Oxidative stress-induced cytotoxic and genotoxic effects of nano-sized titanium dioxide particles in human HaCaT keratinocytes

Effects of Nano-titanium Dioxide on Calcium Homeostasis in Vivo and in Vitro: a Systematic Review and Meta-analysis

With the extensive application of titanium dioxide nanoparticles (TiO₂ NPs), their impacts on calcium homeostasis have aroused extensive attention from scholars. However, there are still some controversies in relevant reports. Therefore, a systematic review was performed followed by a meta-analysis to explore whether TiO₂ NPs could induce the imbalance in calcium homeostasis in vivo and in vitro through Revman5.4 and Stata15.0 in this research. 14 studies were included through detailed database retrieval and literature screening. Results indicated that the calcium levels were significantly increased and the activity of Ca²⁺-ATPase was significantly decreased by TiO₂ NPs in vivo and in vitro. Subgroup analysis of the studies in vivo showed that TiO₂ NPs exposure caused a significant increase in calcium levels in rats, exposure to large-sized TiO₂ NPs (> 10 nm) and long-term (> 30 d) exposure could significantly increase calcium levels, and the activity of Ca²⁺-ATPase showed a concentration-dependent downward trend. Subgroup analysis of the studies in vitro revealed that intracellular calcium levels increased significantly in animal cells, exposure to small-sized TiO₂ NPs (≤ 10 nm) and high concentration (> 10 μg/mL) exposure could induce a significant increase in Ca²⁺ concentration, and the activity of Ca²⁺-ATPase also showed a concentration-dependent downward trend. This research showed that the physicochemical properties of TiO₂ NPs and the experimental scheme could affect calcium homeostasis.

Concerns with Male Infertility Induced by Exposure to Titanium Nanoparticles and the Supporting Impact of Pelargonium graveolens Essential Oil: Morphometric Records in Male-Wistar Rats

Background: Due to the increased use of titanium dioxide nanoparticles (TiO₂ NPs), the risks of their reprotoxic effect arise. This study anticipated examining the potential protective effects of GEO (geranium essential oil) components screened via GC/MS analysis against the reprotoxic impacts of TiO₂ NPs on male rats. Methods: Thirty-two adult male rats were randomly assigned to four groups: control, GEO (75 mg/kg bwt/orally/day/60 days), TiO₂ NPs (100 ppm/rat/IP/day/60 days), and TiO₂ NPs + GEO. After 60 days, hormonal assay, semen appraisal, lipid peroxidation, antioxidant enzymes, testis and prostate morphometry, and the steroidogenesis-related genes’ mRNA expressions were assessed. Results: The TEM and DLS results demonstrated that synthesized TiO₂ NPs are spherical with minimal aggregations polydispersed and varying in size from 50 to 100 nm. TiO₂ NPs IP injection-induced sperm abnormalities decreased the percent of motile sperms in the sperm count, reduced sex hormone levels, altered the testicular oxidant/antioxidant status and mRNA expression of steroid-related genes, and induced architectural alterations in testicular, epididymal, and prostate gland tissues. GEO significantly rescued the TiO₂ NPs-altered spermiogram, sex hormones, and antioxidant capacity, restored the tissue architectures, and enhanced steroidogenesis-related gene mRNA expression. Conclusions: These findings may significantly contribute to developing combinatorial treatments for infertility associated with various environmental and industrial xenobiotic exposures.

Evaluating the role of propolis and bee venom on the oxidative stress induced by gamma rays in rats

Honeybee products consist of many substances, which have long been known for their medicinal and health-promoting properties. This study set out to appraise the protective potential of Egyptian propolis (EP) and bee venom (BV) separately or combined against total body irradiation (TBI) induced oxidative injury in rats. Besides, we assessed the bioactive components in EP and BV using HPLC and UPLC/ ESI-MS analysis in the positive ion mode. The animals were subjected to a source of gamma ionizing radiation at a dose of 6 Gy. Propolis and BV were administered independently and in combination before 14 days of γ-irradiation. Liver and kidney functions were estimated besides, DNA damage index (8- OHdG) by ELISA. Antioxidants, including glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were detected. Gene expression technique investigated for BAX, BCL2, and in plasma also miR125b expression in serum of rats. Besides, the histopathological for the brain, liver, kidney, and heart were investigated. In addition, lipid peroxidation was investigated in plasma and in the previous organs. The present results provide opportunities to advance the use of bee products as promising medicinal sources.

Analysis of cytotoxicity and genotoxicity in a short-term dependent manner induced by a new titanium dioxide nanoparticle in murine fibroblast cells

The extensive use of titanium dioxide nanoparticles (TiO₂ NPs) in cosmetics, food, personal care products, and industries brought concerns about their possible harmful effects. Nowadays it has become important to assess TiO₂ NPs toxic effects as a way to understand their primary risks. In the cellular environment, after cell uptake, TiO₂ NPs were described to induce reactive oxygen species (ROS) production, unbalance oxidative state, and activate apoptosis in several cell lines. Therefore, we aimed to evaluate the cytotoxicity and genotoxicity of a new TiO₂ NP surface-functionalized with sodium carboxylic ligands in a murine fibroblast cell line (LA-9). TEM and DLS analyses were performed to define nanoparticle physicochemical characteristics. We evaluated the metabolic activity and LDH released after 24 h exposition to determine cytotoxic effects. Also, we evaluated DNA damage, intracellular reactive oxygen species (ROS) production, and apoptosis induction after 24 h exposure. The TiO₂ NP impaired the cell membrane integrity at 1000 μg/mL, induced intracellular ROS production and late apoptosis at 24 h. The genotoxic effects were observed at all conditions tested at 24 h. Indeed, in fibroblasts exposed at 100 μg/mL was observed early apoptosis cells. The intracellular ROS content was increased in a dose-dependent manner. Thus, short-term exposure to TiO₂ NP promoted cytotoxicity, genotoxicity and activated apoptosis pathways based on the potential role of oxygen species in the fibroblasts cell line.

ZnO NPs delay the recovery of psoriasis-like skin lesions through promoting nuclear translocation of p-NFκB p65 and cysteine deficiency in keratinocytes

BACKGROUND

This study aimed to evaluate the safety of applying zinc oxide nanoparticles (ZnO NPs) to pathological skin. The majority of previous studies confirmed the safety of applying ZnO NPs to normal skin. However, we know very little about the risks of using sunscreen, cosmetics and topical drugs containing ZnO NPs for individuals with skin diseases.

RESULTS

ZnO NPs passed through gaps between keratinocytes and entered stratum basale of epidermis and dermis in imiquimod-induced psoriasis-like skin lesions. Application of a ZnO NP-containing suspension for 3 connective days delayed the healing of the epidermal barrier; increased the expression levels of inflammatory cytokines; promoted keratinocyte apoptosis and disturbed redox homeostasis. In TNF-α-stimulated HaCaT cells, QNZ and JSH-23 (NFκB inhibitors) blocked ZnO NP-induced inflammation. JSH-23 and NAC (a precursor of cysteine) inhibited ZnO NP-induced nuclear translocation of p-NFκB p65, cysteine deficiency and apoptosis. Additionally, ZnO NPs decreased CD98 level in main pathway and failed to activate transsulfuration pathway in cysteine biosynthesis.

