Synthesis Approaches of Zinc Oxide Nanoparticles: The Dilemma of Ecotoxicity

Cutting-edge nanotechnology: unveiling the role of zinc oxide nanoparticles in combating deadly gastrointestinal tumors

Zinc oxide nanoparticles (ZnO-NPs) have gained significant attention in cancer therapy due to their unique physical and chemical properties, particularly in treating gastrointestinal (GI) cancers such as gastric, colorectal, and hepatocellular carcinoma. These nanoparticles generate reactive oxygen species (ROS) upon entering cancer cells, causing oxidative stress that leads to cellular damage, DNA fragmentation, and apoptosis. ZnO-NPs affect the expression of key proteins involved in apoptosis, including p53, Bax, and Bcl-2, which regulate cell cycle arrest and programmed cell death. Additionally, ZnO-NPs can reduce mitochondrial membrane potential, further enhancing apoptosis in cancer cells. Furthermore, ZnO-NPs inhibit cancer cell proliferation by interfering with cell cycle progression. They reduce levels of cyclins and cyclin-dependent kinases (CDKs), leading to cell cycle arrest. ZnO-NPs also exhibit anti-metastatic properties by inhibiting the migration and invasion of cancer cells through modulation of signaling pathways that affect cell adhesion and cytoskeletal dynamics. The efficacy of ZnO-NPs in overcoming chemotherapy resistance has been demonstrated by their ability to reduce the IC50 values of chemotherapeutic agents, making cancer cells more susceptible to drug-induced cell death. In this review, we summarize the mechanisms by which ZnO-NPs exert anticancer effects in GI cancers, focusing on apoptosis, cell cycle regulation, and metastasis inhibition, while also highlighting the current limitations in translating these findings into effective clinical treatments.

A critical review on printed electronics and its application

In light of the industry's environmental constraints, sustainable manufacturing technology has emerged as a critical goal for emerging applications. Due to the increased need for electronic production around the world, the requirement for environmentally safe technology is the necessity of this decade as the world government shifts towards sustainability in all manufacturing technology. Henceforth, printed electronics will be one such solution to regulate the electronic device and components production requirement of this decade. The article has discussed about the recent advances in inkjet-printed electronics across a wide range of electronics applications. We have discussed several inkjet printing inks and their formulation methods, which are required for minimizing environmental waste. In addition, we have discussed the future scope of printed electronics production and its impact on the economy as well as the environment.

"Harnessing green synthesized zinc oxide nanoparticles for dual action in wound management: Antibiotic delivery and healing Promotion"

Wound infections are characterized by the invasion of microorganisms into bodily tissues, leading to inflammation and potentially affecting any type of wound, including surgical incisions and chronic ulcers. If left untreated, they can delay recovery and cause tissue damage. Healthcare providers face challenges in treating these infections, which necessitate efficient treatment plans involving microbiological testing and clinical evaluation. The effectiveness of conventional treatments like antibiotics is limited by resistance. Various forms of nanotechnology have been developed, each exhibiting unique properties that address particular issues with conventional therapies. Among all the Nanocarriers, zinc oxide nanoparticles (ZnO NPs), offer promising treatments for persistent wound infections. ZnO NPs possess strong antibacterial, antioxidant, anti-inflammatory, and anti-diabetic properties, making them suitable for wound care applications. These nanoparticles can be produced economically and environmentally using green synthesis techniques that minimize toxicity and are biocompatible. While chemical and physical techniques offer precise control over nanoparticle characteristics, they often involve hazardous substances and energy-intensive procedures. The antibacterial qualities, low toxicity, and biological compatibility of green-synthesized ZnO NPs make them a promising treatment for wound infections. Their use in scaffolds, drug delivery systems, and wound dressings provides a viable approach to combat antibiotic resistance and enhance wound treatment outcomes. Furthermore research is necessary to fully realize the benefits of ZnO NPs in clinical practice.

In Vitro and In Vivo Evaluation of Electrospun PVA Nanofiber Containing ZnO/Curcumin for Wound Healing Application

The development of biocompatible wound dressings containing therapeutic agents to accelerate wound healing is an interesting field of study in biomedical sciences. Polyvinyl alcohol (PVA) nanofibers were loaded with zinc oxide nanoparticles (ZnO NPs) and curcumin (Cur) through electrospinning. The dressings were characterized by SEM and XRD and FTIR. The antioxidant, antibacterial, and cytotoxic activities Cur/ZnO/PVA nano dressing were evaluated using DPPH radical scavenging assay, disc diffusion method, and MTT assay, respectively. Cur/ZnO/PVA nano dressing showed sustained Cur release about 19.7% and 61.1% after 8h and 168h, respectively. Cur/ZnO NPs/PVA mixture had higher antioxidant potential than PVA, ZnO NPs, and Cur. The dressing showed a good antibacterial effect. The in vivo wound healing effect of different types of prepared dressings, including PVA, Cur/PVA, Cur/ZnO/PVA, and ZnO/ PVA nanofibers, was also investigated. PVA dressing containing Cur/ZnO NPs resulted in the highest increase of wound contraction in rats. The assembly of Cur and ZnO NPs on PVA nanofibers could propose as an effective delivery method to improve the wound healing process. The investigated wound dressing could be commercialized and used on a large scale after proper further studies, including clinical trials.

Emerging ZnO Semiconductors for Photocatalytic CO2 Reduction to Methanol

Carbon recycling is poised to emerge as a prominent trend for mitigating severe climate change and meeting the rising demand for energy. Converting carbon dioxide (CO2) into green energy and valuable feedstocks through photocatalytic CO2 reduction (PCCR) offers a promising solution to global warming and energy needs. Among all semiconductors, zinc oxide (ZnO) has garnered considerable interest due to its ecofriendly nature, biocompatibility, abundance, exceptional semiconducting and optical properties, cost-effectiveness, easy synthesis, and durability. This review thoroughly discusses recent advances in mechanistic insights, fundamental principles, experimental parameters, and modulation of ZnO catalysts for direct PCCR to C1 products (methanol). Various ZnO modification techniques are explored, including atomic size regulation, synthesis strategies, morphology manipulation, doping with cocatalysts, defect engineering, incorporation of plasmonic metals, and single atom modulation to boost its photocatalytic performance. Additionally, the review highlights the importance of photoreactor design, reactor types, geometries, operating modes, and phases. Future research endeavors should prioritize the development of cost-effective catalyst immobilization methods for solid-liquid separation and catalyst recycling, while emphasizing the use of abundant and non-toxic materials to ensure environmental sustainability and economic viability. Finally, the review outlines key challenges and proposes novel directions for further enhancing ZnO-based photocatalytic CO2 conversion processes.

Roadmap on magnetic nanoparticles in nanomedicine

Magnetic nanoparticles (MNPs) represent a class of small particles typically with diameters ranging from 1 to 100 nanometers. These nanoparticles are composed of magnetic materials such as iron, cobalt, nickel, or their alloys. The nanoscale size of MNPs gives them unique physicochemical (physical and chemical) properties not found in their bulk counterparts. Their versatile nature and unique magnetic behavior make them valuable in a wide range of scientific, medical, and technological fields. Over the past decade, there has been a significant surge in MNP-based applications spanning biomedical uses, environmental remediation, data storage, energy storage, and catalysis. Given their magnetic nature and small size, MNPs can be manipulated and guided using external magnetic fields. This characteristic is harnessed in biomedical applications, where these nanoparticles can be directed to specific targets in the body for imaging, drug delivery, or hyperthermia treatment. Herein, this roadmap offers an overview of the current status, challenges, and advancements in various facets of MNPs. It covers magnetic properties, synthesis, functionalization, characterization, and biomedical applications such as sample enrichment, bioassays, imaging, hyperthermia, neuromodulation, tissue engineering, and drug/gene delivery. However, as MNPs are increasingly explored forin vivoapplications, concerns have emerged regarding their cytotoxicity, cellular uptake, and degradation, prompting attention from both researchers and clinicians. This roadmap aims to provide a comprehensive perspective on the evolving landscape of MNP research.

