Cytotoxicity Of ZnO NPs Research Articles

Phytofabrication of biocompatible zinc oxide nanoparticle using Gymnema sylvestre and its potent in vitro antibacterial, antibiofilm, and cytotoxicity against human breast cancer cells (MDA-MB-231).

The increasing incidence of breast cancer and bacterial biofilm in medical devices significantly heightens global mortality and morbidity, challenging synthetic drugs. Consequently, greener-synthesized nanomaterials have emerged as a versatile alternative for various biomedical applications, offering new therapeutic avenues. This study explores the synthesis of biocompatible zinc oxide (ZnONPs) nanoparticles using Gymnema sylvestre and its antibacterial, antibiofilm, and cytotoxic properties. Characterization of ZnONPs inferred that UV-Vis spectra exhibited a sharp peak at 370nm. Fourier transform infrared spectroscopical analysis revealed the presence of active functional groups such as aldehyde, alkyne, cyclic alkene, sulfate, alkyl aryl ether, and Zn-O bonds. X-ray diffraction analysis results confirmed the crystalline nature of the nanoparticle. Scanning electron microscope analysis evidenced hexagonal morphology, and energy-dispersive X-ray analysis confirmed zinc content. High-resolution transmission electron microscope analysis showed hexagonal and rod-shaped ZnONPs with a size of 5nm. Zeta potential results affirmed the stability of nanoparticles. The ZnONPs effectively inhibited gram-positive (18-20mm) than gram-negative (12-18mm) bacterial pathogens with lower bacteriostatic and higher bactericidal values. Biofilm inhibitory property inferred ZnONPs were more effective against gram-positive (38-94%) than gram-negative bacteria (27-86%). The concentration of ZnONPs to exert 50% biofilm-inhibitory is lower against gram-positive bacteria (179.26-203.95μg/mL) than gram-negative bacteria (201.46-236.19μg/mL). Microscopic visualization inferred that at 250μg/mL, ZnONPs strongly disrupted biofilm formation, as evidenced by decreased biofilm density and altered architecture. The cytotoxicity of ZnONPs against breast cancer cells showed a dose-dependent reduction in cell viability with an IC50 value of 19.4µg/mL. AO/EB staining indicated early and late apoptotic cell death of breast cancer cells under fluorescence microscopy. The results of hemolytic activity validated the biocompatibility of the ZnONPs. Thus, the unique properties of the green-synthesized ZnONPs suggest their potential as effective drug carriers for targeted delivery in cancer therapy and the treatment of biofilm-related infections.

Activity of zinc oxide and zinc borate nanoparticles against resistant bacteria in an experimental lung cancer model.

Recent research indicates a prevalence of typical lung infections, such as pneumonia, in lung cancer patients. Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii stand out as antibiotic-resistant pathogens. Given this, there is a growing interest in alternative therapeutic avenues. Boron and zinc derivatives exhibit antimicrobial, antiviral, and antifungal properties. This research aimed to establish the effectiveness of ZnO and ZB NPs in combating bacterial infections in lung cancer cell lines. Initially, this study determined the minimal inhibitory concentration (MIC) and fractional inhibitory concentration (FIC) of zinc oxide nanoparticles (ZnO NPs) and zinc borate (ZB) on chosen benchmark strains. Subsequent steps involved gauging treatment success through a lung cancer-bacteria combined culture and immunohistochemical analysis. The inhibitory impact of ZnO NPs on bacteria was charted as follows: 0.97µg/mL for K. pneumoniae 700603, 1.95µg/mL for P. aeruginosa 27853, and 7.81µg/mL for Acinetobacter baumannii 19,606. In comparison, the antibacterial influence of zinc borate was measured as 7.81µg/mL for Klebsiella pneumoniae 700603 and 500µg/mL for both P. aeruginosa 27853 and A.baumannii 19606. After 24h, the cytotoxicity of ZnO NPs and ZB was analyzed using the MTT technique. The lowest cell viability was marked in the 500µg/mL ZB NPs group, with a viability rate of 48.83% (P < 0.001). However, marked deviations appeared at ZB concentrations of 61.5µg/mL (P < 0.05) and ZnO NPs at 125µg/mL. A synergistic microbial inhibitory effect was observed when ZnO NP and ZB were combined against the bacteria under investigation.

