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

ZnO based 0-3D diverse nano-architectures, films and coatings for biomedical applications

Thin-film nano-architecting is a promising approach that controls the properties of nanoscale surfaces to increase their interdisciplinary applications in a variety of fields. In this context, zinc oxide (ZnO)-based various nano-architectures (0-3D) such as quantum dots, nanorods/nanotubes, nanothin films, tetrapods, nanoflowers, hollow structures, etc. have been extensively researched by the scientific community in the past decade. Owing to its unique surface charge transport properties, optoelectronic properties and reported biomedical applications, ZnO has been considered as one of the most important futuristic bio-nanomaterials. This review is focused on the design/synthesis and engineering of 0-3D nano-architecture ZnO-based thin films and coatings with tunable characteristics for multifunctional biomedical applications. Although ZnO has been extensively researched, ZnO thin films composed of 0-3D nanoarchitectures with promising thin film device bio-nanotechnology applications have rarely been reviewed. The current review focuses on important details about the technologies used to make ZnO-based thin films, as well as the customization of properties related to bioactivities, characterization, and device fabrication for modern biomedical uses that are relevant. It features biosensing, tissue engineering/wound healing, antibacterial, antiviral, and anticancer activity, as well as biomedical diagnosis and therapy with an emphasis on a better understanding of the mechanisms of action. Eventually, key issues, experimental parameters and factors, open challenges, etc. in thin film device fabrications and applications, and future prospects will be discussed, followed by a summary and conclusion.

Recent Advances of Emerging Metal-Containing Two-Dimensional Nanomaterials in Tumor Theranostics

In recent years, metal-containing two-dimensional (2D) nanomaterials, among various 2D nanomaterials have attracted widespread attention because of their unique physical and chemical properties, especially in the fields of biomedical applications. Firstly, the review provides a brief introduction to two types of metal-containing 2D nanomaterials, based on whether metal species take up the major skeleton of the 2D nanomaterials. After this, the synthetical approaches are summarized, focusing on two strategies similar to other 2D nanomaterials, top-down and bottom-up methods. Then, the performance and evaluation of these 2D nanomaterials when applied to cancer therapy are discussed in detail. The specificity of metal-containing 2D nanomaterials in physics and optics makes them capable of killing cancer cells in a variety of ways, such as photodynamic therapy, photothermal therapy, sonodynamic therapy, chemodynamic therapy and so on. Besides, the integrated platform of diagnosis and treatment and the clinical translatability through metal-containing 2D nanomaterials is also introduced in this review. In the summary and perspective section, advanced rational design, challenges and promising clinical contributions to cancer therapy of these emerging metal-containing 2D nanomaterials are discussed.

Estimating the in vitro cytotoxicity of the newly emerged zinc oxide (ZnO) doped chromium nanoparticles using the human fetal lung fibroblast cells (WI38 cells)

Advances in nanotechnology have been increased for more smart applications and getting the highest level of benefits, recently modification of the surface characters of nanoparticles is a new trend to get the optimal benefits, one of these modification is doping of zinc oxide with chromium nanoparticles (ZnO doped Cr NPs), the present study aimed to identify the surface characters of doped ZnO and their possible cytotoxic effects. The doped NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscope (FESEM), and Electromagnetic Data Exchange (EDX). Human fetal lung fibroblast cells (WI38 Cells) was treated with variable concentrations of pure ZnO and ZnO doped Cr (0.01 %, 0.02 %, 0.03 % and 0.04 %) for 24 hr at 37 °C followed by the MTT assay. The cells treated with the obtained half-maximal inhibitory concentration (IC50). The supernatant and cells were collected for oxidant/anti-oxidant and molecular analysis.The observed FESEM features are in line with the reported XRD analysis confirming the hexagonal crystal symmetry of all samples. The findings revealed that pure ZnO exhibited potent cytotoxic effects followed by (0.03 % and 0.04 %). All tested NPs produce lipid peroxidation significantly (0.03 % and 0.04 %). The significant up regulation of Bcl-2-associated X protein (BAX) and apoptotic Caspase (Cas-3) transcription level were reported in ZnO and 0.03 % and 0.04 % in contrast the anti apoptitic B-cell lymphoma 2 (Bcl-2) is elevated in 0.01 % and 0.02 %. Doping of ZnO with Cr causing significant morphological changes which effect on their toxicity especially with 0.03 % and 0.04 %.

Effect of zinc oxide nanocomposite and ginger extract on lipid profile, glucose, pancreatic tissue and expression of Gpx1 and Tnf-α genes in diabetic rat model

BACKGROUND

Diabetes is a life-threatening health condition that requires expensive treatment and places a significant financial burden on society. Consequently, this study aimed to explore the potential of low and high concentrations of ginger extract, ZnO-NPs, and a combination of both to help manage diabetes and reduce high levels of lipids in diabetic rats.

METHODS AND RESULTS

The research focused on agglomerated nanoparticles under 100 nm, specifically ZnO nanoparticles. The size of the nanoparticles was determined using X-ray diffraction analysis and scanning electron microscopy analysis, with a monodisperse particle size distribution of 20 to 48 nm and an average size of 38 nm, as shown by dynamic light scattering. Fourier transform infrared spectroscopy revealed the presence of typical peaks of ginger extract and ZnO-NPs in the nanocomposite structure. The pancreatic tissue histopathological study indicated that a concentration of 10 mg/kg of the composite had the most significant antidiabetic effect compared to other treatments. Lower concentrations could significantly reduce and balance fasting blood sugar and triglycerides levels while also increasing the high-density lipoproteins levels. However, all treatments induced a significant decrease in total cholesterol and low-density lipoproteins levels. Only metformin and ZnO-NPs in lower concentrations could decrease very low-density lipoproteins levels. The molecular technique showed that a low concentration of the composite led to the most significant decrease in Tnf-α gene expression compared to the diabetic group. The expression of the glutathione peroxidase 1 (Gpx1) gene in treated groups had no significant difference with the level of Gpx1 expression in the control rats.

CONCLUSIONS

In general, this study demonstrated that lower concentrations of the treatments, especially composite, were more effective for treating diabetic rats due to reduced pancreatic tissue damage.