CONCLUSIONS

ZnO NPs can enter psoriasis-like skin lesions and promote inflammation and keratinocyte apoptosis through nuclear translocation of p-NFκB p65 and cysteine deficiency. This work reminds the public that ZnO NPs have harmful effects on the recovery of inflammatory skin diseases.

Nanoencapsulation of Pomegranate Extract to Increase Stability and Potential Dermatological Protection

Pomegranate extract (PG-E) has been reported to exert a protective effect on the skin due to its antioxidant activity. Ingredients rich in phenolic compounds are unstable in extract solutions, and, therefore, the use of a suitable nanosystem to encapsulate this type of extract could be necessary in different biotechnological applications. Thus, we investigated the capacity of Brassica oleracea L. (cauliflower) inflorescence vesicles (CI-vesicles) to encapsulate PG-E and determined the stability and the antioxidant capacity of the system over time. In addition, the protective effect against UV radiation and heavy metals in HaCaT cells was also tested. The CI-vesicles had an entrapment efficiency of around 50%, and accelerated stability tests did not show significant changes in the parameters tested. The results for the HaCaT cells showed the non-cytotoxicity of the CI-vesicles containing PG-E and their protection against heavy metals (lead acetate and mercuric chloride) and UV-B radiation through a reduction of oxidative stress. The reduction of the percentage of deleted mtDNA (mtDNA4977, "common deletion") in UV-treated HaCaT cells due to the presence of CI-vesicles containing PG-E indicated the mechanism of protection. Therefore, the effects of CI-vesicles loaded with PG-E against oxidative stress support their utilization as natural cosmeceuticals to protect skin health against external damage from environmental pollution and UV radiation.

Nanomedicine: Photo-activated nanostructured titanium dioxide, as a promising anticancer agent

The multivariate condition of cancer disease has been approached in various ways, by the scientific community. Recent studies focus on individualized treatments, minimizing the undesirable consequences of the conventional methods, but the development of an alternative effective therapeutic scheme remains to be held. Nanomedicine could provide a solution, filling this gap, exploiting the unique properties of innovative nanostructured materials. Nanostructured titanium dioxide (TiO₂) has a variety of applications of daily routine and of advanced technology. Due to its biocompatibility, it has also a great number of biomedical applications. It is now clear that photo-excited TiO₂ nanoparticles, induce generation of pairs of electrons and holes which react with water and oxygen to yield reactive oxygen species (ROS) that have been proven to damage cancer cells, triggering controlled cellular processes. The aim of this review is to provide insights into the field of nanomedicine and particularly into the wide context of TiO₂-NP-mediated anticancer effect, shedding light on the achievements of nanotechnology and proposing this nanostructured material as a promising anticancer photosensitizer.

Y2O3 decorated TiO2 nanoparticles: Enhanced UV attenuation and suppressed photocatalytic activity with promise for cosmetic and sunscreen applications

Nanoparticulate titanium dioxide (TiO₂) is widely used in cosmetic products and sunscreens. However, primarily due to their photocatalytic activity, some TiO₂ products have been shown to be cytotoxic. Thus, the aim of this study was to reduce the photoactivity and consequent cytotoxicity of TiO₂nanoparticles. As such, in this work, yttrium oxide (Y₂O₃) was deposited onto TiO₂, at 5% and 10% Y/Ti weight ratio, via a hydrothermal method. The nanocomposites produced, TiO₂@Y₂O₃ 5 and 10 wt%, were characterised to assess their physical, photochemical and toxicological properties. These materials exhibit a uniform yttria coating, enhanced UV attenuation in the 280-350 nm range and significantly reduced photoactivity compared with a pristine commercial TiO₂ sample (Degussa Aeroxide® P25). Furthermore, the comparative cytotoxicity and photo-cytotoxicity of these materials to a human keratinocyte cell line (HaCaT), was assessed using a colorimetric tetrazolium salt (MTS) assay. Following 24-hour incubation with cells, both Y₂O₃ loadings exhibited improved biocompatibility with HaCaT cells, compared to the pristine TiO₂ sample, under all subsequent test conditions. In conclusion, the results highlight the potential of these materials for use in products, applied topically, with sun protection in mind.

A Versatile Sunscreen with Minimal ROS Damage and Low Permeability

Organic and inorganic ultraviolet (UV) filters possess themselves advantages, while they suffer from different limitations including photostability, penetration, and cytotoxicity. Integrating organic and inorganic UV filters in a single unit holds great potential for enhanced UV protection. Herein, the dendritic silicon dioxide microspheres (DSMs) are encapsulated with Bi₂Ti₂O₇ nanocomposites (BTO-DSMs), an inorganic filter, and decorated with organic filters including sinapoyl malate (SM) and baicalin (BS/BTO-DSM) to enhance UV protection while significantly reducing ROS and skin permeability under UV exposure. The inorganic BTO-DSM component presents an expanded UV shield range and suppressed photocatalytic properties while preventing the organic filter SM direct contact with the epidermis and penetration behaviors. The baicalin efficiently scavenges the generated ROS from SM and reduces the transmittance of blue light. Notably, the results show that the proposed combined system significantly broadens the UV absorption region. Thus, the BS/BTO-DSM presents advanced in vitro anti-UV performance and in vivo UV protection against keratinocyte apoptosis and epidermal hyperplasia without long-term toxicity. The excellent anti-UV properties coupling with the suppressed photocatalytic capability and minimal epidermal penetration of BS/BTO-DSM make it promising for skin protection.

Survival Mechanisms and Xenobiotic Susceptibility of Keratinocytes Exposed to Metal-Derived Nanoparticles

Metal-derived nanoparticles (Mt-NPs) are increasingly used in cosmetology due to their ultraviolet shielding (titanium dioxide [TiO₂]), antioxidant (cerium dioxide [CeO₂]), and biocidal (silver [Ag]) properties. In the absence of overt toxicity (i.e., cell death), Mt-NPs are considered safe for cosmetic applications. However, there is little understanding about the mechanisms involved in the survival of keratinocytes exposed to subtoxic levels of Mt-NPs. Human keratinocytes (HaCaT) were exposed subacutely to subtoxic concentrations (≤30 μg/mL, 48-72 h) of rutile (r) TiO₂ (cylindrical), CeO₂ (cubic) and Ag (spherical) with a core/hydrodynamic size of <50/<100 nm and >98% purity. Mt-NP uptake was indirectly quantified by changes in the light side scatter, where the kinetics (time/dose-response) suggested that the three types of Mt-NPs were similarly uptaken by keratinocytes. rTiO₂ and CeO₂, but not Ag-NPs, increased autophagy, whose inhibition prompted cell death. No increase in the steady-state levels of reactive oxygen species (ROS) was induced by exposure to any of the Mt-NPs tested. Interestingly, intracellular Ag-NP aggregates observed an increased far-red autofluorescence (≥740 nm em), which has been ascribed to their binding to thiol molecules such as glutathione (GSH). Accordingly, inhibition of GSH synthesis, but not the impairment of oxidized GSH recycling, sensitized keratinocytes to Ag-NPs suggesting that GSH homeostasis, and its direct scavenging of Ag-NPs, but not ROS, is essential for keratinocyte survival upon exposure to Ag-NP. rTiO₂ and Ag, but not CeO₂-NPs, compromised metabolic flux (glycolysis and respiration), but ATP levels were unaltered. Finally, we also observed that exposure to Mt-NPs sensitized keratinocytes to non-UV xenobiotic exposure (arsenite and paraquat). Our results demonstrate the differential contribution of autophagy and GSH homeostasis to the survival of human keratinocytes exposed to subtoxic concentrations of Mt-NPs and highlight the increased susceptibility of keratinocytes exposed to Mt-NPs to a second xenobiotic insult.