Effect of Polygonatum sibiricum on biological toxicity of zinc oxide nanoparticles during respiratory exposure.

Although zinc oxide nanoparticles (ZnO NPs) with distinct physicochemical properties have attracted great attention, the application of ZnO NPs is still limited due to their potential biotoxicity. In this work, ZnO-Polygonatum sibiricum (PS) NPs are synthesized to overcome this challenge. The ZnO NPs stably combine with PS according to microstructural observation, particle size distribution, zeta potential results and Fourier transform infrared spectroscopy analysis. The cytotoxicity of ZnO NPs is alleviated by combining them with PS as a consequence of the diminished generation of reactive oxygen species and reinforced superoxide dismutase activity. Furthermore, the respiratory index and histopathologic results of mice exposed to NPs manifest that the pulmonary dysfunction caused by ZnO NPs is avoided in the ZnO-PS NPs group. This study provides the foundations for the amelioration and universal utilization of ZnO NPs and emphasizes the potential of ZnO-PS NPs in biomedical applications.

Evaluation of the cytotoxicity, antioxidant activity, and molecular docking of biogenic zinc oxide nanoparticles derived from pumpkin seeds.

This study aimed to investigate the characterization of zinc oxide nanoparticles (ZnONPs) produced from Cucurbita pepo L. (pumpkin seeds) and their selective cytotoxic effectiveness on human colon cancer cells (HCT 116) and African Green Monkey Kidney, Vero cells. The study also investigated the antioxidant activity of ZnONPs. The study also examined ZnONPs' antioxidant properties. This was motivated by the limited research on the comparative cytotoxic effects of ZnO NPs on normal and HCT116 cells. The ZnO NPs were characterized using Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Transmission Electron Microscope/Selected Area Electron Diffraction (TEM/SAED), and Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) for determination of chemical fingerprinting, heat stability, size, and morphology of the elements, respectively. Based on the results, ZnO NPs from pumpkins were found to be less than 5 μm and agglomerates in nature. Furthermore, the ZnO NPs fingerprinting and SEM-EDX element analysis were similar to previous literature, suggesting the sample was proven as ZnO NPs. The ZnO NPs also stable at a temperature of 380°C indicating that the green material is quite robust at 60-400°C. The cell viability of Vero cells and HCT 116 cell line were measured at two different time points (24 and 48 h) to assess the cytotoxicity effects of ZnO NP on these cells using AlamarBlue assay. Cytotoxic results have shown that ZnO NPs did not inhibit Vero cells but were slightly toxic to cancer cells, with a dose-response curve IC50 = ~409.7 μg/mL. This green synthesis of ZnO NPs was found to be non-toxic to normal cells but has a slight cytotoxicity effect on HCT 116 cells. A theoretical study used molecular docking to investigate nanoparticle interaction with cyclin-dependent kinase 2 (CDK2), exploring its mechanism in inhibiting CDK2's role in cancer. Further study should be carried out to determine suitable concentrations for cytotoxicity studies. Additionally, DPPH has a significant antioxidant capacity, with an IC50 of 142.857 μg/mL. RESEARCH HIGHLIGHTS: Pumpkin seed extracts facilitated a rapid, high-yielding, and environmentally friendly synthesis of ZnO nanoparticles. Spectrophotometric analysis was used to investigate the optical properties, scalability, size, shape, dispersity, and stability of ZnO NPs. The cytotoxicity of ZnO NPs on Vero and HCT 116 cells was assessed, showing no inhibition of Vero cells and cytotoxicity of cancer cells. The DPPH assay was also used to investigate the antioxidant potential of biogenic nanoparticles. A molecular docking study was performed to investigate the interaction of ZnO NPs with CDK2 and to explore the mechanism by which they inhibit CDK2's role in cancer.

