Comparative study of the cytotoxic and genotoxic potentials of zinc oxide and titanium dioxide nanoparticles

Antimicrobial hybrid coatings: A review on applications of nano ZnO based materials for biomedical applications

The extreme survivability of infectious microorganisms on various surfaces prompts for the risk of disease transmissions, posing a perilous concern for global health. Thus, the treatment of these pathogenic microorganisms using the nanomaterials functionalized with antimicrobial coatings reaps relevant scope in the ongoing trend of research. Driven by their admirable biocompatibility, cost-effectiveness, and minimal toxicity, ZnO nanoparticles (ZnO-NPs) based antimicrobial hybrid coatings have emerged as a robust material to prevent the growth of infectious microorganisms on various surfaces, which in turn boosted their applications in the area of biomedical sciences. In this context, the current review focuses on the synthesis of ZnO-NPs based hybrid coatings using different polymers and inorganic materials for effective utilization in biomedical domains including dentistry, orthopedics, implantable medical devices and wound healing. The synergistic effect of ZnO-NPs hybrids with remarkable antibacterial, antifungal and antiviral property has been discussed. Finally, we highlight the future potential of ZnO-NPs based antimicrobial hybrid coatings for potential clinical translation.

Nanomaterials in Agriculture: A Pathway to Enhanced Plant Growth and Abiotic Stress Resistance

Nanotechnology has emerged as a transformative field in agriculture, offering innovative solutions to enhance plant growth and resilience against abiotic stresses. This review explores the diverse applications of nanomaterials in agriculture, focusing on their role in promoting plant development and improving tolerance to drought, salinity, heavy metals, and temperature fluctuations. The method classifies nanomaterials commonly employed in plant sciences and examines their unique physicochemical properties that facilitate interactions with plants. Key mechanisms of nanomaterial uptake, transport, and influence on plants at the cellular and molecular levels are outlined, emphasizing their effects on nutrient absorption, photosynthetic efficiency, and overall biomass production. The molecular basis of stress tolerance is examined, highlighting nanomaterial-induced regulation of reactive oxygen species, antioxidant activity, gene expression, and hormonal balance. Furthermore, this review addresses the environmental and health implications of nanomaterials, emphasizing sustainable and eco-friendly approaches to mitigate potential risks. The integration of nanotechnology with precision agriculture and smart technologies promises to revolutionize agricultural practices. This review provides valuable insights into the future directions of nanomaterial R&D, paving the way for a more resilient and sustainable agricultural system.

Primary astrocytes as a cellular depot of polystyrene nanoparticles

The continuous increase in plastic production has resulted in increased generation of microplastic particles (MPs), and nanoplastic particles (NPs). Recent evidence suggests that nanoplastics may be a potent neurotoxin because they are able to freely cross the blood-brain barrier and enter the brain. Therefore, the cytotoxic effects of polystyrene nanoparticles (PS-NPs) on cellular systems of cerebral origin should be thoroughly investigated. The aim of the current study is to evaluate the cytotoxic potential of 25 nm PS-NPs on in vitro cultured cells such as primary astrocytes, neurons and their co-cultures established from the cerebral cortex of Wistar pups. The results show that PS-NPs are internalized in both neurons and astrocytes, inducing time- and concentration-dependent cytotoxic effects. However, quantification of fluorescence intensity indicates cell type-dependent differences in the efficiency of PS-NPs uptake. Astrocytes are several times more efficient at accumulating PS-NPs than neurons, and this is a phagocytosis-dependent process. Moreover, the high rate of PS-NPs internalization during prolonged exposure (72 h) promotes astroglial activation, as assessed by analysis of GFAP expression and immunocytochemical imaging. The results show that astroglia act as a cellular depot of PS-NPs to protect neurons. However, once the critical threshold is exceeded, astroglia become overactivated and can lose their protective functions. These results highlight the importance of further research on the mechanisms underlying nanoplastic-induced cellular toxicity, which may have implications for understanding the broader impact of plastic pollution on neurological functions.

Measurement of antibiotic removal efficiency of ZnO-WO3 nanocomposite and its validation through residual antimicrobial activity

Antibiotics are very effective for treatment of infections as well as they are persistent pharmaceutical compounds, and their elimination from the water resources proved to be a major concern. Amoxicillin (AMX), Azithromycin (AZT) and Ofloxacin (OFX) are the most commonly utilized antibiotics for the treatment of infections. Each of the three antibiotics was used for the antimicrobial resistance in the current study. The mixed oxides of ZnO-WO3 were synthesized by the precipitation method by doping 10 % WO3 nanoparticles in 90 % ZnO nanoparticles. The fabricated nanocomposites were characterized by using different techniques such as UV-Vis, XRD, FTIR, SEM and TEM and the photocatalytic activity has been measured in the presence of UV-light. Further the antimicrobial residual activity (AMR) was tested to confirm the degradation of antibiotics using E. coli and Staphyllococcus aureus bacteria respectively. The characterization study revealed the presence of Zn, O and W and confirms the shape of the particle is flaky and spheroidal. The prepared ZnO-WO3 nanocomposite has been utilized for the degradation of antibiotic residues of 10 mg l-1 concentration (AMX, AZT and OFX) with different catalyst concentrations of 10 %, 20 %, 30 % and 40 %. The catalyst concentration of 40 % showed effective degradation of AMX with 89 % efficiency. AZT and OFX showed best degradation at 30 % and 10 % catalyst concentration with 90 % and 98 % efficiency respectively. Further, the AMR has been tested by the disc diffusion method and it showed huge bacterial growth at 48hrs, it was revealed that there is no antibiotic residues are left as the bacterial growth increased in the samples treated with nanocomposite and there was no bacterial growth occurs in the untreated samples. It can be concluded that the after doping with WO3 the efficiency of ZnO increased and showed better degradation of antibiotics in comparison with ZnO nanoparticle.

Zinc Doped Akermanite: A Promising Biomaterial for Orthopedic Application with Enhanced Bioactivity, Mechanical Strength, and Bacterial Study

Incorporating zinc into biocompatible materials has been identified as a potential strategy for promoting bone regeneration and osteogenic activity during hard tissue regeneration. This work aimed to investigate the impact of zinc doping on the structure of akermanite, which was synthesized using the sol-gel combustion method, with the goal of improving the biological response. Powder XRD and FT-IR analysis confirmed the phase purity and the respective functional groups associated with Zn-doped akermanite. Further XPS analysis confirmed the presence of zinc with the respective binding energies in the akermanite matrix. According to the results obtained from the analysis, the apatite-forming ability of Zn-doped akermanite demonstrated enhanced apatite deposition on the surface of the pellet after 9 days of immersion in the SBF medium. The measured mechanical parameters, including compressive strength (140-189 MPa) and Young's modulus (2505-3599 MPa), fall within the range of human cortical bone. Antimicrobial results showed an improved inhibition rate of the doped ceramics compared to pure akermanite with an inhibition percentage of 87% even at lower concentrations. The hemocompatibility of the materials showed hemolysis of human blood cells within the acceptable range without exhibiting toxicity. Cytotoxicity results demonstrate the biocompatibility of the materials with the MG-63 cell line. Based on the results, akermanite doped with zinc at optimal concentrations was found to be compatible and nontoxic promoting it as a potential alternative for bone regeneration in orthopedic applications.

Titanium Dioxide Nanoparticles-Induced Genotoxic Effects in Mosquito Culex quinquefaciatus

Titanium dioxide (TiO2) nanoparticles are being extensively used in a wide range of industrial applications for producing a variety of different consumer products, including medicines and even food items. The consumption of these products is increasing at an alarming rate, and this results in the release of these nanoparticles in the environment, causing a threat to organisms thriving in aquatic as well as terrestrial ecosystems. That is why screening such materials for their genotoxic effects, if any, becomes essential. A toxicity assay was performed to determine the LD20 of these nanoparticles for the mosquito Culex quinquefaciatus by Probit analysis. Early fourth instar larvae were exposed to the selected dose of 50 µg/mL, which is Collapse

Key Words

• Culex quinquefaciatus
• LD20
• chromosomal aberrations
• genotoxic effect
• mitotic index
• titanium dioxide nanoparticles

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MESH Headings Collapse

Grants

• RSP2025R356 King Saud University

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Affiliation(s)

Aastha Saini Department of Zoology, Akal College of Basic Sciences, Eternal University, Baru Sahib, Sirmaur 173101, Himachal Pradesh, India;
Kanwaljit Kaur Ahluwalia Department of Zoology, Akal College of Basic Sciences, Eternal University, Baru Sahib, Sirmaur 173101, Himachal Pradesh, India;
Amrik Singh Ahluwalia Department of Botany, Akal College of Basic Sciences, Eternal University, Baru Sahib, Sirmaur 173101, Himachal Pradesh, India;
Neelam Thakur Department of Zoology, Akal College of Basic Sciences, Eternal University, Baru Sahib, Sirmaur 173101, Himachal Pradesh, India;
Puneet Negi Department of Physics, Akal College of Basic Sciences, Eternal University, Baru Sahib, Sirmaur 173101, Himachal Pradesh, India;
Abeer Hashem Botany and Microbiology Department, College of Science, King Saud University, P.O. Box. 2460, Riyadh 11451, Saudi Arabia;
Khalid F. Almutairi Plant Production Department, College of Food and Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia; (K.F.A.); (E.F.A.)
Elsayed Fathi Abd_Allah Plant Production Department, College of Food and Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia; (K.F.A.); (E.F.A.)

