Limitations and relative utility of screening assays to assess engineered nanoparticle toxicity in a human cell line

Green synthesis of stable antioxidant, anticancer and photocatalytic activity of zinc oxide nanorods from Leea asiatica leaf

The present work reveals zinc oxide nanorods (ZnO NRs) obtained via green synthesis approach utilizing phytochemicals present in the Leea asiatica plant. The synthesized ZnO NRs was confirmed by various characterization methods like X-ray diffraction, FTIR, SEM-EDX, UV-vis, TEM and Raman spectra analysis. The obtained nanorods show less particle size with a distinctive high surface area. The photodegradation activity of obtained ZnO NRs shows 81.3 % of dye degradation at high concentration whereas 42.9 % in low concentration and also antioxidant test shows a better result for free radical scavenging. To understand the safety of the ZnO NRs zebrafish embryos was utilized as a model and found to be less toxic after assessment. Furthermore, to understand the anticancer activity of ZnO NRs it was assessed against breast cancer cell line through MTT, XTT, NRU, and LDH assay. The ZnO NRs exposed against breast cancer cell line (MCF-7) had resulted in necrosis and apoptosis which was further confirmed by genotoxicity assay. Also, the molecular mechanisms behind the necrosis and apoptosis are also discussed to show the involvement of ZnO NRs towards breast cancer cells (MCF-7). The present study on ZnO NRs gives a wide spectrum understanding of using ZnO NRs as a potential drug for human breast cancer by showing its physiological pathways as well as a novel way to synthesize ZnO NRs using Leea asiatica plant extract.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

The Size-dependent Cytotoxicity of Amorphous Silica Nanoparticles: A Systematic Review of in vitro Studies

With the increasing production and application of engineered amorphous silica nanoparticles (aSiNPs), people have more opportunities to be exposed to aSiNPs. However, the knowledge of its adverse health effects and related mechanisms is still limited, compared with the well-studied crystalline micron-sized silica. Since small differences in the physical–chemical properties of nanoparticles could cause significant differences in the toxic effect, it is important to distinguish how these variations influence the outcoming toxicity. Notably, particle size, as one of the essential characterizations of aSiNPs, is relevant to its biological activities. Thus, the aim of this systematic review was to summarize the relationship between the particle size of aSiNPs and its adverse biological effects. In order to avoid the influence of complicated in vivo experimental conditions on the toxic outcome, only in vitro toxicity studies which reported on the cytotoxic effect of different sizes aSiNPs were included. After the systematic literature retrieval, selection, and quality assessment process, 76 eligible scientific papers were finally included in this review. There were 76% of the studies that concluded a size-dependent cytotoxicity of aSiNPs, in which smaller-sized aSiNPs possessed greater toxicity. However, this trend could be modified by certain influence factors, such as the synthetic method of aSiNPs, particle aggregation state in cell culture medium, toxicity endpoint detection method, and some other experimental conditions. The effects of these influence factors on the size-dependent cytotoxicity of aSiNPs were also discussed in detail in the present review.

Comparison of ultrasmall IONPs and Fe salts biocompatibility and activity in multi-cellular in vitro models

In the paper, the results of the first regular studies of ultra-small iron oxide nanoparticles (IONPs) toxicity in vitro were presented. The influence of PEG-coated NPs with 5 nm magnetite core on six different cell lines was examined. These were: human bronchial fibroblasts, human embryonic kidney cells (HEK293T), two glioblastoma multiforme (GBM) cell lines as well as GBM cells isolated from a brain tumor of patient. Additionally, mouse macrophages were included in the study. The influence of IONPs in three different doses (1, 5 and 25 µg Fe/ml) on the viability, proliferation and migration activity of cells was assessed. Moreover, quantifying the intracellular ROS production, we determined the level of oxidative stress in cells exposed to IONPs. In the paper, for the first time, the effect of Fe in the form of IONPs was compared with the analogical data obtained for iron salts solutions containing the same amount of Fe, on the similar oxidation state. Our results clearly showed that the influence of iron on the living cells strongly depends not only on the used cell line, dose and exposure time but also on the form in which this element was administered to the culture. Notably, nanoparticles can stimulate the proliferation of some cell lines, including glioblastoma multiforme. Compared to Fe salts, they have a stronger negative impact on the viability of the cells tested. Ultra-small NPs, also, more often positively affect cell motility which seem to differ them from the NPs with larger core diameters.

Biocompatibility of Biomaterials for Nanoencapsulation: Current Approaches

Nanoencapsulation is an approach to circumvent shortcomings such as reduced bioavailability, undesirable side effects, frequent dosing and unpleasant organoleptic properties of conventional drug delivery systems. The process of nanoencapsulation involves the use of biomaterials such as surfactants and/or polymers, often in combination with charge inducers and/or ligands for targeting. The biomaterials selected for nanoencapsulation processes must be as biocompatible as possible. The type(s) of biomaterials used for different nanoencapsulation approaches are highlighted and their use and applicability with regard to haemo- and, histocompatibility, cytotoxicity, genotoxicity and carcinogenesis are discussed.

Halo and Pseudohalo Gold(I)-NHC Complexes Derived from 4,5-Diarylimidazoles with Excellent In Vitro and In Vivo Anticancer Activities Against HCC

A series of halo and pseudohalo gold(I)-NHC complexes (NHC-Au-X) (X = Cl, Br, I, NCO, and OAc) derived from 4,5-diarylimidazoles were synthesized, structurally characterized, and analyzed for their biological activities. The most active complex was iodo(1,3-diethyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene)gold(I) (6), which was at least 2-fold more cytotoxic than cisplatin and auranofin against hepatocellular carcinoma (HCC) cells. In vivo studies indicated that complex 6 exhibited a considerably higher anticancer efficacy (IRT = 75.7%) than cisplatin (IRT = 44.4%) in a HepG2 xenograft mouse model and ameliorated liver injury caused by CCl₄ in chronic HCC. Further studies revealed that complex 6 can inhibit the expression of the thioredoxin reductase (TrxR) both in vitro and in vivo, block the HepG2 cells in the G2/M phase, induce reactive oxygen species (ROS) production, damage mitochondrial membrane potential (MMP), and promote HepG2 cell apoptosis.

In vitro intestinal toxicity of commercially available spray disinfectant products advertised to contain colloidal silver

The use of colloidal silver-containing products as dietary supplements, immune boosters and surface disinfectants has increased in recent years which has elevated the potential for human exposure to silver nanoparticles and ions. Product mislabeling and long-term use of these products may put consumers at risk for adverse health outcomes including argyria. This study assessed several physical and chemical characteristics of five commercial products as well as their cytotoxicity using a rat intestinal epithelial cell (IEC-6) model. Concentrations of silver were determined for both the soluble and particulate fractions of the products. Primary particle size distribution and elemental composition were determined by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. Hydrodynamic diameters were measured using nanoparticle tracking analysis (NTA) and dynamic light scattering (DLS). The effect of gastrointestinal (GI) simulation on the colloidal silver products was determined using two systems. First, physical and chemical changes of the silver nanoparticles in these products was assessed after exposure to Synthetic Stomach Fluid (SSF) resulting in particle agglomeration, and the appearance of AgCl on the surfaces and between particles. IEC-6 cells were exposed for 24 h to dilutions of the products and assessed for cell viability. The products were also treated with a three-stage simulated GI system (stomach and intestinal fluids) prior to exposure of the IEC-6 cells to the isolated silver nanoparticles. Cell viability was affected by each of the consumer products. Based on the silver nitrate and commercial silver nanoparticle dose response, the cytotoxicity for each of the colloidal silver products was attributed to the particulate silver, soluble silver or non‑silver matrix constituents.