Zinc oxide nanoparticles induce human multiple myeloma cell death via reactive oxygen species and Cyt-C/Apaf-1/Caspase-9/Caspase-3 signaling pathway in vitro

BACKGROUND

Human multiple myeloma (MM) is a malignant and incurable B cell tumor. Zinc oxide nanoparticles (ZnO NPs) have been widely used in biomedical fields including anti-bacterial and anti-tumor. However, the influence of ZnO NPs on MM cells is still unclear. The present study aimed to investigate the effect of ZnO NPs on MM cell (a human myeloma-derived RPMI8226 cell line) death in vitro and the underlying mechanism.

METHODS

The morphology of ZnO NPs was characterized by transmission electron microscopy (TEM), and the inhibitory and apoptotic effect of ZnO NPs on human MM cells was monitored by a CCK-8 method and an Annexin V-FITC/PI assay. Meanwhile, the morphological change in the cells after exposure to ZnO NPs was observed by a light field microscope. Moreover, the effects of ZnO NPs on the ATP level, reactive oxygen species (ROS) generation, and apoptosis were separately explored by the DCFH-DA fluorescent probe, flow cytometry, and ATP bioluminescence assay. Moreover, the expression of cytochrome C (Cyt-C), Apaf-1, Caspase-9 and Caspase-3 at mRNA and protein levels was further determined by using quantitative PCR (Q-PCR) and western blotting. In the present study, the human peripheral blood mononuclear cells (PBMCs) were used as normal control samples for the relevant experiment.

RESULTS

The results indicated that ZnO NPs could significantly inhibit human MM cell proliferation and cell death in a time- and dose-dependent manner in vitro, and this outcome can be confirmed by cell morphology and apoptosis assay. Meanwhile, the results also showed that ZnO NPs could effectively increase ROS production and decrease ATP levels in human MM cells. ZnO NPs could also significantly elevate the expression of Cyt-C, Apaf-1, Caspase-9 and Caspase-3 at mRNA and protein levels, leading to cell death. By contrast, ZnO NPs showed little cytotoxic influence on PBMCs.

CONCLUSION

ZnO NPs can significantly induce human MM cell death in a time- and dose-dependent manner in vitro, decrease the ATP production and enhance the ROS generation. ZnO NPs can also increase Cyt-C, Apaf-1, Caspase-9 and Caspase-3 expression at mRNA and protein levels in human MM cells, and initiate MM cell apoptosis, indicating that Cyt-C, Apaf-1, Caspase-9 and Caspase-3 play crucial roles in ZnO NPs-induced, mitochondria-mediated apoptosis in human MM cells. Overall, ZnO NPs may be a potential agent in treating human multiple myeloma in clinical practice.

Saccharomyces cerevisiae strains as bioindicators for titanium dioxide sunscreen photoprotective and photomutagenic assessment

Although several short-term assays are available for cosmetic photosafety assessment, cell models are usually highly sensitive to UV radiation, tending to overestimate both phototoxic and photomutagenic risks. In addition, these assays are performed with UV doses/fluences that do not correspond to actual environmental conditions. In this sense, Saccharomyces cerevisiae has already proved to be an interesting tool to predict photomutagenic potential of several compounds, including sunscreens. Yeast can support environmental UVB doses compatible with human daily sunlight exposure, allowing the use of irradiation sources to faithfully mimic the external conditions of ambient sunlight. Herein, we used a set of S. cerevisiae mutant strains sensitive to UVA, UVB and Solar Simulated Light sources in order to evaluate their potential as bioindicators for sunscreen development. The bioindicator potential of the strains was tested with the widely-used titanium dioxide inorganic sunscreen. The AWP001 (yno1) and LPW002 (ogg1yno1) strains obtained in this study stood out as promising experimental tools for the validation of this assay. Overall, our results evidenced a set of S. cerevisiae strains particularly useful for evaluating both photoprotective (efficacy) and photo/antiphotomutagenic (safety) potential of UV filters, meeting the industries and regulatory agencies demand for robust and efficient in vitro screening tests.

Fueling a Hot Debate on the Application of TiO2 Nanoparticles in Sunscreen

Titanium is one of the most abundant elements in the earth's crust and while there are many examples of its bioactive properties and use by living organisms, there are few studies that have probed its biochemical reactivity in physiological environments. In the cosmetic industry, TiO2 nanoparticles are widely used. They are often incorporated in sunscreens as inorganic physical sun blockers, taking advantage of their semiconducting property, which facilitates absorbing ultraviolet (UV) radiation. Sunscreens are formulated to protect human skin from the redox activity of the TiO2 nanoparticles (NPs) and are mass-marketed as safe for people and the environment. By closely examining the biological use of TiO2 and the influence of biomolecules on its stability and solubility, we reassess the reactivity of the material in the presence and absence of UV energy. We also consider the alarming impact that TiO2 NP seepage into bodies of water can cause to the environment and aquatic life, and the effect that it can have on human skin and health, in general, especially if it penetrates into the human body and the bloodstream.

Current Highlights About the Safety of Inorganic Nanomaterials in Healthcare

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In recent years inorganic materials are largely present in products intended for health care. Literature gives many examples of inorganic materials used in many healthcare products, mainly in pharmaceutical field.

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Silver, zinc oxide, titanium oxide, iron oxide, gold, mesoporous silica, hydrotalcite-like compound and nanoclays are the most common inorganic materials used in nanosized form for different applications in the health field. Generally, these materials are employed to realize formulations for systemic use, often with the aim to perform a specific targeting to the pathological site. The nanometric dimensions are often preferred to obtain the cellular internalization when the target is localized in the intracellular space.

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Some materials are frequently used in topical formulations as rheological agents, adsorbents, mattifying agents, physical sunscreen (e.g. zinc oxide, titanium dioxide), and others.

