Cellular Uptake and Toxicological Effects of Differently Sized Zinc Oxide Nanoparticles in Intestinal Cells

Enhanced applications in dentistry through autoclave-assisted sonochemical synthesis of Pb/Ag/Cu trimetallic nanocomposites

In recent years, researchers have increasingly focused on the development of multiphase trimetallic nanocomposites (TMNC) incorporating ternary metals or metal oxides, which hold significant potential as alternatives for combatting biofilms and bacterial infections. Enhanced oral health is ensured by the innovative techniques used to effectively prevent bacterial adherence and formation of biofilm on dental sutures. In this investigation, TMNC, which consists of Pb, Ag, and Cu, was synthesized using an autoclave-assisted sonochemical technique. Following synthesis, TMNC were characterized using FTIR, XRD, BET, XPS, TGA, and Raman spectroscopy to analyze their shape and microstructure. Subsequent evaluations, including MTT assay, antibacterial activity testing, and biofilm formation analysis, were conducted to assess the efficiency of the synthesized TMNC. Cytotoxicity and anti-human oral squamous cell carcinoma activities of TMNC were evaluated using the Human Oral Cancer cell line (KB) cell line through MTT assay, demonstrating a dose-dependent increase in anti-human oral squamous cell carcinoma activity against the KB cell line compared to the normal cell line, resulting in notably high cell viability. Furthermore, an ultrasonic probe was employed to incorporate TMNC onto dental suturing threads, with different concentrations of TMNC, ultrasonic power levels, and durations considered to determine optimal embedding conditions that result in the highest antibacterial activity. The inhibitory effects of TMNC, both in well diffusion assays and when incorporated into dental suturing threads, against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria on Mueller-Hinton agar (MHA) were assessed using various concentrations of TMNC. The results of the study indicated that the efficacy of TMNC in inhibiting bacterial growth on dental suturing threads remained impressive, even at low concentrations. Moreover, an evaluation of their potential to destabilize biofilms formed by S. aureus and E. coli, the two pathogens in humans, indicated that TMNC would be a promising anti-biofilm agent.

Toxicological inhalation studies in rats to substantiate grouping of zinc oxide nanoforms

BACKGROUND

Significant variations exist in the forms of ZnO, making it impossible to test all forms in in vivo inhalation studies. Hence, grouping and read-across is a common approach under REACH to evaluate the toxicological profile of familiar substances. The objective of this paper is to investigate the potential role of dissolution, size, or coating in grouping ZnO (nano)forms for the purpose of hazard assessment. We performed a 90-day inhalation study (OECD test guideline no. (TG) 413) in rats combined with a reproduction/developmental (neuro)toxicity screening test (TG 421/424/426) with coated and uncoated ZnO nanoforms in comparison with microscale ZnO particles and soluble zinc sulfate. In addition, genotoxicity in the nasal cavity, lungs, liver, and bone marrow was examined via comet assay (TG 489) after 14-day inhalation exposure.

RESULTS

ZnO nanoparticles caused local toxicity in the respiratory tract. Systemic effects that were not related to the local irritation were not observed. There was no indication of impaired fertility, developmental toxicity, or developmental neurotoxicity. No indication for genotoxicity of any of the test substances was observed. Local effects were similar across the different ZnO test substances and were reversible after the end of the exposure.

CONCLUSION

With exception of local toxicity, this study could not confirm the occasional findings in some of the previous studies regarding the above-mentioned toxicological endpoints. The two representative ZnO nanoforms and the microscale particles showed similar local effects. The ZnO nanoforms most likely exhibit their effects by zinc ions as no particles could be detected after the end of the exposure, and exposure to rapidly soluble zinc sulfate had similar effects. Obviously, material differences between the ZnO particles do not substantially alter their toxicokinetics and toxicodynamics. The grouping of ZnO nanoforms into a set of similar nanoforms is justified by these observations.

