of ZnO nanomaterials based on their ability to photodegrade methyl blue dye (MB) and to show their antibacterial properties against different types of Gram-positive bacteria (Bacillus manliponensis, Micrococcus luteus, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). In this study, ZnO nanomaterials were synthesized rapidly and easily in the presence of 1-4 M NaOH at a low temperature of 40 °C within 4 h. It was found that the ZnO nanomaterials obtained from the 1.0 M (ZnO-1M) and 2.0 M (ZnO-2M) aqueous solutions of NaOH had spherical and needle-shaped forms, respectively. As the concentration of NaOH increased, needle thickness increased and the particles became rod-like. Although the ZnO nanomaterial shapes were different, the bandgap size remained almost unchanged. However, as the NaOH concentration increased, the energy position of the conduction band shifted upward. Photo current curves and photoluminescence intensities suggested that the recombination between photoexcited electrons and holes was low in the ZnO-4M materials prepared in 4.0 M NaOH solution; however, charge transfer was easy. ∙O2- radicals were generated more than ∙OH radicals in ZnO-4M particles, showing stronger antibacterial activity against both Gram-positive and Gram-negative bacteria and stronger decomposition ability on MB dye. The results of this study suggest that on the ZnO nanomaterial surface, ∙O2- radicals generated are more critical for antibacterial activity than particle shape.

ZnO Nanomaterials and Ionic Zn Partition within Wastewater Sludge Investigated by Isotopic Labeling.

The increasing commercial use of engineered zinc oxide nanomaterials necessitates a thorough understanding of their behavior following their release into wastewater. Herein, the fates of zinc oxide nanoparticles (ZnO NPs) and ionic Zn in a real primary sludge collected from a municipal wastewater system are studied via stable isotope tracing at an environmentally relevant spiking concentration of 15.2 µg g-1. Due to rapid dissolution, nanoparticulate ZnO does not impart particle-specific effects, and the Zn ions from NP dissolution and ionic Zn display indistinguishable behavior as they partition equally between the solid, liquid, and ultrafiltrate phases of the sludge over a 4-h incubation period. This work provides important constraints on the behavior of engineered ZnO nanomaterials in primary sludge-the first barrier in a wastewater treatment plant-at low, realistic concentrations. As the calculated solid-liquid partition coefficients are significantly lower than those reported in prior studies that employ unreasonably high spiking concentrations, this work highlights the importance of using low, environmentally relevant doses of engineered nanomaterials in experiments to obtain accurate risk assessments.

A p-n Heterojunction Based Pd/PdO@ZnO Organic Frameworks for High-Sensitivity Room-Temperature Formaldehyde Gas Sensor.

As formaldehyde is an extremely toxic volatile organic pollutant, a highly sensitive and selective gas sensor for low-concentration formaldehyde monitoring is of great importance. Herein, metal-organic framework (MOF) derived Pd/PdO@ZnO porous nanostructures were synthesized through hydrothermal method followed by calcination processes. Specifically, porous Pd/PdO@ZnO nanomaterials with large surfaces were synthesized using MOFs as sacrificial templates. During the calcination procedure, an optimized temperature of 500°C was used to form a stable structure. More importantly, intensive PdO@ZnO inside the material and composite interface provides lots of p-n heterojunction to efficiently manipulate room temperature sensing performance. As the height of the energy barrier at the junction of PdO@ZnO exponentially influences the sensor resistance, the Pd/PdO@ZnO nanomaterials exhibit high sensitivity (38.57% for 100 ppm) at room temperature for 1-ppm formaldehyde with satisfactory selectivity towards (ammonia, acetone, methanol, and IPA). Besides, due to the catalytic effect of Pd and PdO, the adsorption and desorption of the gas molecules are accelerated, and the response and recovery time is as small as 256 and 264 s, respectively. Therefore, this MOF-driven strategy can prepare metal oxide composites with high surface area, well-defined morphology, and satisfactory room-temperature formaldehyde gas sensing performance for indoor air quality control.

ZnO Nanomaterials: Current Advancements in Antibacterial Mechanisms and Applications.

The prevalence of various diseases caused by bacteria has been increasing, and some traditional antibiotics have been reported to have varying degrees of resistance. ZnO nanomaterials (ZnO-NMs), due to their excellent broad-spectrum antibacterial properties, lasting antibacterial effects, and excellent biocompatibility, have quickly become the research focus of new antibacterial agents. While the narrow light response range of ZnO-NMs has limited the antibacterial performance to some extent and modifying it by various means to improve its response under visible light, such as doping metal/non-metal atoms, depositing noble metals and coupling carbon materials, which is a new research hotspot. Herein, the current mainstream claims about the antibacterial mechanisms and applications of ZnO-NMs are reviewed.

Spatially Resolved Dissolution and Speciation Changes of ZnO Nanorods during Short-Term in Situ Incubation in a Simulated Wastewater Environment.

Zinc oxide engineered nanomaterials (ZnO ENMs) are used in a variety of applications worldwide due to their optoelectronic and antibacterial properties with potential contaminant risk to the environment following their disposal. One of the main potential pathways for ZnO nanomaterials to reach the environment is via urban wastewater treatment plants. So far there is no technique that can provide spatiotemporal nanoscale information about the rates and mechanisms by which the individual nanoparticles transform. Fundamental knowledge of how the surface chemistry of individual particles change, and the heterogeneity of transformations within the system, will reveal the critical physicochemical properties determining environmental damage and deactivation. We applied a methodology based on spatially resolved in situ X-ray fluorescence microscopy (XFM), allowing observation of real-time dissolution and morphological and chemical evolution of synthetic template-grown ZnO nanorods (∼725 nm length, ∼140 nm diameter). Core-shell ZnO-ZnS nanostructures were formed rapidly within 1 h, and significant amounts of ZnS species were generated, with a corresponding depletion of ZnO after 3 h. Diffuse nanoparticles of ZnS, Zn3(PO4)2, and Zn adsorbed to Fe-oxyhydroxides were also imaged in some nonsterically impeded regions after 3 h. The formation of diffuse nanoparticles was affected by ongoing ZnO dissolution (quantified by inductively coupled plasma mass spectrometry) and the humic acid content in the simulated sludge. Complementary ex situ X-ray absorption spectroscopy and scanning electron microscopy confirmed a significant decrease in the ZnO contribution over time. Application of time-resolved XFM enables predictions about the rates at which ZnO nanomaterials transform during their first stages of the wastewater treatment process.