Enhanced bactericidal, antibiofilm and antioxidative response of Lawsonia inermis leaf extract synthesized ZnO NPs loaded with commercial antibiotic

Globally, antibiotic resistance is a challenging issue in healthcare sector. The emergence of multiple drug-resistant bacteria has forced us to modify existing medicines and or formulate newer medicines that are effective and inexpensive. In this perspective, this study involves the formation of zinc oxide nanoparticles (ZnO NPs) by utilizing the Lawsonia inermis (Li) leaf extract. The prepared L. inermis leaf extract mediated ZnO NPs (Li-ZnO NPs) were bio-physically characterized. The antibacterial and radical scavenging effects of Li-ZnO NPs were evaluated. In addition, ZnO NPs were conjugated with standard antibiotic (ciprofloxacin) and its drug loading efficiency, drug release and antibacterial efficacy were tested and compared with non-drug loaded ZnO NPs. An absorbance peak at 340 nm was noted for Li-ZnO NPs. After conjugation with the drug, two absorbance peaks- one at 242 nm characteristic of ciprofloxacin and the other at 350 nm characteristics of ZnO NPs were observed. The crystallite size was 18.7 nm as determined by XRD. The antibacterial effect was higher on Gram-positive (S. aureus and S. pyogenes) than the Gram-negative pathogens (E. coli and K. pneumoniae). Inhibition of S. aureus and S. pyogenes biofilm at 100 μg mL-1were, respectively, 97.5 and 92.6%. H2O2 free radicals was inhibited to 90% compared to the standard ascorbic acid at 100 μg mL-1. After drug loading, the FTIR spectrum confirmed the existence of ciprofloxacin peaks at 965 cm-1 and Zn-O bond at 492 cm-1. The drug loading capacity of 15 nm sized ZnO NPs was higher (58, 75, 90 and 95% at 1, 2.5, 5 and 10% drug concentrations, respectively) compared to 20 nm. Similarly, the percentage of drug (ciprofloxacin) released from 15 nm ZnO NPs were increased to 90% at 10% drug-loaded samples, respectively. Also, the antibiotic loaded ZnO NPs had significant antibacterial effects against tested bacteria compared to Li-ZnO NPs and ciprofloxacin alone. This revealed that the antibiotic loaded ZnO NPs offer a sustainable route to treat multi-drug-resistant bacterial infections.

Metallic nanoparticles and photosynthesis organisms: Comprehensive review from the ecological perspective

This review presents a comprehensive analysis of the ecological implications of metallic nanoparticles (MNPs) on photosynthetic organisms, particularly plants and algae. We delve into the toxicological impacts of various MNPs, including gold, silver, copper-based, zinc oxide, and titanium dioxide nanoparticles, elucidating their effects on the growth and health of these organisms. The article also summarizes the toxicity mechanisms of these nanoparticles in plants and algae from previous research, providing insight into the cellular and molecular interactions that underpin these effects. Furthermore, it discusses the reciprocal interactions between different types of MNPs, their combined effects with other metal contaminants, and compares the toxicity between MNPs with their counterpart. This review highlights the urgent need for a deeper understanding of the environmental impact, considering their escalating use and the potential risks they pose to ecological systems, especially in the context of photosynthetic organisms that are vital to ecosystem health and stability.

Modeling of gas sensor based on zinc oxide thin films by feedback loop using operational amplifier

Nanostructured Zincoxide thin-film is widely used as a sensing material because of its tunable surface microstructure and wide optical bandgap but synthesizing a film with desired value of resistance and reproducibility of film is challenging, particularly by chemical method. In this work, we showed how a ZnO film of arbitrary resistance can be used as a sensor without application of heat using operational amplifier. Zinc oxide thin film was synthesized by using the Sol-gel method (Spin coating) and was characterized by XRD and SEM which revealed wurtzite polycrystalline nature of Zinc oxide film with average grain size 17-25 nm. In this report, we designed a noble electronic circuit capable of detecting analyte gas molecule even if very small change in film resistance occurs due to the influence of gas molecule. In recently available sensors, the quality of the film degrades over time due to repeated heating and cooling, resulting in a reduced lifetime for the sensor. To address this issue and achieve higher sensitivity, as well as to fabricate an affordable, portable, precise, energy-efficient and durable device, this electronic model offers advantages over classical temperature-dependent sensors.

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.

Recent Advances, Challenges, and Future Perspectives of ZnO Nanostructure Materials Towards Energy Applications

In this approach, zinc oxide (ZnO) is a multipurpose substance with remarkable characteristics such as high sensitivity, a large specific area, non-toxicity, excellent compatibility, and a high isoelectric point, which make it attractive for discussion with some limitations. It is the most favorable possible option for the collection of nanostructures in terms of structure and their characteristics. The development of numerous ZnO nanostructure-based electrochemical sensors and biosensors used in health diagnosis, pharmaceutical evaluation, food hygiene, and contamination of the environment monitoring is described, as well as the production of ZnO nanostructures. Nanostructured ZnO has good chemical and temperature durability as an n-type semiconducting material, making it useful in a wide range of uses, from luminous materials to supercapacitors, batteries, solar cells, photocatalysis, biosensors, medicinal devices, and more. When compared to the bulk materials, the nanosized materials have both a higher rate of disintegration and a higher solubility. Furthermore, ZnO nanoparticles are regarded as top contenders for electrochemical sensors due to their strong electrochemical behaviors and electron transmission characteristics. The impact of many factors, including selectivity, sensitivity, detection limit, strength, and structures, arrangements, and their respective functioning processes, has been investigated. This study concentrated a substantial amount of its attention on the recent advancements that have been made in ZnO-based nanoparticles, composites, and modified materials for use in the application areas of energy storage and conversion devices as well as biological applications. Supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, medicinal, and biological systems have been studied. ZnO-based materials are constantly analyzed for their advantages in energy and life science applications.

Immobilization of Aspergillus oryzae tyrosine hydroxylase on ZnO nanocrystals for improved stability and catalytic efficiency towards L-dopa production

The current study focuses on the submerged fermentation of tyrosine hydroxylase (TH) from Aspergillus oryzae IIB-9 and its immobilization on zinc oxide nanocrystals (ZnO-NPs) for increased L-dopa production. The volume of Vogel's medium (75 ml), period of incubation (72 h), initial pH (5.5), and size of inoculum (1.5 ml) were optimal for maximum TH activity. The watch glass-dried (WG) and filter paper-dried (FP) ZnO-NPs were prepared and characterized using analytical techniques. The UV-Vis spectra revealed 295 and 285 nm absorption peaks for WG-ZnO-NPs and FP-ZnO-NPs dispersed in isopropanol. X-ray diffraction analysis confirmed the crystalline nature of ZnO-NPs. FTIR spectra band from 740 to 648.1/cm and 735.8/cm to 650.1/cm showed the stretching vibrations of WG-ZnO-NPs and FP-ZnO-NPs, respectively. The particle size of ZnO-NPs observed by scanning electron microscopy (SEM) images was between 130 and 170 nm. Furthermore, the stability of immobilized TH on ZnO-NPs was determined by varying the incubation period (10 min for WG-NPs and 15 min for FP-NPs) and temperature (45 °C and 30 °C for WG and FP-NPs, respectively). Incubating enzymes with various copper, iron, manganese, and zinc salts studied the catalytic efficiency of TH. Immobilization of TH on ZnO-NPs resulted in an 11.05-fold increase in TH activity, thus enhancing stability and catalytic efficiency.