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Collaborators Collapse

A multi-technique analytical approach to support (eco)toxicological investigation of zinc oxide nanoparticles

Understanding the mechanism of toxicity of nanoparticles and their behavior in biological environments is crucial for designing materials with reduced side effects and improved performance. Among the factors influencing nanoparticle behavior in biological environments, the release and bioavailability of potentially toxic metal ions can alter equilibria and cause adverse effects. In this study, we applied two on-line Field-Flow Fractionation (FFF) strategies and compared the results with off-line benchmarking centrifugal ultrafiltration to assess a key descriptor, namely the solubility of zinc oxide (ZnO) nanoparticles. We found that, at the highest nanoparticle concentrations, the nanoparticle-ion ratio quickly reaches equilibrium, and the stability is not significantly affected by the separation technique. However, at lower concentrations, dynamic, non-equilibrium behavior occurs, and the results depend on the method used to separate the solid from the ionic fraction, where FFF yielded a more representative dissolution pattern. To support the (eco)toxicological profiling of the investigated nanoparticles, we generated experimental data on colloidal stability over typical (eco)toxicological assay durations. The Zeta Potential vs pH curves revealed two distinct scenarios typical of surfaces that have undergone significant modification, most likely due to pH-dependent dissolution and re-precipitation of surface groups. Finally, to enhance hazard assessment screening, we investigated ion-dependent toxicity and the effects of exposure to fresh water. Using an in vitro human skin model, we evaluated the cytotoxicity of fresh and aged ZnO nanoparticles (exposed for 72 h in M7), revealing time-dependent, dose-dependent, and nanoparticle-dependent cytotoxicity, with lower toxicity observed in the case of aged samples.

Toxicity of zinc oxide nanoparticles: Cellular and behavioural effects

Due to their extensive use, the release of zinc oxide nanoparticles (ZnO NP) into the environment is increasing and may lead to unintended risk to both human health and ecosystems. Access of ZnO NP to the brain has been demonstrated, so their potential toxicity on the nervous system is a matter of particular concern. Although evaluation of ZnO NP toxicity has been reported in several previous studies, the specific effects on the nervous system are not completely understood and, particularly, effects on genetic material and on organism behaviour are poorly addressed. We evaluated the potential toxic effects of ZnO NP in vitro and in vivo, and the role of zinc ions (Zn2+) in these effects. In vitro, the ability of ZnO NP to be internalized by A172 glial cells was verified, and the cytotoxic and genotoxic effects of ZnO NP or the released Zn2+ ions were addressed by means of vital dye exclusion and comet assay, respectively. In vivo, behavioural alterations were evaluated in zebrafish embryos using a total locomotion assay. ZnO NP induced decreases in viability of A172 cells after 24 h of exposure and genetic damage after 3 and 24 h. The involvement of the Zn2+ ions released from the NP in genotoxicity was confirmed. ZnO NP exposure also resulted in decreased locomotor activity of zebrafish embryos, with a clear role of released Zn2+ ions in this effect. These findings support the toxic potential of ZnO NP showing, for the first time, genetic effects on glial cells and proving the intervention of Zn2+ ions.

Potential effects of spirulina and date palm pollens on zinc oxide nanoparticles -induced hepatoxicity, oxidative stress, and inflammation in male albino rats

INTRODUCTION

The application of Zinc oxide nanoparticles (ZnO NPs) is substantially growing in industrial products. Therefore, humans are increasingly exposed to ZnO NPs daily due to their extensive range of applications, raising worries about their possible toxicity.

AIM

In this study, the ameliorative effects of raw Phoenix dactylifera L. (date palm) pollens (DPP) and Spirulina platensis (SP) independently against ZnO NPS-induced hepatoxicity in male albino rats were examined.

METHODS

Six groups (6/group) of adult male albino rats received oral treatment using distilled water (control), SP (1000 mg/kg b. wt.), DPP (100 mg/kg b. wt.), ZnO NPs (100 mg/kg b. wt.), ZnO NPs +SP, and ZnO NPs + DPP respectively for 15 days.

RESULTS

The results of the biochemical investigation indicated that the administration of ZnO NPs substantially upregulated (p < 0.05) transaminases, alkaline phosphatase, and bilirubin serum levels. Malondialdehyde and pro-inflammatory cytokine serum levels were also elevated after ZnO NPs administration. Simultaneously, the downregulated catalase and glutathione peroxidase serum activities were significantly suppressed in ZnO NPs treated rats. Moreover, exposure to ZnO NPs induced liver histopathological alterations. The administration of SP and DPP ameliorated the aforementioned effects caused by ZnO NPs. This result can be attributable to the downregulation of hepatic transaminases, alkaline phosphatase, and bilirubin in the serum and the antioxidation system's equilibration, thus alleviating the accumulation of reactive oxygen species.

CONCLUSION

SP and DPP are natural antioxidants with the potential to eliminate inflammation as well as oxidative damage caused by ZnO NPs in hepatic tissue.

Assessment of Genotoxicity of Zinc Oxide Nanoparticles Using Mosquito as Test Model

The widespread applications of ZnO NPs in the different areas of science, technology, medicine, agriculture, and commercial products have led to increased chances of their release into the environment. This created a growing public concern about the toxicological and environmental effects of the nanoparticles. The impact of these NPs on the genetic materials of living organisms is documented in some cultured cells and plants, but there are only a few studies regarding this aspect in animals. In view of this, the present work regarding the assessment of the genotoxicity of zinc oxide nanoparticles using the mosquito Culex quinquefaciatus has been taken up. Statistically significant chromosomal aberrations over the control are recorded after the exposure of the fourth instar larvae to a dose of less than LD20 for 24 h. In order to select this dose, LD20 of ZnO NPs for the mosquito is determined by Probit analysis. Lacto-aceto-orcein stained chromosomal preparations are made from gonads of adult treated and control mosquitoes. Both structural aberrations, such as chromosomal breaks, fragments, translocations, and terminal fusions, resulting in the formation of rings and clumped chromosomes, and numerical ones, including hypo- and hyper-aneuploidy at metaphases, bridges, and laggards at the anaphase stage are observed. The percentage frequency of abnormalities in the shape of sperm heads is also found to be statistically significant over the controls. Besides this, zinc oxide nanoparticles are also found to affect the reproductive potential and embryo development as egg rafts obtained from the genetic crosses of ZnO nanoparticle-treated virgin females and normal males are small in size with a far smaller number of eggs per raft. The percentage frequencies of dominant lethal mutations indicated by the frequency of unhatched eggs are also statistically significant (p < 0.05) over the control. The induction of abnormalities in all of the three short-term assays studied during the present piece of work indicates the genotoxic potential of ZnO NPs, which cannot be labeled absolutely safe, and this study pinpoints the need to develop strategies for the protection of the environment and living organisms thriving in it.