Effects of Zinc Oxide Nanoparticles Supplementation on Growth Performance, Meat Quality and Serum Biochemical Parameters in Broiler Chicks

The zinc oxide nanoparticles (ZnONPs) have attracted exhilarating research interest due to their novel distinguishing characteristics such as size, shape, high surface activity, large surface area and biocompatibility. Being highly bioavailable and exerting a superior efficacy than conventional zinc sources, ZnONPs is emerging as an alternative feed supplement for poultry. The present study involves the synthesis of ZnONPs through a cost effective and eco-friendly method using planetary ball milling technique and characterized for its size, shape, optical property, functional group and elemental concentration using particle size analyzer, Transmission Electron Microscopy, X-Ray Diffraction analysis, Fourier Transform Infra-Red spectroscopy, UV-Vis spectroscopy and Inductively Coupled Plasma-Mass Spectroscopy. In vitro cytotoxicity study using Baby Hamster kidney (BHK-21) cells, Vero cells and primary chick liver culture cells revealed that ZnONPs can be safely incorporated in the broiler chick's feed up to the concentration of 100 mg/kg. To investigate the effects of ZnONPs on production performances in broiler chicks, a feeding trial was carried out using 150-day-old broiler chicks randomly allotted in five treatment groups. The dietary treatment groups were: T1 (80 mg/kg of zinc oxide), T2 (60 mg/kg of zinc methionine) and T3, T4 and T5 received 60, 40 and 20 mg/kg of ZnONPs respectively. The results showed a significant improvement (p < 0.05) in the body weight gain and feed conversion ratio of broiler chicks supplemented with 20 and 40 mg/kg of ZnONPs. The ZnONPs supplementation significantly (p < 0.05) increased the dressing percentage in addition to significant (p < 0.05) reduction in the meat pH compared to inorganic and organic zinc supplementation. Overall, an eco-friendly method for ZnONPs synthesis was demonstrated and the optimum dietary level (20 mg/kg) of ZnONPs could enhance the growth, the meat quality and Zn uptake without any negative effects on selected serum biochemical parameters in the broiler chicks.

Peptides with Charged Amino Acids Mitigate nZnO-Induced Growth Inhibition of Lactobacillus rhamnosus LRa05

Growing concern is about the potential side effects of nanomaterials from food packaging, notably zinc oxide nanoparticles (nZnO). Previous research revealed that walnut-derived peptides could mitigate this inhibitory effect, but the mechanism involved is unclear. Here, we found that not all peptides have such an effect. Based on the growth inhibition model of Lactobacillus rhamnosus LRa05 induced by nZnO, we assessed the protective effects of various peptides. Notably, four peptides containing charged amino acids (PPKNW, WPPKN, ADIYTE, and WEREEQE) were found to effectively alleviate the growth inhibition phenomenon. We hypothesize that the peptide-nZnO interaction modifies this effect, as confirmed through infrared, Raman, and fluorescence spectroscopy. Our results highlight amide bonds, amino groups, carboxyl groups, and benzene rings as key peptide binding sites on nZnO, with static quenching primarily due to hydrogen bonds and van der Waals forces. This study elucidates peptide characteristics in nZnO interactions, facilitating a deeper exploration of food matrix-nanocomposite interactions.

Enantioselective Antiviral Activities of Chiral Zinc Oxide Nanoparticles

Chiral nanoparticles (C-NPs) play a crucial role in biomedical applications, especially in their biological effects on cytotoxicity and metabolism. However, there are rare reports about the antivirus property of C-NPs and their working mechanism. Here, three different types of chiral ZnO NPs (l-ZnO, d-ZnO, and dl-ZnO) were prepared as enantioselective antivirals. Biocompatibility test results showed that the three different chiral ZnO NPs varied significantly in cytotoxicity. Evaluation of their effects against porcine reproductive and respiratory syndrome virus (PRRSV) indicated that compared with d-ZnO and dl-ZnO NPs, l-ZnO NPs exhibited stronger anti-PRRSV activity due to their higher cognate cell adhesion and uptake. Furthermore, the high concentration of l-ZnO NPs can obviously reduce cellular reactive oxygen species (ROS) in MARC-145 cells, thus effectively preventing PRRSV-induced oxidative damage. This study demonstrated the outstanding antiviral properties of l-ZnO NPs, which may facilitate the development and application of C-NPs in antiviral drugs and tissue engineering.