Principles of Photocatalysts and Their Different Applications: A Review

Human existence and societal growth are both dependent on the availability of clean and fresh water. Photocatalysis is a type of artificial photosynthesis that uses environmentally friendly, long-lasting materials to address energy and environmental issues. There is currently a considerable demand for low-cost, high-performance wastewater treatment equipment. By changing the structure, size, and characteristics of nanomaterials, the use of nanotechnology in the field of water filtration has evolved dramatically. Semiconductor-assisted photocatalysis has recently advanced to become among the most promising techniques in the fields of sustainable energy generation and ecological cleanup. It is environmentally beneficial, cost-effective, and strictly linked to the zero waste discharge principle used in industrial effluent treatment. Owing to the reduction or removal of created unwanted byproducts, the green synthesis of photoactive nanomaterial is more beneficial than chemical synthesis approaches. Furthermore, unlike chemical synthesis methods, the green synthesis method does not require the use of expensive, dangerous, or poisonous ingredients, making it a less costly, easy, and environmental method for photocatalyst synthesis. This work focuses on distinct greener synthesis techniques utilized for the production of new photocatalysts, including metals, metal doped-metal oxides, metal oxides, and plasmonic nanostructures, including the application of artificial intelligence and machine learning to the design and selection of an innovative photocatalyst in the context of energy and environmental challenges. A brief overview of the industrial and environmental applications of photocatalysts is also presented. Finally, an overview and recommendations for future research are given to create photocatalytic systems with greatly improved stability and efficiency.

Synthesis of zinc oxide nanoparticles using methanol propolis extract (Pro-ZnO NPs) as antidiabetic and antioxidant

In recent times, the overall health of individuals has been declining due to unhealthy lifestyles, leading to various diseases, including diabetes. To address this issue, antidiabetic and antioxidant agents are required to back-up human well-being. Zinc oxide (ZnO) is one such substance known for its antidiabetic and antioxidant effects. To enhance its capability and effectiveness, propolis was utilized to synthesize zinc oxide nanoparticles (Pro-ZnO NPs). The objective of this study was to synthesize Pro-ZnO NPs and assess their performance by conducting inhibition assays against α-amylase and α-glucosidase enzymes, as well as a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The results showed that Pro-ZnO NPs were formed in a hexagonal wurtzite structure, with particle sizes ranging from 30 to 50 nm and an absorption band observed at 341 nm. The stability, chemical properties, and crystallography of Pro-ZnO NPs were also thoroughly examined using appropriate methods. The Pro-ZnO NPs demonstrated significant inhibitory effects against α-amylase and α-glucosidase enzymes, with inhibition rates reaching 69.52% and 73.78%, respectively, whereas the antioxidant activity was as high as 70.76%. Consequently, with their high inhibition rates, the Pro-ZnO NPs demonstrate the potential to be employed as a natural agent for combating diabetes and promoting antioxidant effects.

Organic and inorganic nanomaterials: fabrication, properties and applications

Nanomaterials and nanoparticles are a burgeoning field of research and a rapidly expanding technology sector in a wide variety of application domains. Nanomaterials have made exponential progress due to their numerous uses in a variety of fields, particularly the advancement of engineering technology. Nanoparticles are divided into various groups based on the size, shape, and structural morphology of their bodies. The 21st century's defining feature of nanoparticles is their application in the design and production of semiconductor devices made of metals, metal oxides, carbon allotropes, and chalcogenides. For the researchers, these materials then opened a new door to a variety of applications, including energy storage, catalysis, and biosensors, as well as devices for conversion and medicinal uses. For chemical and thermal applications, ZnO is one of the most stable n-type semiconducting materials available. It is utilised in a wide range of products, from luminous materials to batteries, supercapacitors, solar cells to biomedical photocatalysis sensors, and it may be found in a number of forms, including pellets, nanoparticles, bulk crystals, and thin films. The distinctive physiochemical characteristics of semiconducting metal oxides are particularly responsible for this. ZnO nanostructures differ depending on the synthesis conditions, growth method, growth process, and substrate type. A number of distinct growth strategies for ZnO nanostructures, including chemical, physical, and biological methods, have been recorded. These nanostructures may be synthesized very simply at very low temperatures. This review focuses on and summarizes recent achievements in fabricating semiconductor devices based on nanostructured materials as 2D materials as well as rapidly developing hybrid structures. Apart from this, challenges and promising prospects in this research field are also discussed.

Biogenic Zinc Oxide Nanoparticles and Their Biomedical Applications: A Review

Nanotechnology has inscribed novel perception into the material science and one of the most extensively used nanomaterials is Zinc oxide nanoparticles (ZnO NPs) with healthcare and biomedical applications. Because of its outstanding biocompatibility, low toxicity, and low cost, ZnO NPs have become one of the most prominent metal oxide NPs in biological applications. This review highlights the different aspects of ZnO NPs, like their green synthesis as a substitute of conventional route due to avoidance of threat of hazardous, costly precursors and subsequent mostly therapeutic applications. Due to their wide bandwidth and high excitation binding energy, ZnO NPs have undergone extensive research. In addition to their potential applications as antibiotics, antioxidants, anti-diabetics, and cytotoxic agents, ZnO NPs also hold a promising future as an antiviral treatment for SARS-CoV-2. Zn has antiviral properties and may be effective against a variety of respiratory virus species, particularly SARS-CoV-2. This review includes a variety of topics, including the virus's structural properties, an overview of infection mechanism, and current COVID-19 treatments. Nanotechnology-based techniques for the prevention, diagnosis, and treatment of COVID-19 are also discussed in this review.

Physiochemical characterization of sodium doped zinc oxide nano powder for antimicrobial applications

Zinc oxide (ZnO) is one of the semiconductor materials with unique antimicrobial properties towards various microorganisms. In this article, pure and Na doped ZnO nanopowders were synthesized by easiest and cost-effective co-precipitation process. X-ray diffraction (XRD),Fourier transform infrared spectroscopy(FT-IR), ultraviolet - visible (UV - Vis) spectroscopy, scanning electron microscopy(SEM), and Energy dispersive X-ray analysis (EDAX) techniques were used to characterize the particle size, surface morphology and chemical composition of prepared materials. The XRD analysis revealed that the samples exhibiting hexagonal wurtzite crystal structure with high crystallinity and the average crystallite size values increased from 23.51 to 28.118 nm. The UV - Vis spectroscopy results exposed that the bandgap energy (E_g) of the samples with the values in the range of 3.068-3.301 eV. The SEM micrographs showed that the morphology of the of synthesized particles are hexagonal and spherical in nanometric size. The EDX spectra confirmed the elemental composition of Na, Zn and O in the crystal lattice and FTIR spectroscopic data proved the formation of functional groups and the presence of chemical bonding at the ZnO interface.Antibacterial activity of pure and Na doped Zinc oxide nanoparticles against Gram-negative pathogenssuch as Escherichia coli, Pseudomonas aeruginosa & Klebsiella pneumoniae and Gram-positive pathogens such as Staphylococcus aureus reveal that the zone of inhibition increases with increasing Na concentration. The antifungal activity against Aspergillus and Candida was investigated.These results demonstrated that the pure and Na doped ZnO samples exhibit enhanced antibacterial and antifungal activity with increasing particle sizein presence of visible light and they could be used as good antibacterial as well as antifungal agents.