Biocompatibility Evaluation of TiO2, Fe3O4, and TiO2/Fe3O4 Nanomaterials: Insights into Potential Toxic Effects in Erythrocytes and HepG2 Cells

Nanomaterials such as titanium dioxide and magnetite are increasingly used in several fields, such as water remediation and agriculture. However, this has raised environmental concerns due to potential exposure to organisms like humans. Nanomaterials can cause adverse interactions depending on physicochemical characteristics, like size, morphology, and composition, when interacting with living beings. To ensure safe use and prevent the risk of exposure to nanomaterials, their biocompatibility must be assessed. In vitro cell cultures are beneficial for assessing nanomaterial-cell interactions due to their easy handling. The present study evaluated the biocompatibility of TiO2, Fe3O4, and TiO2/Fe3O4 nanomaterials thermally treated at 350 °C and 450 °C in erythrocytes and HepG2 cells. According to the hemolysis experiments, non-thermally treated NMs are toxic (>5% hemolysis), but their thermally treated counterparts do not present toxicity (<2%). This behavior indicates that the toxicity derives from some precursor (solvent or surfactant) used in the synthesis of the nanomaterials. All the thermally treated nanomaterials did not show hemolytic activity under different conditions, such as low-light exposure or the absence of blood plasma proteins. In contrast, non-thermally treated nanomaterials showed a high hemolytic behavior, which was reduced after the purification (washing and thermal treatment) of nanomaterials, indicating the presence of surfactant residue used during synthesis. An MTS cell viability assay shows that calcined nanomaterials do not reduce cell viability (>11%) during 24 h of exposure. On the other hand, a lactate dehydrogenase leakage assay resulted in a higher variability, indicating that several nanomaterials did not cause an increase in cell death as compared to the control. However, a holotomographic microscopy analysis reveals a high accumulation of nanomaterials in the cell structure at a low concentration (10 µg mL-1), altering cell morphology, which could lead to cell membrane damage and cell viability reduction.

Characterization, dose dependent assessment of hepatorenal oxidative stress, hematological parameters and histopathological divulging of the hepatic damages induced by Zinc oxide nanoparticles (ZnO-NPs) in adult male Sprague Dawley rats

Nanoparticles are beneficial in many aspects to human life but their excessive use can cause various abnormalities. They dispose in the environment through transport, industrial and agricultural usage and enter in living body through dermal, respiratory route or ingested with the lipsticks and there higher concentration produces toxicity. Therefore, current study characterized ZnO-NPs to evaluate toxic ability by X-rays diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques and showed 29.83 and 35 nm size, respectively with hexagonal crystalline structure. LC50 value of ZnO-NPs was also evaluated as 72.48 ± 10.33 mg/kg BW. Male Sprague Dawley (Post weaning) rats were divided into five groups with five rats in each group. Control (C) group received no treatment, placebo (S) group received normal saline (0.9% sodium chloride) intraperitoneally and three treated groups received different levels of ZnO- NPs intraperitoneally at the dose of either 10 or 20 or 30 mg/kg for 21 days on alternate days and named as 1G1, 1G2 and 1G3, respectively for the assessment of toxicity for better understanding of precautionary measures in future. Oxidative stress enzymes of liver and kidney, hepatorenal function enzymes and hematological parameters along with hepatic histology were measured at the end of the experiment. Results showed highly significant variations in all parameters in a dose dependent manner as compared to control group while groups receiving 10 or 20 mg/kg of ZnO-NPs showed low to moderate pathological changes in both organs. Liver histological analysis showed congestion, necrosis, hemorrhage, RBC's accumulations; inflammatory cells infiltration and severe abnormalities in high dose group while medium, low dose group showed moderate and least effects, respectively. It is concluded that ZnO-NPs are highly toxic at more concentration so their careful usage is needed in daily routine.

Cytotoxicity and hemolysis of rare earth ions and nanoscale/bulk oxides (La, Gd, and Yb): Interaction with lipid membranes and protein corona formation

The widespread application of rare earth elements (REEs) has raised concerns about their potential release into the environment and subsequent ingestion by humans. Therefore, it is essential to evaluate the cytotoxicity of REEs. Here, we investigated the interactions between three typical REEs (La, Gd, and Yb) ions as well as their nanometer/μm-sized oxides and red blood cells (RBCs), a plausible contact target for nanoparticles when they enter the bloodstream. Hemolysis of REEs at 50-2000 μmol L^-1 was examined to simulate their cytotoxicity under medical or occupational exposure. We found that the hemolysis due to the exposure of REEs was highly dependent on their concentration, and the cytotoxicity followed the order of La³⁺ > Gd³⁺ > Yb³⁺. The cytotoxicity of REE ions (REIs) is higher than REE oxides (REOs), while nanometer-sized REO caused more hemolysis than that μm-sized REO. The production of reactive oxygen species (ROS), ROS quenching experiment, as well as the detection of lipid peroxidation, confirmed that REEs causes cell membrane rupture by ROS-related chemical oxidation. In addition, we found that the formation of a protein corona on REEs increased the steric repulsion between REEs and cell membranes, hence mitigating the cytotoxicity of REEs. The theoretical simulation indicated the favorable interaction of REEs with phospholipids and proteins. Therefore, our findings provide a mechanistic explanation for the cytotoxicity of REEs to RBCs once they have entered the blood circulation system of organisms.

Nanomedicine for drug resistant pathogens and COVID-19 using mushroom nanocomposite inspired with bacteriocin – A Review

Multidrug resistant (MDR) pathogens have become a major global health challenge and have severely threatened the health of society. Current conditions have gotten worse as a result of the COVID-19 pandemic, and infection rates in the future will rise. It is necessary to design, respond effectively, and take action to address these challenges by investigating new avenues. In this regard, the fabrication of metal NPs utilized by various methods, including green synthesis using mushroom, is highly versatile, cost-effective, eco-compatible, and superior. In contrast, biofabrication of metal NPs can be employed as a powerful weapon against MDR pathogens and have immense biomedical applications. In addition, the advancement in nanotechnology has made possible to modify the nanomaterials and enhance their activities. Metal NPs with biomolecules composite to prevents their microbial adhesion and kills the microbial pathogens through biofilm formation. Bacteriocin is an excellent antimicrobial peptide that works well as an augmentation substance to boost the antimicrobial effects. As a result, we concentrate on the creation of new, eco-compatible mycosynthesized metal NPs with bacteriocin nanocomposite via electrostatic, covalent, or non-covalent bindings. The synergistic benefits of metal NPs with bacteriocin to combat MDR pathogens and COVID-19, as well as other biomedical applications, are discussed in this review. Moreover, the importance of the adverse outcome pathway (AOP) in risk analysis of manufactured metal nanocomposite nanomaterial and their future possibilities also discussed.

The role of quercetin in the formation of titanium dioxide nanoparticles for nanomedical applications

The current work aimed to synthesize and characterize titanium dioxide nanoparticles (TiO₂NPs) using quercetin (QE) and evaluate their biological activities, i.e., anti-hemolytic, anti-inflammatory, and cytotoxicity effects. The crystallographic phase and morphology of biosynthesized QE-TiO₂NPs were characterized by XRD (X-Ray Diffraction) and TEM/FE-SEM (Transmission/Field-Emission Scanning Electron Microscopy) micrographs. Functional groups involved in the synthesis process were determined by FTIR spectroscopy (Fourier Transform-Infrared Spectroscopy). Based on the characterization results, selected QE-TiO₂NPs showed a rutile phase, spherical shape, and a size range of 7.3-39 nm. The QE-TiO₂NPs did not show a hemolytic effect. They indicated 95.3% red blood cells (RBCs) membrane stabilization activity and 82.6% inhibition of bovine serum albumin (BSA) denaturation, similar to a standard drug, which proved their anti-inflammatory effects. The attained results from cytotoxicity studies revealed the toxic effects of QE-TiO₂NPs with IC50 values below 100 and 50 μg/mL for human breast cancer cells of MCF-7 and melanoma cancer cells of A375, respectively. These NPs did not significantly affect normal skin fibroblast cells up to 50 μg/mL and only showed a 16% inhibition rate on the cell viability at 100 μg/mL. These NPs also induced excessive ROS generation. This work established the blood/biocompatibility and excellent nanomedical applications of biosynthesized QE-TiO₂NPs.

Synthesis of Mixed-Phase TiO2-ZrO2 Nanocomposite for Photocatalytic Wastewater Treatment

The use of TiO₂ nanoparticles for photocatalysis for the degradation of organic dyes under UV light for wastewater treatment has been widely studied. However, the photocatalytic characteristics of TiO₂ nanoparticles are inadequate due to their UV light response and higher band gap. In this work, three nanoparticles were synthesized: (i) TiO₂ nanoparticle was synthesized by a sol-gel process. (ii) ZrO₂ was prepared using a solution combustion process and (iii) mixed-phase TiO₂-ZrO₂ nanoparticles were synthesized by a sol-gel process to remove Eosin Yellow (EY) from aqueous solutions in the wastewater. XRD, FTIR, UV-VIS, TEM, and XPS analysis methods were used to examine the properties of the synthesized products. The XRD investigation supported the tetragonal and monoclinic crystal structures of the TiO₂ and ZrO₂ nanoparticles. TEM studies identified that mixed-phase TiO₂-ZrO₂ nanoparticles have the same tetragonal structure as pure mixed-phase. The degradation of Eosin Yellow (EY) was examined using TiO₂, ZrO₂, and mixed-phase TiO₂-ZrO₂ nanoparticles under visible light. The results confirmed that the mixed-phase TiO₂-ZrO₂nanoparticles show a higher level of photocatalytic activity, and the process is accomplished at a high degradation rate in lesser time and at a lower power intensity.