Are Zn(II) pincer complexes efficient apoptosis inducers? a deep insight into their activity against A549 lung cancer cells

To expand the array of chemotherapeutic drugs, earth-abundant metal complexes are found to be the future direction. In this regard, new zinc(II) complexes 1-3 of 8-aminoquinoline-based pincer ligands were synthesized, characterized and tested for their anticancer activity. The IC50 values of these complexes were estimated by an MTT assay to be 16.35-17.95 μM and 33.35-40 μM against A549 lung and MCF-7 breast cancer cells respectively. Among them, 3 was slightly better than the other complexes and, thus, subjected to detailed studies. Moreover, the ligand corresponding to 3 was less active against both the cell lines than the complex. Further, 3 showed no toxicity against normal fibroblast cell line L929, which instantly elevated the drug characteristic of our complex. An AO-EB staining assay revealed that 3 can induce apoptosis in A549, and it was quantified by flow cytometry as 22.77%. Moreover, the depolarization of the mitochondrial membrane potential determined by JC-1 staining indicated excess ROS production sites in the mitochondria, which was confirmed by carboxy-H2DCFDA staining. Interestingly, the present complexes show better activity than that of the standard drug cisplatin against A549 cells. Overall, the studies provided promising results that can be extended for clinical applications.

Effects of Long-Term Dietary Zinc Oxide Nanoparticle on Liver Function, Deposition, and Absorption of Trace Minerals in Intrauterine Growth Retardation Pigs

To investigate the long-term effects of dietary zinc oxide nanoparticle (Nano-ZnO, 20-40 nm) on the relative organ weight, liver function, deposition, and absorption of trace minerals in intrauterine growth retardation (IUGR) pigs, piglets were allocated to NBW (6 normal birth weight piglets fed basal diets), IUGR (6 IUGR piglets fed basal diets) and IUGR+NZ (6 IUGR piglets fed basal diets + 600 mg Zn/kg from Nano-ZnO) groups at weaning (21 days of age), which were sampled at 163 days of age. There were no noteworthy changes in the relative weight of organs, hepatic histomorphology, serum alkaline phosphatase, glutamic pyruvic transaminase and glutamic oxalacetic transaminase activities, and Mn, Cu, and Fe concentrations in leg muscle, the liver, the tibia, and feces among the IUGR, NBW, and IUGR+NZ groups (P>0.05), and no intact Nano-ZnO in the jejunum, liver, and muscle was observed, while dietary Nano-ZnO increased the Zn concentrations in the tibia, the liver, serum, and feces (P<0.05) and mRNA expression of metallothionein (MT) 1A, MT2A, solute carrier family 39 member (ZIP) 4, ZIP14, ZIP8, divalent metal transporter 1, solute carrier family 30 member (ZnT) 1, ZnT4 and metal regulatory transcription factor 1, and ZIP8 protein expression in jejunal mucosa (P<0.05). Immunohistochemistry showed that dietary Nano-ZnO increased the relative optical density of ZIP8 (mainly expressed in cells of brush border) and MT2A (mainly expressed in villus lamina propria and gland/crypt) (P<0.05). In conclusion, long-term dietary Nano-ZnO showed no obvious side effects on the development of the major organs, liver function, and metabolism of Cu, Fe, and Mn in IUGR pigs, while it increased the Zn absorption and deposition via enhancing the expression of transporters (MT, ZIP, and ZnT families) in the jejunum, rather than via endocytosis as the form of intact nanoparticles.

Zinc Oxide Nanoparticles Biosynthesized by Eriobotrya japonica Leaf Extract: Characterization, Insecticidal and Antibacterial Properties

Zinc oxide nanoparticles (ZnO-NPs) have gained significant attention in nanotechnology due to their unique properties and potential applications in various fields, including insecticidal and antibacterial activities. The ZnO-NPs were biosynthesized by Eriobotrya japonica leaf extract and characterized by various techniques such as UV-visible (UV-vis) spectrophotometer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential analysis. The results of SEM revealed that NPs were irregular and spherical-shaped, with a diameter between 5 and 27 nm. Meanwhile, DLS supported that the measured size distributions were 202.8 and 94.7 nm at 11.1° and 90.0°, respectively, which supported the polydisperse nature of NPs, and the corresponding zeta potential was -20.4 mV. The insecticidal activity of the produced ZnO-NPs was determined against the adult stage of coleopteran pests, Sitophilus oryzae (Linnaeus) (Curculionidae) and Tribolium castaneum (Herbst) (Tenebrionidae). The LC50 values of ZnO-NPs against adults of S. oryzae and T. castaneum at 24 h of exposure were 7125.35 and 5642.65 μg/mL, respectively, whereas the LC90 values were 121,824.56 and 66,825.76 μg/mL, respectively. Moreover, the biosynthesized nanoparticles exhibited antibacterial activity against three potato bacterial pathogens, and the size of the inhibition zone was concentration-dependent. The data showed that the inhibition zone size increased with an increase in the concentration of nanoparticles for all bacterial isolates tested. The highest inhibition zone was observed for Ralstonia solanacearum at a concentration of 5 µg/mL, followed by Pectobacterium atrosepticum and P. carotovorum. Eventually, ZnO-NPs could be successfully used as an influential agent in pest management programs against stored-product pests and potato bacterial diseases.

Biosorption of Escherichia coli Using ZnO-Trimethyl Chitosan Nanocomposite Hydrogel Formed by the Green Synthesis Route

In this study, we tested the biosorption capacity of trimethyl chitosan (TMC)-ZnO nanocomposite (NC) for the adsorptive removal of Escherichia coli (E. coli) in aqueous suspension. For the formation of ZnO NPs, we followed the green synthesis route involving Terminalia mantaly (TM) aqueous leaf extract as a reducing agent, and the formed ZnO particles were surface-coated with TMC biopolymer. On testing of the physicochemical characteristics, the TM@ZnO/TMC (NC) hydrogel showed a random spherical morphology with an average size of 31.8 ± 2.6 nm and a crystal size of 28.0 ± 7.7 nm. The zeta potential of the composite was measured to be 23.5 mV with a BET surface area of 3.01 m² g^-1. The spectral profiles of TM@ZnO/TMC NC hydrogel on interaction with Escherichia coli (E. coli) revealed some conformational changes to the functional groups assigned to the stretching vibrations of N-H, C-O-C, C-O ring, and C=O bonds. The adsorption kinetics of TM@ZnO/TMC NC hydrogel revealed the pseudo-second-order as the best fit mechanism for the E. coli biosorption. The surface homogeneity and monolayer adsorption of the TM@ZnO/TMC NC hydrogel reflects majorly the entire adsorption mechanism, observed to display the highest correlation for Jovanovic, Redlich-Peterson, and Langmuir's isotherm models. Further, with the use of TM@ZnO/TMC NC hydrogel, we measured the highest adsorption capacity of E. coli to be 4.90 × 10 mg g^-1, where an in-depth mechanistic pathway was proposed by making use of the FTIR analysis.