Eliminating xenobiotics organic compounds from greywater through green synthetic nanoparticles

Xenobiotic Organic Compounds (XOCs) have been widely considered to be pollutant compounds due to their harmful impacts on aquatic life. However, there have been few rigorous studies of cutting-edge technology used to eradicate XOCs and their presence in bathroom greywater. The present review provides a comprehensive examination of current methodologies used for removing XOCs by photocatalysis of green nanoparticles. It was appeared that zinc oxide nanoparticles (ZnO NPs) have high efficiency (99%) in photocatalysis process. Green synthesis provides proven processes that do not require dangerous chemicals or expensive equipment, making photocatalysis a potential solution for the status quo. XOCs residue was decomposed, and pollutants were eliminated with varied degrees of efficiency using green synthesis ZnO nanoparticles. It is hypothesized that the utilization of photocatalysis can create a greywater treatment system capable of degrading the toxic XOCs in greywater while increasing the pace of production. Hence, this review will be beneficial in improving greywater quality and photocatalysis using green nanoparticles can be an immediate platform in solving the issue regarding the existence of XOCs in greywater in Malaysia. Researchers in the future may benefit from focusing on optimizing photocatalytic degradation using green-synthesis ZnO. It might also help with the creativity and productivity of the next generation of authoritative concerns, notably water conservation.

"Green"-synthesized zinc oxide nanoparticles and plant extracts: A comparison between synthesis processes and antihyperglycemic activity

Zinc oxide nanoparticles (ZnONPs) have shown antidiabetic activity in multiple studies and can be produced by different plant-mediated ("green") methods. This study aimed to compare ZnONPs prepared via different "green" approaches (heating at high temperatures (400 °C) vs. low temperature (70 °C)). The low temperature method involved addition of suspending agents (Tween 80 or gum arabic) and pH variations followed by lyophilization. The study evaluated the hypoglycemic potential of ZnONPs with the best properties (quantity of capped agents and stability) compared to the plant extract per se. The ZnONP synthesis involved a mixture of zinc nitrate hexahydrate as the zinc precursor and a plant extract with high antioxidant activity as the capping agent supplier. The results of the studies showed that the procedure using high-temperature heating resulted in almost uncapped nanoparticles with phytocompounds (0.01 % of phenolic compounds) and nanoparticle sizes larger than 300 nm. The low-temperature method produced ZnONPs with high retention of capping agents (92.90 % of phenolic compounds) and a size of approximately 200 nm. The use of Tween 80 with pH adjustment between 9 and 10 resulted in more stable nanoparticles than with gum arabic. These nanoparticles prepared with Tween 80, exhibited a pronounced in vivo antihyperglycemic activity at a much lower dose (10 mg ZnO/kg capped by 0.31 mg phenolic compounds per kg) than the extracts alone (400 mg extract/kg) following an oral glucose tolerance test. These results demonstrated that green-synthesized ZnONPs with a high retention rate of phytochemicals can induce antihyperglycemic effects at a low dose.

Stabilization of glutathione redox dynamics and CYP2E1 by green synthesized Moringa oleifera-mediated zinc oxide nanoparticles against acrylamide induced hepatotoxicity in rat model: Morphometric and molecular perspectives

The terrible reality is that acrylamide (AA) is a common food contaminant found in a wide variety of commonly consumed foods. This research involves the advancement of a more dependable technique for the bio-fabrication of zinc oxide nanoparticles (ZNPs) through the green method using Moringa Oleifera extract (MO-ZNPs) as an efficient chelating agent for acrylamide (AA). The effects of AA on glutathione redox dynamics, liver function, lipid profile, and zinc residues in Sprague Dawley rats are investigated. Finally, the microarchitecture and immunohistochemical staining of Caspase-3 and CYP2E1 were determined in the liver tissue of rats. Four separate groups, including control, MO-ZNPs (10 mg/kg b.wt), AA (20 mg/kg b.wt), and AA + MO-ZNPs for 60 days. The results revealed a suppressed activity of glutathione redox enzymes (GSH, GPX,and GSR) on both molecular and biochemical levels. Also, AA caused elevated liver enzymes, hepatosomatic index, and immunohistochemical staining of caspase-3 and CYP2E1 expression. MO-ZNPs co-treatment, on the other hand, stabilized glutathione-related enzyme gene expression, normalized hepatocellular enzyme levels, and restored hepatic tissue microarchitectures. It could be assumed that MO-ZNPs is a promising hepatoprotective molecule for alleviating AA-induced hepatotoxicity. We witnessed changes in glutathione redox dynamics to be restorative. Glutathione and cytochrome P450 2E1 play crucial roles in AA detoxification, so maintaining a healthy glutathione redox cycle is necessary for disposing of AA toxicity.

Biocosmetics: technological advances and future outlook

The paper provides an overview of biocosmetics, which has tremendous potential for growth and is attracting huge business opportunities. It emphasizes the immediate need to replace conventional fossil-based ingredients in cosmetics with natural, safe, and effective ingredients. It assembles recent technologies viable in the production/extraction of the bioactive ingredient, product development, and formulation processes, its rapid and smooth delivery to the target site, and fosters bio-based cosmetic packaging. It further explores industries that can be a trailblazer in supplying raw material for extraction of bio-based ingredients for cosmetics, creating biodegradable packaging, or weaving innovation in fashion clothing. Lastly, the paper discusses what it takes to become the first generation of a circular economy and supports the implementation of strict regulatory guidelines for any cosmetic sold globally.

Synthesis, Characterization, and Antibacterial Properties of ZnO Nanostructures Functionalized Flexible Carbon Fibers

BACKGROUND

Studies on the surface functionalization of flexible carbon fibers without any substrate by using cost-effective, fast, and practical processes that may provide antibacterial properties to carbon fiber have received great importance recently.

OBJECTIVE

The objective of this patent study is to obtain zinc oxide nanostructures functionalized carbon fibers by a facile, cheap, fast, and repeatable method, and to show their effective antibacterial activity.

METHODS

Electroplating and electrochemical anodization were used to synthesize zinc oxide nanostructures on carbon fiber surfaces, respectively, and their antibacterial properties were studied by zone inhibition test against Staphylococcus aureus and Pseudomonas aeruginosa.

RESULTS

The zinc oxide nanostructures on carbon fiber surfaces were successfully synthesized in minutes, and they exhibited effective antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa. The morphological properties of the nanocomposite were studied using scanning electron microscopy, which showed that ZnO on the CF surface exhibits a flake-like nanostructure. Fourier transform infrared spectrophotometer, x-ray diffraction spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy were used to analyze the composite's compositional, structural, crystallographic, and spectral characteristics. The results from all analyses were in a good agreement, indicating that the wurtzite crystalline ZnO nanostructure was successfully produced on the CF surface.

CONCLUSION

As a consequence, a method for the surface functionalization of carbon fiber using zinc oxide nanostructures has been developed that is feasible, low-cost, rapid, and repeatable. The flexible nanocomposite structure has a significant potential to be employed as a scaffold in sensor technology, wearable devices, and particularly in medical textiles due to its antibacterial and woven-able properties.