Nano-Calcium Carbonate Affect the Respiratory and Function Through Inducing Oxidative Stress: A Cross-sectional Study Among Occupational Exposure of Workers and a Further Research for Underlying Mechanisms

OBJECTIVE

The aim of the study is to investigate whether nano-calcium carbonate (nano-CaCO 3 ) occupational exposure could induce adverse health effects in workers.

METHODS

A cross-sectional study was conducted in a nano-CaCO 3 manufacturing plant in China. Then, we have studied the dynamic distribution of nano-CaCO 3 in nude mice and examined the oxidative damage biomarkers of subchronic administrated nano-CaCO 3 on Sprague-Dawley rats.

RESULTS

The forced vital capacity (%) and the ratio of FEV1 to FVC is the rate of one second of workers were significantly decreased than unexposed individuals. Dynamic imaging in mice of fluorescence labeled nano-CaCO 3 showed relatively high uptake and slow washout in lung. Similar to population data, the decline in serum glutathione level and elevation in serum MDA were observed in nano-CaCO 3 -infected Sprague-Dawley rats.

CONCLUSIONS

We found that nano-CaCO 3 exposure may result in the poor pulmonary function in workers and lead to the changes of oxidative stress indexes.

The role of nanoparticles in plant biochemical, physiological, and molecular responses under drought stress: A review

Drought stress (DS) is a serious challenge for sustaining global crop production and food security. Nanoparticles (NPs) have emerged as an excellent tool to enhance crop production under current rapid climate change and increasing drought intensity. DS negatively affects plant growth, physiological and metabolic processes, and disturbs cellular membranes, nutrient and water uptake, photosynthetic apparatus, and antioxidant activities. The application of NPs protects the membranes, maintains water relationship, and enhances nutrient and water uptake, leading to an appreciable increase in plant growth under DS. NPs protect the photosynthetic apparatus and improve photosynthetic efficiency, accumulation of osmolytes, hormones, and phenolics, antioxidant activities, and gene expression, thus providing better resistance to plants against DS. In this review, we discuss the role of different metal-based NPs to mitigate DS in plants. We also highlighted various research gaps that should be filled in future research studies. This detailed review will be an excellent source of information for future researchers to adopt nanotechnology as an eco-friendly technique to improve drought tolerance.

Silica nanoparticles derived from Arundo donax L. ash composite with Titanium dioxide nanoparticles as an efficient nanocomposite for photocatalytic degradation dye

Water pollution is a serious problem that threatens both developed and developing countries. Several methods have been used to purify contaminated water, among which the photocatalytic decomposition approach is widely used to purify contaminated water from organic pollutants. In this work, biomass derived SiO₂ nanoparticles composite with TiO₂ semiconductors used as an efficient photocatalyst for degradation of RhB dye molecules under UV-visible light irradiation is proclaimed. The different weight percentages of Arundo donax L. ash-derived SiO₂ nanoparticles combined with TiO₂ nanoparticles were prepared through the wet impregnation method. The photocatalytic degradation ability of the as-prepared samples has been scrutinized against the degradation of Rh B dye in which the pronounced photocatalytic degradation efficiency 93.7% is successfully achieved on 50 wt % SiO₂-50 wt % TiO₂ nanocomposite photocatalyst. The catalytic performance of the nanocomposite decreases with an increase of 50%-75% in SiO₂ nanoparticles. There could have been a decrease in degradation efficiency due to an excess amount of SiO₂ covering TiO₂ nanoparticles, which prevented photons from reaching the nanoparticles. The efficiency of cyclic decomposition of the 50 wt% SiO₂-50 wt% TiO₂ composite showed only a slight change in photocatalytic capacity compared to the first cycle, which ensures the durability of the sample. However, the hydroxyl radical species play the main role in the degradation process, which has been confirmed by the scavenger test. The probable reaction mechanism is also deliberated in detail. The high photocatalytic performance of novel eco-friendly SiO₂-TiO₂ photocatalyst make it ideal for water purification applications.

Low-Temperature Highly Robust Hydrogen Sensor Using Pristine ZnO Nanorods with Enhanced Response and Selectivity

We report the hydrogen-sensing response on low-cost-solution-derived ZnO nanorods (NRs) on a glass substrate, integrated with aluminum as interdigitated electrodes (IDEs). The hydrothermally grown ZnO NRs on ZnO seed-layer-glass substrates are vertically aligned and highly textured along the c-axis (002 plane) with texture coefficient ∼2.3. An optimal hydrogen-sensing response of about 21.46% is observed for 150 ppm at 150 °C, which is higher than the responses at 100 and 50 °C, which are ∼12.98 and ∼10.36%, respectively. This can be attributed to the large surface area of ∼14.51 m²/g and pore volume of ∼0.013 cm³/g, associated with NRs and related defects, especially oxygen vacancies in pristine ZnO nanorods. The selective nature is investigated with different oxidizing and reducing gases like NO₂, CO, H₂S, and NH₃, showing relatively much lower ∼4.28, 3.42, 6.43, and 3.51% responses, respectively, at 50 °C for 50 ppm gas concentration. The impedance measurements also substantiate the same as the observed surface resistance is initially more than bulk, which reduces after introducing the hydrogen gas during sensing measurements. The humidity does not show any significant change in the hydrogen response, which is ∼20.5 ± 1.5% for a large humidity range (from 10 to 65%). More interestingly, the devices are robust against sensing response, showing no significant change after 10 months or even more.

Mitochondrial Dysfunction Induced by Zinc Oxide Nanoparticles

The constant evolution and applications of metallic nanoparticles (NPs) make living organisms more susceptible to being exposed to them. Among the most used are zinc oxide nanoparticles (ZnO-NPs). Therefore, understanding the molecular effects of ZnO-NPs in biological systems is extremely important. This review compiles the main mechanisms that induce cell toxicity by exposure to ZnO-NPs and reported in vitro research models, with special attention to mitochondrial damage. Scientific evidence indicates that in vitro ZnO-NPs have a cytotoxic effect that depends on the size, shape and method of synthesis of ZnO-NPs, as well as the function of the cells to which they are exposed. ZnO-NPs come into contact with the extracellular region, leading to an increase in intracellular [Zn2+] levels. The mechanism by which intracellular ZnO-NPs come into contact with organelles such as mitochondria is still unclear. The mitochondrion is a unique organelle considered the “power station” in the cells, participates in numerous cellular processes, such as cell survival/death, multiple biochemical and metabolic processes, and holds genetic material. ZnO-NPs increase intracellular levels of reactive oxygen species (ROS) and, in particular, superoxide levels; they also decrease mitochondrial membrane potential (MMP), which affects membrane permeability and leads to cell death. ZnO-NPs also induced cell death through caspases, which involve the intrinsic apoptotic pathway. The expression of pro-apoptotic genes after exposure to ZnO-NPs can be affected by multiple factors, including the size and morphology of the NPs, the type of cell exposed (healthy or tumor), stage of development (embryonic or differentiated), energy demand, exposure time and, no less relevant, the dose. To prevent the release of pro-apoptotic proteins, the damaged mitochondrion is eliminated by mitophagy. To replace those mitochondria that underwent mitophagy, the processes of mitochondrial biogenesis ensure the maintenance of adequate levels of ATP and cellular homeostasis.