MDM2 upregulation induces mitophagy deficiency via Mic60 ubiquitination in fetal microglial inflammation and consequently neuronal DNA damage caused by exposure to ZnO-NPs during pregnancy

During pregnancy, the human body is quite vulnerable to external stimuli. Zinc oxide nanoparticles (ZnO-NPs) are widely used in daily life, and they enter the human body via environmental or biomedical exposure, thus having potential risks. Although accumulating studies have demonstrated the toxic effects of ZnO-NPs, few studies have addressed the effect of prenatal ZnO-NP exposure on fetal brain tissue development. Here, we systematically studied ZnO-NP-induced fetal brain damage and the underlying mechanism. Using in vivo and in vitro assays, we found that ZnO-NPs could cross the underdeveloped bloodbrain barrier and enter fetal brain tissue, where they could be endocytosed by microglia. ZnO-NP exposure impaired mitochondrial function and induced autophagosome overaccumulation by downregulation of Mic60, thus inducing microglial inflammation. Mechanistically, ZnO-NPs increased Mic60 ubiquitination by activating MDM2, resulting in imbalanced mitochondrial homeostasis. Inhibition of Mic60 ubiquitination by MDM2 silencing significantly attenuated the mitochondrial damage induced by ZnO-NPs, thereby preventing autophagosome overaccumulation and reducing ZnO-NP-mediated inflammation and neuronal DNA damage. Our results demonstrate that ZnO-NPs are likely to disrupt mitochondrial homeostasis, inducing abnormal autophagic flux and microglial inflammation and secondary neuronal damage in the fetus. We hope the information provided in our study will improve the understanding of the effects of prenatal ZnO-NP exposure on fetal brain tissue development and draw more attention to the daily use of and therapeutic exposure to ZnO-NPs among pregnant women.

Fabrication of ZnO/Gypsum/Gelatine nanocomposites films and their antibacterial mechanism against Staphylococcus aureus

Staphylococcus aureus (S. aureus) has long been acknowledged as being one of the most harmful bacteria for human civilization. It is the main contributor to skin and soft tissue infections. The gram positive pathogen also contributes to bloodstream infections, pneumonia, or bone and joint infections. Hence, developing an efficient and targeted treatment for these illnesses is greatly desired. Recently, studies on nanocomposites (NCs) have significantly increased due to their potent antibacterial and antibiofilm properties. These NCs provide an intriguing way to control the growth of bacteria without causing the development of resistance strains that come from improper or excessive use of the conventional antibiotics. In this context, we have demonstrated the synthesis of a NC system by precipitation of ZnO nanoparticles (NPs) on Gypsum followed by encapsulation with Gelatine, in the present study. Fourier transform infrared (FTIR) spectroscopy was used to validate the presence of ZnO NPs and Gypsum. The film was characterized by X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM). The system exhibited promising antibiofilm action and was effective in combating S. aureus and MRSA in concentrations between 10 and 50 ug/ml. The bactericidal mechanism by release of reactive oxygen species (ROS) was anticipated to be induced by the NC system. Studies on cell survival and in-vitro infection support the film's notable biocompatibility and its potential for treating Staphylococcus infections in the future.

Recent advances in nanomaterials based sustainable approaches for mitigation of emerging organic pollutants

Emerging organic pollutants (EOPs) are a category of pollutants that are relatively new to the environment and recently garnered a lot of attention. The majority of EOPs includes endocrine-disrupting chemicals (EDCs), antibiotic resistance genes (ARGs), pesticides, dyes and pharmaceutical and personal care products (PPCPs). Exposure to contaminated water has been linked to an increase in incidences of malnutrition, intrauterine growth retardation, respiratory illnesses, liver malfunctions, eye and skin diseases, and fatalities. Consequently, there is a critical need for wastewater remediation technologies which are effective, reliable, and economical. Conventional wastewater treatment methods have several shortcomings that can be addressed with the help of nanotechnology. Unique characteristics of nanomaterials (NMs) make them intriguing and efficient alternative in wastewater treatment strategies. This review emphasis on the occurrence of divers emerging organic pollutants (EOPs) in water and their effective elimination via different NMs based methods with in-depth mechanisms. Furthermore, it also delves the toxicity assessment of NMs and critical challenges, which are crucial steps for practical implementations.

3D printed neural tissues with in situ optical dopamine sensors

Engineered neural tissues serve as models for studying neurological conditions and drug screening. Besides observing the cellular physiological properties, in situ monitoring of neurochemical concentrations with cellular spatial resolution in such neural tissues can provide additional valuable insights in models of disease and drug efficacy. In this work, we demonstrate the first three-dimensional (3D) tissue cultures with embedded optical dopamine (DA) sensors. We developed an alginate/Pluronic F127 based bio-ink for human dopaminergic brain tissue printing with tetrapodal-shaped-ZnO microparticles (t-ZnO) additive as the DA sensor. DA quenches the autofluorescence of t-ZnO in physiological environments, and the reduction of the fluorescence intensity serves as an indicator of the DA concentration. The neurons that were 3D printed with the t-ZnO showed good viability, and extensive 3D neural networks were formed within one week after printing. The t-ZnO could sense DA in the 3D printed neural network with a detection limit of 0.137 μM. The results are a first step toward integrating tissue engineering with intensiometric biosensing for advanced artificial tissue/organ monitoring.

Green Synthesized Zinc Oxide Nanoparticles Using Moringa olifera Ethanolic Extract Lessens Acrylamide-Induced Testicular Damage, Apoptosis, and Steroidogenesis-Related Gene Dysregulation in Adult Rats

This study assessed the possible protective role of green synthesized zinc oxide nanoparticles using Moringa olifera leaf extract (MO-ZNPs) in acrylamide (ACR)-induced reproductive dysfunctions in male rats. ACR (20 mg/kg b.wt/day) and/or MO-ZNPs (10 mg/kg b.wt/day) were given orally by gastric gavage for 60 days. Then, sperm parameters; testicular enzymes; oxidative stress markers; reproductive hormones including testosterone, luteinizing hormone (LH)-estradiol, and follicle-stimulating hormone (FSH) concentration; testis histology; steroidogenesis-related gene expression; and apoptotic markers were examined. The findings revealed that MO-ZNPs significantly ameliorated the ACR-induced decline in the gonadosomatic index and altered the pituitary-gonadal axis, reflected by decreased serum testosterone and FSH with increased estradiol and LH, and sperm analysis disruption. Furthermore, a notable restoration of the tissue content of antioxidants (catalase and reduced glutathione) but depletion of malondialdehyde was evident in MO-ZNPs+ACR-treated rats compared to ACR-exposed ones. In addition, MO-ZNPs oral dosing markedly rescued the histopathological changes and apoptotic caspase-3 reactions in the testis resulting from ACR exposure. Furthermore, in MO-ZNPs+ACR-treated rats, ACR-induced downregulation of testicular steroidogenesis genes and proliferating cell nuclear antigen (PCNA) immune-expression were reversed. Conclusively, MO-ZNPs protected male rats from ACR-induced reproductive toxicity by suppressing oxidative injury and apoptosis while boosting steroidogenesis and sex hormones.