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Recent studies highlighted that the use of nanosized inorganic materials can represent a risk for health. The very small dimension (nanometric) until a few years ago represented a fundamental requirement; however, it is currently held responsible for the inorganic material toxicity. This aspect is very important to be considered as actually numerous inorganic materials can be found in many products available in the market, often dedicated to infants and children. These materials are used without taking into account their dimensional properties with increased risk for the user/patient.

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This review deals with a deep analysis of current researches documenting the toxicity of nanometric inorganic materials especially those largely used in products available in the market.

N-acetylcysteine reverses the decrease of DNA methylation status caused by engineered gold, silicon, and chitosan nanoparticles

Introduction: Engineered nanoparticles (ENPs) are one of the most widely used types of nanomaterials. Recently, ENPs have been shown to cause cellular damage by inducing ROS (reactive oxygen species) both directly and indirectly, leading to the changes in DNA methylation levels, which is an important epigenetic mechanism. In this study, we investigated the effect of ENP-induced ROS on DNA methylation.

Materials and methods: Human embryonic kidney and human keratinocyte (HaCaT) cells were exposed to three different types of ENPs: gold nanoparticles, silicon nanoparticles (SiNPs), and chitosan nanoparticles (CSNPs). We then evaluated the cytotoxicity of the ENPs by measuring cell viability, morphology, cell apoptosis, cell proliferation, cell cycle distribution and ROS levels. Global DNA methylation levels was measured using 5-methylcytosine immunocytochemical staining and HPLC analysis. DNA methylation levels of the transposable elements, long interspersed element-1 (LINE-1) and Alu, were also measured using combined bisulfite restriction analysis technique. DNA methylation levels of the TEs LINE-1 and Alu were also measured using combined bisulfite restriction analysis technique.

Results: We found that HaCaT cells that were exposed to SiNPs exhibited increased ROS levels, whereas HaCaT cells that were exposed to SiNPs and CSNPs experienced global and Alu hypomethylation, with no change in LINE-1 being observed in either cell line. The demethylation of Alu in HaCaT cells following exposure to SiNPs and CSNPs was prevented when the cells were pretreated with an antioxidant.

Conclusion: The global DNA methylation that is observed in cells exposed to ENPs is associated with methylation of the Alu elements. However, the change in DNA methylation levels following ENP exposure is specific to particular ENP and cell types and independent of ROS, being induced indirectly through disruption of the oxidative defense process.

The Effects of Apigenin-Biosynthesized Ultra-Small Platinum Nanoparticles on the Human Monocytic THP-1 Cell Line

Generally, platinum nanoparticles (PtNPs) are considered non-toxic; however, toxicity depends on the size, dose, and physico-chemical properties of materials. Owing to unique physico-chemical properties, PtNPs have emerged as a material of interest for several biomedical applications, particularly therapeutics. The adverse effect of PtNPs on the human monocytic cell line (THP-1) is not well-established and remains elusive. Exposure to PtNPs may trigger oxidative stress and eventually lead to inflammation. To further understand the toxicological properties of PtNPs, we studied the effect of biologically synthesized ultra-small PtNPs on cytotoxicity, genotoxicity, and proinflammatory responses in the human monocytic cell line (THP-1). Our observations clearly indicated that PtNPs induce cytotoxicity in a dose-dependent manner by reducing cell viability and proliferation. The cytotoxicity of THP-1 cells correlated with an increase in the leakage of lactate dehydrogenase, generation of reactive oxygen species, and production of malondialdehyde, nitric oxide, and carbonylated proteins. The involvement of mitochondria in cytotoxicity and genotoxicity was confirmed by loss of mitochondrial membrane potential, lower ATP level, and upregulation of proapoptotic and downregulation of antiapoptotic genes. Decreases in the levels of antioxidants such as reduced glutathione (GSH), oxidized glutathione (GSH: GSSG), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), and thioredoxin (TRX) were indicative of oxidative stress. Apoptosis was confirmed with the significant upregulation of key apoptosis-regulating genes. Oxidative DNA damage was confirmed by the increase in the levels of 8-oxodG and 8-oxoG and upregulation of DNA damage and repair genes. Finally, the proinflammatory responses to PtNPs was determined by assessing the levels of multiple cytokines such as interleukin-1β (IL-1β), IL-6, IL-8, tumor necrosis factor-α (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF), and monocyte chemoattractant protein 1 (MCP-1). All the cytokines were significantly upregulated in a dose-dependent manner. Collectively, these observations suggest that THP-1 cells were vulnerable to biologically synthesized ultra-small PtNPs.

Endocytosis, intracellular fate, accumulation, and agglomeration of titanium dioxide (TiO2) nanoparticles in the rainbow trout liver cell line RTL-W1

There is increasing evidence that titanium dioxide (TiO2) nanoparticles (NPs) present in water or diet can be taken up by fish and accumulate in internal organs including the liver. However, their further fate in the organ is unknown. This study provides new insights into the interaction, uptake mechanism, intracellular trafficking, and fate of TiO2 NPs (Aeroxide® P25) in fish liver parenchymal cells (RTL-W1) in vitro using high-resolution transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectrometry (spICP-MS) as complementary analytical techniques. The results demonstrate that following their uptake via caveolae-mediated endocytosis, TiO2 NPs were trafficked through different intracellular compartments including early endosomes, multivesicular bodies, and late endosomes/endo-lysosomes, and eventually concentrated inside multilamellar vesicles. TEM and spICP-MS results provide evidence that uptake was nano-specific. Only NPs/NP agglomerates of a specific size range (~ 30-100 nm) were endocytosed; larger agglomerates were excluded from uptake and remained located in the extracellular space/exposure medium. NP number and mass inside cells increased linearly with time and was associated with an increase in particle diameter suggesting intracellular agglomeration/aggregation. No alterations in the expression of genes regulated by the redox balance-sensitive transcription factor Nrf-2 including superoxide dismutase, glutamyl cysteine ligase, glutathione synthetase, glutathione peroxidase, and glutathione S-transferase were observed. This shows that, despite the high intracellular NP burden (~ 3.9 × 102 ng Ti/mg protein after 24 h) and NP-interaction with mitochondria, cellular redox homeostasis was not significantly affected. This study contributes to a better mechanistic understanding of in vitro particokinetics as well as the potential fate and effects of TiO2 NPs in fish liver cells.

Silver nanoparticles coated with dodecanethiol used as fillers in non-cytotoxic and antifungal PBAT surface based on nanocomposites

In the present study, we report the preparation of antifungal and non-cytotoxic polymer nanocomposites with potential application in biomedical materials. Dodecanethiol-protected silver nanoparticles (AgNPs-DDT) were synthesized by a reduction/precipitation method and dispersed in chloroform to obtain stable colloidal dispersions. PBAT-based nanocomposites containing 0.25, 0.5 and 2 wt% AgNPs-DDT were prepared by casting method. The incorporation of AgNPs-DDT in PBAT matrix resulted in nanocomposites which combine improved mechanical performance and antifungal properties with a non-cytotoxic characteristic.