Nano-priming as emerging seed priming technology for sustainable agriculture-recent developments and future perspectives

Nano-priming is an innovative seed priming technology that helps to improve seed germination, seed growth, and yield by providing resistance to various stresses in plants. Nano-priming is a considerably more effective method compared to all other seed priming methods. The salient features of nanoparticles (NPs) in seed priming are to develop electron exchange and enhanced surface reaction capabilities associated with various components of plant cells and tissues. Nano-priming induces the formation of nanopores in shoot and helps in the uptake of water absorption, activates reactive oxygen species (ROS)/antioxidant mechanisms in seeds, and forms hydroxyl radicals to loosen the walls of the cells and acts as an inducer for rapid hydrolysis of starch. It also induces the expression of aquaporin genes that are involved in the intake of water and also mediates H2O2, or ROS, dispersed over biological membranes. Nano-priming induces starch degradation via the stimulation of amylase, which results in the stimulation of seed germination. Nano-priming induces a mild ROS that acts as a primary signaling cue for various signaling cascade events that participate in secondary metabolite production and stress tolerance. This review provides details on the possible mechanisms by which nano-priming induces breaking seed dormancy, promotion of seed germination, and their impact on primary and secondary metabolite production. In addition, the use of nano-based fertilizer and pesticides as effective materials in nano-priming and plant growth development were also discussed, considering their recent status and future perspectives.

Glassy-like Metal Oxide Particles Embedded on Micrometer Thicker Alginate Films as Promising Wound Healing Nanomaterials

Micrometer-thicker, biologically responsive nanocomposite films were prepared starting from alginate-metal alkoxide colloidal solution followed by sol-gel chemistry and solvent removal through evaporation-induced assembly. The disclosed approach is straightforward and highly versatile, allowing the entrapment and growth of a set of glassy-like metal oxide within the network of alginate and their shaping as crake-free transparent and flexible films. Immersing these films in aqueous medium triggers alginate solubilization, and affords water-soluble metal oxides wrapped in a biocompatible carbohydrate framework. Biological activity of the nano-composites films was also studied including their hemolytic activity, methemoglobin, prothrombin, and thrombine time. The effect of the films on fibroblasts and keratinocytes of human skin was also investigated with a special emphasis on the role played by the incorporated metal oxide. This comparative study sheds light on the crucial biological response of the ceramic phase embedded inside of the films, with titanium dioxide being the most promising for wound healing purposes.

Exploring the Journey of Zinc Oxide Nanoparticles (ZnO-NPs) toward Biomedical Applications

The field of nanotechnology is concerned with the creation and application of materials having a nanoscale spatial dimensioning. Having a considerable surface area to volume ratio, nanoparticles have particularly unique properties. Several chemical and physical strategies have been used to prepare zinc oxide nanoparticles (ZnO-NPs). Still, biological methods using green or natural routes in various underlying substances (e.g., plant extracts, enzymes, and microorganisms) can be more environmentally friendly and cost-effective than chemical and/or physical methods in the long run. ZnO-NPs are now being studied as antibacterial agents in nanoscale and microscale formulations. The purpose of this study is to analyze the prevalent traditional method of generating ZnO-NPs, as well as its harmful side effects, and how it might be addressed utilizing an eco-friendly green approach. The study's primary focus is on the potential biomedical applications of green synthesized ZnO-NPs. Biocompatibility and biomedical qualities have been improved in green-synthesized ZnO-NPs over their traditionally produced counterparts, making them excellent antibacterial and cancer-fighting drugs. Additionally, these ZnO-NPs are beneficial when combined with the healing processes of wounds and biosensing components to trace small portions of biomarkers linked with various disorders. It has also been discovered that ZnO-NPs can distribute and sense drugs. Green-synthesized ZnO-NPs are compared to traditionally synthesized ones in this review, which shows that they have outstanding potential as a potent biological agent, as well as related hazardous properties.

Assessing Genotoxicity of Ten Different Engineered Nanomaterials by the Novel Semi-Automated FADU Assay and the Alkaline Comet Assay

Increased engineered nanomaterial (ENM) production and incorporation in consumer and biomedical products has raised concerns about the potential adverse effects. The DNA damaging capacity is of particular importance since damaged genetic material can lead to carcinogenesis. Consequently, reliable and robust in vitro studies assessing ENM genotoxicity are of great value. We utilized two complementary assays based on different measurement principles: (1) comet assay and (2) FADU (fluorimetric detection of alkaline DNA unwinding) assay. Assessing cell viability ruled out false-positive results due to DNA fragmentation during cell death. Potential structure-activity relationships of 10 ENMs were investigated: three silica nanoparticles (SiO2-NP) with varying degrees of porosity, titanium dioxide (TiO2-NP), polystyrene (PS-NP), zinc oxide (ZnO-NP), gold (Au-NP), graphene oxide (GO) and two multi-walled carbon nanotubes (MWNT). SiO2-NPs, TiO2-NP and GO were neither cytotoxic nor genotoxic to Jurkat E6-I cells. Quantitative interference corrections derived from GO results can make the FADU assay a promising screening tool for a variety of ENMs. MWNT merely induced cytotoxicity, while dose- and time-dependent cytotoxicity of PS-NP was accompanied by DNA fragmentation. Hence, PS-NP served to benchmark threshold levels of cytotoxicity at which DNA fragmentation was expected. Considering all controls revealed the true genotoxicity for Au-NP and ZnO-NP at early time points.

Immunotoxicity of nanomaterials in health and disease: Current challenges and emerging approaches for identifying immune modifiers in susceptible populations

Nanosafety assessment has experienced an intense era of research during the past decades driven by a vivid interest of regulators, industry, and society. Toxicological assays based on in vitro cellular models have undergone an evolution from experimentation using nanoparticulate systems on singular epithelial cell models to employing advanced complex models more realistically mimicking the respective body barriers for analyzing their capacity to alter the immune state of exposed individuals. During this phase, a number of lessons were learned. We have thus arrived at a state where the next chapters have to be opened, pursuing the following objectives: (1) to elucidate underlying mechanisms, (2) to address effects on vulnerable groups, (3) to test material mixtures, and (4) to use realistic doses on (5) sophisticated models. Moreover, data reproducibility has become a significant demand. In this context, we studied the emerging concept of adverse outcome pathways (AOPs) from the perspective of immune activation and modulation resulting in pro-inflammatory versus tolerogenic responses. When considering the interaction of nanomaterials with biological systems, protein corona formation represents the relevant molecular initiating event (e.g., by potential alterations of nanomaterial-adsorbed proteins). Using this as an example, we illustrate how integrated experimental-computational workflows combining in vitro assays with in silico models aid in data enrichment and upon comprehensive ontology-annotated (meta)data upload to online repositories assure FAIRness (Findability, Accessibility, Interoperability, Reusability). Such digital twinning may, in future, assist in early-stage decision-making during therapeutic development, and hence, promote safe-by-design innovation in nanomedicine. Moreover, it may, in combination with in silico-based exposure-relevant dose-finding, serve for risk monitoring in particularly loaded areas, for example, workplaces, taking into account pre-existing health conditions. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Advances in genotoxicity of titanium dioxide nanoparticles in vivo and in vitro

Titanium dioxide nanoparticles (TiO₂ NPs) are currently one of the most widely used nanomaterials. Due to an increasing scope of applications, the exposure of humans to TiO₂ NP is inevitable, such as entering the body through the mouth with food additives or drugs, invading the damaged skin with cosmetics, and entering the body through the respiratory tract during the process of production and handling. Compared with TiO₂ coarse particles, TiO₂ NPs have stronger conductivity, reaction activity, photocatalysis, and permeability, which may lead to greater toxicity to organisms. Given that TiO₂ was classified as a category 2B carcinogen (possibly carcinogenic to humans), the genotoxicity of TiO₂ NPs has become the focus of attention. There have been a series of previous studies investigating the potential genotoxicity of TiO₂ NPs, but the existing research results are still controversial and difficult to conclude. More than half of studies have shown that TiO₂ NPs can cause genotoxicity, suggesting that TiO₂ NPs are likely to be genotoxic to humans. And the genotoxicity of TiO₂ NPs is closely related to the exposure concentration, mode and time, and experimental cells/animals as well as its physicochemical properties (crystal type, size, and shape). This review summarized the latest research progress of related genotoxic effects through in vivo studies and in vitro cell tests, hoping to provide ideas for the evaluation of TiO₂ NPs genotoxicity.