Structural growth of zinc oxide nanograins on carbon cloth as flexible electrochemical platform for hydroxychloroquine detection

Pharmaceutical pollution that imposes a health threat worldwide is making accurate and rapid detection crucial to prevent adverse effects. Herein, binder-free zinc oxide nanograins on carbon cloth (ZnO NGs@CC) have been synthesized hydrothermally and employed to fabricate a flexible electrochemical sensor for the quantification of hydroxychloroquine (HCQ) that is typical pharmaceutical pollution. The characteristics of ZnO NGs@CC were investigated by various in-depth electron microscopic, spectroscopic and electroanalytical approaches. Compared with the pristine CC platform, the ZnO NGs@CC platform exhibits superior electrochemical performance in detecting HCQ with a large oxidation current at a low over-potential of +0.92 V with respect to the Ag/AgCl (Sat. KCl) reference electrode. With the support of desirable characteristics, the fabricated ZnO NGs@CC-based electrochemical sensor for HCQ detection displays good performances in terms of wide sensing range (0.5-116 μM), low detection limit (0.09 μM), high sensitivity (0.279 μA μM^-1 cm^-2), and strong selectivity. By the resulting 3D hierarchical nanoarchitecture, ZnO NGs@CC has progressive structural advantages that led to its excellent electrochemical performance in sensing applications. Furthermore, the electrochemical sensor is employed to detect HCQ in biological and environmental samples and also achieves good recovery rates. Thus, the designed ZnO NGs@CC demonstrates admirable electrochemical activity toward HCQ real-time monitoring and would be an excellent electrochemical platform for HCQ sensing.

Bacillus sp. extract used to fabricate ZnO nanoparticles for their antagonist effect against phytopathogens

In order to achieve the food demand of a growing population, agricultural productivity needs to be increased by employing safe strategies. In the present study we have evaluated ZnONPs that were synthesized from the culture supernatant of Bacillus subtilis. Bio mimetically synthesized ZnONPs showed a surface resonance peak of 355 nm corresponding to NPs formation. Further, NPs were examined for their size, shape and element confirmation by DLS, AFM, SEM, TEM and EDAX, which confirmed the synthesized NPs were nearly spherical in size with average diameter of 32 nm by TEM. Surface charge of + 34.3 mV was observed for NPs with a low poly-dispersity index of 0.21. In vitro efficacy studies against fungi Colletotrichum capsici, Sclerotium rolfsii, Alternaria solani and Fusarium oxysporum f. sp. cicero showed up to 99% mycelial growth inhibition at 0.125% ZnONPs. Further, in-vitro disk-diffusion assay showed inhibition zones of 23 ± 0.4 mm and 12.67 ± 0.24 mm for Xanthomonas axonopodis pv. punicae (Xap) and Xanthomonas oryzae pv. oryzae (Xoo) bacterial cultures. Plant toxicity study was observed that ≤ 0.14% NPs concentration was safe under greenhouse conditions. Overall, the present study emphasizes the potential effect of ZnONPs against agricultural pathogens which play an important role in agriculture production.

Antibacterial activity of nano zinc oxide green-synthesised from Gardenia thailandica triveng. Leaves against Pseudomonas aeruginosa clinical isolates: in vitro and in vivo study

The increasing emergence of bacterial resistance is a challenge for the research community, thus novel antibacterial agents should be developed. Metal nanoparticles are promising antibacterial agents and could solve the problem of antibiotic resistance. Herein, we used Gardenia thailandica methanol extract (GTME) to biogenically synthesise zinc oxide nanoparticles (ZnO-NPs). The characterisation of ZnO-NPs was performed by UV spectroscopy, FTIR, scanning and transmission electron microscopes, dynamic light scattering, and X-ray diffraction. The antibacterial activity of ZnO-NPs was studied both in vitro and in vivo against Pseudomonas aeruginosa clinical isolates. Its minimum inhibitory concentration values ranged from 2 to 64 µg/mL, and it significantly decreased the membrane integrity and resulted in a significant increase in the inner and outer membrane permeability. Also, the ZnO-NPs treated cells possessed a distorted and deformed shape when examined by scanning electron microscope. The in vivo study (biochemical parameters and histological investigation) was conducted and it revealed a protective effect of ZnO-NPs against the deleterious influences of P. aeruginosa bacteria on lung, liver, and kidney tissues. LC-ESI-MS/MS revealed a phytochemical tentative identification of 57 compounds for the first time. We propose that GTME is a useful source for ZnO-NPs which has a promising antibacterial activity.

Sterilizable and Reusable UV-Resistant Graphene-Polyurethane Elastomer Composites

Shortages of personal protective equipment (PPE) at the start of the COVID-19 pandemic caused medical workers to reuse medical supplies such as N95 masks. While ultraviolet germicidal irradiation (UVGI) is commonly used for sterilization, UVGI can also damage the elastomeric components of N95 masks, preventing effective fit and thus weakening filtration efficacy. Although PPE shortage is no longer an acute issue, the development of sterilizable and reusable UV-resistant elastomers remains of high interest from a long-term sustainability and health perspective. Here, graphene nanosheets, produced by scalable and sustainable exfoliation of graphite in ethanol using the polymer ethyl cellulose (EC), are utilized as UV-resistant additives in polyurethane (PU) elastomer composites. By increasing the graphene/EC loading up to 1 wt %, substantial UV protection is imparted by the graphene nanosheets, which strongly absorb UV light and hence suppress photoinduced degradation of the PU matrix. Additionally, graphene/EC provides mechanical reinforcement, such as increasing Young's modulus, elongation at break, and toughness, with negligible changes following UV exposure. These graphene/EC-PU composites remain mechanically robust over at least 150 sterilization cycles, enabling safe reuse following UVGI. Beyond N95 masks, these UVGI-compatible graphene/EC-PU composites have potential utility in other PPE applications to address the broader issue of single-use waste.

Cow dung extract mediated green synthesis of zinc oxide nanoparticles for agricultural applications

In the present study, zinc oxide nanoparticles (ZnO) were synthesized using cow dung extract to apply sustainable agriculture from rural resources. Studies on their antibacterial potential against E. coli DH 5 alpha indicated lower antimicrobial activities than the bulk Zn and commercial Zn nanoparticles. Compared with control and commercial ZnO nanoparticles, the maximum seed germination, root length, and shoot length were observed after the priming of synthesized ZnO NPs. This study suggests that ZnO may significantly increase seed germination and have lower antimicrobial potential. Further, the lower in-vitro cellular leakage and reactive oxygen species (ROS) production provided new hope for using cow dung extract mediated nanoparticles for agricultural and industrial applications.

An Evaluation of the Biocatalyst for the Synthesis and Application of Zinc Oxide Nanoparticles for Water Remediation—A Review

Global water scarcity is threatening the lives of humans, and it is exacerbated by the contamination of water, which occurs because of increased industrialization and soaring population density. The available conventional physical and chemical water treatment techniques are hazardous to living organisms and are not environmentally friendly, as toxic chemical elements are used during these processes. Nanotechnology has presented a possible way in which to solve these issues by using unique materials with desirable properties. Zinc oxide nanoparticles (ZnO NPs) can be used effectively and efficiently for water treatment, along with other nanotechnologies. Owing to rising concerns regarding the environmental unfriendliness and toxicity of nanomaterials, ZnO NPs have recently been synthesized through biologically available and replenishable sources using a green chemistry or green synthesis protocol. The green-synthesized ZnO NPs are less toxic, more eco-friendly, and more biocompatible than other chemically and physically synthesized materials. In this article, the biogenic synthesis and characterization techniques of ZnO NPs using plants, bacteria, fungi, algae, and biological derivatives are reviewed and discussed. The applications of the biologically prepared ZnO NPs, when used for water treatment, are outlined. Additionally, their mechanisms of action, such as the photocatalytic degradation of dyes, the production of reactive oxygen species (ROS), the generation of compounds such as hydrogen peroxide and superoxide, Zn2+ release to degrade microbes, as well as their adsorbent properties with regard to heavy metals and other contaminants in water bodies, are explained. Furthermore, challenges facing the green synthesis of these nanomaterials are outlined. Future research should focus on how nanomaterials should reach the commercialization stage, and suggestions as to how this ought to be achieved are presented.