Recent advances in antibacterial coatings for orthodontic appliances

In the process of orthodontic treatment, the presence of orthodontic appliances makes it difficult to clean tooth surfaces. This can lead to an increased level of bacterial colonization, resulting in enamel demineralization and periodontal diseases. Considering the large surface area that orthodontic appliances usually have and that they can be in direct contact with bacteria throughout the treatment, modifications in the form of coatings on the surface of orthodontic appliances can be an effective and practical approach to reducing bacterial proliferation and preventing relevant adverse effects. In this mini-review, we discuss various antibacterial coatings which have been applied onto orthodontic appliances in recent 5 years, as well as their antibacterial mechanisms and methods for the preparation of these coatings. From this mini-review, both orthodontists and researchers can get the latest findings in the field of antibacterial coatings onto orthodontic appliances, which is helpful for the decision-making in clinical practice and research activities.

Investigating the Role of Classical Ayurveda-Based Incineration Process on the Synthesis of Zinc Oxide Based Jasada Bhasma Nanoparticles and Zn2+ Bioavailability

Jasada bhasma (JB) is a zinc oxide-based Indian traditional Ayurveda-based herbo-metallic nanoparticle used for the treatment of zinc (Zn) deficiency and autoimmune and inflammatory disorders. JB is made by following the Ayurveda-based guidelines using zinc oxide (ZnO) as a raw material and going through 17 cycles of the high-temperature incineration and trituration process known as "Ma̅raṇa" in the presence of herbal decoctions prepared from the leaves ofAzadirachta indica andAloe vera gel. These cycles improve the purity of the parent material and transform its physicochemical properties, converting it into nanoparticles. However, there still exists a knowledge gap regarding the role of incineration in the physicochemical transformation of the Zn raw material into JB nanoparticles and the biological interaction of the final product. In the present study, the JB samples obtained during different Ma̅raṇa cycles were carefully studied for their physicochemical transformation using analytical methods such as powdered X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and dynamic light scattering (DLS). According to the XRD results, the Zn and oxygen molecules in hexagonal ZnO wurtzite crystals gradually realigned as a result of repeated heat treatments that caused lattice tension and crystal size reduction from 53.14 to 42.40 nm. A morphological transition from 1.5 μm rod shape to 31 nm in the JB particles can be seen using FESEM and SAXS analyses. The existence of 10 nm-sized nanoparticles in the finished product was confirmed by HRTEM. The presence of ZnO was confirmed in all samples by FTIR and Raman spectroscopies. Cell viability analysis showed an inhibitory concentration 50% of >1000 μg/mL for JB nanoparticles, revealing no adverse effects in human colon Caco-2 cells. A dose-dependent uptake and intracellular accumulation of JB nanoparticles were observed in Caco-2 cells using inductively coupled plasma-based mass spectroscopy (ICP-MS). Bioavailability of Zn²⁺ ions (6% w/w) through JB dissolution in acidic pH 4.0 was observed, representing the stomach and intracellular lysosomal physiological conditions. Therefore, the study showed that the repeated incineration cycles produced biocompatible JB nanoparticles through the physicochemical transformation at molecular levels capable of delivering bioavailable Zn²⁺ ions under physiological conditions. In conclusion, the medicinal properties of JB nanoparticles described in Ayurveda were found to originate from their small size and dissolution properties, formed through the classical incineration-based synthesis process.

Development of New Health Risk Assessment of Nanoparticles: EPA Health Risk Assessment Revised

The concentration of nanoparticles in the ambient air can lead to induced toxicities; however, it appears that nanoparticles’ unique properties are completely omitted when assessing health risks. This paper aims to enhance the EPA health risk assessment by incorporating two new variables that consider the size of nanoparticles: the toxicity multiplier and the size multiplier. The former considers the qualitative aspect of the size of particles within a concentration, whilst the latter takes into account the effects associated with the number of particles of the specific i-th size distribution interval. To observe the impact of the new variables, a case study was performed. The studied element was cadmium, which was measured using ICP-MS to discover concentrations of size fractions, ranging from <15.1 to <9830 nm. Next, the cadmium concentration is assessed using both the current state-of-the-art method and the proposed method with adjustments. Based on the new approach, the final risk was 1.1 × 10−5, which was almost 24 times higher compared with the current method. The contribution of nanoparticles to the risk value grew from barely 6% to an alarming 88%. Therefore, the enhanced method can lead to more realistic results when assessing the health risks of nanoparticles.

Effect of Repeated Contact to Food Simulants on the Chemical and Functional Properties of Nano ZnO Composited LDPE Films for Reusable Food Packaging

The effect of repeated contact with food simulants on the properties and functionality of zinc oxide (ZnO) in nanocomposite films was investigated to examine possible safety hazards from the point of view of long-term use as food packaging. Low-density polyethylene (LDPE) embedded with 5 wt% nano-ZnO was immersed in distilled water, 50% ethanol, 4% acetic acid, and n-heptane. The cycle of immersion-rinse-dry was repeated up to 40 times for same sample under constant condition. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), field emission-scanning electron microscopy (FE-SEM), and UV-Vis spectroscopy analyses were performed to identify the changes in the chemical and functional properties of the nanocomposite film. Acetic acid had the greatest impact on the LDPE-ZnO nanocomposite films, while other food simulants caused little change. A new carboxylate bond was formed by the reaction of ZnO with acetic acid, as evidenced by the FTIR spectra. In addition, XRD and XAS confirmed the phase changes of nano-ZnO into zinc salts such as zinc hydroxy acetate or zinc acetate dihydrate. Furthermore, the light barrier property of the nanocomposite film drastically decreased, owing to the change in the bandgap of ZnO and film morphology.

Biocompatibility and Connectivity of Semiconductor Nanostructures for Cardiac Tissue Engineering Applications

Nano- or microdevices, enabling simultaneous, long-term, multisite, cellular recording and stimulation from many excitable cells, are expected to make a strategic turn in basic and applied cardiology (particularly tissue engineering) and neuroscience. We propose an innovative approach aiming to elicit bioelectrical information from the cell membrane using an integrated circuit (IC) bearing a coating of nanowires on the chip surface. Nanowires grow directly on the backend of the ICs, thus allowing on-site amplification of bioelectric signals with uniform and controlled morphology and growth of the NWs on templates. To implement this technology, we evaluated the biocompatibility of silicon and zinc oxide nanowires (NWs), used as a seeding substrate for cells in culture, on two different primary cell lines. Human cardiac stromal cells were used to evaluate the effects of ZnO NWs of different lengths on cell behavior, morphology and growth, while BV-2 microglial-like cells and GH4-C1 neuroendocrine-like cell lines were used to evaluate cell membrane–NW interaction and contact when cultured on Si NWs. As the optimization of the contact between integrated microelectronics circuits and cellular membranes represents a long-standing issue, our technological approach may lay the basis for a new era of devices exploiting the microelectronics’ sensitivity and “smartness” to both improve investigation of biological systems and to develop suitable NW-based systems available for tissue engineering and regenerative medicine.