Fabrication of nano-decorated ZnO-fibrillar chitosan exhibiting a superior performance as a promising replacement for conventional ZnO

In this research, bioactive nano-hybrids based on the nano-fibrillar chitosan-ZnO (NF-CS-ZnO) were synthesized to diminish the toxicity of ZnO-NPs. The successful formation of nano-hybrids was confirmed by FT-IR, UV-Vis, and FE-SEM analyses, showing a uniform spherical ZnO-NPs with an average diameter of 20-30 nm, homogeneously dispersed on NF-CS. The obtained results demonstrated a remarkable antibacterial activity of NF-CS-ZnO-0.6 nano-hybrid against E. coli and S. aureus and, interestingly, no cytotoxic on normal cells (even at a high concentration of 100 μg/mL). Furthermore, NF-CS hybridization efficiently decreased the up-regulation in Cas3, Cas9, and Il6 of inspected fishes compared to the ZnO-NPs. Histopathological examination revealed hepatocyte necrosis in the fish exposed to ZnO-NPs and hyperemia exposed to NF-CS-ZnO-0.6 nano-hybrid. Finally, NF-CS efficiently improved the bio-safety and bactericidal activity of ZnO-NPs; therefore, NF-CS-ZnO nano-hybrid is prominently recommended as a talented low-toxicity antibacterial agent replacement of conventional ZnO-NPs for use in different applications.

Synthesis of a Dual-Functional Nanofertilizer by Embedding ZnO and CuO Nanoparticles on an Alginate-Based Hydrogel

Recent scientific breakthroughs in the field of agriculture have led to the abundant usage of nanoparticles in agrochemicals to maintain proper nutrient uptake in plants. Since less attention has been given to the supply of vital micronutrients to crop plants, the objective of this study was to develop a nanofertilizer capable of releasing micronutrients while nourishing its surrounding soil. As the initial nanonutrients, Zn and Cu were used in their metal oxide forms, which promote seed germination. Alginic acid was used as the agent responsible for soil conditioning. To form the fertilizing complex, nanoparticles were reacted with sodium alginate, which resulted in a hydrogel where alginate chains were cross-linked with Zn(II) and Cu(II) and excess metal oxide nanoparticles were distributed on the hydrogel. Spectroscopic characterization of the nanofertilizer confirmed that alginate chains were cross-linked by Zn(II) and Cu(II), while morphological analysis by scanning electron microscopy (SEM) showed that ZnO and CuO nanoparticles were embedded on the alginate matrix. The release behavior of cations in soil and water environments, experimented using the tea bag method, revealed that the cationic release was slowly increasing with time. Micronutrient uptake by plants was studied by conducting leaf analyses in tomato plants for 30 consecutive days. To experiment the release behavior of micronutrients in the presence of compost, the nanofertilizer was added with predetermined amounts of compost to tomato plants. Flame atomic absorption spectroscopy (FAAS) results indicated that in the fertilizer-applied plants, Cu concentrations showed a steady increase with time while Zn concentrations remained undetected.

In vitro investigation of zinc oxide nanoparticle toxic effects in spermatogonial cells at the molecular level

Because spermatogonia transmit genetic information across generations, their DNA must be protected from environmental damages, including exposure to zinc oxide nanoparticles (ZnO NPs), which are frequently used in modern technology. Here, we used an in vitro system enriched for spermatogonia and exposed them to 10 and 20 μg/ml ZnO NPs for one/seven days. We did not detect any significant cell death, chromosomal instability, or DNA fragmentation in the spermatogonia treated with the ZnO NPs following one-day treatment with 10 or 20 μg/ml ZnO NPs. However, ZnO NPs (both 10 and 20 μg/ml) induced chromosomal instability in the spermatogonia after seven days of treatment. Moreover, one-day exposure to these NPs induced reactive oxygen species (ROS) generation and upregulation of apoptotic pathway-related genes p53, Caspase3 and Il6, as an inflammatory factor. Taken together, our study provides preliminary evidence for possible damages induced by low concentrations of ZnO NPs in spermatogonia. We should pay increased attention when using these NPs because of the silent damages in spermatogonia that can be transmitted to the next generation and cause severe effects. However, more data and validation of these results are required to determine the extent of this concern.

Nutrient Element Decorated Polyetheretherketone Implants Steer Mitochondrial Dynamics for Boosted Diabetic Osseointegration

As a chronic metabolic disease, diabetes mellitus (DM) creates a hyperglycemic micromilieu around implants, resulting inthe high complication and failure rate of implantation because of mitochondrial dysfunction in hyperglycemia. To address the daunting issue, the authors innovatively devised and developed mitochondria-targeted orthopedic implants consisted of nutrient element coatings and polyetheretherketone (PEEK). Dual nutrient elements, in the modality of ZnO and Sr(OH)2 , are assembled onto the sulfonated PEEK surface (Zn&Sr-SPEEK). The results indicate the synergistic liberation of Zn2+ and Sr2+ from coating massacres pathogenic bacteria and dramatically facilitates cyto-activity of osteoblasts upon the hyperglycemic niche. Intriguingly, Zn&Sr-SPEEK implants are demonstrated to have a robust ability to recuperate hyperglycemia-induced mitochondrial dynamic disequilibrium and dysfunction by means of Dynamin-related protein 1 (Drp1) gene down-regulation, mitochondrial membrane potential (MMP) resurgence, and reactive oxygen species (ROS) elimination, ultimately enhancing osteogenicity of osteoblasts. In vivo evaluations utilizing diabetic rat femoral/tibia defect model at 4 and 8 weeks further confirm that nutrient element coatings substantially augment bone remodeling and osseointegration. Altogether, this study not only reveals the importance of Zn2+ and Sr2+ modulation on mitochondrial dynamics that contributes to bone formation and osseointegration, but also provides a novel orthopedic implant for diabetic patients with mitochondrial modulation capability.

Discovery of a Potent Glutathione Peroxidase 4 Inhibitor as a Selective Ferroptosis Inducer

Potent and selective ferroptosis regulators promote an intensive understanding of the regulation and mechanisms underlying ferroptosis, which is highly associated with various diseases. In this study, through a stepwise structure optimization, a potent and selective ferroptosis inducer was developed targeting to inhibit glutathione peroxidase 4 (GPX4), and the structure-activity relationship (SAR) of these compounds was uncovered. Compound 26a exhibited outstanding GPX4 inhibitory activity with a percent inhibition up to 71.7% at 1.0 μM compared to 45.9% of RSL-3. At the cellular level, 26a could significantly induce lipid peroxide (LPO) increase and effectively induce ferroptosis with satisfactory selectivity (the value of 31.5). The morphological analysis confirmed the ferroptosis induced by 26a. Furthermore, 26a significantly restrained tumor growth in a mouse 4T1 xenograft model without obvious toxicity.

Smart Shockwave Responsive Titania-Based Nanoparticles for Cancer Treatment

Nanomedicine is an emerging treatment approach for many cancers, characterized by having high sensitivity and selectivity for tumor cells and minimal toxic effects induced by the conventional chemotherapeutics. In these context, smart nanoparticles (NPs) are getting increasingly relevant in the development of new therapies. NPs with specific chemical composition and/or structure and being stimuli-responsive to magnetic, light or ultrasound waves are new promising tools. In the present work, amorphous-titania propyl-amine functionalized (a-TiO₂-NH₂) NPs, coated with bovine serum albumin (BSA), are stimulated with high energy shock waves to induce cytotoxic effects in cancer cells. First, a new method to coat a-TiO₂-NH₂ NPs with BSA (a-TiO₂-NH₂/BSA) was proposed, allowing for a high dispersion and colloidal stability in a cell culture media. The a-TiO₂-NH₂/BSA NPs showed no cancer cell cytotoxicity. In a second step, the use of shock waves to stimulate a-TiO₂-NH₂/BSA NPs, was evaluated and optimized. A systematic study was performed in in vitro cell culture aiming to impair the cancer cell viability: NP concentrations, time steps and single versus multiple shock waves treatments were studied. The obtained results highlighted the relevance of NPs design and administration time point with respect to the shock wave treatment and allow to hypothesize mechanical damages to cells.

Green Synthesized ZnO Nanoparticles Mediated by Streptomyces plicatus: Characterizations, Antimicrobial and Nematicidal Activities and Cytogenetic Effects

Zinc oxide nanoparticles (ZnO-NPs) are regarded as one of the most promising kinds of materials in a variety of fields, including agriculture. Therefore, this study aimed to biosynthesize and characterize ZnO-NPs and evaluate their different biological activities. Seven isolates of actinomycetes were obtained and screened for ZnO-NPs synthesis. The isolate MK-104 was chosen and identified as the Streptomyces plicatus MK-104 strain. The biosynthesized ZnO-NPs exhibited an absorbance peak at 350 nm and were spherical in shape with an average size of 21.72 ± 4.27 nm under TEM. XRD and DLS methods confirmed these results. The biosynthesized ZnO-NPs demonstrated activity against plant pathogenic microbes such as Erwinia amylovora, Aspergillus flavus, Aspergillus niger, Fusarium oxysporum, Fusarium moniliform and Alternaria alternata, with MIC values ranging from 15.6 to 500 µg/mL. Furthermore, ZnO-NPs had a significant effect on Meloidogyne incognita, with death percentages of 88.2, 93.4 and 96.72% after 24, 48 and 72 h of exposure, respectively. Vicia faba seeds were treated with five concentrations of ZnO-NPs (12.5, 25, 50, 100 and 200 µg/mL). Low-moderate ZnO-NP concentrations (12.5-50 µg/mL) were shown to promote seed germination and seedling development, while the mitotic index (MI) decreased as the dosage of ZnO-NPs increased. Micronuclei (MNs) and the chromosomal abnormality index increased as well.