The Promising Antibacterial and Anticancer Activity of Green Synthesized Zinc Nanoparticles in Combination with Silver and Gold Nanoparticles

AbstractZinc nanoparticles (ZnNPs) are showing promising medical applications. However, their cytotoxicity is relatively high. This study aims to use a green synthesis technique based on the natural propolis (honeybees glue) and produce three counterparts of Zinc nanoparticles (ZnO-NPs, AuNPs@ZnO and AgNPs@ZnO). Then, the three would be analyzed for their potential antibacterial activity and cytotoxicity. The study compares the antibacterial activity and cytotoxicity of ZnO-NPs alone to its combination with gold and silver (AuNPs@ZnO and AgNPs@ZnO). The results showed that AgNPs@ZnO had contributed significantly to antibacterial activity against Gram-positive and Gram-negative bacteria. Moreover, AuNPs@ZnO and AgNPs@ZnO showed similar cytotoxicity to ZnO-NPs with higher safety. Furthermore, the Scanning and Transmission Electron Microscopes’ micrographs (SEM and TEM) displayed the biosynthesized ZnNPs that have a spherical shape with sizes ranging from 17 to 70 nm, from 45 to 75 nm, and from 22 to 73 nm for ZnONPs, ZnO-AgNPs, free AgNPs, and ZnO-AuNPs, respectively. In addition, zeta potential values for ZnONPs were 11.4 mV, while ZnO-AgNPs and ZnO-AuNPs have a higher overall charge of 13.6 mV and 23.9 mV, respectively. Furthermore, ZnNPs exhibited antibacterial activity, yet AgNPs@ZnO demonstrated the highest antibacterial action against Gram-negative and Gram-positive bacteria. In addition, cytotoxicity analyses of biosynthesized ZnNPs on three cell lines; breast cancer cell (MCF-7), liver cancer cell (HepG-2) and Human skin fibroblast (HSF) revealed that Zn-NPs in a combination could function as an anticancer agent. Therefore, there are promising medical applications for the biosynthesized ZnNPs in combinations with other metals, such as ZnO-AgNPs, as safe antibacterial and anticancer medicines. Graphical Abstract

Mesoporous TiO2 Coatings Regulate ZnO Nanoparticle Loading and Zn2+ Release on Titanium Dental Implants for Sustained Osteogenic and Antibacterial Activity.

Two major issues are currently hindering the clinical practice of titanium dental implants for the lack of biological activities: immediate/early loading risks and peri-implantitis. To solve these issues, it is urgent to develop multifunctional implants modified with effective osteogenic and antibacterial properties. Zinc oxide nanoparticles (ZnO NPs) possess superior antibacterial activity; however, they can rapidly release Zn2+, causing cytotoxicity. In this study, a potential dental implant modification was creatively developed as ZnO nanoparticle-loaded mesoporous TiO2 coatings (nZnO/MTC-Ti) via the evaporation-induced self-assembly method (EISA) and one-step spin coating. The mesoporous TiO2 coatings (MTCs) regulated the synthesis and loading of ZnO NPs inside the nanosized pores. The synergistic effects of MTC and ZnO NPs on nZnO/MTC-Ti not only controlled the long-term steady-state release of Zn2+ but also optimized the charge distribution on the surface. Therefore, the cytotoxicity of ZnO NPs was resolved without triggering excessive reactive oxygen species (ROS). The increased extracellular Zn2+ further promoted a favorable intracellular zinc ion microenvironment through the modulation of zinc transporters (ZIP1 and ZnT1). Owing to that, the adhesion, proliferation, and osteogenic activity of bone mesenchymal stem cells (BMSCs) were improved. Additionally, nZnO/MTC-Ti inhibited the proliferation of oral pathogens (Pg and Aa) by inducing bacterial ROS production. For in vivo experiments, different implants were implanted into the alveolar fossa of Sprague-Dawley rats immediately after tooth extraction. The nZnO/MTC-Ti implants were found to possess a higher capability for enhancing bone regeneration, antibiosis, and osseointegration in vivo. These findings suggested the outstanding performance of nZnO/MTC-Ti implants in accelerating osseointegration and inhibiting bacterial infection, indicating a huge potential for solving immediate/early loading risks and peri-implantitis of dental implants.