Mitochondrial dysfunction, perturbations of mitochondrial dynamics and biogenesis involved in endothelial injury induced by silica nanoparticles

As silica nanoparticles (SiNPs) pervade the global economy, however, the followed emissions during the manufacturing, use, and disposal stages inevitably bring an environmental release, potentially result in harmful impacts. Endothelial dysfunction precedes cardiovascular disease, and is often accompanied by mitochondrial impairment and dysfunction. We had reported endothelial dysfunction induced by SiNPs, however, the related mechanisms by which SiNPs interact with mitochondria are not well understood. In the present study, we examined SiNPs-induced mitochondrial dysfunction, and further demonstrated their adverse effects on mitochondrial dynamics and biogenesis in endothelial cells (HUVECs). Consequently, SiNPs entered mitochondria, caused mitochondrial swelling, cristae disruption and even disappearance. Further analyses revealed SiNPs increased the intracellular level of mitochondrial reactive oxygen species, eventually resulting in the collapse of mitochondrial membrane potential, impairments in ATP synthesis, cellular respiration and the activities of three ATP-dependent enzymes (including Na⁺/K⁺-ATPase, Ca²⁺-ATPase and Ca²⁺/Mg²⁺-ATPase), as well as an elevated intracellular calcium level. Furthermore, mitochondria in SiNPs-treated HUVECs displayed a fission phenotype. Accordingly, dysregulation of the key gene expressions (FIS1, DRP1, OPA1, Mfn1 and Mfn2) involved in fission/fusion event further certified the SiNPs-induced perturbation of mitochondrial dynamics. Meanwhile, SiNPs-treated HUVECs displayed declined levels of mitochondrial DNA copy number, PGC-1α, NRF1 and also TFAM, indicating an inhibition of mitochondrial biogenesis triggered by SiNPs via PGC-1α-NRF1-TFAM signaling. Overall, SiNPs triggered endothelial toxicity through mitochondria as target, including the induction of mitochondrial dysfunction, as well as the perturbations of their dynamics and biogenesis.

Increased Level of α2,6-Sialylated Glycans on HaCaT Cells Induced by Titanium Dioxide Nanoparticles under UV Radiation

As one of the most widely used nanomaterials, the safety of nano-TiO₂ for human beings has raised concern in recent years. Sialylation is an important glycosylation modification that plays a critical role in signal transduction, apoptosis, and tumor metastasis. The aim of this work was to investigate the cytotoxicity and phototoxicity of nano-TiO₂ with different crystalline phases for human skin keratinocytes (HaCaT cells) under ultraviolet (UV) irradiation and detect sialic acid alterations. The results showed that the mixture of crystalline P25 had the highest cytotoxicity and phototoxicity, followed by pure anatase A25, whereas pure rutile R25 had the lowest cytotoxicity and phototoxicity. A25 and R25 had no effects on the expression of sialic acids on HaCaT cells. However, HaCaT cells treated with P25 and UV showed an increased level of alterations in α2,6-linked sialic acids, which was related to the level of reactive oxygen species (ROS) generated by nano-TiO₂ and UV. The abundance of α2,6-linked sialic acids increased as ROS production increased, and vice versa. Antioxidant vitamin C (VC) reversed the abnormal expression of α2,6-linked sialic acids caused by nano-TiO₂ and protected cells by eliminating ROS. These findings indicate that nano-TiO₂ can alter the sialylation status of HaCaT cells under UV irradiation in a process mediated by ROS.

Confinement of Reactive Oxygen Species in an Artificial-Enzyme-Based Hollow Structure To Eliminate Adverse Effects of Photocatalysis on UV Filters

Skin cancers caused by UV irradiation have been a major public health problem. One simple and effective way to avoid the above detrimental effects is the use of UV-protective sunscreens. However, there has been considerable concern with the issue of the production of reactive oxygen species (ROS) through the photodegradation of commercial UV filters. Herein, for the first time, it is reported that the integration of ZnO nanoparticles and CeO_x nanoparticles into hollow microspheres (ZnO/CeO_x HMS) could provide broad-spectrum UV protection and scavenge generated ROS under UV irradiation. Benefiting from the cooperative effect of the hollow structure and the antioxidative activity of CeO_x , ROS generated under UV irradiation could be confined to a limited space and effectively conversion into nontoxic molecules is catalyzed as a consequence of increased collision frequency. Therefore, both primary, direct UV-induced damage and secondary ROS toxicity could be greatly reduced.

Assessment of pulmonary toxicity of gold nanorods following intra-tracheal instillation in rats

The present investigation was aimed to evaluate the pulmonary toxicity of 10 and 25nm gold nanorods (GNRs) following intra-tracheal instillation in rats using bronchoalveolar lavage (BAL) fluid and lung histopathological analysis. The GNRs displayed that the dose-dependent toxicity via elevated lactate dehydrogenase leakage, alkaline phosphatase, lipid peroxidation and total microprotein levels in BAL fluids after 1day, 1 week and 1 month post exposure periods. All the parameters were returned to normal values after 3 months post exposure period may be due to recovery. The rat lung histopathology displayed that accumulation of macrophages, inflammatory response and tissue thickening for both sizes of GNRs. 10nm GNRs increased all BAL fluid parameters significantly following 1day, 1 week and 1 month post exposure periods whereas 25nm GNRs have shown similar effects but less extent. These investigations proposed that the dose and size dependent pulmonary toxicity of GNRs.

Evaluation of oxidative stress induction in rats following exposure to silver nanorods

The study investigated the oxidative stress induction by the 10 and 25 nm silver nanorods (SNRs) following intra-tracheal instillation in rats after 1 day, 1 week, 1 month and 3 months post instillation periods at 1 and 5 mg/kg b.w. doses. The blood was withdrawn by retro orbital plexus method after exposure periods and different oxidative stress markers were estimated. The results showed that the both sizes of SNRs induced increased levels of malondialdehyde (MDA) and depleted glutathione (GSH) levels after 1 day and 1 week post exposure periods. The 10 and 25 nm SNRs at both doses displayed that significantly reduced levels of superoxide dismutase (SOD) and catalase following 1 day and 1 week post exposure periods. Also, the results have shown that decrease in total antioxidant capacity (TAC) of both sizes of SNRs significantly following 1 day and 1 week post exposure periods, indicating the oxidative stress induction by SNRs. In spite, there were no significant changes in oxidative stress markers following 1 month and 3 months post exposure periods may be due to recovery. The increased levels of MDA and decreased levels of GSH, SOD, catalase and TAC activity are strongly associated to ROS production and lipid peroxidation, suggesting the induction of oxidative stress in rats. The 10 nm SNRs at 5 mg/kg b.w. dose exposures in rats have shown greater changes in all oxidative stress parameters, indicating the greater induction of oxidative stress when compared with the 25 nm SNRs, representing the size-dose-dependent induction of oxidative stress of SNRs.