Ovarian toxicity of nanoparticles

The ovary is a highly important organ for female reproduction. The main functions include sex steroid hormone synthesis, follicular development, and achievement of oocyte meiotic and development competence for proper fertilization. Nanoparticle (NP) exposure is becoming unavoidable because of its wide use in different products, including cosmetics, food, health, and personal care products. Studies examining different nonreproductive tissues or systems have shown that characteristics such as the size, shape, core material, agglomeration, and dissolution influence the effects of NPs. However, most studies evaluating NP-mediated reproductive toxicity have paid little or no attention to the influence of the physicochemical characteristics of NP on the observed effects. As accumulating evidence indicates that NP may reach the ovary to impair proper functions, this review summarizes the available data on NP accumulation in ovarian tissue, as well as data describing toxicity to ovarian functions, including sex steroid hormone production, follicular development, oocyte quality, and fertility. Due to their toxicological relevance, this review also describes the main physicochemical characteristics involved in NP toxicity and the importance of considering NP physicochemical characteristics as factors influencing the ovarian toxicity of NPs. Finally, this review summarizes the main mechanisms of toxicity described in ovarian cells.

In vitro bio-interaction responses and hemocompatibility of nano-based linear low-density polyethylene polymer embedded with heterogeneous TiO2/ZnO nanocomposites for biomedical applications

An innovative nano-base polymer that scavenges radicals and reactive oxygen species exhibits potential antibacterial properties, which are crucial in the biomedical field, particularly in reducing nosocomial infections. However, the safety of this nano-based polymer, which has direct contact with the human system, has not been fully understood. The present study investigated the cytocompatibility and hemocompatibility responses of linear low-density polyethylene polymer (LLDPE) embedded with difference ratios of heterogeneous TiO₂/ZnO nanocomposites. Exposure of the blood and fibroblast cells to LLDPE/100Z and LLDPE/25T75Z/10% nanocomposite films for 48 and 72 h decreased their viability by less than 40%, compared with LLDPE, LLDPE/100T and LLDPE/25T75Z/5% nanocomposite films. It also presented possible cellular damage and cytotoxicity, which was supported by the findings from the significant release of extracellular lactate dehydrogenase profiles and cell survival assay Further observation using an electron microscope revealed that LLDPE films with heterogeneous 25T75Z/5% promoted cell adhesion. Moreover, no hemolysis was detected in all ratios of heterogeneous TiO₂/ZnO nanocomposite in LLDPE film as it was less than 0.2%, suggesting that these materials were hemocompatible. This study on LLDPE film with heterogeneous TiO₂/ZnO nanocomposites demonstrated favorable biocompatible properties that were significant for advanced biomedical polymer application in a hospital setting.

Photoinduced Fabrication of Zinc Oxide Nanoparticles: Transformation of Morphological and Biological Response on Light Irradiance

The photoinduced synthesis of zinc oxide nanoparticles (ZnO NPs) was carried out to unveil the effects of change in wavelength of photons. ZnO NPs were synthesized by the coprecipitation technique exposed to different light regimes [dark environment, daylight, and blue-, green-, yellow-, and red-colored light-emitting diodes (LEDs)] at room temperature. X-ray diffractogram (XRD) revealed the wurtzite structure of ZnO NPs. A small change in the size of ZnO NPs (17.11-22.56 nm) was observed with the variation in wavelength of lights from 350 to 700 nm. Spherical to hexagonal disks and rodlike surface morphologies were observed by scanning electron microscopy (SEM). The elemental composition and surface chemistry of NPs were studied by energy-dispersive X-ray diffractive (EDX) and Fourier transform infrared (FTIR) spectra. Maximum free radical quenching activity, cation radical scavenging, and total antioxidant capacity were found in ZnO NPs synthesized under green light (28.78 ± 0.18, 30.05 ± 0.21%, and 36.55 ± 2.63 μg AAE/mg, respectively). Daylight-synthesized NPs (DL-ZNPs) showed the greatest total reducing potential (15.81 ± 0.33 μg AAE/mg) and metal-chelating activity (37.77 ± 0.31%). Photoinduced ZnO NPs showed significant enzyme inhibitory effects on amylase, lipase, and urease by red-light NPs (87.49 ± 0.19%), green-light NPs (91.44 ± 0.29%), and blue-light NPs (92.17 ± 0.34%), respectively. Photoinduced ZnO NPs have been employed as nanozymes and found to exhibit intrinsic peroxidase-like activity as well. Blue-light-synthesized ZnO NPs displayed the strongest antibacterial activity (23 mm) against methicillin-resistant Staphylococcus aureus (MRSA). This study can be considered as a novel step toward the synthetic approach using LEDs to synthesize ZnO NPs with specific physicochemical properties and extends a great prospect in the environmental chemistry, food safety, and biomedical fields as nanozyme, antioxidant, antibacterial, anti-α-amylase, antiurease, and antilipase agents.

EFSA Panel on Food Additives and Flavourings (FAF), Younes M, Aquilina G, Castle L, Engel K, Fowler P, Frutos Fernandez MJ, Fürst P, Gundert‐Remy U, Gürtler R, Husøy T, Manco M, Mennes W, Moldeus P, Passamonti S, Shah R, Waalkens‐Berendsen I, Wölfle D, Corsini E, Cubadda F, De Groot D, FitzGerald R, Gunnare S, Gutleb AC, Mast J, Mortensen A, Oomen A, Piersma A, Plichta V, Ulbrich B, Van Loveren H, Benford D, Bignami M, Bolognesi C, Crebelli R, Dusinska M, Marcon F, Nielsen E, Schlatter J, Vleminckx C, Barmaz S, Carfí M, Civitella C, Giarola A, Rincon AM, Serafimova R, Smeraldi C, Tarazona J, Tard A, Wright M. Safety assessment of titanium dioxide (E171) as a food additive

The present opinion deals with an updated safety assessment of the food additive titanium dioxide (E 171) based on new relevant scientific evidence considered by the Panel to be reliable, including data obtained with TiO2 nanoparticles (NPs) and data from an extended one-generation reproductive toxicity (EOGRT) study. Less than 50% of constituent particles by number in E 171 have a minimum external dimension < 100 nm. In addition, the Panel noted that constituent particles < 30 nm amounted to less than 1% of particles by number. The Panel therefore considered that studies with TiO2 NPs < 30 nm were of limited relevance to the safety assessment of E 171. The Panel concluded that although gastrointestinal absorption of TiO2 particles is low, they may accumulate in the body. Studies on general and organ toxicity did not indicate adverse effects with either E 171 up to a dose of 1,000 mg/kg body weight (bw) per day or with TiO2 NPs (> 30 nm) up to the highest dose tested of 100 mg/kg bw per day. No effects on reproductive and developmental toxicity were observed up to a dose of 1,000 mg E 171/kg bw per day, the highest dose tested in the EOGRT study. However, observations of potential immunotoxicity and inflammation with E 171 and potential neurotoxicity with TiO2 NPs, together with the potential induction of aberrant crypt foci with E 171, may indicate adverse effects. With respect to genotoxicity, the Panel concluded that TiO2 particles have the potential to induce DNA strand breaks and chromosomal damage, but not gene mutations. No clear correlation was observed between the physico-chemical properties of TiO2 particles and the outcome of either in vitro or in vivo genotoxicity assays. A concern for genotoxicity of TiO2 particles that may be present in E 171 could therefore not be ruled out. Several modes of action for the genotoxicity may operate in parallel and the relative contributions of different molecular mechanisms elicited by TiO2 particles are not known. There was uncertainty as to whether a threshold mode of action could be assumed. In addition, a cut-off value for TiO2 particle size with respect to genotoxicity could not be identified. No appropriately designed study was available to investigate the potential carcinogenic effects of TiO2 NPs. Based on all the evidence available, a concern for genotoxicity could not be ruled out, and given the many uncertainties, the Panel concluded that E 171 can no longer be considered as safe when used as a food additive.