Biosynthesis of ZnO NPs from pumpkin seeds’ extract and elucidation of its anticancer potential against breast cancer

Abstract The cost-effective and environmental friendly biosynthesis of metal nanoparticles is becoming increasingly important in biomedical science. This study biosynthesized zinc oxide nanoparticles (ZnO NPs) from pumpkin seed extract and assessed its anticancer activity by using different molecular biology experiments in human breast cancer (MDA-MB-231) cell lines. The well-known analytical techniques, such as UV-visible spectrophotometry, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy (TEM), were used to confirm the synthesis and characterize the morphological and structural features of biogenic ZnO NPs. The formation of spherical nanoparticles with an average size of 50–60 nm was recorded using scanning electron microscopy and TEM. We observed the dose-dependent increase in cytotoxicity of ZnO NPs in the MDA-MB-231 cell line with a 50% inhibitory concentration of 10 µg/mL. Moreover, the ZnO NPs also showed significant cell morphology changes, apoptosis induction, and reactive oxygen species production at the highest tested concentration. The cellular adhesion and migration assay indicated cell death and inhibition in the migration of breast cancer cells in response to ZnO NPs’ treatment. These results clearly demonstrated the significant anticancer potential of ZnO NPs against the studied breast cancer cell line. However, an extension of this study is recommended in different cancer models and, based on the results, in vivo validation should be done.

The Cytotoxicity of ZnO NPs on Breast Cancer Cell Lines MCF-7 Depending on the Dispersion Solution

The Cytotoxicity of ZnO NPs on Breast Cancer Cell Lines MCF-7 Depending on the Dispersion Solution

Green synthesized zinc oxide nanoparticles induce apoptosis by suppressing PI3K/Akt/mTOR signaling pathway in osteosarcoma MG63 cells

This study aimed to assess the apoptosis-inducing mechanism of zinc oxide nanoparticles (ZnO NPs) stabilized by Solanum xanthocarpum plant extract in human osteosarcoma MG63 cells. In the present study, we synthesized ZnO NPs from S. xanthocarpum extract and evaluated its anticancer mechanism on MG 63 cells. The synthesized ZnO NPs were characterized by ultraviolet spectroscopy, X-ray crystallography, transmission electron microscopy, energy dispersive X-ray, and Fourier-transform infrared spectroscopy analysis. The mean size of the synthesized ZnO NPs was 21.62 ± 7.45 nm and spherical in shape. The cytotoxicity of ZnO NPs on MG63 cells was determined by MTT assay. The Western blot analysis was carried out to examine the expression of apoptotic and autophagy-related proteins in MG63 cells. The findings of the study reveal that ZnO NPs treatment showed concentration-dependent cytotoxicity, increased lipid peroxidation, decreased antioxidant activity, increased reactive oxygen species generation, and increased DNA damage. In addition, ZnO NPs treatment increased the expression of apoptotic members such as p53, Bax, caspase-3, -8, and -9 while downregulating Bcl-2 expression in MG63 cells. Furthermore, ZnO NPs treatment suppressed the P13K/AKT/mTOR signaling pathway and increased the expression of LC3 and beclin-1 in MG63 cells. The present study demonstrated that ZnO NPs induced apoptosis and autophagy in MG63 cells through modifying apoptotic and autophagy-related proteins.