Impact of anatase titanium dioxide nanoparticles on mutagenic and genotoxic response in Chinese hamster lung fibroblast cells (V-79): The role of cellular uptake

The unique physico-chemical properties of nano crystalline anatase titanium dioxide nanoparticles (TiO₂ NPs) render them with different biological and chemical activities. Hence, it is widely used in industrial and consumer applications. Previous studies have shown the genotoxicity of TiO₂ NPs. However, there is a paucity of data regarding mutagenicity of these NPs. In the present study, the cellular uptake, sub-cellular localization, cytotoxicity and short term DNA interaction of TiO₂ NPs (1-100 μgmL^-1) of diameter ranging from 12 to 25 nm on mammalian lung fibroblast cells (V-79) has been studied. The flow cytometric analysis and electron micrographs of V-79 monolayer showed the internalization of TiO₂ NPs in the cytoplasm with the confirmation of elemental composition through SEM/EDX analysis. TEM analysis also showed TiO₂ NPs induced ultra-structural changes such as swollen mitochondria and nuclear membrane disruption in V-79 cells. TiO₂ NPs generated free radicals, which induced indirect mutagenic and genotoxic responses. Apart from measuring the genotoxicity by Comet assay, the mutagenic potential of TiO₂ NPs in V-79 cells was evaluated by mammalian HGPRT gene forward mutation assay, showing a 2.98- fold increase in 6TG^R HGPRT mutant frequency (*p < 0.05, **p < 0.01, ***p < 0.001) by culture plate method, which is an early indicator of potential carcinogenicity. Hence, TiO₂ NPs should be closely monitored and there should be a judicious use and disposal of NPs.

Reproductive toxicity provoked by titanium dioxide nanoparticles and the ameliorative role of Tiron in adult male rats

Titanium dioxide nanoparticles (TDN) are widely used in paints, plastics, ceramics, cosmetics, printing ink, rubber and paper. Tiron is a water soluble metal chelator and antioxidant. This study was designed to investigate the reproductive toxicity of TDN in male albino rats and the ameliorative role of Tiron to minimize such toxic effects. Eighty adult male albino rats were assigned into 4 equal groups, group 1: control; group 2: received TDN at 100 mg/kg/day orally for 8 weeks; group 3: received Tiron at 470 mg/kg/day intraperitoneally for 2 weeks (the last 2 weeks of the experimental period); group 4: received both TDN and Tiron by the same previously mentioned dose, route and duration. The results revealed that TDN provoked reproductive toxicity which was proved by the deteriorated spermogram picture, high incidence of micronucleated RBCs, elevated oxidative stress parameters and up regulation of Testin gene. Whereas, Tiron co-treatment ameliorated most of these toxic alterations. Our findings highlighted the protective role of tiron against TDN intoxication.

Formulation and ex vivo evaluation of polymeric nanoparticles for controlled delivery of corticosteroids to the skin and the corneal epithelium

Controlled delivery of corticosteroids using nanoparticles to the skin and corneal epithelium may reduce their side effects and maximize treatment effectiveness. Dexamethasone-loaded ethyl cellulose, Eudragit® RS and ethyl cellulose/Eudragit® RS nanoparticles were prepared by the solvent evaporation method. Dexamethasone release from the polymeric nanoparticles was investigated in vitro using Franz diffusion cells. Drug penetration was also assessed ex vivo using excised human skin. Nanoparticle toxicity was determined by MTT and H2DCFDA assays. Eudragit® RS nanoparticles were smaller and positively charged but had a lower dexamethasone loading capacity (0.3-0.7%) than ethyl cellulose nanoparticles (1.4-2.2%). By blending the two polymers (1:1), small (105nm), positively charged (+37mV) nanoparticles with sufficient dexamethasone loading (1.3%) were obtained. Dexamethasone release and penetration significantly decreased with decreasing drug to polymer ratio and increased when Eudragit® RS was blended with ethyl cellulose. Ex vivo, drug release and penetration from the nanoparticles was slower than a conventional cream. The nanoparticles bear no toxicity potentials except ethyl cellulose nanoparticles had ROS generation potential at high concentration. In conclusion, the nanoparticles showed great potential to control the release and penetration of corticosteroids on the skin and mucus membrane and maximize treatment effectiveness.

Interaction of New-Developed TiO₂-Based Photocatalytic Nanoparticles with Pathogenic Microorganisms and Human Dermal and Pulmonary Fibroblasts

TiO₂-based photocatalysts were obtained during previous years in order to limit pollution and to ease human daily living conditions due to their special properties. However, obtaining biocompatible photocatalysts is still a key problem, and the mechanism of their toxicity recently received increased attention. Two types of TiO₂ nanoparticles co-doped with 1% of iron and nitrogen (TiO₂-1% Fe–N) atoms were synthesized in hydrothermal conditions at pH of 8.5 (HT1) and 5.5 (HT2), and their antimicrobial activity and cytotoxic effects exerted on human pulmonary and dermal fibroblasts were assessed. These particles exhibited significant microbicidal and anti-biofilm activity, suggesting their potential application for microbial decontamination of different environments. In addition, our results demonstrated the biocompatibility of TiO₂-1% Fe–N nanoparticles at low doses on lung and dermal cells, which may initiate oxidative stress through dose accumulation. Although no significant changes were observed between the two tested photocatalysts, the biological response was cell type specific and time- and dose-dependent; the lung cells proved to be more sensitive to nanoparticle exposure. Taken together, these experimental data provide useful information for future photocatalytic applications in the industrial, food, pharmaceutical, and medical fields.

Formation and Controlled Growth of Bismuth Titanate Phases into Mesoporous Silica Nanoparticles: An Efficient Self-Sealing Nanosystem for UV Filtering in Cosmetic Formulation

The application of nanosized inorganic UV filters in cosmetic field is limited by their high photocatalytic properties that could induce the degradation or dangerous transformation of the organic molecules in sunscreen formulations. To overcome this problem and simultaneously enlarge the window of filter's absorption, we propose the growth of bismuth titanates Bi_xTi_yO_z into mesoporous silica nanoparticles (MSN). We investigated the chemical-physical properties by means of XRPD, TEM, UV-vis spectroscopy, N₂ physisorption, XPS, and SF-ICP-MS analysis, while the influence on the environment was evaluated through photocatalytic tests. The growing process of this new nanosystem is discussed underlining the key role of the Bi³⁺ ion that, acting as a low-melting point agent for the silica framework, led to a self-sealing mechanism. The excellent UV shielding properties combined with a radical suppression of the photocatalytic activity make the proposed nanosystem a perfect candidate for the development of the next generation nanomaterials for sunscreen formulations.

