Exposure to titanium dioxide nanomaterials provokes inflammation of an in vitro human immune construct

Designing biomaterials with immunomodulatory properties for tissue engineering and regenerative medicine

Recent research in the vaccine and immunotherapy fields has revealed that biomaterials have the ability to activate immune pathways, even in the absence of other immune-stimulating signals. Intriguingly, new studies reveal these responses are influenced by the physicochemical properties of the material. Nearly all of this work has been done in the vaccine and immunotherapy fields, but there is tremendous opportunity to apply this same knowledge to tissue engineering and regenerative medicine. This review discusses recent findings that reveal how material properties-size, shape, chemical functionality-impact immune response, and links these changes to emerging opportunities in tissue engineering and regenerative medicine. We begin by discussing what has been learned from studies conducted in the contexts of vaccines and immunotherapies. Next, research is highlighted that elucidates the properties of materials that polarize innate immune cells, including macrophages and dendritic cells, toward either inflammatory or wound healing phenotypes. We also discuss recent studies demonstrating that scaffolds used in tissue engineering applications can influence cells of the adaptive immune system-B and T cell lymphocytes-to promote regenerative tissue microenvironments. Through greater study of the intrinsic immunogenic features of implantable materials and scaffolds, new translational opportunities will arise to better control tissue engineering and regenerative medicine applications.

Pre- and post-surgical evaluation of the inflammatory response in patients with aortic stenosis treated with different types of prosthesis

Background

The inflammatory process in aortic valvular stenosis persists after surgery to replace the valve in almost half of the patients. No association has been found to its persistence. The main objective of this study was to evaluate the inflammatory response in patients with aortic stenosis through the determination of several biomarkers in plasma measured before and after the valvular replacement and to seek an association with the type of prosthesis used.

Methods

This is an observational study with a follow up of 6 months in subjects with severe aortic stenosis. Seric concentrations of TNFa, IL-1, IL-6 and ICAM and echocardiographic variables were quantified previous to the surgery and a week and 6 months after it. A group of control subjects paired by age and gender was included.

Results

Seventy-nine subjects were studied of which 57% were male; the average age was of 59 (± 11.4) years. Previous to surgery, the concentration of cytokines was higher in patients than in control subjects. A biological prosthesis was implanted in 48 patients and a mechanical prosthesis in 31. Both, types of prosthesis have components made of titanium. The echocardiograms 1 week and 6 months after the surgery showed a decrease in the mean aortic gradient and an increase in the valvular area (p = 0.001). Half of the patients still showed high proinflammatory cytokine levels. There were no differences according to the type of prosthesis implanted after adjustments for demographic variables, comorbidities and echocardiographic data.

Conclusions

The inflammatory response caused by both types of valvular prothesis at 6 months after implantation were similar. Both types of prosthesis are recommended, they had similarities in hemodynamic profiles registered with Doppler echocardiography. Age of the patient or the suitability use of anticoagulants determines the type of prosthesis to be used.

Role of Metallic Nanoparticles in Vaccinology: Implications for Infectious Disease Vaccine Development

Subunit vaccines are safer but less immunogenic than live-attenuated vaccines or whole cell inactivated vaccines. Adjuvants are used to enhance and modulate antigen (Ag) immunogenicity, aiming to induce a protective and long-lasting immune response. Several molecules and formulations have been studied for their adjuvanticity, but only seven have been approved to formulate human vaccines. Metallic nanoparticles (MeNPs), particularly those containing gold and iron oxides, are widely used in medicine for diagnosis and therapy and have been used as carriers for drugs and vaccines. However, little is known about the immune response elicited by MeNPs or about their importance in the development of new vaccines. There is evidence that these particles display adjuvant characteristics, promoting cell recruitment, antigen-presenting cell activation, cytokine production, and inducing a humoral immune response. This review focuses on the characteristics of MeNPs that could facilitate the induction of a cellular immune response, particularly T-helper 1 and T-helper 17, and their potential functions as adjuvants for subunit vaccines.