Effects of silver nanoparticles on T98G human glioblastoma cells

Nanotechnology has been well developed in recent decades because it provides social progress and welfare. Consequently, exposure of population is increasing and further increases in the near future are forecasted. Therefore, assessing the safety of applications involving nanoparticles is strongly advisable. We assessed the effects of silver nanoparticles at a non-cytotoxic concentration on the performance of T98G human glioblastoma cells mainly by an omic approach. We found that silver nanoparticles are able to alter several molecular pathways related to inflammation. Cellular repair and regeneration were also affected by alterations to the fibroblast growth factor pathways operating mainly via mitogen-activated protein kinase cascades. It was concluded that, given the relevant role of glia on central nervous system maintenance homeostasis, exposure to silver nanoparticles could eventually lead to severe toxicity in the central nervous system, although current exposure levels do not pose a significant risk.

Improving Quality in Nanoparticle-Induced Cytotoxicity Testing by a Tiered Inter-Laboratory Comparison Study

The quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing. We used two well-described model nanoparticles, 40-nm carboxylated polystyrene (PS-COOH) and 50-nm amino-modified polystyrene (PS-NH2). We followed a tiered approach using well-developed standard operating procedures (SOPs) and sharing the same cells, serum and nanoparticles. We started with determination of the cell growth rate (tier 1), followed by a method transfer phase, in which all laboratories performed the first ILC on the MTS assay (tier 2). Based on the outcome of tier 2 and a survey of laboratory practices, specific training was organized, and the MTS assay SOP was refined. This led to largely improved intra- and inter-laboratory reproducibility in tier 3. In addition, we confirmed that PS-COOH and PS-NH2 are suitable negative and positive control nanoparticles, respectively, to evaluate impact of nanomaterials on cell viability using the MTS assay. Overall, we have demonstrated that the tiered process followed here, with the use of SOPs and representative control nanomaterials, is necessary and makes it possible to achieve good inter-laboratory reproducibility, and therefore high-quality nanotoxicological data.

Emerging Nanotechnology in Non-Surgical Periodontal Therapy in Animal Models: A Systematic Review

Periodontitis is one of the most prevalent inflammatory diseases. Its treatment, mostly mechanical and non-surgical, shows limitations. The aim of this systematic review was to investigate the effect of nanoparticles as a treatment alone in non-surgical periodontal therapy in animal models. A systematic search was conducted in Medline/PubMed, Web of Science, The Cochrane Library and Science Direct. The eligibility criteria were: studies (i) using nanoparticles as chemotherapeutic agent or as delivery system; (ii) including preclinical controlled animal model (experimental periodontitis); (iii) reporting alveolar bone loss; (iv) written in English; and (v) published up to June 2019. Risk of bias was evaluated according to the SYstematic Review Centre for Laboratory Animal Experimentation. On the 1324 eligible studies, 11 were included. All reported advantages in using nanoparticles for the treatment of periodontitis, highlighted by a reduction in bone loss. Agents modulating inflammation seem to be more relevant than antibiotics, in terms of efficiency and risk of antibiotic resistance. In addition, poly(lactic-co-glycolic acid) or drugs used as their own carrier appear to be the most interesting nanoparticles in terms of biocompatibility. Risk of bias assessment highlighted many criteria scored as unclear. There are encouraging preclinical data of using nanoparticles as a contribution to the treatment of periodontitis.

Interference: A Much-Neglected Aspect in High-Throughput Screening of Nanoparticles

Despite several studies addressing nanoparticle (NP) interference with conventional toxicity assay systems, it appears that researchers still rely heavily on these assays, particularly for high-throughput screening (HTS) applications in order to generate "big" data for predictive toxicity approaches. Moreover, researchers often overlook investigating the different types of interference mechanisms as the type is evidently dependent on the type of assay system implemented. The approaches implemented in the literature appear to be not adequate as it often addresses only one type of interference mechanism with the exclusion of others. For example, interference of NPs that have entered cells would require intracellular assessment of their interference with fluorescent dyes, which has so far been neglected. The present study investigated the mechanisms of interference of gold NPs and silver NPs in assay systems implemented in HTS including optical interference as well as adsorption or catalysis. The conventional assays selected cover all optical read-out systems, that is, absorbance (XTT toxicity assay), fluorescence (CytoTox-ONE Homogeneous membrane integrity assay), and luminescence (CellTiter Glo luminescent assay). Furthermore, this study demonstrated NP quenching of fluorescent dyes also used in HTS (2',7'-dichlorofluorescein, propidium iodide, and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzamidazolocarbocyanin iodide). To conclude, NP interference is, as such, not a novel concept, however, ignoring this aspect in HTS may jeopardize attempts in predictive toxicology. It should be mandatory to report the assessment of all mechanisms of interference within HTS, as well as to confirm results with label-free methodologies to ensure reliable big data generation for predictive toxicology.

Potential Toxicity of Iron Oxide Magnetic Nanoparticles: A Review

The noteworthy intensification in the development of nanotechnology has led to the development of various types of nanoparticles. The diverse applications of these nanoparticles make them desirable candidate for areas such as drug delivery, coasmetics, medicine, electronics, and contrast agents for magnetic resonance imaging (MRI) and so on. Iron oxide magnetic nanoparticles are a branch of nanoparticles which is specifically being considered as a contrast agent for MRI as well as targeted drug delivery vehicles, angiogenic therapy and chemotherapy as small size gives them advantage to travel intravascular or intracavity actively for drug delivery. Besides the mentioned advantages, the toxicity of the iron oxide magnetic nanoparticles is still less explored. For in vivo applications magnetic nanoparticles should be nontoxic and compatible with the body fluids. These particles tend to degrade in the body hence there is a need to understand the toxicity of the particles as whole and degraded products interacting within the body. Some nanoparticles have demonstrated toxic effects such inflammation, ulceration, and decreases in growth rate, decline in viability and triggering of neurobehavioral alterations in plants and cell lines as well as in animal models. The cause of nanoparticles' toxicity is attributed to their specific characteristics of great surface to volume ratio, chemical composition, size, and dosage, retention in body, immunogenicity, organ specific toxicity, breakdown and elimination from the body. In the current review paper, we aim to sum up the current knowledge on the toxic effects of different magnetic nanoparticles on cell lines, marine organisms and rodents. We believe that the comprehensive data can provide significant study parameters and recent developments in the field. Thereafter, collecting profound knowledge on the background of the subject matter, will contribute to drive research in this field in a new sustainable direction.