In vitro genotoxicity assessment of biosynthesized zinc oxide nanoparticles

There are various studies on the toxicological potentials of conventionally synthesized zinc oxide (ZnO) nanoparticles, which are useful tools for many medical applications. However, knowledge about the biologically synthesized ones is still limited. In this study, the potential of producing ZnO nanoparticles via a green synthesis method, which enables safer, environmentally, economical and controlled production by using the Symphoricarpos albus L. plant, was investigated. For this purpose, aqueous extract was obtained from the fruits of the plant and reacted with zinc nitrate precursor. Characterization of the synthesized product was carried out by SEM and EDAX analyzes. In addition, the biosafety of the product was also investigated by using the Ames/Salmonella, E. coli WP2, Yeast DEL, seed germination, and RAPD test systems. The results obtained from SEM studies showed that spherical nanoparticles with an average diameter of 30 nm were synthesized as a result of the reaction. EDAX findings confirmed that these nanoparticles were composed of Zn and O elements. On the other hand, according to the findings of the biocompatibility tests, the synthesized nanoparticle did not show any toxic and genotoxic effects up to a concentration of 640 μg/ml in any of the test systems. Accordingly, considering the findings of our study, it was concluded that the aqueous extract of S. albus fruits can be used for the green synthesis of ZnO nanoparticles, the products obtained successfully passed the biocompatibility tests in our study, and additionally, more comprehensive biocompatibility tests should be performed before industrial scale production.

Influence of Dietary Biosynthesized Zinc Oxide Nanoparticles on Broiler Zinc Uptake, Bone Quality, and Antioxidative Status

A total of 180 broiler chickens (Cobb500) were randomly allotted to five experimental groups consisting of six replicates and six birds in each pen. Each group was fed a basal diet supplemented with 100 mg/kg ZnO (control) and 10, 40, 70, and 100 mg/kg ZnO NPs for 35 days. Resultantly, Zn uptake and accumulation in serum, breast muscle, tibia bone, and liver were linearly and significantly (p < 0.05) increased with increasing dietary ZnO NPs supplementation at 100 mg/kg compared to the control group (dietary 100 mg/kg ZnO), implying effective absorption capacity of ZnO NPs. This was followed by lower Zn excretion in feces in broilers fed ZnO NPs compared to controls (p < 0.05). Furthermore, dietary ZnO NPs at 40, 70, and 100 mg/kg levels improved broiler tibia bone morphological traits, such as weight, length, and thickness. Similarly, tibia bone mineralization increased in broilers fed ZnO NPs at 100 mg/kg compared to the control (p < 0.05), as demonstrated by tibia ash, Zn, Ca, and P retention. Antioxidative status in serum and liver tissue was also increased in broilers fed dietary ZnO NPs at 70 and 100 mg/kg compared to the control (p < 0.05). In conclusion, dietary ZnO NPs increased Zn absorption in broiler chickens and had a positive influence on tibia bone development and antioxidative status in serum and liver tissue, with dietary ZnO NPs supplementation at 70 and 100 mg/kg showing the optimum effects.

Electric field responsive nanotransducers for glioblastoma

Background

Electric field therapies such as Tumor Treating Fields (TTFields) have emerged as a bioelectronic treatment for isocitrate dehydrogenase wild-type and IDH mutant grade 4 astrocytoma Glioblastoma (GBM). TTFields rely on alternating current (AC) electric fields (EF) leading to the disruption of dipole alignment and induced dielectrophoresis (DEP) during cytokinesis. Although TTFields have a favourable side effect profile, particularly compared to cytotoxic chemotherapy, survival benefits remain limited (~ 4.9 months) after an extensive treatment regime (20 hours/day for 18 months). The cost of the technology also limits its clinical adoption worldwide. Therefore, the discovery of new technology that can enhance both the therapeutic efficiency and efficacy of these TTFields will be of great benefit to cancer treatment and decrease healthcare costs worldwide.