Titanium Dioxide Nanoparticles Evoke Proinflammatory Response during Murine Norovirus Infection Despite Having Minimal Effects on Virus Replication

Noroviruses (NoV) have enhanced tropism for the gastrointestinal (GI) tract and are the major cause of nonbacterial gastroenteritis in humans. Titanium dioxide (TiO2) nanoparticles (NPs) used as food additives, dietary supplements, and cosmetics accumulate in the GI tract. We investigated the effect anatase TiO2 NPs on NoV replication and host response during virus infection, using murine norovirus (MNV-1) infection of RAW 264.7 macrophages. Pretreatment with 20 μg/ml anatase NPs significantly reduced the viability of macrophages alone or during virus infection, but did not alter virus replication. In contrast, pre-incubation with 2 μg/ml anatase NPs reduced virus replication fivefold at 48 h. The presence of anatase NPs during MNV-1 infection evoked a pro-inflammatory response, as measured by a significant increase in expression of cytokines, including IL-6, IFN-γ, TNFα and the TGFβ1. No genotoxic insults due to anatase TiO2 NPs alone or to their presence during MNV-1 infection were detected. This study highlights important safety considerations related to NP exposure of the GI tract in individuals infected with noroviruses or other foodborne viruses.

Toxicity assessment of hydroxyapatite nanoparticles in rat liver cell model in vitro

Hydroxyapatite nanoparticles (HAP NPs) are widely used for preparations of biomedical and biotechnological fields such as drug delivery, gene therapy, and molecular imaging. However, the current toxicological knowledge about HAP NPs is relatively limited. The present study was designed to investigate the toxicity potentials of various concentrations (0–1000 µg cm−2) of HAP NPs in cultured primary rat hepatocytes. Cell viability was detected by 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. The DNA damage was also analyzed via scoring liver micronuclei rates and determining 8-oxo-2-deoxyguanosine (8-OH-dG) levels. The results of MTT and LDH assays showed that the higher concentrations of dispersed HAP NPs (300, 500, and 1000 µg cm−2) decreased cell viability. Also, HAP NPs increased TOS (500 and 1000 µg cm−2) levels and decreased TAC (300, 500, and 1000 µg cm−2) levels in cultured hepatocytes. On the basis of increasing doses, the NPs as depending on dose caused significant increases of the number of micronucleated hepatocytes and 8-OH-dG levels as compared to control culture. Furthermore, the highest concentration of HAP NPs (1000 µg cm−2) exhibited cytotoxic activity. Based on these results, HAP NPs have a dose-dependent toxic effect in rat hepatocytes. Further extensive research in this field is promising and reasonable.

Silica nanoparticles activate purinergic signaling via P2X7 receptor in dendritic cells, leading to production of pro-inflammatory cytokines

We examined the mechanism of SNP-mediated stimulation of IL-1β and IL-18 production via P2R-mediated pathways in mouse bone marrow dendritic cells (mBMDCs). Examination of uptake of SNPs with diameters of 30, 70, and 300nm (SNP30, SNP70, and SNP300, respectively) by lipopolysaccharide-matured mBMDCs revealed that significant uptake of SNP30 occurred within as short a time as 1h. Production of IL-1β and IL-18 by cells exposed to SNPs increased dose-dependently, and was highest in cells exposed to SNP30. The SNP30-induced cytokine production was significantly inhibited by ATPase (apyrase) and by P2X7 receptor antagonist (A438079). ATP release was also highest in SNP30-exposed cells. Treatment of mBMDCs with exogenous ATP induced release of high levels of IL-1β and IL-18, and this release was also significantly inhibited by apyrase and A438079. The order of effectiveness of the three SNPs for inducing intracellular reactive oxygen species (ROS) production accorded well with those of cytokine production and ATP release. ROS production was inhibited by diphenyleneiodonium chloride (DPI). SNPs, especially SNP30, activate purinergic signaling in matured mBMDCs by inducing ATP release via P2X7 receptor. ATP induces ROS production via NADPH oxidase, and ROS activate inflammasomes, leading to caspase-1-dependent processing of pro-cytokines and release of IL-1β and IL-18.