The impact of synthetic amorphous silica (E 551) on differentiated Caco-2 cells, a model for the human intestinal epithelium

For several decades, food-grade synthetic amorphous silica (SAS) have been used as a technological additive to reduce caking of food powders. Human exposure is thus inevitable and safety concerns are taken seriously. The toxicity of silica in general and SAS in particular has been studied extensively. Overall, there is little evidence that food-grade SAS pose any health risks to humans. However, from the available data it was often not clear which type of silica was used. Accordingly, the latest report of the European food safety authority requested additional toxicity data for well-characterised "real food-grade SAS". To close this gap, we screened a panel of ten well-defined, food-grade SAS for potential adverse effects on differentiated Caco-2 cells. Precipitated and fumed SAS with low, intermediate and high specific surface area were included to determine structure-activity relationships. In a physiological dose-range up to 50 μg/ml and 48 h of incubation, none of the materials induced adverse effects on differentiated Caco-2 cells. This held true for endpoints of acute cytotoxicity as well as epithelial specific measures of barrier integrity. These results showed that despite considerable differences in production routes and material characteristics, food-relevant SAS did not elicit acute toxicity responses in intestinal epithelial cells.

Mind your assays: Misleading cytotoxicity with the WST-1 assay in the presence of manganese

The WST-1 assay is the most common test to assess the in vitro cytotoxicity of chemicals. Tetrazolium-based assays can, however, be affected by the interference of tested chemicals, including carbon nanotubes or Mg particles. Here, we report a new interference of Mn materials with the WST-1 assay. Endothelial cells exposed to Mn particles (Mn alone or Fe-Mn alloy from 50 to 1600 μg/ml) were severely damaged according to the WST-1 assay, but not the ATP content assay. Subsequent experiments revealed that Mn particles interfere with the reduction of the tetrazolium salt to formazan. Therefore, the WST-1 assay is not suitable to evaluate the in vitro cytotoxicity of Mn-containing materials, and luminescence-based assays such as CellTiter-Glo^® appear more appropriate.

Transcriptomics in Toxicogenomics, Part I: Experimental Design, Technologies, Publicly Available Data, and Regulatory Aspects

The starting point of successful hazard assessment is the generation of unbiased and trustworthy data. Conventional toxicity testing deals with extensive observations of phenotypic endpoints in vivo and complementing in vitro models. The increasing development of novel materials and chemical compounds dictates the need for a better understanding of the molecular changes occurring in exposed biological systems. Transcriptomics enables the exploration of organisms' responses to environmental, chemical, and physical agents by observing the molecular alterations in more detail. Toxicogenomics integrates classical toxicology with omics assays, thus allowing the characterization of the mechanism of action (MOA) of chemical compounds, novel small molecules, and engineered nanomaterials (ENMs). Lack of standardization in data generation and analysis currently hampers the full exploitation of toxicogenomics-based evidence in risk assessment. To fill this gap, TGx methods need to take into account appropriate experimental design and possible pitfalls in the transcriptomic analyses as well as data generation and sharing that adhere to the FAIR (Findable, Accessible, Interoperable, and Reusable) principles. In this review, we summarize the recent advancements in the design and analysis of DNA microarray, RNA sequencing (RNA-Seq), and single-cell RNA-Seq (scRNA-Seq) data. We provide guidelines on exposure time, dose and complex endpoint selection, sample quality considerations and sample randomization. Furthermore, we summarize publicly available data resources and highlight applications of TGx data to understand and predict chemical toxicity potential. Additionally, we discuss the efforts to implement TGx into regulatory decision making to promote alternative methods for risk assessment and to support the 3R (reduction, refinement, and replacement) concept. This review is the first part of a three-article series on Transcriptomics in Toxicogenomics. These initial considerations on Experimental Design, Technologies, Publicly Available Data, Regulatory Aspects, are the starting point for further rigorous and reliable data preprocessing and modeling, described in the second and third part of the review series.

Cross-Linked Polyamide Chains Enhanced the Fluorescence of Polymer Carbon Dots

Carbon dots (CDs) have attracted tremendous attention for their outstanding advantages in luminescence. Here, α-amino-substituted lysine derivatives with the determined chemical structure were employed as precursors to obtain bright and highly stable fluorescent CDs through a facile hydrothermal route. The relationships among the chemical structure of precursors, CD fluorescence, and particle size were investigated. The results indicated that increased numbers of functional groups in precursors could promote the degree of cross-linking and lead to a smaller size, better fluorescent properties, and stronger stability of CDs. The C-CDs that were prepared from lysine derivatives with most functional groups showed excitation-dependent dual excitation and dual emission (DE2), high-stability luminescence, strong resistance to photobleaching, and high selectivity to Fe3+ and could be used as a sensitive probe for Fe3+ detection.

Topical Minoxidil-Loaded Nanotechnology Strategies for Alopecia

Androgenetic alopecia (AGA) is a multifactorial and age-related condition characterized by substantial hair loss affecting both men and women. Conventional treatments include the use of topical minoxidil (MNX) formulations to stimulate hair growth and restore hair condition. However, those treatments are associated with limited performance and a lack of tolerability and compliance due to the emergence of adverse effects. Considering that the development of nanotechnology-based formulations as hair loss therapeutic strategies has been clearly growing, topical MNX delivery by means of these innovative formulations is known to enhance MNX skin permeation and depot formation into hair follicles, allowing for MNX-controlled release, increased MNX skin bioavailability and enhanced therapeutic efficacy with minimal adverse effects. This review highlights the potential of nanotechnology-based MNX delivery formulations for improved hair loss therapeutics, including a thorough assessment of their in vitro and in vivo performances, as well as regulatory and nanosafety considerations.

Differential Cytotoxicity Induced by Transition Metal Oxide Nanoparticles is a Function of Cell Killing and Suppression of Cell Proliferation

The application of nanoparticles (NPs) in industry is on the rise, along with the potential for human exposure. While the toxicity of microscale equivalents has been studied, nanoscale materials exhibit different properties and bodily uptake, which limits the prediction ability of microscale models. Here, we examine the cytotoxicity of seven transition metal oxide NPs in the fourth period of the periodic table of the chemical elements. We hypothesized that NP-mediated cytotoxicity is a function of cell killing and suppression of cell proliferation. To test our hypothesis, transition metal oxide NPs were tested in a human lung cancer cell model (A549). Cells were exposed to a series of concentrations of TiO₂, Cr₂O₃, Mn₂O₃, Fe₂O₃, NiO, CuO, or ZnO for either 24 or 48 h. All NPs aside from Cr₂O₃ and Fe₂O₃ showed a time- and dose-dependent decrease in viability. All NPs significantly inhibited cellular proliferation. The trend of cytotoxicity was in parallel with that of proliferative inhibition. Toxicity was ranked according to severity of cellular responses, revealing a strong correlation between viability, proliferation, and apoptosis. Cell cycle alteration was observed in the most toxic NPs, which may have contributed to promoting apoptosis and suppressing cell division rate. Collectively, our data support the hypothesis that cell killing and cell proliferative inhibition are essential independent variables in NP-mediated cytotoxicity.