Screening of four accelerated synthesized techniques in green fabrication of ZnO nanoparticles using Willow leaf extract

Using hydro-alcoholic extract of Willow leaf, zinc oxide nanoparticles (ZnO NPs) were synthesized via four accelerated different heating methods namely, Bain-Marie heating (40 °C for 2 h), Conventional heating with stirrer (80 °C for 2 h), hydrothermal autoclave (1.5 atm and 121 °C for 15 min) and microwave irradiation (800 W and 160 °C for 3 min). Calcination process was finally completed on the obtained colloidal solutions in a furnace (350 °C for 2 h). The characteristics of the resulted ZnO NPs including particle size, grain size, crystallinity, specific surface area, morphology, photocatalytic, antioxidant bactericidal activities were estimated using X-ray diffractometry, scanning electron microscopy and Ultraviolet-visible spectroscopy techniques. Attained results indicated that among four different utilized synthetic methods, the fabricated ZnO NPs via Bain-Marie heating, had desired physico-chemical characteristics and bactericidal effect including small particle size (70 nm), high specific area (284 m2/gr), antioxidant activity (28.5%), photocatalytic activity (degradation of 50% of Methylene Blue), and bactericidal effects against Escherichia coli (clear zone diameter of 1.4 ± 0.1 cm) and Staphylococcus aureus (1.3 ± 0.1 cm).

Insights into the mapping of green synthesis conditions for ZnO nanoparticles and their toxicokinetics

Research on ZnO nanoparticles (NPs) has broad medical applications. However, the green synthesis of ZnO NPs involves a wide range of properties requiring optimization. ZnO NPs show toxicity at lower doses. This toxicity is a function of NP properties and pharmacokinetics. Moreover, NP toxicity and pharmacokinetics are affected by the species type and age of the animals tested. Physiologically based pharmacokinetic (PBPK) modeling offers a mechanistic platform to scrutinize the colligative effect of the interplay between these factors, which reduces the need for in vivo studies. This review provides a guide to choosing green synthesis conditions that result in minimal toxicity using a mechanistic tool, namely PBPK modeling.

Applicability of bio-synthesized nanoparticles in fungal secondary metabolites products and plant extracts for eliminating antibiotic-resistant bacteria risks in non-clinical environments

The abundance of antibiotic-resistant bacteria in the prawn pond effluents can substantially impact the natural environment. The settlement ponds, which are the most common treatment method for farms wastewater, might effectively reduce the suspended solids and organic matter. However, the method is insufficient for bacterial inactivation. The current paper seeks to highlight the environmental issue associated with the distribution of antibiotic resistant bacteria (ARB) from prawn farm wastewater and their impact on the microbial complex community in the surface water which receiving these wastes. The inactivation of antibiotic-resistant bacteria in prawn wastewater is strongly recommended because the presence of antibiotic-resistant bacteria in the environment causes water pollution and public health issues. The nanoparticles are more efficient for bacterial inactivation. They are widely accepted due to their high chemical and mechanical stability, broad spectrum of radiation absorption, high catalytic activity, and high antimicrobial activity. Many studies have examined the use of fungi or plants extract to synthesis zinc oxide nanoparticles (ZnO NPs). It is evident from recent papers in the literature that green synthesized ZnO NPs from microbes and plant extracts are non-toxic and effective. ZnO NPs inactivate the bacterial cells as a function for releasing reactive oxygen species (ROS) and zinc ions. The inactivation of antibiotic-resistant bacteria tends to be more than 90% which exhibit strong antimicrobial behavior against bacterial species.

Green Synthesized ZnO Nanoparticles as Biodiesel Blends and Their Effect on the Performance and Emission of Greenhouse Gases

Pollution and global warming are a few of the many reasons for environmental problems, due to industrial wastes and greenhouse gases, hence there are efforts to bring down such emissions to reduce pollution and combat global warming. In the present study, zinc oxide nanoparticles are green synthesized using cow dung as fuel, through combustion. Synthesized material was characterized by FTIR, XRD, UV, and FESEM. The as-prepared ZnO-GS NPs were employed as a transesterification catalyst for the preparation of biodiesel from discarded cooking oil. The biodiesel obtained is termed D-COME (discarded cooking oil methyl ester), which is blended with 20% commercial diesel (B20). Additionally, this blend, i.e., B20, is further blended with varying amounts of as-prepared ZnO-GS NPs, in order to ascertain its effects on the quality of emissions of various greenhouse gases such as hydrocarbons, CO_x, NO_x. Moreover, the brake thermal efficiency (BTHE) and brake specific fuel consumption (BSFC) were studied for their blends. The blend (B20) with 30 mg of ZnO-GS, i.e., B20-30, displays the best performance and reduced emissions. Comparative studies revealed that the ZnO-GS NPs are as efficient as the ZnO-C NPs, indicating that the green synthetic approach employed does not affect the efficiency of the ZnO NPs.

ZnO Films from Thermal Oxidation of Zn Films: Effect of the Thickness of the Precursor Films on the Structural, Morphological, and Optical Properties of the Products

Zinc oxide (ZnO) films with different structural, morphological, and optical properties were obtained by (fixed) thermal oxidation of deposited metallic zinc (Zn) films. The main characteristics of the oxidized films are discussed in terms of the Zn film thickness. On-axis preferential crystallographic oriented growth of ZnO can be tuned based on the control of the thickness of the deposited Zn: c-axis (a-axis) for the thinnest (thicker) Zn film. The thicker ZnO film is rather a-textured, whereas the grains hosted by the ZnO films corresponding to the Zn films of intermediate thicknesses are more randomly oriented. For Zn films of ever-increasing thickness, a tendency towards the crystallization of larger ZnO nanocrystals holds, combined with a continuous increment on the surface roughness. In contrast, the fundamental bandgap of the resultant oxide-based films decreases with thickness. The roughness of the ZnO films is not directly measured. It is qualitatively described by the analysis of Zn-film micrographs obtained by Scanning Electron Microscopy and by the demonstration of strong optical scattering interactions present in the thicker ZnO films by their random lasing activity.

ZnO nanoparticles embedded silk fibroin-a piezoelectric composite for nanogenerator applications

This paper demonstrates a flexible nanogenerator (NG) using Silk-Zinc Oxide (ZnO) composite by exploiting the inherent piezoelectric properties of silk and ZnO. A direct precipitation method was employed to synthesize Zinc Oxide nanoparticles (NPs). Silk-ZnO composite film was then prepared by spin-coating the homogenous silk-ZnO solution. The composition and morphology of silk-ZnO composite were analyzed using various standard characterization procedures. The biocompatibility study of the composite film was also performed through cell viability testing. The utility of as prepared composites was demonstrated through the fabrication of piezoelectric nanogenerator. This hybrid nanogenerator was capable to generate a maximum open circuit voltage of 25 V (peak to peak value) in the bending state for a specific ZnO concentration. The output response of the nanogenerator exhibited a good correlation with the bending angle of the device. A peak outputpower density of 6.67 mW cm^-3was achieved from the nanogenerator. The fabricated prototype is efficient to light-up commercial red LEDs and to harvest energy from human body movement. The piezoelectric coefficient (d₃₃) of silk-ZnO composite film was also experimentally figured out.