Spondias pinnata (L.f.) Kurz Leaf Extract Derived Zinc Oxide Nanoparticles Induce Dual Modes of Apoptotic-Necrotic Death in HCT 116 and K562 Cells

This study evaluates the effects of phyto-derived zinc oxide nanoparticles (ZnONPs) on human cancer cells, colon carcinoma HCT 116, and chronic myelogenous leukemic K562, along with normal lymphocytes/erythrocytes. The commercial, chemically synthesized ZnONPs (cZnONPs) were also assessed in parallel. Using an eco-friendly approach devoid of harmful chemicals, biogenic nanoparticles were synthesized from aqueous leaf extract of Spondias pinnata (SpLZnONPs) by a sol-gel method. Optical, structural, and elemental characterization of both particle types were carried out deploying UV-Vis/photoluminescence spectroscopy, FTIR, XRD, FESEM, HRTEM, and EDX. Both SpLZnONPs and cZnONPs displayed hexagonal wurtzite structure with particle sizes averaging 30 and 48.5 nm, respectively. SpLZnONPs were found to be cytotoxic to both cancer cell types while cZnONPs exhibited toxicity only against HCT 116 cells. Interestingly, the cytomorphological changes and analysis of DNA laddering pattern observed in these treated cells were indicative of simultaneous induction of dual modes of death involving apoptosis and necrosis. Flow cytometric analysis of cell-cycle distribution, clonogenic, wound healing, and comet assays provided evidences of the antiproliferative potential of the tested nanoparticles. Apoptosis induction via oxidative stress-mediated Ca²⁺ release, ROS generation, loss of mitochondrial membrane potential, and externalization of phosphatidylserine was also determined biochemically. Relative expression of apoptotic genes was quantified using RT-qPCR and Western blot analysis. Mitotic index analysis, MTT, and hemolytic assays on lymphocytes and erythrocytes clearly revealed the absence of any deleterious effect(s) of SpLZnONPs in these cells compared with the toxicity of the chemically derived cZnONPs, thereby attesting to the biocompatibility and selective action of the biogenic nanoparticles.

Effects of polystyrene nanoplastics on Ctenopharyngodon idella (grass carp) after individual and combined exposure with zinc oxide nanoparticles

The toxicity of polystyrene nanoparticles (PS NPs) and ZnO nanoparticles (ZnO NPs), in combination is poorly known. Thus, the aim of the current study was to evaluate the effects of PS NPs (760 μg/L) on Ctenopharyngodon idella exposed to it, both in separate and in combination with ZnO NPs (760 μg/L), based on behavioral, biochemical and genotoxic biomarkers. Current data have indicated that PS NPs, for a short exposure period (3 days), both in separate and in combination with nanoparticles, have affected animals' response to the mirror test. On the other hand, all treatments have equally induced C. idella inactivity towards alarm substances and DNA damage. There was increased oxidative stress, mainly in groups exposed to PS NPs (in combination, or not, with nanoparticles); although increased, the evaluated antioxidant levels did not appear to be enough to inhibit the effects of treatment-induced production of free radicals. Together, these results are likely co-responsible for the observed changes. The current study did not observe antagonistic, synergistic or additive effect on animals exposed to the combination between PS NPs and ZnO NPs; however, this outcome should not discourage the performance of similar studies focused on assessing the (eco)toxicity of pollutant mixtures comprising nanomaterials.

Recent Advances in Zinc Oxide Nanostructures with Antimicrobial Activities

This article reviews the recent developments in the synthesis, antibacterial activity, and visible-light photocatalytic bacterial inactivation of nano-zinc oxide. Polycrystalline wurtzite ZnO nanostructures with a hexagonal lattice having different shapes can be synthesized by means of vapor-, liquid-, and solid-phase processing techniques. Among these, ZnO hierarchical nanostructures prepared from the liquid phase route are commonly used for antimicrobial activity. In particular, plant extract-mediated biosynthesis is a single step process for preparing nano-ZnO without using surfactants and toxic chemicals. The phytochemical molecules of natural plant extracts are attractive agents for reducing and stabilizing zinc ions of zinc salt precursors to form green ZnO nanostructures. The peel extracts of certain citrus fruits like grapefruits, lemons and oranges, acting as excellent chelating agents for zinc ions. Furthermore, phytochemicals of the plant extracts capped on ZnO nanomaterials are very effective for killing various bacterial strains, leading to low minimum inhibitory concentration (MIC) values. Bioactive phytocompounds from green ZnO also inhibit hemolysis of Staphylococcus aureus infected red blood cells and inflammatory activity of mammalian immune system. In general, three mechanisms have been adopted to explain bactericidal activity of ZnO nanomaterials, including direct contact killing, reactive oxygen species (ROS) production, and released zinc ion inactivation. These toxic effects lead to the destruction of bacterial membrane, denaturation of enzyme, inhibition of cellular respiration and deoxyribonucleic acid replication, causing leakage of the cytoplasmic content and eventual cell death. Meanwhile, antimicrobial activity of doped and modified ZnO nanomaterials under visible light can be attributed to photogeneration of ROS on their surfaces. Thus particular attention is paid to the design and synthesis of visible light-activated ZnO photocatalysts with antibacterial properties.

A review on biogenic synthesis, applications and toxicity aspects of zinc oxide nanoparticles

Nanoparticles (NPs) have become an important field of research over the past several decades with applications in various sectors, such as biomedical, cosmetic, food and many others, because of their unique characteristics. The green synthesis of nanoparticles has been preferred because of the naturally occurring reductants present in biological systems that decreases exposure to toxic chemicals compared with physico-chemical methods and is eco-friendly. Zinc oxide (ZnO) NPs exhibit broad and potential applications in different fields with their specific characteristics such as surface area, size, shape, low toxicity, optical properties, high binding energy and large band gap. This paper focuses on the bio-synthesis of ZnO NPs by utilizing extracts of different plant parts (stem, flower, fruit, peel, and leaves) through efficient, economical, simple, pure, and eco-friendly green routes. In this process, zinc salts have been used as precursor and phytochemicals in the plant extract reduce the metal salt to lower oxidation state as well as stabilize the ZnO NPs. The morphological and physico-chemical properties of obtained NPs analyzed by various characterization techniques have been discoursed. Further, antimicrobial activity and potential photocatalytic application in terms of the degradation of dyes have also been reviewed in addition to the toxicity aspects of these NPs on human beings and animals.

Interactions of Zinc Oxide Nanostructures with Mammalian Cells: Cytotoxicity and Photocatalytic Toxicity

This article presents a state-of-the-art review and analysis of literature studies on the morphological structure, fabrication, cytotoxicity, and photocatalytic toxicity of zinc oxide nanostructures (nZnO) of mammalian cells. nZnO with different morphologies, e.g., quantum dots, nanoparticles, nanorods, and nanotetrapods are toxic to a wide variety of mammalian cell lines due to in vitro cell-material interactions. Several mechanisms responsible for in vitro cytotoxicity have been proposed. These include the penetration of nZnO into the cytoplasm, generating reactive oxygen species (ROS) that degrade mitochondrial function, induce endoplasmic reticulum stress, and damage deoxyribonucleic acid (DNA), lipid, and protein molecules. Otherwise, nZnO dissolve extracellularly into zinc ions and the subsequent diffusion of ions into the cytoplasm can create ROS. Furthermore, internalization of nZnO and localization in acidic lysosomes result in their dissolution into zinc ions, producing ROS too in cytoplasm. These ROS-mediated responses induce caspase-dependent apoptosis via the activation of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), CCAAT/enhancer-binding protein homologous protein (chop), and phosphoprotein p53 gene expressions. In vivo studies on a mouse model reveal the adverse impacts of nZnO on internal organs through different administration routes. The administration of ZnO nanoparticles into mice via intraperitoneal instillation and intravenous injection facilitates their accumulation in target organs, such as the liver, spleen, and lung. ZnO is a semiconductor with a large bandgap showing photocatalytic behavior under ultraviolet (UV) light irradiation. As such, photogenerated electron-hole pairs react with adsorbed oxygen and water molecules to produce ROS. So, the ROS-mediated selective killing for human tumor cells is beneficial for cancer treatment in photodynamic therapy. The photoinduced effects of noble metal doped nZnO for creating ROS under UV and visible light for killing cancer cells are also addressed.