Quantitative Flow Cytometric Evaluation of Oxidative Stress and Mitochondrial Impairment in RAW 264.7 Macrophages after Exposure to Pristine, Acid Functionalized, or Annealed Carbon Nanotubes

Conventional nanotoxicological assays are subjected to various interferences with nanoparticles and especially carbon nanotubes. A multiparametric flow cytometry (FCM) methodology was developed here as an alternative to quantify oxidative stress, mitochondrial impairment, and later cytotoxic and genotoxic events. The experiments were conducted on RAW264.7 macrophages, exposed for 90 min or 24 h-exposure with three types of multiwalled carbon nanotubes (MWCNTs): pristine (Nanocyl™ CNT), acid functionalized (CNTf), or annealed treatment (CNTa). An original combination of reactive oxygen species (ROS) probes allowed the simultaneous quantifications of broad-spectrum ROS, superoxide anion (O₂^•-), and hydroxyl radical (•OH). All MWCNTs types induced a slight increase of broad ROS levels regardless of earlier antioxidant catalase activity. CNTf strongly stimulated the O₂^•- production. The •OH production was downregulated for all MWCNTs due to their scavenging capacity. The latter was quantified in a cell-free system by electron paramagnetic resonance spectroscopy (EPR). Further FCM-based assessment revealed early biological damages with a mitochondrial membrane potential collapse, followed by late cytotoxicity with chromatin decondensation. The combined evaluation by FCM analysis and cell-free techniques led to a better understanding of the impacts of MWCNTs surface treatments on the oxidative stress and related biological response.

Zinc oxide nanoparticles synthesized from Allium cepa prevents UVB radiation mediated inflammation in human epidermal keratinocytes (HaCaT cells)

The extensive relevance of nanoparticles arouses the requirement for manufacturing although the predictable technique are frequently perilous and energy saving. In the current study, zinc oxide nanoparticles manufactured from Allium cepa avert UVB radiation interceded irritation in human epidermal keratinocytes (HaCaT cells). In the current study, the zinc oxide nanoparticles (ZnO-NPs) was synthesized from the extract of A. cepa. The optimized ZnO-NPs hence attained and was enumerated and exemplified by UV visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscope (SEM) and EDAX impending analysis. In addition, amalgamated ZnO-NPs were experienced for cell viability (MTT), formation of reactive oxygen species (ROS), apoptosis, and antioxidant and lipid peroxidation (TBARS) levels. Also, we explored the effect of A. cepa ZnO-NPs in molecular level by evaluating the inflammatory and apoptotic markers, in which ZnO-NPs reinstated the interleukins 6, 10 and related signaling molecules like iNOS, COX-2 levels. Ultimately, ZnO-NPs induce apoptotic markers (Bax, Bcl-2) and also recommended that ZnO-NPs might aggravate cancer cell apoptosis in HaCaT cells.

Biotechnological approach to induce human fibroblast apoptosis using superparamagnetic iron oxide nanoparticles

Cancer-Associated Fibroblasts (CAFs) contribute to tumour progression and have received significant attention as a therapeutic target. These cells produce growth factors, cytokines and chemokines, stimulating cancer cell proliferation and inhibiting their apoptosis. Recent advances in drug delivery have demonstrated a significant promise of iron oxide nanoparticles in clinics as theranostic agents, mainly due to their magnetic properties. Here, we designed superparamagnetic iron oxide nanoparticles (SPIONs) to induce apoptosis of human fibroblasts. SPIONs were synthesized via co-precipitation method and coated with sodium citrate (SPION_Cit). We assessed the intracellular uptake of SPIONs by human fibroblast cells, as well as their cytotoxicity and ability to induce thermal effects under the magnetic field. The efficiency and time of nanoparticle internalization were assessed by Prussian Blue staining, flow cytometry and transmission electron microscopy. SPIONs_Cit were detected in the cytoplasm of human fibroblasts 15 min after in vitro exposure, entering into cells mainly via endocytosis. Analyses through Cell Titer Blue assay, AnnexinV-fluorescein isothiocyanate (FITC) and propidium iodide (PI) cellular staining demonstrated that concentrations below 8 × 10^-2 mg/mL of SPIONs_Cit did not alter cell viability of human fibroblast. Furthermore, it was also demonstrated that SPIONs_Cit associated with alternating current magnetic field were able to induce hyperthermia and human fibroblast cell death in vitro, mainly through apoptosis (83.5%), activating caspase 8 (extrinsic apoptotic via) after a short exposure period. Collectively these findings suggest that our nanoplatform is biocompatible and can be used for therapeutic purposes in human biological systems, such as inducing apoptosis of CAFs.

Animal simulations facilitate smart drug design through prediction of nanomaterial transport to individual tissue cells

Smart drug design for antibody and nanomaterial-based therapies allows optimization of drug efficacy and more efficient early-stage preclinical trials. The ideal drug must display maximum efficacy at target tissue sites, with transport from tissue vasculature to the cellular environment being critical. Biological simulations, when coupled with in vitro approaches, can predict this exposure in a rapid and efficient manner. As a result, it becomes possible to predict drug biodistribution within single cells of live animal tissue without the need for animal studies. Here, we successfully utilized an in vitro assay and a computational fluid dynamic model to translate in vitro cell kinetics (accounting for cell-induced degradation) to whole-body simulations for multiple species as well as nanomaterial types to predict drug distribution into individual tissue cells. We expect this work to assist in refining, reducing, and replacing animal testing, while providing scientists with a new perspective during the drug development process.

Advances and controversies in studying sunscreen delivery and toxicity

This review critically evaluates the sunscreen delivery and toxicity field. We chose to focus on approved sunscreens in this review. Optimal sunscreen use prevents skin cancer and photoageing but there is an important knowledge gap in sunscreen/skin interactions. Sunscreen delivery is a key for efficacy, but studying sunscreen delivery is not straightforward. We review the strengths and weaknesses of in vitro, excised skin and clinical approaches. Understanding positive and negative sunscreen effects on skin homeostasis is also challenging. The results in this field, especially in vitro testing, are controversial and experimental design varies widely which further supports disparities between some findings. We hypothesize that bias towards showing sunscreen toxicity to increase impact could be problematic. We explore that perception through a detailed review of experimental design, especially in cell culture models. Our conclusion is that emerging, non- and minimally invasive technologies are enabling new approaches to volunteer studies that could significantly improve knowledge of sunscreen delivery and interactions.

Are Fe-Based Stenting Materials Biocompatible? A Critical Review of In Vitro and In Vivo Studies

Fe-based materials have increasingly been considered for the development of biodegradable cardiovascular stents. A wide range of in vitro and in vivo studies should be done to fully evaluate their biocompatibility. In this review, we summarized and analyzed the findings and the methodologies used to assess the biocompatibility of Fe materials. The majority of investigators drew conclusions about in vitro Fe toxicity based on indirect contact results. The setup applied in these tests seems to overlook the possible effects of Fe corrosion and does not allow for understanding of the complexity of released chemical forms and their possible impact on tissue. It is in particular important to ensure that test setups or interpretations of in vitro results do not hide some important mechanisms, leading to inappropriate subsequent in vivo experiments. On the other hand, the sample size of existing in vivo implantations is often limited, and effects such as local toxicity or endothelial function are not deeply scrutinized. The main advantages and limitations of in vitro design strategies applied in the development of Fe-based alloys and the correlation with in vivo studies are discussed. It is evident from this literature review that we are not yet ready to define an Fe-based material as safe or biocompatible.