Comparison of the effects of commercial coated and uncoated ZnO nanomaterials and Zn compounds in kidney bean (Phaseolus vulgaris) plants.

Bean (Phaseolus vulgaris) plants were grown for 45 days in soil amended with either uncoated (Z-COTE®) and coated (Z-COTE HP1®) ZnO nanomaterials (NMs), bulk ZnO and ZnCl2, at 0-500mg/kg. At harvest, growth parameters, chlorophyll, and essential elements were determined. None of the treatments affected germination and pod production, and only ZnCl2 at 250 and 500mg/kg reduced relative chlorophyll content by 34% and 46%, respectively. While Z-COTE® did not produce phenotypic changes, Z-COTE HP1®, at all concentrations, increased root length (∼44%) and leaf length (∼13%) compared with control. Bulk ZnO reduced root length (53%) at 62.5mg/kg and ZnCl2 reduced leaf length (16%) at 125mg/kg. Z-COTE®, at 125mg/kg, increased Zn by 203%, 139%, and 76% in nodules, stems, and leaves, respectively; while at the same concentration, Z-COTE HP1® increased Zn by 89%, 97%, and 103% in roots, stems, and leaves, respectively. At 125mg/kg, Z-COTE HP1® increased root S (65%) and Mg (65%), while Z-COTE® increased stem B (122%) and Mn (73%). Bulk ZnO and ZnCl2 imposed more toxicity to kidney bean than the NMs, since they reduced root and leaf elongation, respectively, and the concentration of several essential elements in tissues.

Renewable Lignosulfonate-Assisted Synthesis of Hierarchical Nanoflake-Array-Flower ZnO Nanomaterials in Mixed Solvents and Their Photocatalytic Performance.

With the assistance of sodium lignosulfonate, hierarchical nanoflake-array-flower nanostructure of ZnO has been fabricated by a facile precipitation method in mixed solvents. The sodium lignosulfonate amount used in our synthetic route is able to fine-tune ZnO morphology and an abundance of pores have been observed in the nanoflake-array-flower ZnO, which result in specific surface area reaching as high as 82.9 m(2) · g(-1). The synthesized ZnO exhibits superior photocatalytic activity even under low-power UV illumination (6 W). It is conjectured that both nanoflake-array structure and plenty of pores embedded in ZnO flakes may provide scaffold microenvironments to enhance photocatalytic activity. Additionally, this catalyst can be used repeatedly without a significant loss in photocatalytic activity. The low-cost, simple synthetic approach as well as high photocatalytic and recycling efficiency of our ZnO nanomaterials allows for application to treat wastewater containing organic pollutants in an effective way.

Effects of aspect ratio (AR) and specific surface area (SSA) on cytotoxicity and phototoxicity of ZnO nanomaterials.

With growing interests in the applications of high aspect ratio (AR) ZnO nanomaterials (NMs), their potential toxicity to human health and nature environment remains a critical concern because these NMs have extremely large specific surface area (SSA) that could dramatically enhance interactions between NMs and surrounding molecules. In addition, originated to their intrinsic photocatalytical activity, ZnO NMs may induce phototoxicity under environmentally UV exposure. In this paper, ZnO spheres, grains, rods and needles with increasing AR (from 1.1 to 17.8) and various SSA (from 2.0 m(2) g(-1) to 27.4 m(2) g(-1)) were used to study the influence of AR and SSA on viabilities of WIL2-NS human lymphoblastoid cells in both dark and UV conditions. In dark, SSA was the main influencing factor for toxicity of NMs with low AR (spheres, grains and rods) and smaller SSA leads to higher cell viability. However, ZnO needles with the smallest SSA did not further enhance cell viability which may be possibly attributed to its high AR. Cell viability measured under UV irradiation did not show evident relationship with SSA or AR, but indicated that lower photocatalytic activity could mitigate phototoxicity.

Shape-dependent plasma-catalytic activity of ZnO nanomaterials coated on porous ceramic membrane for oxidation of butane.

In order to explore the effects of the shape of ZnO nanomaterials on the plasma-catalytic decomposition of butane and the distribution of byproducts, three types of ZnO nanomaterials (nanoparticles (NPs), nanorods (NRs) and nanowires (NWs)) were prepared and coated on multi-channel porous alumina ceramic membrane. The structures and morphologies of the nanomaterials were confirmed by X-ray diffraction method and scanning electron microscopy. The observed catalytic activity of ZnO in the oxidative decomposition of butane was strongly shape-dependent. It was found that the ZnO NWs exhibited higher catalytic activity than the other nanomaterials and could completely oxidize butane into carbon oxides (COx). When using the bare or ZnO NPs-coated ceramic membrane, several unwanted partial oxidation and decomposition products like acetaldehyde, acetylene, methane and propane were identified during the decomposition of butane. When the ZnO NWs- or ZnO NRs-coated membrane was used, however, the formation of such unwanted byproducts except methane was completely avoided, and full conversion into COx was achieved. Better carbon balance and COx selectivity were obtained with the ZnO NWs and NRs than with the NPs.