Moving into advanced nanomaterials. Toxicity of rutile TiO2 nanoparticles immobilized in nanokaolin nanocomposites on HepG2 cell line

Immobilization of nanoparticles on inorganic supports has been recently developed, resulting in the creation of nanocomposites. Concerning titanium dioxide nanoparticles (TiO₂ NPs¹), these have already been developed in conjugation with clays, but so far there are no available toxicological studies on these nanocomposites. The present work intended to evaluate the hepatic toxicity of nanocomposites (C-TiO₂²), constituted by rutile TiO₂ NPs immobilized in nanokaolin (NK³) clay, and its individual components. These nanomaterials were analysed by means of FE-SEM⁴ and DLS⁵ analysis for physicochemical characterization. HepG2 cells were exposed to rutile TiO₂ NPs, NK clay and C-TiO₂ nanocomposite, in the presence and absence of serum for different exposure periods. Possible interferences with the methodological procedures were determined for MTT,⁶ neutral red uptake, alamar blue (AB), LDH,⁷ and comet assays, for all studied nanomaterials. Results showed that MTT, AB and alkaline comet assay were suitable for toxicity analysis of the present materials after slight modifications to the protocol. Significant decreases in cell viability were observed after exposure to all studied nanomaterials. Furthermore, an increase in HepG2 DNA damage was observed after shorter periods of exposure in the absence of serum proteins and longer periods of exposure in their presence. Although the immobilization of nanoparticles in micron-sized supports could, in theory, decrease the toxicity of single nanoparticles, the selection of a suitable support is essential. The present results suggest that NK clay is not the appropriate substrate to decrease TiO₂ NPs toxicity. Therefore, for future studies, it is critical to select a more appropriate substrate for the immobilization of TiO₂ NPs.

Specific uptake mechanisms of well-tolerated thermoresponsive polyglycerol-based nanogels in antigen-presenting cells of the skin

Engineered nanogels are of high value for a targeted and controlled transport of compounds due to the ability to change their chemical properties by external stimuli. As it has been indicated that nanogels possess a high ability to penetrate the stratum corneum, it cannot be excluded that nanogels interact with dermal dendritic cells, especially in diseased skin. In this study the potential crosstalk of the thermoresponsive nanogels (tNGs) with the dendritic cells of the skin was investigated with the aim to determine the immunotoxicological properties of the nanogels. The investigated tNGs were made of dendritic polyglycerol (dPG) and poly(glycidyl methyl ether-co-ethyl glycidyl ether) (p(GME-co-EGE)), as polymer conferring thermoresponsive properties. Although the tNGs were taken up, they displayed neither cytotoxic and genotoxic effects nor any induction of reactive oxygen species in the tested cells. Interestingly, specific uptake mechanisms of the tNGs by the dendritic cells were depending on the nanogels cloud point temperature (Tcp), which determines the phase transition of the nanoparticle. The study points to caveolae-mediated endocytosis as being the major tNGs uptake mechanism at 37°C, which is above the Tcp of the tNGs. Remarkably, an additional uptake mechanism, beside caveolae-mediated endocytosis, was observed at 29°C, which is the Tcp of the tNGs. At this temperature, which is characterized by two different states of the tNGs, macropinocytosis was involved as well. In summary, our study highlights the impact of thermoresponsivity on the cellular uptake mechanisms which has to be taken into account if the tNGs are used as a drug delivery system.

Comparative analysis of the relative potential of silver, Zinc-oxide and titanium-dioxide nanoparticles against UVB-induced DNA damage for the prevention of skin carcinogenesis

Sunscreen formulations containing UVB filters, such as Zinc-oxide (ZnO) and titanium-dioxide (TiO2) nanoparticles (NPs) have been developed to limit the exposure of human skin to UV-radiations. Unfortunately, these UVB protective agents have failed in controlling the skin cancer incidence. We recently demonstrated that silver nanoparticles (Ag-NPs) could serve as novel protective agents against UVB-radiations. Here our goal was to perform comparative analysis of direct and indirect UVB-protection efficacy of ZnO-, TiO2- and Ag-NPs. Sun-protection-factor calculated based on their UVB-reflective/absorption abilities was the highest for TiO2-NPs followed by Ag- and ZnO-NPs. This was further confirmed by studying indirect protection of UVB radiation-induced death of HaCaT cells. However, only Ag-NPs were active in protecting HaCaT cells against direct UVB-induced DNA-damage by repairing bulky-DNA lesions through nucleotide-excision-repair mechanism. Moreover, Ag-NPs were also effective in protecting HaCaT cells from UVB-induced oxidative DNA damage by enhancing SOD/CAT/GPx activity. In contrast, ZnO- and TiO2-NPs not only failed in providing any direct protection from DNA-damage, but rather enhanced oxidative DNA-damage by increasing ROS production. Together, these findings raise concerns about safety of ZnO- and TiO2-NPs and establish superior protective efficacy of Ag-NPs.

Contribution of oxidative stress to TiO2 nanoparticle-induced toxicity

With the rapid development of nanotechnology, titanium dioxide nanoparticles (TNPs) are widely used in many fields. People in such workplaces or researchers in laboratories are at a higher risk of being exposed to TNPs, so are the consumers. Moreover, increasing evidence revealed that the concentrations of TNPs are elevated in animal organs after systematic exposure and such accumulated TNPs could induce organ dysfunction. Although cellular responses such as oxidative stress, inflammatory response, apoptosis, autophagy, signaling pathways, and genotoxic effects contribute to the toxicity of TNPs, the interrelationship among them remains obscure. Given the pivotal role of oxidative stress, we summarized relevant articles covering the involvement of oxidative stress in TNPs' toxicity and found that TNP-induced oxidative stress might play a central role in toxic mechanisms. However, available data are far from being conclusive and more investigations should be performed to further confirm whether the toxicity of TNPs might be attributed in part to the cascades of oxidative stress. Tackling this uncertain issue may help us to comprehensively understand the interrelationship among toxic cellular responses induced by TNPs and might shed some light on methods to alleviate toxicity of TNPs.

Formulation and comparative in vitro evaluation of various dexamethasone-loaded pH-sensitive polymeric nanoparticles intended for dermal applications

pH-sensitive nanoparticles have a great potential for dermal and transfollicular drug delivery. In this study, pH-sensitive, dexamethasone-loaded Eudragit^® L 100, Eudragit^® L 100-55, Eudragit^® S 100, HPMCP-50, HPMCP-55 and cellulose acetate phthalate nanoparticles were prepared by nanoprecipitation and characterized. The pH-dependent swelling, erosion, dissolution and drug release kinetics were investigated in vitro using dynamic light scattering and Franz diffusion cells, respectively. Their toxicity potential was assessed by the ROS and MTT assays. 100-700nm nanoparticles with high drug loading and entrapment efficiency were obtained. The nanoparticles bear no toxicity potential. Cellulose phthalates nanoparticles were more sensitive to pH than acrylates nanoparticles. They dissolved in 10mM pH 7.5 buffer and released>80% of the drug within 7h. The acrylate nanoparticles dissolved in 40mM pH 7.5 buffer and released 65-70% of the drug within 7h. The nanoparticles remained intact in 10 and 40mM pH 6.0 buffers (HPMCP nanoparticles dissolved in 40mM pH 6.0 buffer) and released slowly. The nanoparticles properties could be modulated by blending the different polymers. In conclusion, various pH-sensitive nanoparticles that could release differently on the skin surface and dissolve and release in the hair follicles were obtained.