Comparative evaluation on the toxic effect of silver (Ag) and zinc oxide (ZnO) nanoparticles on different trophic levels in aquatic ecosystems-A review

Silver (Ag) and zinc oxide (ZnO) are considered to be harmful nanoparticles (NPs) to the aquatic organisms as their intake causes toxic impacts to wildlife, through direct ingestion or by the transference along trophic levels. Over usage and ultimate disposal of metallic particles from the industries subsequently lead to pollution of the aquatic environment. Exposure of NPs in aquatic ecosystem alters biological and physicochemical parameters of the water and aquatic organisms and determine their potential ecotoxicological impacts. Prolonged exposure of aquatic organisms to these NPs results in differential bioaccumulation and distribution into internal organs like liver, kidney, gills, brain and muscle tissue. The contact of NPs to aquatic organisms induces various types of toxic traits including cytotoxicity, genotoxicity and epigeneticity. Taking this in consideration this present review focus on the comparative impact of ZnO and Ag nanoparticles towards both vertebrates and invertebrates in aquatic ecosystems.

Current advancements on the fabrication, modification, and industrial application of zinc oxide as photocatalyst in the removal of organic and inorganic contaminants in aquatic systems

Industrial wastewaters contain hazardous contaminants that pollute the environment and cause socioeconomic problems, thus demanding the employment of effective remediation procedures such as photocatalysis. Zinc oxide (ZnO) nanomaterials have emerged to be a promising photocatalyst for the removal of pollutants in wastewater owing to their excellent and attractive characteristics. The dynamic tunable features of ZnO allow a wide range of functionalization for enhanced photocatalytic efficiency. The current review summarizes the recent advances in the fabrication, modification, and industrial application of ZnO photocatalyst based on the analysis of the latest studies, including the following aspects: (1) overview on the properties, structures, and features of ZnO, (2) employment of dopants, heterojunction, and immobilization techniques for improved photodegradation performance, (3) applicability of suspended and immobilized photocatalytic systems, (4) application of ZnO hybrids for the removal of various types of hazardous pollutants from different wastewater sources in industries, and (5) potential of bio-inspired ZnO hybrid nanomaterials for photocatalytic applications using renewable and biodegradable resources for greener photocatalytic technologies. In addition, the knowledge gap in this field of work is also highlighted.

Biosynthesis and Characterizations of Silver Nanoparticles from Annona squamosa Leaf and Fruit Extracts for Size-Dependent Biomedical Applications

Green synthesis differs in the way that the plant produces chemicals that act as reducing and stabilizing agents, and by adopting this green synthesis, we have synthesized silver nanoparticles (AgNPs) from the leaf and fruit extracts of Annona squamosa (also known as Sharifa), where these extracts have played an important role as reducing and capping agents. The nanoparticles were synthesized as the consequence of a reduction that happened between plant extracts and the precursor solution. The prepared AgNPs were then characterized using scanning electron microscopy, UV-Visible spectroscopy, and X-ray diffraction to study their morphology, optical response, and crystallinity. A single distinctive absorption peak of colloidal AgNPs samples was observed at 430 nm and 410 nm for leaf and fruit extract samples, having an optical bandgap of 2.97 eV and 2.88 eV, respectively, with a spherical shape having a diameter in the range of 35–90 nm and 15–50 nm, respectively, whilst XRD studies supported the FCC cubic structure of the mediated AgNPs. These green synthesized AgNPs have a wide variety of uses, particularly in the biomedical domain, where they have the potential to treat numerous diseases and are reported to be efficient against antibacterial, anti-cancer, and anti-diabetic activities.

Multifunctional Eco-Friendly Synthesis of ZnO Nanoparticles in Biomedical Applications

This work describes an environmental-friendly preparation of ZnO nanoparticles using aqueous oat extract. The advanced electrochemical and optical features of green synthesized ZnONPs displayed excellent antibacterial activity and exhibited an important role in pharmaceutical determinations. The formation of nanoscale ZnO was confirmed using various spectroscopic and microscopic investigations. The formed nanoparticles were found to be around 100 nm. The as-prepared ZnONPs were monitored for their antibacterial potential against different bacterial strains. The inhibition zones for ZnONPs were found as Escherichia coli (16 mm), Pseudomonas aeruginosa (17 mm), Staphylococcus aureus (12 mm) and Bacillus subtilis (11 mm) using a 30-µg mL-1 sample concentration. In addition, ZnONPs exhibited significant antioxidant effects, from 58 to 67%, with an average IC50 value of 0.88 ± 0.03 scavenging activity and from 53 to 71% (IC50 value of 0.73 ± 0.05) versus the scavenging free radicals DPPH and ABTS, respectively. The photocatalytic potential of ZnONPs for Rhodamine B dye degradation under UV irradiation was calculated. The photodegradation process was carried out as a function of time-dependent and complete degradation (nearly 98%), with color removal after 120 min. Conclusively, the synthesized ZnONPs using oat biomass might provide a great promise in the future for biomedical applications.

Sustainable Green Nanotechnologies for Innovative Purifications of Water: Synthesis of the Nanoparticles from Renewable Sources

Polluting the natural water resources is a serious global issue, which is confirmed by the fact that today at least 2 billion people consume water from contaminated sources. The conventional wastewater treatment methods cannot effectively remove the persistent pollutants (e.g., drugs, organic dyes, pesticides) from the aqueous environment. Heterogeneous photocatalysis is a promising and sustainable alternative for water remediation. It is based on the interaction between light irradiation and the semiconductors (e.g., TiO₂, ZnO) as photocatalysts, but these compounds, unfortunately, have some disadvantages. Hence, great attention has been paid to the nanotechnology as a possible way of improvement. Nanomaterials have extraordinary properties; however, their conventional synthesis is often difficult and requires a significant amount of dangerous chemicals. This concise topical review gives recent updates and trends in development of sustainable and green pathways in the synthesis of nanomaterials, as well as in their application for water remediation. In our review we put emphasis on the eco-friendly, mostly plant extract-based materials. The importance of this topic, including this study as well, is proved by the growing number of publications since 2018. Due to the current serious environmental issues (e.g., global warming, shortage of pure and quality water), it is necessary for the traditional TiO₂ and ZnO semiconductors to be replaced with the harmless, non-toxic, and more powerful nanocomposites as photocatalysts. Not only because of their higher efficiency as compared to the bulk semiconductors, but also because of the presence of biomolecules that can add up to the pollutant removal efficiency, which has been already confirmed in many researches. However, despite the fact that the application of heterogeneous photocatalysis together with green nanotechnology is absolutely the future in water purification, there are some challenges which have to be overcome. The exact effects of the biomolecules obtained from plants in the synthesis of nanoparticles, as well as in the photocatalytic processes, are not exactly known and require further investigation. Furthermore, heterogeneous photocatalysis is a well-known and commonly examined process; however, its practical use outside the laboratory is expensive and difficult. Thus, it has to be simplified and improved in order to be available for everyone. The aim of our review is to suggest and prove that using these bio-inspired compounds it is possible to reduce human footprint in the nature.