Synthesis of eco-friendly facile nano-sized zinc oxide particles using aqueous extract of Cymodocea serrulata and its potential biological applications

Green synthesis of nanoparticles is an emerging branch of nanotechnology due to its low cost and effectiveness. In this study, zinc oxide (ZnO-NPs) nanoparticles were biosynthesized by an eco-friendly method using Cymodocea serrulata. They were characterized by Ultraviolet–visible (UV–vis) spectroscopy, energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray diffractometer (XRD), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. The synthesized crystalline nanoparticles were found to be 26.0–52.0 nm in size. The antioxidant activity of synthesized ZnO nanoparticles at 1000 µg/ml have revealed 75.55% in DPPH, 69.5% in deoxy-ribose, 62.75% in ABTS, 71.25% in nitric oxide and 74.10% in superoxide-scavenging assays. They also depicted significant bactericidal action against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, and Shigella flexneri. ZnO nanoparticles at 100 µg/ml concentration showed increased inhibition against B. subtilis with 18.0 mm, whereas moderate inhibition was seen against S. flexneri with 14.3 ± 0.25 mm. The cytotoxicity of ZnO-NPs was evaluated on A549 and H520 cell lines. The anti-proliferative effect was seen at 120 µg concentration on A549 and H520 cell lines with IC50 values of 55.0 ± 0.25 and 60.0 ± 0.50 µg/ml at 24 h. C. serrulata-coated zinc nanoparticles was found potential against bacterial pathogens and cancer cells. Therefore, they may be developed in future for biomedical applications.

Radiosensitization effect of ZnO nanoparticles in lung cancer cells at clinically relevant megavoltage energy

Introduction: Radiation therapy is one of the major modalities that have long been used in cancer treatment. Radiotherapy is often accompanied by early and late toxicity and side effects and narrow therapeutic window. Similarity in radiation absorption properties of tumors and neighboring healthy tissues is often the reason for low specificity of radiation therapy. Development of nanomaterials for localized energy deposition under irradiation can increases radiation absorption by cancer tissue, expanding the therapeutic window and, thus, increasing specificity and efficacy of the treatment. ZnO nanoparticle is a wide band gap semiconductor with photo-oxidizing capacity under uv radiation. Recent studies have investigated photo-oxidizing under kilovoltage x-ray energy named as radiosensitization. The purpose of this study was to assess ZnO radiosensitization at clinically relevant MV X-ray energy. Materials and Methods: ZnO nanoparticles with mean size of 10 nm were synthetized by a chemical precipitation method. The size, morphology and crystalline structure of the nanoparticles were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The cytotoxicity of ZnO nps was evaluated on SKLC-6 lung cancer cell line by cell proliferation assay. The effect of ZnO nps on cell radiosensitivity under 6MV energy x-ray irradiation was evaluated using colonogenic assay. Mode of cell death was evaluated by flow cytometry. Results: TEM images showed spherical ZnO NPs with narrow size distributions were synthesized. XRD pattern of purely synthesized NPs exhibited seven reflection peaks that can be indexed to the ZnO wurtzite structure. ZnO NPs were cytotoxic to the SKLC-6 cells in a dose-dependent manner as cell viability was decrease with the increase concentrations of ZnO nps. When comparing the radiation effects between the nanoparticle-containing and nanoparticle-free samples, the calculated radiation enhancement ratio of about 1.35-fold was achieved. FLow cytometry analysis confirmed that ZnO NPs, irradiation and combination of two induce apoptosis in SKLC-6 cells. Conclusion: The potential of the ZnO nanoparticles for radiosensitization at MV energy was demonstrated in human lung cancer cell line (SKLC-6). Nanoparticle-mediated Enhancement Ratio was 1.35. Radiosensitizing effect can be attributed to X-ray-induced radiocatalysis by the nanoparticles at MV energy. Further development of ZnO nps might provide a new useful tool for research and clinical therapy in the field of oncology.