Development and Assessment of Nano-Technologies for Cancer Treatment: Cytotoxicity and Hyperthermia Laboratory Studies

Cancer treatment by magnetic hyperthermia offers numerous advantages, but for practical applications many variables still need to be adjusted before developing a controlled and reproducible cancer treatment that is bio-compatible (non-damaging) to healthy cells. In this work, Fe₃O₄ and CoFe₂O₄ were synthesized and systematically studied for the development of efficient therapeutic agents for applications in hyperthermia. The biocompatibility of the materials was further evaluated using HepG2 cells as biological model. Colorimetric and microscopic techniques were used to evaluate the interaction of magnetic nano-materials (MNMs) and HepG2 cells. Finally, the behavior of MNMs was evaluated under the influence of an alternating magnetic field (AMF), observing a more efficient temperature increment for CoFe₂O₄, a desirable behavior for biomedical applications since lower doses and shorter expositions to alternating magnetic field might be required.

Shape-Depended Biological Properties of Ag3PO4 Microparticles: Evaluation of Antimicrobial Properties and Cytotoxicity in In Vitro Model-Safety Assessment of Potential Clinical Usage

Implant-related infections are an emerging clinical and economic problem. Therefore, we decided to assess potential clinical usefulness and safety of silver orthophosphate microparticles (SOMPs) regarding their shape. We synthesized and then assessed antimicrobial properties and potential cytotoxicity of six shapes of SOMPs (tetrapod, cubes, spheres, tetrahedrons, branched, and rhombic dodecahedron). We found that SOMPs had a high antimicrobial effect; they were more efficient against fungi than bacteria. SOMPs exerted an antimicrobial effect in concentrations not toxic to mammalian cells: human fetal osteoblast (hFOB1.19), osteosarcoma (Saos-2), mouse preosteoblasts (MC3T3-E1), skin fibroblast (HDF), and mouse myoblast (C2C12). At higher concentration SOMPs, induced shape- and concentration-dependent cytotoxicity (according to MTT and BrdU assays). Tetrapod SOMPs had the smallest effect, whereas cubical SOMPs, the highest on cell viability. hFOB1.19 were the most resistant cells and C2C12, the most susceptible ones. We have proven that the induction of oxidative stress and inflammation is involved in the cytotoxic mechanism of SOMPs. After treatment with microparticles, we observed changes in levels of reactive oxygen species, first-line defense antioxidants-superoxide dismutase (SOD1, SOD3), and glutathione peroxidase (GPX4), metalloproteinase (MMP1, MMP3), and NF-κB protein. Neither cell cycle distribution nor ultrastructure was altered as determined by flow cytometry and transmission electron microscopy, respectively. In conclusion, silver orthophosphate may be a safe and effective antimicrobial agent on the implant surface. Spherical-shaped SOMPs are the most promising for biomedical application.

Behavioral Impairments and Oxidative Stress in the Brain, Muscle, and Gill Caused by Chronic Exposure of C70 Nanoparticles on Adult Zebrafish

There is an imperative need to develop efficient whole-animal-based testing assays to determine the potential toxicity of engineered nanomaterials. While previous studies have demonstrated toxicity in lung and skin cells after C70 nanoparticles (NPs) exposure, the potential detrimental role of C70 NPs in neurobehavior is largely unaddressed. Here, we evaluated the chronic effects of C70 NPs exposure on behavior and alterations in biochemical responses in adult zebrafish. Two different exposure doses were used for this experiment: low dose (0.5 ppm) and high dose (1.5 ppm). Behavioral tests were performed after two weeks of exposure of C70 NPs. We found decreased locomotion, exploration, mirror biting, social interaction, and shoaling activities, as well as anxiety elevation and circadian rhythm locomotor activity impairment after ~2 weeks in the C70 NP-exposed fish. The results of biochemical assays reveal that following exposure of zebrafish to 1.5 ppm of C70 NPs, the activity of superoxide dismutase (SOD) in the brain and muscle tissues increased significantly. In addition, the concentration of reactive oxygen species (ROS) also increased from 2.95 ± 0.12 U/ug to 8.46 ± 0.25 U/ug and from 0.90 ± 0.03 U/ug to 3.53 ± 0.64 U/ug in the muscle and brain tissues, respectively. Furthermore, an increased level of cortisol was also observed in muscle and brain tissues, ranging from 17.95 ± 0.90 pg/ug to 23.95 ± 0.66 pg/ug and from 3.47 ± 0.13 pg/ug to 4.91 ± 0.51 pg/ug, respectively. Increment of Hif1-α level was also observed in both tissues. The elevation was ranging from 11.65 ± 0.54 pg/ug to 18.45 ± 1.00 pg/ug in the muscle tissue and from 4.26 ± 0.11 pg/ug to 6.86 ± 0.37 pg/ug in the brain tissue. Moreover, the content of DNA damage and inflammatory markers such as ssDNA, TNF-α, and IL-1β were also increased substantially in the brain tissues. Significant changes in several biomarker levels, including catalase and malondialdehyde (MDA), were also observed in the gill tissues. Finally, we used a neurophenomic approach with a particular focus on environmental influences, which can also be easily adapted for other aquatic fish species, to assess the toxicity of metal and carbon-based nanoparticles. In summary, this is the first study to illustrate the adult zebrafish toxicity and the alterations in several neurobehavior parameters after zebrafish exposure to environmentally relevant amounts of C70 NPs.

Preparation, characterization, and biological evaluation of retinyl palmitate and Dead Sea water loaded nanoemulsions toward topical treatment of skin diseases

Millions of people suffer from different types of skin diseases worldwide. In the last decade, the development of nanocarriers has been the focus of the pharmaceutical and cosmetic industries to enhance the performance of their products, and to meet consumers’ demands. Several delivery systems have been developed to improve the efficiency and minimize possible side effects. In this study, retinyl palmitate and Dead Sea water loaded nanoemulsions were developed as carriers to treat skin conditions such as photoaging, psoriasis, or atopic dermatitis. Toxicity profiles were carried out by means of viability, cell membrane asymmetry study, evaluation of oxidative stress induction (reactive oxygen species), and inflammation via cytokines production with a human keratinocyte cell line (HaCaT) and a mouse embryo fibroblasts cell line (BALB/3T3). Results showed that loaded nanoemulsions were found to be non-cytotoxic under the conditions of the study. Furthermore, no oxidative stress induction was observed. Likewise, an efficacy test of these loaded nanoemulsions was also tested on human skin organ cultures, before and after ultraviolet B light treatment. Viability and caspase-3 production assessment, in response to the exposure of skin explants to the loaded nanoemulsions, indicated non-toxic effects on human skin in culture, both with and without ultraviolet B irradiation. Further the ability of loaded nanoemulsions to protect the skin against ultraviolet B damage was assessed on skin explants reducing significantly the apoptotic activation after ultraviolet B irradiation. Our promising results indicate that the developed loaded nanoemulsions may represent a topical drug delivery system to be used as an alternative treatment for recurrent skin diseases.