Study on the biological effects of ZnO nanosheets on EBL cells

In this study, the biological effects of ZnO nanosheets were initially investigated using embryonic bovine lung (EBL) cells cultured in vitro as a model. ZnO nanosheets were prepared by a hydrothermal method, and their structure and morphology were characterized, and their effects on EBL cell viability, oxidative stress, cell proliferation, and apoptosis were investigated. The results showed that 12.5 μg ml⁻¹ ZnO nanosheets can cause morphological changes in EBL cells. The toxic effects of ZnO nanosheets on EBL cells were time-dependent. Caspase-3 activity in EBL cells changed under certain conditions with the introduction of 25 μg ml⁻¹ ZnO nanomaterials, and EBL cell apoptosis was promoted. Under different concentration and time effects, ZnO nanosheets induced an increase in ROS levels in EBL cells, indicating that they have an oxidative damage effect on cells. The toxic effects of ZnO nanosheets on EBL cells were discussed, including concentration effect, time effect, and cytotoxic effect, which eventually led to cell oxidative damage.

Size-Dependent Impact of Magnetic Nanoparticles on Growth and Sporulation of Aspergillus niger

Magnetic nanoparticles (MNPs) are becoming important DNA nanocarriers for genetic engineering of industrial fungi. However, the biological effect of MNPs on industrial fungi remains unknown. In this study, we prepared three kinds of magnetic nanoparticles with different sizes (i.e., 10 nm, 20 nm, and 200 nm) to investigate their impact on the growth and sporulation of the important industrial fungus Aspergillus niger. Transmission electron microscopy, X-ray diffraction analysis and Zeta potential analysis revealed that the three kinds of MNPs, including MNP10, MNP20 and MNP200, had uniform size distribution, regular Fe₃O₄ X-ray diffraction (XRD) patterns and similar Zeta potentials. Interestingly, although the three kinds of MNPs did not obviously inhibit growth of the fungus, the MNP20 at 500 mg/L strongly attenuated sporulation, leading to a remarkable decrease in spore numbers on culturing plates. Further investigation showed that MNP20 at the high concentration led to drastic chitin accumulation in the cell wall, indicating cell wall disruption of the MNP20-treated fungal cells. Moreover, the MNPs did not cause unusual iron dissolution and reactive oxygen species (ROS) accumulation, and the addition of ferrous ion, ferric ion or the reactive oxygen species scavenger N-acetyl-L-cysteine (NAC) had no impact on the sporulation of the fungus, suggesting that both iron dissolution and ROS accumulation did not contribute to attenuated sporulation by MNP20. This study revealed the size-dependent effect of MNPs on fungal sporulation, which was associated with MNP-induced cell wall disruption.

L-cysteine embedded core-shell ZnO microspheres composed of nanoclusters enhances anticancer activity against liver and breast cancer cells

Nano-based products have become an apparent and effective option to treat liver cancer, which is a deadly disease, and minimize or eradicate these problems. The Core-shell ZnO microspheres composed of nanoclusters (ZnOMS-NCs) have shown that it is very worthwhile to administer the proliferation rate in HepG2 and MCF-7 cancer cells even at a very low concentration (5 μg/mL). ZnOMS-NCs were prepared through hydrothermal solution process and well characterized. The MTT assay revealed that the cytotoxic effects were dose-dependent (2.5 μg/mL-100 μg/mL) on ZnOMS-NCs. The diminished activity in cell viability induces the cytotoxicity response to the ZnOMS-NCs treatment of human cultured cells. The qPCR data showed that the cells (HepG2 and MCF-7) were exposed to ZnOMS-NCs and exhibited up-and downregulated mRNA expression of apoptotic and anti-apoptotic genes, respectively. In conclusion, flow cytometric data exhibited significant apoptosis induction in both cancer cell lines at low concentrations. The possible mechanism also describes the role of ZnOMS-NCs against cancer cells and their responses.

Zinc oxide nanoparticles: Chemical and green synthesis, characterization, and comparative evaluation of their effects on caprine testis in vitro

The present research was designed to investigate the potential effects of zinc oxide nanoparticles synthesized by both chemical and green method in caprine testis. In this study, rod-shaped zinc oxide nanoparticles (ZnONPs) with diameter less than 100 nm were prepared by chemical and green method using polyvinyl pyrrolidone (PVP) and Ocimum sanctum leaf extract as stabilizing agents respectively. X-ray diffraction, Fourier transform infrared spectroscopy, LCMS, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and EDX were utilized to characterize the synthesized zinc oxide nanoparticles. The histomorphological alterations of both chemically synthesized and biosynthesized zinc oxide nanoparticles were evaluated after administration of two doses (10 µg/ml and 20 µg/ml) for exposure duration of 4 h and 8 h. Chemically synthesized zinc oxide nanoparticles induced significant damage in testicular cells in dose and time-dependent manner. The Histomorphological changes included desquamation in germinal epithelium, pyknosis in germ cells, increased vacuolization, loss of mature spermatozoa from lumen and wide interstitial space between seminiferous tubules. Protective effects of biosynthesized zinc oxide nanoparticles were recorded at lower dose whereas some alterations were observed when treated with 20 µg/ml for 4 h and 8 h culture duration. The results confirmed that phytochemicals present in leaf extract of O. sanctum mitigated the zinc oxide nanoparticles induced toxicity, proving biosynthesized nanoparticles are better than chemically synthesized nanoparticles.

Impact of in vitro digested zinc oxide nanoparticles on intestinal model systems

Background

Zinc oxide nanoparticles (ZnO NP) offer beneficial properties for many applications, especially in the food sector. Consequently, as part of the human food chain, they are taken up orally. The toxicological evaluation of orally ingested ZnO NP is still controversial. In addition, their physicochemical properties can change during digestion, which leads to an altered biological behaviour. Therefore, the aim of our study was to investigate the fate of two different sized ZnO NP (< 50 nm and < 100 nm) during in vitro digestion and their effects on model systems of the intestinal barrier. Differentiated Caco-2 cells were used in mono- and coculture with mucus-producing HT29-MTX cells. The cellular uptake, the impact on the monolayer barrier integrity and cytotoxic effects were investigated after 24 h exposure to 123–614 µM ZnO NP.