Euphorbia heterophylla (L.) mediated fabrication of ZnO NPs: Characterization and evaluation of antibacterial and anticancer properties

Abstract Euphorbia heterophylla leaves extract mediated synthesis of multifunctional Zinc oxide nanoparticles (ZnO NPs) by green chemistry approaches. The prepared product was well characterized using various analytical tools namely X-ray diffraction (XRD), Ultra Violet-Diffused reflectance spectroscopy (UV-DRS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX) and Transmission electron microscopy (TEM) etc. The XRD pattern of ZnO NPs showed hexagonal phase with wurtzite structure. The UV-DR Spectrum reveled that characteristic peak at 370 nm and its energy band gap was found to be ~3.15 eV indicating the formation of ZnO NPs. The FT-IR spectrum results showed the presence of functional groups. The Raman spectrum showed the presence of phonon modes of vibrations in ZnO NPs. The morphological analysis of ZnO NPs exhibit hexagonal, conical and pyramidal nature with mean particle size of ~40 nm which is in close agreement with XRD pattern. ZnO NPs shows significant antibacterial activity against pathogenic bacterial strains both Gram positive and Gram negative bacteria by agar well diffusion method. Furthermore, the cytotoxicity of ZnO NPs was evaluated against cancer cell lines such as lung (A549) and hepatocellular carcinoma (HepG2) cell lines. Therefore, the study reveals that, the E. heterophylla is an effective reducing agent for the formation of ZnO NPs with significant antibacterial and cytotoxicity properties.

Cytotoxicity of ZnO NPs towards fresh water algae Scenedesmus obliquus at low exposure concentrations in UV-C, visible and dark conditions

Continuous increase in the usage of ZnO nanoparticles in commercial products has exacerbated the risk of release of these particles into the aquatic environment with possible harmful effects on the biota. In the current study, cytotoxic effects of two types of ZnO nanoparticles, having different initial effective diameters in filtered and sterilized lake water medium [487.5±2.55nm for ZnO-1 NPs and 616.2±38.5nm for ZnO-2 NPs] were evaluated towards a dominant freshwater algal isolate Scenedesmus obliquus in UV-C, visible and dark conditions at three exposure concentrations: 0.25, 0.5 and 1mg/L. The toxic effects were found to be strongly dependent on the initial hydrodynamic particle size in the medium, the exposure concentrations and the irradiation conditions. The loss in viability, LDH release and ROS generation were significantly enhanced in the case of the smaller sized ZnO-1 NPs than in the case of ZnO-2 NPs under comparable test conditions. The toxicity of both types of ZnO NPs was considerably elevated under UV-C irradiation in comparison to that in dark and visible light conditions, the effects being more enhanced in case of ZnO-1 NPs. The size dependent dissolution of the ZnO NPs in the test medium and possible toxicity due to the released Zn2+ ions was also noted. The surface adsorption of the nanoparticles was substantiated by scanning electron microscopy. The internalization/uptake of the NPs by the algal cells was confirmed by fluorescence microscopy, transmission electron microscopy, and elemental analyses.

In vitro cytotoxicity of silver nanoparticles and zinc oxide nanoparticles to human epithelial colorectal adenocarcinoma (Caco-2) cells

With the increasing applications of silver nanoparticles (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) in foods and cosmetics, the concerns about the potential toxicities to human have been raised. The aims of this study are to observe the cytotoxicity of Ag NPs and ZnO NPs to human epithelial colorectal adenocarcinoma (Caco-2) cells in vitro, and to discover the toxicity mechanism of nanoparticles on Caco-2 cells. Caco-2 cells were exposed to 10, 25, 50, 100, 200μg/mL of Ag NPs and ZnO NPs (90nm). AO/EB double staining was used to characterize the morphology of the treated cells. The cell counting kit-8 (CCK-8) assay was used to detect the proliferation of the cells. Reactive oxygen species (ROS), superoxide dismutase (SOD) and glutathione (GSH) assay were used to explore the oxidative damage of Caco-2 cells. The results showed that Ag NPs and ZnO NPs (0–200μg/mL) had highly significant effect on the Caco-2 cells activity. ZnO NPs exerted higher cytotoxicity than Ag NPs in the same concentration range. ZnO NPs have dose-depended toxicity. The LD50 of ZnO NPs in Caco-2 cells is 0.431mg/L. Significant depletion of SOD level, variation in GSH level and release of ROS in cells treated by ZnO NPs were observed, which suggests that cytotoxicity of ZnO NPs in intestine cells might be mediated through cellular oxidative stress. While Caco-2 cells treated with Ag NPs at all experimental concentrations showed no cellular oxidative damage. Moreover, the cells’ antioxidant capacity increased, and reached the highest level when the concentration of Ag NPs was 50μg/mL. Therefore, it can be concluded that Ag NPs are safer antibacterial material in food packaging materials than ZnO NPs.