Tungsten Oxide Nanoplates; the Novelty in Targeting Metalloproteinase-7 Gene in Both Cervix and Colon Cancer Cells

In this study, we synthesized tungsten oxide (WO₃) nanoplates, both crystallographic phases and the morphology of the samples were determined by powder x-ray diffraction and the scanning electron microscopy, respectively. The obtained data clarified that, the all prepared WO₃·H₂O samples were composed of large quantity of nanoplates. The cytotoxicity patterns of nanoplates were checked on both normal and cancer mammalian cell lines. Both nanoplates cytotoxicity did not exceed the 50 % inhibitory concentration (IC50) on the all normal tested cells even by using concentrations up to 1 mg/ml. In addition, orthorhombic tungsten oxide nanoplate was more potent against both Caco2 and Hela cells by showing inhibition percentages in cellular viability 64.749 and 72.27, respectively, and with cancer selectivity index reached 3.2 and 2.6 on both colon and cervix cancer, respectively. The anticancer effects of nanoplates were translated to alteration in both pro-apoptotic and anti-apoptotic genes expressions. Tungsten oxide nanoplates down regulated the expression of B cell lymphoma 2 (Bcl-2) and metalloproteinase-7 (MMP7) genes. In addition, orthorhombic tungsten oxide nanoplates showed more potentiation in IL2 and IL8 induction (40.43 pg/ml) and upregulation of TNF-α gene expression but with lower folds than Escherichia coli lipopolysaccharide (LPS) induction.

Titanium dioxide nanoparticles augment allergic airway inflammation and Socs3 expression via NF-κB pathway in murine model of asthma

Titanium dioxide nanoparticles (nTiO2) previously considered to possess relatively low toxicity both in vitro and in vivo, although classified as possibly carcinogenic to humans. Also, their adjuvant potential has been reported to promote allergic sensitization and modulate immune responses. Previously, in OVA induced mouse model of asthma we found high expression of Socs3 and low expression of Stat3 and IL-6. However, a clear understanding regarding the signaling pathways associated with nTiO2 adjuvant effect in mouse model of asthma is lacking. In the present study we investigated the status of Stat3/IL-6 and Socs3 and their relationship with NF-κB, with nTiO2 as an adjuvant in mouse model of asthma. nTiO2 when administered with ovalbumin (OVA) during sensitization phase augmented airway hyper-responsiveness (AHR), biochemical markers of lung damage and a mixed Th2/Th1 dependent immune response. At the same time, we observed significant elevation in the levels of Stat3, Socs3, NF-κB, IL-6 and TNF-α. Furthermore, transient in vivo blocking of NF-κB by NF-κB p65 siRNA, downregulated the expression of Socs3, IL-6 and TNF-α. Our study, thus, shows that nTiO2 exacerbate the inflammatory responses in lungs of pre-sensitized allergic individuals and that these changes are regulated via NF-κB pathway.

Materials design at the interface of nanoparticles and innate immunity

Engineered nanoparticle platforms have been developed intensely in recent years, yielding significantly broadened applications from interrogating novel biology to new therapies. Using these platforms requires improved understanding of design rules to improve our ability to control nanoparticle-immune system interactions.

Ti–O based nanomaterials ameliorate experimental autoimmune encephalomyelitis and collagen-induced arthritis

Administration of Ti–O based nanomaterials ameliorated the clinical severity of experimental autoimmune encephalomyelitis and collagen induced arthritis, thus provide novel therapeutic approach for multiple sclerosis and rheumatoid arthritis.