Results

In vitro digested ZnO NP went through a morphological and chemical transformation with about 70% free zinc ions after the intestinal phase. The cellular zinc content increased dose-dependently up to threefold in the monoculture and fourfold in the coculture after treatment with digested ZnO NP. This led to reactive oxygen species but showed no impact on cellular organelles, the metabolic activity, and the mitochondrial membrane potential. Only very small amounts of zinc (< 0.7%) reached the basolateral area, which is due to the unmodified transepithelial electrical resistance, permeability, and cytoskeletal morphology.

Conclusions

Our results reveal that digested and, therefore, modified ZnO NP interact with cells of an intact intestinal barrier. But this is not associated with serious cell damage.

Intracellular Trafficking and Distribution of Cd and InP Quantum Dots in HeLa and ML-1 Thyroid Cancer Cells

The study of the interaction of engineered nanoparticles, including quantum dots (QDs), with cellular constituents and the kinetics of their localization and transport, has provided new insights into their biological consequences in cancers and for the development of effective cancer therapies. The present study aims to elucidate the toxicity and intracellular transport kinetics of CdSe/ZnS and InP/ZnS QDs in late-stage ML-1 thyroid cancer using well-tested HeLa as a control. Our XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) viability assay (Cell Proliferation Kit II) showed that ML-1 cells and non-cancerous mouse fibroblast cells exhibit no viability defect in response to these QDs, whereas HeLa cell viability decreases. These results suggest that HeLa cells are more sensitive to the QDs compared to ML-1 cells. To test the possibility that transporting rates of QDs are different between HeLa and ML-1 cells, we performed a QD subcellular localization assay by determining Pearson’s Coefficient values and found that HeLa cells showed faster QDs transporting towards the lysosome. Consistently, the ICP-OES test showed the uptake of CdSe/ZnS QDs in HeLa cells was significantly higher than in ML-1 cells. Together, we conclude that high levels of toxicity in HeLa are positively correlated with the traffic rate of QDs in the treated cells.

Recent advances in ZnO-based photosensitizers: Synthesis, modification, and applications in photodynamic cancer therapy

Zinc oxide nanoparticles (ZnO NPs) are important semiconductor materials with interesting photo-responsive properties. During the past, ZnO-based NPs have received considerable attention for photodynamic therapy (PDT) due to their biocompatibility and excellent potential of generating tumor-killing reactive oxygen species (ROS) through gentle photodynamic activation. This article provides a comprehensive review of the recent developments and improvements in optical properties of ZnO NPs as photosensitizers for PDT. The optical properties of ZnO-based photosensitizers are significantly dependent on their charge separation, absorption potential, band gap engineering, and surface area, which can be adjusted/tuned by doping, compositing, and morphology control. Here, we first summarize the recent progress in the charge separation capability, absorption potential, band gap engineering, and surface area of nanosized ZnO-based photosensitizers. Then, morphology control that is closely related to their synthesis method is discussed. Following on, the state-of-art for the ZnO-based NPs in the treatment of hypoxic tumors is comprehensively reviewed. Finally, we provide some outlooks on common targeted therapy methods for more effective tumor killing, including the attachment of small molecules, antibodies, ligands molecules, and receptors to NPs which further improve their selective distribution and targeting, hence improving the therapeutic effectiveness. The current review may provide useful guidance for the researchers who are interested in this promising dynamic cancer treatment technology.

Preparation of Cotton-Zinc Composites by Magnetron Sputtering Metallization and Evaluation of their Antimicrobial Properties and Cytotoxicity

The aim of this investigation was to evaluate the biological properties of cotton-zinc composites. A coating of zinc (Zn) on a cotton fabric was successfully obtained by a DC magnetron sputtering system using a metallic Zn target (99.9%). The new composite was characterized using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), UV/Vis transmittance, and atomic absorption spectrometry with flame excitation (FAAS). The composite was tested for microbial activity against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and antifungal activity against Aspergillus niger and Chaetomium globosum fungal mold species as model microorganisms. Cytotoxicity screening of the tested modified material was carried out on BALB/3T3 clone mouse fibroblasts. The SEM/EDS and FAAS tests showed good uniformity of zinc content on a large surface of the composite. The conducted research showed the possibility of using the magnetron sputtering technique as a zero-waste method for producing antimicrobial textile composites.

Versatile activity and morphological effects of zinc oxide submicron particles as anticancer agents

Background: Submicron particles (SMPs), as novel bionanomaterials, offer complementary benefits to their conventional nano-counterparts. Aim: To explore zinc oxide (ZnO) SMPs' bioimaging and anticancer potentials. Materials & methods: ZnO SMPs were synthesized into two shapes. Fluorescent spectrum and microscopy were studied for the bioimaging property. Wound healing and Live/Dead assays of glioblastoma cells were characterized for anticancer activities. Results: ZnO SMPs exhibited a high quantum yield (49%) with stable orange fluorescence emission. Both morphologies (most significant in the rod shape) showed tumor-selective properties in cytotoxicity, inhibition to cell migration and attenuating the cancer-upregulated genes. The tumor selectivity was attributed to particle degradation and surface properties on pH dependency. Conclusion: The authors propose that ZnO SMPs could be a promising anticancer drug with tunable, morphology-dependent properties for bioimaging and controlled release.

Metal nanoparticles as a promising technology in targeted cancer treatment

Traditional anticancer treatments have several limitations, but cancer is still one of the deadliest diseases. As a result, new anticancer drugs are required for the treatment of cancer. The use of metal nanoparticles (NPs) as alternative chemotherapeutic drugs is on the rise in cancer research. Metal NPs have the potential for use in a wide range of applications. Natural or surface-induced anticancer effects can be found in metals. The focus of this review is on the therapeutic potential of metal-based NPs. The potential of various types of metal NPs for tumor targeting will be discussed for cancer treatment. The in vivo application of metal NPs for solid tumors will be reviewed. Risk factors involved in the clinical application of metal NPs will also be summarized.

Antibacterial action and target mechanisms of zinc oxide nanoparticles against bacterial pathogens

Zinc oxide nanoparticles (ZnO NPs) are one of the most widely used nanoparticulate materials due to their antimicrobial properties, but their main mechanism of action (MOA) has not been fully elucidated. This study characterized ZnO NPs by using X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy. Antimicrobial activity of ZnO NPs against the clinically relevant bacteria Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and the Gram-positive model Bacillus subtilis was evaluated by performing resazurin microtiter assay (REMA) after exposure to the ZnO NPs at concentrations ranging from 0.2 to 1.4 mM. Sensitivity was observed at 0.6 mM for the Gram-negative and 1.0 mM for the Gram-positive cells. Fluorescence microscopy was used to examine the interference of ZnO NPs on the membrane and the cell division apparatus of B. subtilis (amy::pspac-ftsZ-gfpmut1) expressing FtsZ-GFP. The results showed that ZnO NPs did not interfere with the assembly of the divisional Z-ring. However, 70% of the cells exhibited damage in the cytoplasmic membrane after 15 min of exposure to the ZnO NPs. Electrostatic forces, production of Zn²⁺ ions and the generation of reactive oxygen species were described as possible pathways of the bactericidal action of ZnO. Therefore, understanding the bactericidal MOA of ZnO NPs can potentially help in the construction of predictive models to fight bacterial resistance.