In vitro toxicity of different-sized ZnO nanoparticles in Caco-2 cells

There has been rapid growth in nanotechnology in both the public and private sectors worldwide, but concern about nanosafety exists. To assess size-dependent cytotoxicity on human cancer cells, we studied the cytotoxic effect of three kinds of zinc oxide nanoparticles (ZnO NPs) on human epithelial colorectal adenocarcinoma (Caco-2) cells. Nanoparticles were first characterized by size, distribution, and intensity. Multiple assays have been adopted to measure the cell activity and oxidative stress. The cytotoxicity of ZnO NPs was time dependent and dose dependent. The 24-h exposure was chosen to confirm the viability and accessibility of the cells and taken as the appropriate time for the following test system. The IC50 value was found at a low concentration. The oxidative stress elicited a significant reduction in glutathione with increase in reactive oxygen species and lactate dehydrogenase. The toxicity resulted in a deletion of cells in the G1 phase and an accumulation of cells in the S and G2/M phases. One type of metallic oxide (ZnO) exerted different cytotoxic effects according to different particle sizes. Data from the previous experiments showed that 26-nm ZnO NPs appeared to have the highest toxicity to Caco-2 cells. The study demonstrated the toxicity of ZnO NPs to Caco-2 cells and the impact of particle size, which could be useful in the medical applications.

Effect of Zinc Oxide Nanoparticles on the Function of MC3T3-E1 Osteoblastic Cells

Zinc oxide nanoparticles (ZnO NPs) can be ingested directly when used in food, food packaging, drug delivery, and cosmetics. This study evaluated the cellular effects of ZnO NPs (50 and 100 nm diameter particle sizes) on the function of osteoblastic MC3T3-E1 cells. ZnO NPs showed cytotoxicity at concentrations of above 50 μg/ml, and there was no significant effect of the size on the cytotoxicity of ZnO NPs. Within the testing concentrations of 0.01~1 μg/ml, which did not cause a marked drop in cell viability, ZnO NPs (0.1 μg/ml) caused a significant elevation of alkaline phosphatase activity, collagen synthesis, mineralization, and osteocalcin content in the cells (P < 0.05). Moreover, pretreatment with ZnO NPs (0.01~1 μg/ml) significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, and ATP loss. Measurement of reactive oxygen species (ROS) indicated decrease in ROS level upon exposure to ZnO nanoparticles (0.01 μg/ml). Hence, our study indicated that ZnO nanoparticles can have protective effects on osteoblasts at low concentrations where there are little or no observable cytotoxic effects.

Comprehensive Study on the Toxicology of Surface-Coated ZnO Nanoparticles in Human Alveolar Adenocarcinoma (A549) Cells

The impact of surface coating of zinc oxide nanoparticles (ZnO NPs) with chitosan, cell culture medium and oleic acid (OA) on their cytotoxicity in human alveolar adenocarcinoma (A549) cells has been studied in terms of particle induced-toxicity, membrane damage, generation of intracellular reactive oxygen species (ROS) and cell apoptosis. The chitosan-coated NPs with negatively charged hydroxyl group are less toxic than OA-coated NPs with positively charged alkyl groups, thereby highlights its potential for reducing metal oxide NPs toxicity. The potential of surface coatings to reduce the cytotoxicity was ordered as chitosan-, mediumand OA-coated. The reduction in the cytotoxicity of surface-coated ZnO NPs was attributed to lesser interaction of NPs with the cells and decrease in Zn2+ ions into the cell medium, resulting in decrease of reactive oxygen species production and apoptotic cell death. The mechanism involved in the cytotoxicity of ZnO NPs was also studied in detail.