Methods

In this work, we report the role of electrically conductive gold (GNPs), dielectric silica oxide (SiO₂), and semiconductor zinc oxide (ZnO) nanoparticles (NPs) as transducers for enhancing EF mediated anticancer effects on patient derived GBM cells. Physicochemical properties of these NPs were analyzed using spectroscopic, electron microscopy, and light-scattering techniques.

Results

In vitro TTFields studies indicated an enhanced reduction in the metabolic activity of patient-derived Glioma INvasive marginal (GIN 28) and Glioma contrast enhanced core (GCE 28) GBM As per our journal style, article titles should not include capitalised letters unless these are proper nouns/acronyms. We have therefore used the article title “Electric field responsive nanotransducers for glioblastoma” as opposed to “Electric Field Responsive Nanotransducers for Glioblastoma” as given in the submission system. Please check if this is correct.cells in groups treated with NPs vs. control groups, irrespective of NPs dielectric properties. Our results indicate the inorganic NPs used in this work enhance the intracellular EF effects that could be due to the virtue of bipolar dielectrophoretic and electrophoretic effects.

Conclusions

This work presents preliminary evidence which could help to improve future EF applications for bioelectronic medicine. Furthermore, the merits of spherical morphology, excellent colloidal stability, and low toxicity, make these NPs ideal for future studies for elucidating the detailed mechanism and efficacy upon their delivery in GBM preclinical models.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42234-022-00099-7.

Recent advances in biobased and biodegradable polymer nanocomposites, nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs-this is biosynthesized from plant extracts-showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.

Lethality of Zinc Oxide Nanoparticles Surpasses Conventional Zinc Oxide via Oxidative Stress, Mitochondrial Damage and Calcium Overload: A Comparative Hepatotoxicity Study

Zinc oxide nanoparticles (ZnO NPs) with high bioavailability and excellent physicochemical properties are gradually becoming commonplace as a substitute for conventional ZnO materials. The present study aimed to investigate the hepatotoxicity mechanism of ZnO NPs and traditional non-nano ZnO particles, both in vivo and in vitro, and identify the differences in their toxic effects. The results showed that the extent and conditions of zinc ion release from ZnO NPs were inconsistent with those of ZnO. The RNA-seq results revealed that the expression quantity of differentially expressed genes (DEGs) and differentially expressed transcripts (DETs) affected by ZnO NPs was more than in ZnO, and the overall differences in genes or transcripts in the ZnO NPs group were more pronounced than in the ZnO group. Furthermore, the cell inactivation, oxidative stress, mitochondrial damage, and intracellular calcium overload induced by ZnO NPs were more serious than ZnO in HepG2 cells. Moreover, compared with traditional ZnO, the rat liver damage induced by ZnO NPs was more significant, with evidence of higher AST and ALT levels, weaker antioxidant capacity, and more serious histopathological damage (p < 0.05). In summary, the hepatotoxicity of ZnO NPs was more serious than that of conventional ZnO, which is helpful to understand the hepatotoxicity mechanism of Zn compounds in different states and improve the risk assessment of novel nano ZnO products in a variety of applications.

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.