Effects of Metal Oxide Nanoparticles in Zebrafish

Metal oxide nanoparticles (MO NPs) are increasingly employed in many fields with a wide range of applications from industries to drug delivery. Due to their semiconducting properties, metal oxide nanoparticles are commonly used in the manufacturing of several commercial products available in the market, including cosmetics, food additives, textile, paint, and antibacterial ointments. The use of metallic oxide nanoparticles for medical and cosmetic purposes leads to unavoidable human exposure, requiring a proper knowledge of their potentially harmful effects. This review offers a comprehensive overview of the possible toxicity of metallic oxide nanoparticles in zebrafish during both adulthood and growth stages, with an emphasis on the role of oxidative stress.

Antioxidant and Antibacterial Profiling of Pomegranate-pericarp Extract Functionalized-zinc Oxide Nanocomposite

With the advancement in green nanotechnology, considerable attention is being given to the synthesis of different kinds of nanomaterials for biological applications. In this study, zinc oxide nanocomposites (ZnO NPs) were synthesized using Punica granatum L. (Pomegranate) pericarp ethanolic extract (PE) by the chemical precipitation method. The prepared ZnO NPs showed a characteristic peak at 270 nm in the UV-Vis spectrophotometer and chemical bond stretching in the Fourier transforms infrared spectroscopy (FT-IR) spectra, indicated the formation of PE-functionalized zinc oxide nanocomposite (PE-ZnO NPs). The SEM results showed agglomerated PE-ZnO NPs of a spherical shape with an average size of 80-100 nm. Moreover, biological assessment of the PE-ZnO NPs revealed significant scavenging activity in DPPH (116.5%) and ABTS^·+ (95.2%) radical assay methods, and substantial antibacterial activity against Bacillus cereus, Bacillus licheniformis, and Escherichia coli. Furthermore, PE-ZnO NPs showed about 96.3% of cell viability for human HaCaT cells at the maximum concentration (100 µg/mL), marked as a reliable bioactive agent. Therefore, the developed PE-ZnO NPs were elucidated with substantial ROS scavenger and non-antibiotic antibacterial agent and hence, can be applied in respective biological applications.

Curcumin nanoformulations to combat aging-related diseases

Aging increases the susceptibility to a diverse set of diseases and disorders, including neurodegeneration, cancer, diabetes, and arthritis. Natural compounds are currently being explored as alternative or complementary agents to treat or prevent aging-related malfunctions. Curcumin, a phytochemical isolated from the spice turmeric, has garnered great interest in recent years. With anti-oxidant, anti-inflammatory, anti-microbial, and other physiological activities, curcumin has great potential for health applications. However, the benefits of curcumin are restricted by its low bioavailability and stability in biological systems. Curcumin nanoformulations, or nano-curcumin, may overcome these limitations. This review discusses different forms of nano-curcumin that have been evaluated in vitro and in vivo to treat or prevent aging-associated health impairments. We describe current barriers for the routine use of curcumin nanoformulations in the clinic. Our review highlights outstanding questions and future work that is needed to ensure nano-curcumin is efficient and safe to lessen the burden of aging-related health problems.

Antiprotozoal and anthelmintic activity of zinc oxide nanoparticles

Nanomaterials represent a wide alternative for the treatment of several diseases that affect both human and animal health. The use of these materials mainly involves trying to solve the problem of resistance that pathogenic organisms acquire to conventional drugs. A well-studied example that represents a potential component for biomedical applications is the use of zinc oxide (ZnO) nanoparticles (NPs). Its antimicrobial function is related, especially the ability to generate/induce ROS that affects the homeostasis of the pathogen in question. Protozoa and helminths that harm human health and the economic performance of animals have already been exposed to this type of nanoparticle. Thus, through this review, our goal is to discuss the state-of-the-art effect of ZnO NPs on these parasites.

An updated overview on metal nanoparticles toxicity

Although thousands of different nanoparticles (NPs) have been identified and synthesized to date, well-defined, consistent guidelines to control their exposure and evaluate their potential toxicity have yet to be fully established. As potential applications of nanotechnology in numerous fields multiply, there is an increased awareness of the issue of nanomaterials' toxicity among scientists and producers managing them. An updated inventory of customer products containing NPs estimates that they currently number over 5.000; ten years ago, they were one fifth of this. More often than not, products bear no information regarding the presence of NPs in the indicated list of ingredients or components. Consumers are therefore largely unaware of the extent to which nanomaterials have entered our lives, let alone their potential risks. Moreover, the lack of certainties with regard to the safe use of NPs is curbing their applications in the biomedical field, especially in the diagnosis and treatment of cancer, where they are performing outstandingly but are not yet being exploited as much as they could. The production of radical oxygen species is a predominant mechanism leading to metal NPs-driven carcinogenesis. The release of particularly reactive metal ions capable of crossing cell membranes has also been implicated in NPs toxicity. In this review we discuss the origin, behavior and biological toxicity of different metal NPs with the aim of rationalizing related health hazards and calling attention to toxicological concerns involved in their increasingly widespread use.

Multifunctional CuxS- and DOX-loaded AuNR@mSiO2 platform for combined melanoma therapy with inspired antitumor immunity

Combined antitumor therapies based on nanomedicines have shown efficacy in various tumor models in recent years, overcoming the disadvantages of inefficiency and undesired toxicity of traditional therapies. Herein, we present a copper sulfide- and doxorubicin-loaded gold nanorods@mesoporous SiO2 multifunctional nanocomposite (AuNR@mSiO2@DOX-CuxS-PEG) to integrate chemotherapy, the photothermal properties of AuNRs, and the photodynamic properties of CuxS into a single nanoplatform based on hydrophobic interaction and electrostatic attraction. Upon near-infrared light irradiation, the AuNR@mSiO2@DOX-CuxS-PEG nanocomposites exhibit a synergistic therapeutic effect and inhibit the in situ tumor growth and lung metastasis in a melanoma model. This occurs because of the high photothermal conversion efficiency, boosted intracellular reactive oxygen species production, and excellent doxorubicin (DOX) release, as well as an induced tumor-specific immune response. The inspired antitumor immunity was confirmed by elevated infiltration of activated T cells in tumor tissues and improved maturation and activation of dendritic cells in tumor-draining lymph nodes. This study highlights the superior antitumor therapeutic effect elicited by a multifunctional nanoplatform for skin with in situ melanoma and lung metastasis inhibition, indicating its satisfactory clinical application prospects.