Fluorescein sodium loaded by polyethyleneimine for fundus fluorescein angiography improves adhesion

Aim: To improve the retention of fluorescein sodium (FS) as a kind of clinical contrast agent for fundus fluorescein angiography (FFA). Materials & methods: Polyethyleneimine (PEI) was designed to synthesize PEI–NHAc–FS nanoparticles (NPs), and the formed NPs were characterized by both physicochemical properties and their effects on FFA. Results: Compared with free FS, PEI–NHAc–FS NPs showed similar optical performance, and could obviously reduce cellular adsorption and uptake both in vitro and in vivo, which could promote the metabolism of NPs in ocular blood vessels. Conclusion: PEI–NHAc–FS NPs represent a smart nanosize fluorescence contrast agent, which hold promising potential for clinical FFA diagnosis, therapy and research work.

Development of a Novel Shallow Liquid Interface Exposure System for MWCNT Toxicity Assessment

Increasing applications of multiwalled carbon nanotubes (MWCNT) lead to significant occupational exposure and potential health concerns. Toxicity of MWCNT should be carefully elucidated since the conventional (CON) method with fully immersed condition fails to mimic the air-liquid interface (ALI) in airways. Additionally, quantification of MWCNT in cells was a real challenge. Currently available ALI exposure devices are costly, posing problems to conducting in vitro evaluations for emerging nanomaterials. A novel system, consisting of a shaker fluidized-bed atomizer (SFA) and electrostatic shallow liquid interface (ESLI) exposure chamber, has been developed for investigating nanotoxicity of well-dispersed pristine-MWCNT (pMWCNT) and carboxylized-MWCNT (cMWCNT). After 24-h exposure, LDH, MCP-1, IL-1β, IL-6, and TNF-α releases were determined, and cell uptakes were quantified according to the molybdenum content in cells. Biological responses triggered by SLI exposure are obviously more sensitive compared with those caused by CON exposure at equivalent doses. Exposure dose-dependent release of LDH and IL-6 was highlighted in A549 cells, indicating higher cytotoxicity and inflammatory responses of cMWCNT attributed to its shorter length, smaller size, and higher cell uptake. Cell-associated dose-dependent release of LDH and IL-6 was highlighted in RAW264.7 cells, revealing the higher adverse health risk of pMWCNT due to frustrated phagocytosis and its much higher molybdenum content. These results suggest that inherent characteristics of cells and distinct physicochemical properties of pMWCNT and cMWCNT lead to either exposure dose-dependent or cell-associated dose-dependent responses. Notably, the SLI is superior to the CON exposure method and well suited for nanotoxicity assessment of different MWCNTs.

In vitro evaluation of magnetite nanoparticles in human mesenchymal stem cells: comparison of different cytotoxicity assays

This work was aimed at defining the suitable test for evaluating Fe₃O₄ NPs cytotoxicity after short-term exposure in human mesenchymal stem cells (hMSCs) using different viability tests, namely NRU, MTT and TB assays, paralleled by cell morphology analyses for cross checking. MTT and NRU data (culture medium with/without hMSCs plus Fe₃O₄NPs) indicated artificial/false increments in cell viability after Fe₃O₄NPs. These observations did not fit with the morphological analyses showing reduced cell density, loss of monolayer features, and morphological alterations at Fe₃O₄NPs ≥50 μg/ml. Fe₃O₄NPs alone induced a substantial increased absorbance at the wavelength required for MTT and NRU. A significant death (25%) of hMSC at Fe₃O₄NPs ≥10 μg/ml, with a maximum effect (45%) at 300 μg/ml after 24 h, exacerbated after 48 h, was observed when applying TB test. These results paralleled the effects on cell morphology. The optical properties and stability of Fe₃O₄NP suspension (tendency to agglomerate in a specific culture medium) represent factors that limit in vitro result interpretation. These findings suggest the non applicability of the spectrophotometric assays for hMSC culture conditions, while TB is an accurate method for determining cell viability after Fe₃O₄NP exposure in this model. In relation to NPs safety assessment: cell-based assays must be considered on case-by-case basis; selection of relevant cell models is also important for predictive toxicological studies; application of a testing strategy is fundamental for understanding the toxicity pathways driving cellular responses.

An Alternative In Vitro Method for Examining Nanoparticle-Induced Cytotoxicity

Conventional in vitro assays are often used as initial screens to identify potential toxic effects of nanoparticles (NPs). However, many NPs have shown interference with conventional in vitro assays, resulting in either false-positive or -negative outcomes. Here, we report an alternative method for the in vitro assessment of NP-induced cytotoxicity utilizing Fluoro-Jade C (FJ-C). To provide proof of concept and initial validation data, Ag-NPs and Au-NPs were tested in 3 different cell cultures including rat brain microvessel endothelial cells, mouse neural stem cells, and the human SH-SY5Y cell line. Conventional 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and lactate dehydrogenase (LDH) assays were run in parallel with the new method and served as references. The results demonstrate for the first time that FJ-C labeling can be a useful tool for assessing NP-induced cytotoxicity in vitro. Using these approaches, it was also demonstrated that removal of Ag-NPs-while keeping the Ag-ions that were released from the Ag-NPs in culture media-abolished the measured cytotoxicity, indicating that Ag-NPs rather than Ag-ions in solution contributed to the observed cytotoxic effects. Further, co-treatment of Ag-NPs with N-acetyl cysteine (NAC) prevented the observed cytotoxicity, suggesting a protective role of NAC in Ag-NP-induced cytotoxicity. Thus, this alternative in vitro assay is well suited for identify potential cytotoxicity associated with exposure to NPs.

Methods for Assessing Mast Cell Responses to Engineered Nanomaterial Exposure

Mast cells are key effector cells in inflammatory and allergic immune responses such as asthma, rhinitis, and atopic dermatitis. Activation of mast cells leads to immediate release of preformed mediators such as histamine and proteases, which can regulate vascular permeability and the function of a number of immune and nonimmune cells. Engineered nanomaterials (ENM) have been utilized for a wide range of applications and introduced into a number of consumer products; yet the consequent increase in human exposure and any potential adverse effects have not been fully evaluated. Modulation of the immune system function has been shown to be a major toxicological consequence of ENM exposure. The implication of mast cells in ENM-mediated toxicity, including the most widely utilized carbon and metal-based ENMs, has been previously demonstrated; and therefore, understanding direct ENM interaction with mast cells at the cellular and molecular level is of critical importance for the safe implementation of ENMs into consumer products.

Sensitive method for endotoxin determination in nanomedicinal product samples

Aim: Nanomaterials and nanomedicinal products tend to interfere with various commonly used assays, including regulatory required endotoxin detection methods for medicines. We developed a method to quantify endotoxin levels that is compatible with nanomaterials and nanomedicinal products. Materials & methods: The method is based on measuring endotoxin indirectly via 3-hydroxylated fatty acids of lipid-A, using Ultra High Performance Liquid Chromatography coupled with mass spectrometry. The outcome was related to results of the commonly used Limulus Amebocyte Lysate method. Results: The ultra high performance liquid chromatography coupled with mass spectrometry method has clear advantages compared with other endotoxin determination assays; particularly the absence of nanospecific interference. Conclusion: The method is sensitive, straightforward and accurate in determining and quantifying endotoxin in nanomedicinal product samples.