Effects of morphology and surface hydroxyl on the toxicity of BiOCl in human HaCaT cells

Recently, bismuth oxychloride nanomaterials (BiOCls) are showing great promise in pollutant removal. Residues from these environmental remediations are potential hazardous materials. Unfortunately, human health risks of BiOCls are still unexplored widely. In the present study, we focused on the influence of physicochemical properties on the cytotoxicity of BiOCls toward a human skin derived cell line (HaCaT). Results showed that morphology and surface hydroxyl both had a profound effect on the toxicity of BiOCls. Microsphere-shaped BiOCl caused less toxicity than nanosheet-shaped BiOCl because of weaker particle-membrane interactions, while the presence of surface hydroxyl on microsphere-shaped BiOCl significantly raised the toxicity owing to the increased interaction with cell membrane. Both microsphere-shaped BiOCl with surface hydroxyl and nanosheet-shaped BiOCl caused significant cell membrane damage (PI uptake and LDH release), however, based on the different mechanism. The former may be a predominant "chemical" mechanism involved an oxidative stress paradigm, as manifested by elevated ROS and depleted GSH, while the latter is mainly due to a direct "physical" damage to cell membrane. Both "physical" and "chemical" response led to cell death. Furthermore, a set of experiments including MMP collapse, cell cycle arrest, and apoptosis/necrosis were conducted to propose a scenario for toxicological aspects of BiOCls. Data presented here would help to enable the rational design of BiOCls for either reducing their unintended consequences or increasing their application potentials.

Poly[acrylonitrile-co-(N-vinyl pyrrolidone)] nanoparticles - Composition-dependent skin penetration enhancement of a dye probe and biocompatibility

Nanoparticles can improve topical drug delivery: size, surface properties and flexibility of polymer nanoparticles are defining its interaction with the skin. Only few studies have explored skin penetration for one series of structurally related polymer particles with systematic alteration of material composition. Here, a series of rigid poly[acrylonitrile-co-(N-vinyl pyrrolidone)] model nanoparticles stably loaded with Nile Red or Rhodamin B, respectively, was comprehensively studied for biocompatibility and functionality. Surface properties were altered by varying the molar content of hydrophilic NVP from 0 to 24.1% and particle size ranged from 35 to 244nm. Whereas irritancy and genotoxicity were not revealed, lipophilic and hydrophilic nanoparticles taken up by keratinocytes affected cell viability. Skin absorption of the particles into viable skin ex vivo was studied using Nile Red as fluorescent probe. Whilst an intact stratum corneum efficiently prevented penetration, almost complete removal of the horny layer allowed nanoparticles of smaller size and hydrophilic particles to penetrate into viable epidermis and dermis. Hence, systematic variations of nanoparticle properties allows gaining insights into critical criteria for biocompatibility and functionality of novel nanocarriers for topical drug delivery and risks associated with environmental exposure.

Evaluation of Mitochondrial Respiratory Chain on the Generation of Reactive Oxygen Species and Cytotoxicity in HaCaT Cells Induced by Nanosized Titanium Dioxide Under UVA Irradiation

Nanosized titanium dioxide (nano-TiO2) is widely used in the chemical, electrical, and electronic industries. Nanosized TiO2 has been reported to be an efficient photocatalyst, which is able to produce reactive oxygen species (ROS) under UVA irradiation. In the present work, we evaluate the effect of mitochondrial respiratory chain on the generation of ROS and cytotoxicity in keratinocyte (HaCaT) cells induced by nano-TiO2 under UVA irradiation. HaCaT cells were pretreated with different inhibitors of mitochondrial respiratory chain and followed by treatment with 200 µg/mL nano-TiO2, then exposed to UVA (365 nm) for 1 hour and cultured for 24 hours. Our results demonstrated that the complexes I and III of the mitochondrial respiratory chain are the major site in the ROS generation induced by nano-TiO2. Our results also demonstrated that the uncouplers of mitochondrial oxidative phosphorylation resulted in obvious changes in the production of intracellular ROS induced by nano-TiO2. The ROS sources of lipoxygenase, cyclooxygenase, and nicotinamide adenine dinucleotide phosphate oxidase had no significant effect on the ROS production. To some extent, nitric oxide synthase had effect on the ROS production. These results indicated that mitochondrial respiratory chain may be the main source of intracellular ROS production induced by nano-TiO2.

Formulation and in vitro evaluation of polymeric enteric nanoparticles as dermal carriers with pH-dependent targeting potential

pH-sensitive nanoparticles which release in a controlled fashion on the skin or dissolve in the hair follicle could significantly improve treatment effectiveness and make transfollicular drug delivery a success. Dexamethasone-loaded Eudragit® L 100 nanoparticles were prepared by nanoprecipitation from an organic drug-polymer solution. Their toxicity potential was assessed using isolated human fibroblasts. pH-dependent swelling and erosion kinetics of the nanoparticles were investigated by dynamic light scattering and viscosity measurements and its effect on drug release was assessed in vitro with Franz diffusion cells. Stable, 100-550nm-sized dexamethasone-loaded Eudragit® L 100 nanoparticles with drug loading capacity and entrapment efficiency as high as 8.3% and 85%, respectively, were obtained by using polyvinyl alcohol as a stabilizer and ethanol as organic solvent. The nanoparticles showed little or no toxicity on isolated normal human fibroblasts. Dexamethasone existed in the nanoparticles as solid solution or in amorphous form. The nanoparticles underwent extensive swelling and slow drug release in media with a low buffer capacity (as low as 10mM) and a higher pH or at a pH close to the dissolution pH of the polymer (pH6) and a higher buffer capacity. In 40mM buffer and above pH6.8, the nanoparticles eroded fast or dissolved completely and thus released the drug rapidly. pH-sensitive nanoparticles which potentially release in a controlled manner on the stratum corneum but dissolve in the hair follicle could be prepared.

Exposure to TiO2 nanoparticles increases Staphylococcus aureus infection of HeLa cells

Background

Titanium dioxide (TiO₂) is one of the most common nanoparticles found in industry ranging from food additives to energy generation. Approximately four million tons of TiO₂ particles are produced worldwide each year with approximately 3000 tons being produced in nanoparticulate form, hence exposure to these particles is almost certain.

Results

Even though TiO₂ is also used as an anti-bacterial agent in combination with UV, we have found that, in the absence of UV, exposure of HeLa cells to TiO₂ nanoparticles significantly increased their risk of bacterial invasion. HeLa cells cultured with 0.1 mg/ml rutile and anatase TiO₂ nanoparticles for 24 h prior to exposure to bacteria had 350 and 250 % respectively more bacteria per cell. The increase was attributed to bacterial polysaccharides absorption on TiO₂ NPs, increased extracellular LDH, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO₂ particles ingested 40 % fewer bacteria, further increasing the risk of infection.

Conclusions

In combination, these two factors raise serious concerns regarding the impact of exposure to TiO₂ nanoparticles on the ability of organisms to resist bacterial infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-016-0184-y) contains supplementary material, which is available to authorized users.