Analysis of the In Vitro Toxicity of Nanocelluloses in Human Lung Cells as Compared to Multi-Walled Carbon Nanotubes

Cellulose micro/nanomaterials (CMNM), comprising cellulose microfibrils (CMF), nanofibrils (CNF), and nanocrystals (CNC), are being recognized as promising bio-nanomaterials due to their natural and renewable source, attractive properties, and potential for applications with industrial and economical value. Thus, it is crucial to investigate their potential toxicity before starting their production at a larger scale. The present study aimed at evaluating the cell internalization and in vitro cytotoxicity and genotoxicity of CMNM as compared to two multi-walled carbon nanotubes (MWCNT), NM-401 and NM-402, in A549 cells. The exposure to all studied NM, with the exception of CNC, resulted in evident cellular uptake, as analyzed by transmission electron microscopy. However, none of the CMNM induced cytotoxic effects, in contrast to the cytotoxicity observed for the MWCNT. Furthermore, no genotoxicity was observed for CNF, CNC, and NM-402 (cytokinesis-block micronucleus assay), while CMF and NM-401 were able to significantly raise micronucleus frequency. Only NM-402 was able to induce ROS formation, although it did not induce micronuclei. Thus, it is unlikely that the observed CMF and NM-401 genotoxicity is mediated by oxidative DNA damage. More studies targeting other genotoxicity endpoints and cellular and molecular events are underway to allow for a more comprehensive safety assessment of these nanocelluloses.

Effects of Zinc Oxide Nanoparticles on Model Systems of the Intestinal Barrier

Zinc oxide nanoparticles (ZnO NP) are often used in the food sector, among others, because of their advantageous properties. As part of the human food chain, they are inevitably taken up orally. The debate on the toxicity of orally ingested ZnO NP continues due to incomplete data. Therefore, the aim of our study was to examine the effects of two differently sized ZnO NP (<50 nm and <100 nm primary particle size; 123–614 µmol/L) on two model systems of the intestinal barrier. Differentiated Caco-2 enterocytes were grown on Transwell inserts in monoculture and also in coculture with the mucus-producing goblet cell line HT29-MTX. Although no comprehensive mucus layer was detectable in the coculture, cellular zinc uptake was clearly lower after a 24-h treatment with ZnO NP than in monocultured cells. ZnO NP showed no influence on the permeability, metabolic activity, cytoskeleton and cell nuclei. The transepithelial electrical resistance was significantly increased in the coculture model after treatment with ≥307 µmol/L ZnO NP. Only small zinc amounts (0.07–0.65 µg/mL) reached the basolateral area. Our results reveal that the cells of an intact intestinal barrier interact with ZnO NP but do not suffer serious damage.

Comparison Study of Cytotoxicity of Bare and Functionalized Zinc Oxide Nanoparticles

In this paper, a study of the cytotoxicity of bare and functionalized zinc oxide nanoparticles (ZnO NPs) is presented. The functionalized ZnO NPs were obtained by various types of biological methods including microbiological (intra- and extracellular with Lactobacillus paracasei strain), phytochemical (Medicago sativa plant extract) and biochemical (ovalbumin from egg white protein) synthesis. As a control, the bare ZnO NPs gained by chemical synthesis (commercially available) were tested. The cytotoxicity was measured through the use of (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye as well as lactate dehydrogenase (LDH) assays against murine fibroblast L929 and Caco-2 cell lines. As a complementary method, scanning electron microscopy (SEM) was performed to assess the morphology of the tested cells after treatment with ZnO NPs. The microscopic data confirmed the occurrence of apoptotic blebbing and loss of membrane permeability after the administration of all ZnO NPs. The reactive oxygen species (ROS) concentration during the cell lines’ exposure to ZnO NPs was measured fluorometrically. Additionally, the photocatalytic degradation of methylene blue (MB) dye in the different light conditions, as well as the antioxidant activity of bare and functionalized ZnO NPs, is also reported. The addition of all types of tested ZnO NPs to methylene blue resulted in enhanced rates of photo-degradation in the presence of both types of irradiation, but the application of UV light resulted in higher photocatalytic activity of ZnO NPs. Furthermore, bare (chemically synthetized) NPs have been recognized as the strongest photocatalysts. In the context of the obtained results, a mechanism underlying the toxicity of bio-ZnO NPs, including (a) the generation of reactive oxygen species and (b) the induction of apoptosis, is proposed.