Mixed Fluorinated/Hydrogenated Self-Assembled Monolayer-Protected Gold Nanoparticles: In Silico and In Vitro Behavior

Gold nanoparticles (AuNPs) covered with mixtures of immiscible ligands present potentially anisotropic surfaces that can modulate their interactions at complex nano-bio interfaces. Mixed, self-assembled, monolayer (SAM)-protected AuNPs, prepared with incompatible hydrocarbon and fluorocarbon amphiphilic ligands, are used here to probe the molecular basis of surface phase separation and disclose the role of fluorinated ligands on the interaction with lipid model membranes and cells, by integrating in silico and experimental approaches. These results indicate that the presence of fluorinated amphiphilic ligands enhances the membrane binding ability and cellular uptake of gold nanoparticles with respect to those coated only with hydrogenated amphiphilic ligands. For mixed monolayers, computational results suggest that ligand phase separation occurs on the gold surface, and the resulting anisotropy affects the number of contacts and adhesion energies with a membrane bilayer. This reflects in a diverse membrane interaction for NPs with different surface morphologies, as determined by surface plasmon resonance, as well as differential effects on cells, as observed by flow cytometry and confocal microscopy. Overall, limited changes in monolayer features can significantly affect NP surface interfacial properties, which, in turn, affect the interaction of SAM-AuNPs with cellular membranes and subsequent effects on cells.

Usefulness of fish cell lines for the initial characterization of toxicity and cellular fate of graphene-related materials (carbon nanofibers and graphene oxide)

Graphene-related materials (GRMs) are one of the most attractive materials from an application perspective, consequently their release into aquatic environments is highly likely. In the present work, the potential of fish hepatocytes (topminnow fish hepatoma cell line, PLHC-1) and macrophages (carp leukocyte cell line, CLC) to study the toxicity and intracellular fate of helical-ribbon carbon nanofibers (CNFs) and graphene oxide (GO) used in a variety of intermediate industrial products was evaluated, allowing a first ranking of GRMs according to their cytotoxicity. Cells were exposed to a concentration range of 0-200 μg ml^-1 of GRMs for 24 and 72 h and cell viability was assessed by measuring mitochondrial activity (AlamarBlue assay), plasma membrane integrity (5-carboxyfluorescein diacetate-acetoxymethyl ester assay) and lysosomal function (neutral red uptake assay). Results showed that both the cell type and the choice of endpoint determined the toxicity of GRMs. In both cell lines, CNFs appeared to have higher toxicity than GO and the highest degree of graphitization in fibers was associated with lower toxicity. Transmission electron microscopy revealed that CNFs were taken up into membrane-bound compartments of PLHC-1 cells in a size-independent manner, whereas in CLC, longer CNFs were encountered free in the cytoplasm and only the shorter CNFs were localized in membrane-surrounded vesicles. GO sheets were present within vesicles as well as free in the cytoplasm of both cell types. These findings contribute to the understanding of the toxicity and behaviour of these GRMs in living systems, therefore aiding in designing safer materials for the environment.

Meta-Analysis of Nanoparticle Cytotoxicity via Data-Mining the Literature

Developing predictive modeling frameworks of potential cytotoxicity of engineered nanoparticles is critical for environmental and health risk analysis. The complexity and the heterogeneity of available data on potential risks of nanoparticles, in addition to interdependency of relevant influential attributes, makes it challenging to develop a generalization of nanoparticle toxicity behavior. Lack of systematic approaches to investigate these risks further adds uncertainties and variability to the body of literature and limits generalizability of existing studies. Here, we developed a rigorous approach for assembling published evidence on cytotoxicity of several organic and inorganic nanoparticles and unraveled hidden relationships that were not targeted in the original publications. We used a machine learning approach that employs decision trees together with feature selection algorithms ( e.g., Gain ratio) to analyze a set of published nanoparticle cytotoxicity sample data (2896 samples). The specific studies were selected because they specified nanoparticle-, cell-, and screening method-related attributes. The resultant decision-tree classifiers are sufficiently simple, accurate, and with high prediction power and should be widely applicable to a spectrum of nanoparticle cytotoxicity settings. Among several influential attributes, we show that the cytotoxicity of nanoparticles is primarily predicted from the nanoparticle material chemistry, followed by nanoparticle concentration and size, cell type, and cytotoxicity screening indicator. Overall, our study indicates that following rigorous and transparent methodological experimental approaches, in parallel to continuous addition to this data set developed using our approach, will offer higher predictive power and accuracy and uncover hidden relationships. Results obtained in this study help focus future studies to develop nanoparticles that are safe by design.

Hydrophilic Quantum Dots Functionalized with Gd(III)-DO3A Monoamide Chelates as Bright and Effective T1-weighted Bimodal Nanoprobes

Magnetic resonance imaging (MRI) is a powerful non-invasive diagnostic tool that enables distinguishing healthy from pathological tissues, with high anatomical detail. Nevertheless, MRI is quite limited in the investigation of molecular/cellular biochemical events, which can be reached by fluorescence-based techniques. Thus, we developed bimodal nanosystems consisting in hydrophilic quantum dots (QDs) directly conjugated to Gd(III)-DO3A monoamide chelates, a Gd(III)-DOTA derivative, allowing for the combination of the advantages of both MRI and fluorescence-based tools. These nanoparticulate systems can also improve MRI contrast, by increasing the local concentration of paramagnetic chelates. Transmetallation assays, optical characterization, and relaxometric analyses, showed that the developed bimodal nanoprobes have great chemical stability, bright fluorescence, and high relaxivities. Moreover, fluorescence correlation spectroscopy (FCS) analysis allowed us to distinguish nanosystems containing different amounts of chelates/QD. Also, inductively coupled plasma optical emission spectrometry (ICP - OES) indicated a conjugation yield higher than 75%. Our nanosystems showed effective longitudinal relaxivities per QD and per paramagnetic ion, at least 5 times [per Gd(III)] and 100 times (per QD) higher than the r1 for Gd(III)-DOTA chelates, suitable for T1-weighted imaging. Additionally, the bimodal nanoparticles presented negligible cytotoxicity, and efficiently labeled HeLa cells as shown by fluorescence. Thus, the developed nanosystems show potential as strategic probes for fluorescence analyses and MRI, being useful for investigating a variety of biological processes.

Amorphous aggregation of tau in the presence of titanium dioxide nanoparticles: biophysical, computational, and cellular studies

Background

Nanoparticles (NPs) when injected into the body can reach target tissues like nervous system and interact with tau proteins and neurons. This can trigger conformational changes of tau and may affect NP toxicity.