ZnO Semiconductor Nanoparticles and Their Application in Photocatalytic Degradation of Various Organic Dyes

The biosynthesis of oxide semiconductor nanoparticles (NPs) using materials found in nature opens a wide field of study focused on sustainability and environmental protection. Biosynthesized NPs have the capacity to eliminate organic dyes, which pollute water and cause severe damage to the environment. In the present work, the green synthesis of zinc oxide (ZnO) NPs was carried out using Capsicum annuum var. Anaheim extract. The photocatalytic elimination of methylene blue (MB), methyl orange (MO), and Rhodamine B (RhB) in UV radiation was evaluated. The materials were characterized by scanning and transmission electron microscopy (SEM and TEM) and SEM-coupled energy dispersive spectroscopy (EDS), attenuated total reflectance-infrared (ATR-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Photoluminescence (PL), and ultraviolet-visible spectroscopy (UV-Vis). The TEM analysis showed the NPs have an average size of 40 nm and quasi-spherical shape. ATR-IR showed the ZnO NPs contained functional groups from the extract. The analysis through XRD indicated that the NPs have a hexagonal zincite crystal structure with an average crystallite size of approximately 17 nm. The photoluminescence spectrum (PL) presented an emission band at 402 nm. From the UV-Vis spectra and TAUC model, the band-gap value was found to be 2.93 eV. Finally, the photocatalytic assessment proved the ZnO NPs achieved 100% elimination of MB at 60 min exposure, and 85 and 92% degradation of MO and RhB, respectively, at 180 min. This indicates that ZnO NPs, in addition to using a friendly method for their synthesis, manage to have excellent photocatalytic activity in the degradation of various organic pollutants.

Combating Drug-Resistant Bacteria Using Photothermally Active Nanomaterials: A Perspective Review

Injudicious use of antibiotics has been the main driver of severe bacterial non-susceptibility to commonly available antibiotics (known as drug resistance or antimicrobial resistance), a global threat to human health and healthcare. There is an increase in the incidence and levels of resistance to antibacterial drugs not only in nosocomial settings but also in community ones. The drying pipeline of new and effective antibiotics has further worsened the situation and is leading to a potentially "post-antibiotic era." This requires novel and effective therapies and therapeutic agents for combating drug-resistant pathogenic microbes. Nanomaterials are emerging as potent antimicrobial agents with both bactericidal and potentiating effects reported against drug-resistant microbes. Among them, the photothermally active nanomaterials (PANs) are gaining attention for their broad-spectrum antibacterial potencies driven mainly by the photothermal effect, which is characterized by the conversion of absorbed photon energy into heat energy by the PANs. The current review capitalizes on the importance of using PANs as an effective approach for overcoming bacterial resistance to drugs. Various PANs leveraging broad-spectrum therapeutic antibacterial (both bactericidal and synergistic) potentials against drug-resistant pathogens have been discussed. The review also provides deeper mechanistic insights into the mechanisms of the action of PANs against a variety of drug-resistant pathogens with a critical evaluation of efflux pumps, cell membrane permeability, biofilm, and quorum sensing inhibition. We also discuss the use of PANs as drug carriers. This review also discusses possible cytotoxicities related to the therapeutic use of PANs and effective strategies to overcome this. Recent developments, success stories, challenges, and prospects are also presented.

Influence of Physical Dimension and Morphological-Dependent Antibacterial Characteristics of ZnO Nanoparticles Coated on Orthodontic NiTi Wires

White spot lesions (WSLs) are one of the adverse effects of fixed orthodontic treatments. They are the primary sign of caries, which means inhibiting this process by antibacterial agents will reverse the procedure. The current study tested the surface modification of nickel-titanium (NiTi) wires with ZnO nanoparticles (NPs), as antimicrobial agents. As the morphology of NPs is one of the most critical factors for their properties, the antibacterial properties of different morphologies of ZnO nanostructures coated on the NiTi wire were investigated. For the preparation of ZnO nanostructures, five coating methods, including chemical vapor deposition (CVD), chemical precipitation method, polymer composite coating, sol-gel synthesis, and electrospinning process, were used. The antibacterial activity of NPs was assessed against Streptococcus mutans by the colony counting method. The obtained results showed that all the samples had antibacterial effects. The antibacterial properties of ZnO NPs were significantly improved when the specific surface area of particles increased, by the ZnO nanocrystals prepared via the CVD coating method.

Detection and remediation of pollutants to maintain ecosustainability employing nanotechnology: A review

Environmental deterioration due to anthropogenic activities is a threat to sustainable, clean and green environment. Accumulation of hazardous chemicals pollutes soil, water and air and thus significantly affects all the ecosystems. This article highlight the challenges associated with various conventional techniques such as filtration, absorption, flocculation, coagulation, chromatographic and mass spectroscopic techniques. Environmental nanotechnology has provided an innovative frontier to combat the aforesaid issues of sustainable environment by reducing the non-requisite use of raw materials, electricity, excessive use of agrochemicals and release of industrial effluents into water bodies. Various nanotechnology based approaches including surface enhance scattering, surface plasmon resonance; and distinct types of nanoparticles like silver, silicon oxide and zinc oxide have contributed significantly in detection of environmental pollutants. Biosensing technology has also gained significant attention for detection and remediation of pollutants. Furthermore, nanoparticles of gold, ferric oxide and manganese oxide have been used for the on-site remediation of antibiotics, organic dyes, pesticides, and heavy metals. Recently, green nanomaterials have been given more attention to address toxicity issues of chemically synthesized nanomaterials. Hence, nanotechnology has provided a platform with tremendous applications to have sustainable environment for present as well as future generations. This review article will help to understand the fundamentals for achieving the goals of sustainable development, and healthy environment.

Recent Advances in Zinc Oxide Nanoparticles (ZnO NPs) for Cancer Diagnosis, Target Drug Delivery, and Treatment

Cancer is regarded as one of the most deadly and mirthless diseases and it develops due to the uncontrolled proliferation of cells. To date, varieties of traditional medications and chemotherapies have been utilized to fight tumors. However, their immense drawbacks, such as reduced bioavailability, insufficient supply, and significant adverse effects, make their use limited. Nanotechnology has evolved rapidly in recent years and offers a wide spectrum of applications in the healthcare sectors. Nanoscale materials offer strong potential for curing cancer as they pose low risk and fewer complications. Several metal oxide NPs are being developed to diagnose or treat malignancies, but zinc oxide nanoparticles (ZnO NPs) have remarkably demonstrated their potential in the diagnosis and treatment of various types of cancers due to their biocompatibility, biodegradability, and unique physico-chemical attributes. ZnO NPs showed cancer cell specific toxicity via generation of reactive oxygen species and destruction of mitochondrial membrane potential, which leads to the activation of caspase cascades followed by apoptosis of cancerous cells. ZnO NPs have also been used as an effective carrier for targeted and sustained delivery of various plant bioactive and chemotherapeutic anticancerous drugs into tumor cells. In this review, at first we have discussed the role of ZnO NPs in diagnosis and bio-imaging of cancer cells. Secondly, we have extensively reviewed the capability of ZnO NPs as carriers of anticancerous drugs for targeted drug delivery into tumor cells, with a special focus on surface functionalization, drug-loading mechanism, and stimuli-responsive controlled release of drugs. Finally, we have critically discussed the anticancerous activity of ZnO NPs on different types of cancers along with their mode of actions. Furthermore, this review also highlights the limitations and future prospects of ZnO NPs in cancer theranostic.