A comparative study of toxicity of graphdiyne and graphene oxide to human umbilical vein endothelial cells

The success of graphene oxide (GO) has attracted extensive research interests in developing novel 2D nanomaterials (NMs). Graphdiyne (GDY) is a new member of carbon-based 2D NMs possessing sp- and sp² -hybridized carbon atoms. However, the toxicity of GDY is less investigated as GO. In this study, we compared the toxicity of GDY and GO with human umbilical vein endothelial cells (HUVECs). Exposure to up to 100-μg/ml GDY and GO induced cytotoxicity, but there was no statistically significant difference between GDY and GO. At noncytotoxic concentration, 25-μg/ml GDY or GO led to the internalization of NMs, typically in cytoplasm but not in nuclei. Only GO but not GDY significantly increased THP-1 adhesion onto NM-exposed HUVECs. Meanwhile, compared with GDY, GO more effectively promoted the release of soluble intracellular cell adhesion molecule-1 (sICAM-1), indicating the differential effects of GDY and GO on endothelial activation. Neither GDY nor GO induced intracellular superoxide. However, GO significantly promoted the expression of endoplasmic reticulum (ER) stress genes activating transcription factor 4 (ATF4) and X-box binding protein 1 spliced (XBP-1s), as well pyroptosis genes NLR family pyrin domain containing 3 (NLRP3) and gasdermin D (GSDMD), whereas GDY did not show this effect. The results suggested that GDY and GO could be internalized into HUVECs leading to cytotoxic effects. However, GO was more potent to activate endothelial activation probably due to the activation of ER stress and pyroptosis genes.

CdSe/ZnS Core-Shell-Type Quantum Dot Nanoparticles Disrupt the Cellular Homeostasis in Cellular Blood-Brain Barrier Models

Two immortalized brain microvascular endothelial cell lines (hCMEC/D3 and RBE4, of human and rat origin, respectively) were applied as an in vitro model of cellular elements of the blood–brain barrier in a nanotoxicological study. We evaluated the impact of CdSe/ZnS core-shell-type quantum dot nanoparticles on cellular homeostasis, using gold nanoparticles as a largely bioorthogonal control. While the investigated nanoparticles had surprisingly negligible acute cytotoxicity in the evaluated models, a multi-faceted study of barrier-related phenotypes and cell condition revealed a complex pattern of homeostasis disruption. Interestingly, some features of the paracellular barrier phenotype (transendothelial electrical resistance, tight junction protein gene expression) were improved by exposure to nanoparticles in a potential hormetic mechanism. However, mitochondrial potential and antioxidant defences largely collapsed under these conditions, paralleled by a strong pro-apoptotic shift in a significant proportion of cells (evidenced by apoptotic protein gene expression, chromosomal DNA fragmentation, and membrane phosphatidylserine exposure). Taken together, our results suggest a reactive oxygen species-mediated cellular mechanism of blood–brain barrier damage by quantum dots, which may be toxicologically significant in the face of increasing human exposure to this type of nanoparticles, both intended (in medical applications) and more often unintended (from consumer goods-derived environmental pollution).

Antitumor and Radiosensitizing Effects of Zinc Oxide-Caffeic Acid Nanoparticles against Solid Ehrlich Carcinoma in Female Mice

This study aimed to evaluate the anticancer and radio-sensitizing efficacy of Zinc Oxide-Caffeic Acid Nanoparticles (ZnO-CA NPs). ZnO-CA NPs were formulated by the conjugation of Zinc Oxide nanoparticles (ZnO NPs) with caffeic acid (CA) that were characterized by Fourier Transform Infrared Spectra (FT-IR), X-ray Diffractometer (XRD), and Transmission Electron Microscopy (TEM). In vitro anticancer potential of ZnO-CA NPs was evaluated by assessing cell viability in the human breast (MCF-7) and hepatocellular (HepG2) carcinoma cell lines. In vivo anticancer and radio-sensitizing effects of ZnO-CA NPs in solid Ehrlich carcinoma-bearing mice (EC mice) were also assessed. Treatment of EC mice with ZnO-CA NPs resulted in a considerable decline in tumor size and weight, down-regulation of B-cell lymphoma 2 (BCL2) and nuclear factor kappa B (NF-κB) gene expressions, decreased vascular cell adhesion molecule 1 (VCAM-1) level, downregulation of phosphorylated-extracellular-regulated kinase 1 and 2 (p-ERK1/2) protein expression, DNA fragmentation and a recognizable peak at sub-G0/G1 indicating dead cells' population in cancer tissues. Combined treatment of ZnO-CA NPs with γ-irradiation improved these effects. In conclusion: ZnO-CA NPs exhibit in-vitro as well as in-vivo antitumor activity, which is augmented by exposure of mice to γ-irradiation. Further explorations are warranted previous to clinical application of ZnO-CA NPs.

Comparison of cytotoxicity of Ag/ZnO and Ag@ZnO nanocomplexes to human umbilical vein endothelial cells in vitro

Novel metal and metal oxide-based nanocomplexes are being developed due to their superior properties compared with nanoparticles (NPs) based on single composition. In this study, we synthesized Ag-coated ZnO (Ag/ZnO) and Ag-doped ZnO (Ag@ZnO) NPs. The cytotoxicity and mechanisms associated with the synthesized NPs were investigated to understand the influence of Ag positions on biocompatibility of the NPs. After exposure to human umbilical vein endothelial cells (HUVECs), Ag/ZnO, Ag@ZnO, and ZnO NPs all significantly induced cytotoxicity, but the cytotoxic effects of Ag/ZnO and Ag@ZnO NPs were more modest in comparison with ZnO NPs. At cytotoxic concentrations, all NPs significantly induced intracellular Zn ions, which suggested a role of excessive Zn ions on cytotoxicity of NPs. All types of NPs significantly induced the expression of endoplasmic reticulum (ER) stress genes including DNA damage-inducible transcript 3 (DDIT3), X-box binding protein 1 (XBP-1), and ER to nucleus signaling 1 (ERN1), but Ag/ZnO and Ag@ZnO NPs were less effective to induce DDIT3 and XBP-1 expression compared with ZnO NPs. Not surprisingly, only ZnO NPs significantly induced the expression of caspase 3. Combined, the results from this study showed that Ag/ZnO and Ag@ZnO NPs were less cytotoxic and less potent to induce ER stress gene expression compared with ZnO NPs, but there were no significant differences between Ag/ZnO and Ag@ZnO NPs. Our results may provide novel understanding about the biocompatibility of Ag-ZnO nanocomplexes.

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.