Methods

In this study, we used several biophysical techniques (extrinsic and intrinsic fluorescence spectroscopy, circular dichroism (CD) spectroscopy, ultraviolet (UV)-visible spectroscopy), transmission electron microscopy (TEM) investigations, molecular docking and molecular dynamics studies, and cellular assays [3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) and flow cytometry) to reveal how structural changes of tau protein can change the cytotoxicity of titanium dioxide (TiO₂) NPs against neuron-like cells (SH-SY5Y) cells.

Results

It was shown that TiO₂ NPs result in hydrophilic interactions, secondary and tertiary structural changes, and the formation of amorphous tau aggregates. Conformational changes of tau increased the induced cytotoxicity by TiO₂ NPs. These data revealed that the denatured adsorbed protein on the NP surface may enhance NP cytotoxicity.

Conclusion

Therefore, this study provides useful insights on the NP-protein interactions and discusses how the protein corona can increase cytotoxicity to determine the efficacy of targeted delivery of nanosystems.

Interaction of biologically relevant proteins with ZnO nanomaterials: A confounding factor for in vitro toxicity endpoints

The results of in vitro toxicological studies for manufactured nanomaterials (MNs) are often contradictory and not reproducible. Interference of the MNs with assays has been suggested. However, understanding for which materials and how these artefacts occur remains a major challenge. This study investigated interactions between two well-characterized ZnO MNs (NM-110 and NM-111) and lactate dehydrogenase (LDH), and two interleukins (IL-6 and IL-8). Particles (10 to 640 μg/mL) and proteins were incubated for up to 24 h in routine in vitro assays test conditions. LDH activity (OD_LDH), but not interleukins concentrations, decreased sharply in a dose-dependent manner within an hour after exposure (OD_LDH < 60% of OD_ref for both MNs at 10 μg/mL). A Freundlich adsorption isotherm was successfully applied, indicating multilayer adsorption of LDH. ZnO MNs and LDH had neutral to slightly negative surface charges in dispersion, precluding electrostatic attachment. Particle sedimentation was not a limiting factor. Fast dissolution of ZnO MNs was shown and Zn²⁺ could play a role in the OD_LDH drop. To summarize, ZnO MNs quickly reduced OD_LDH due to concentration-dependent adsorption and LDH inhibition by interaction with dissolved Zn. The control of particle interference in toxicological in vitro assays should become mandatory to avoid misleading interpretation of results.

Electrospun Patch Functionalized with Nanoparticles Allows for Spatiotemporal Release of VEGF and PDGF-BB Promoting In Vivo Neovascularization

The use of nanomaterials as carriers for the delivery of growth factors has been applied to a multitude of applications in tissue engineering. However, issues of toxicity, stability, and systemic effects of these platforms have yet to be fully understood, especially for cardiovascular applications. Here, we proposed a delivery system composed of poly(dl-lactide- co-glycolide) acid (PLGA) and porous silica nanoparticles (pSi) to deliver vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). The tight spatiotemporal release of these two proteins has been proven to promote neovascularization. In order to minimize tissue toxicity, localize the release, and maintain a stable platform, we conjugated two formulations of PLGA-pSi to electrospun (ES) gelatin to create a combined ES patch releasing both PDGF and VEGF. When compared to freely dispersed particles, the ES patch cultured in vitro with neonatal cardiac cells had significantly less particle internalization (2.0 ± 1.3%) compared to free PLGA-pSi (21.5 ± 6.1) or pSi (28.7 ± 2.5) groups. Internalization was positively correlated to late-stage apoptosis with PLGA-pSi and pSi groups having increased apoptosis compared to the untreated group. When implanted subcutaneously, the ES patch was shown to have greater neovascularization than controls evidenced by increased expression of α-SMA and CD31 after 21 days. Quantitative reverse transcription-polymerase chain reaction results support increased angiogenesis by the upregulation of VEGFA, VEGFR2, vWF, and COL3A1, exhibiting a synergistic effect with the release of VEGF-A164 and PDGF-BB after 21 days in vivo. The results of this study proved that the ES patch reduced cellular toxicity and may be tailored to have a dual release of growth factors promoting localized neovascularization.

Biochemical effects of some CeO2, SiO2, and TiO2 nanomaterials in HepG2 cells

The potential mammalian hepatotoxicity of nanomaterials was explored in dose-response and structure-activity studies in human hepatic HepG2 cells exposed to between 10 and 1000 μg/ml of five different CeO₂, three SiO₂, and one TiO₂-based particles for 3 days. Various biochemical parameters were then evaluated to study cytotoxicity, cell growth, hepatic function, and oxidative stress. Few indications of cytotoxicity were observed between 10 and 30 μg/ml. In the 100 to 300 μg/ml exposure range, a moderate degree of cytotoxicity was often observed. At 1000 μg/ml exposures, all but TiO₂ showed a high degree of cytotoxicity. Cytotoxicity per se did not seem to fully explain the observed patterns of biochemical parameters. Four nanomaterials (all three SiO₂) decreased glucose 6-phosphate dehydrogenase activity with some significant decreases observed at 30 μg/ml. In the range of 100 to 1000 μg/ml, the activities of glutathione reductase (by all three SiO₂) and glutathione peroxidase were decreased by some nanomaterials. Decreased glutathione concentration was also found after exposure to four nanomaterials (all three nano SiO₂ particles). In this study, the more responsive and informative assays were glucose 6-phosphate dehydrogenase, glutathione reductase, superoxide dismutase, lactate dehydrogenase, and aspartate transaminase. In this study, there were six factors that contribute to oxidative stress observed in nanomaterials exposed to hepatocytes (decreased glutathione content, reduced glucose 6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, superoxide dismutase, and increased catalase activities). With respect to structure-activity, nanomaterials of SiO₂ were more effective than CeO₂ in reducing glutathione content, glucose 6-phosphate dehydrogenase, glutathione reductase, and superoxide dismutase activities.

Interference of engineered nanomaterials in flow cytometry: A case study

Nanotechnology is regarded as the enabling technology of the 21st century. However, only a relatively small number of nano-enabled medical and healthcare products finally made their way to the market. There are several reasons why such innovative approaches fail in translation, with one key factor being the uncertainty surrounding their safety assessment. Although well described, interference reactions of engineered nanomaterials (ENM) with classical cytotoxicity assays remain a major source of uncertainty. Flow cytometry is a powerful, widely used, in vitro technique. Its readout is based on the detection of refracted laser light and fluorescence signals. It is therefore susceptible to ENM interference. Here we investigated possible interferences of ENM in the Annexin V/propidium iodide (PI) assay, which quantifies apoptotic and necrotic cell populations by flow cytometry. Two case studies were conducted using either silica or gold nanoparticles differing in size, specific surface area and surface chemistry. Both ENM types were found to cause distinct interference reactions at realistic concentrations. Silica particles induced false-positive signals; however only in the absence of a protein corona and in conjunction with a particular fluorophore combination (FITC/PI). In contrast, gold particles led to complex quenching effects which were only marginally influenced by the presence of proteins and occurred for both fluorophore combinations analyzed. We present a versatile spike-in approach which is applicable to all ENM and cell types. It further allows for the identification of a broad range of different interference phenomena, thereby increasing the reliability and quality of flow cytometry and ENM hazard assessment.