Modulation of Human Macrophage Responses to Mycobacterium tuberculosis by Silver Nanoparticles of Different Size and Surface Modification

Exposure to silver nanoparticles (AgNP) used in consumer products carries potential health risks including increased susceptibility to infectious pathogens. Systematic assessments of antimicrobial macrophage immune responses in the context of AgNP exposure are important because uptake of AgNP by macrophages may lead to alterations of innate immune cell functions. In this study we examined the effects of exposure to AgNP with different particle sizes (20 and 110 nm diameters) and surface chemistry (citrate or polyvinlypyrrolidone capping) on cellular toxicity and innate immune responses against Mycobacterium tuberculosis (M.tb) by human monocyte-derived macrophages (MDM). Exposures of MDM to AgNP significantly reduced cellular viability, increased IL8 and decreased IL10 mRNA expression. Exposure of M.tb-infected MDM to AgNP suppressed M.tb-induced expression of IL1B, IL10, and TNFA mRNA. Furthermore, M.tb-induced IL-1β, a cytokine critical for host resistance to M.tb, was inhibited by AgNP but not by carbon black particles indicating that the observed immunosuppressive effects of AgNP are particle specific. Suppressive effects of AgNP on the M.tb-induced host immune responses were in part due to AgNP-mediated interferences with the TLR signaling pathways that culminate in the activation of the transcription factor NF-κB. AgNP exposure suppressed M.tb-induced expression of a subset of NF-κB mediated genes (CSF2, CSF3, IFNG, IL1A, IL1B, IL6, IL10, TNFA, NFKB1A). In addition, AgNP exposure increased the expression of HSPA1A mRNA and the corresponding stress-induced Hsp72 protein. Up-regulation of Hsp72 by AgNP can suppress M.tb-induced NF-κB activation and host immune responses. The observed ability of AgNP to modulate infectious pathogen-induced immune responses has important public health implications.

Biocompatibility of Dead Sea Water and retinyl palmitate carrying poly(3-hydroxybutyrate-co-3-hydroxyvalerate) micro/nanoparticles designed for transdermal skin therapy

In this study, novel drug carriers were developed for the treatment of skin conditions such as psoriasis, aging, or ultraviolet damage using micro/nanocapsules and micro/nanospheres of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The sizes of the particles were in the micron range and were loaded with retinyl palmitate and Dead Sea Water. In some tests, MgCl2 was used as a substitute for Dead Sea Water for accurate determination of released ions of Dead Sea Water. Encapsulation efficiency and loading of water-soluble excipients Dead Sea Water and MgCl2 were almost eight times lower than the hydrophobic compound retinyl palmitate. The particles were not cytotoxic as determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test using L929 mouse fibroblasts, BALB/3T3 mouse embryo fibroblasts, and HaCaT human keratinocytes. Ames test showed that the carriers were not genotoxic. The particles penetrated the membrane of human osteosarcoma cells Saos 2 and accumulated in their cytoplasm. No reactive oxygen species production could be detected which indicated low or no inflammatory response toward the particles. In the tests with intact human skin, 1.2% of the retinyl palmitate–loaded poly(3-hydroxybutyrate-co-3-hydroxyvalerate) particles penetrated into the human skin, but when the skin was without stratum corneum and increased to 6.9%. In conclusion, these carriers have shown a significant potential as topical drug delivery systems in the personalized treatment of skin diseases because their contents could be modified according to a patient’s needs and several drugs could be loaded in one type of microparticle, or several populations, each carrying a different drug, can be used in the treatment.

Adjuvants in micro- to nanoscale: current state and future direction

Adjuvants have been used in vaccines for over 70 years to promote long-lived and sterilizing immunity. Since then, various adjuvant systems were developed by combining nanotechnology with natural and/or synthetic immunomodulatory molecules. These systems are biocompatible, immunogenic, and possess higher antigen carrying capacity. This article showcases advancements made in the adjuvant systems formulations, their synthesis routes, and the improvement of these adjuvants have brought in response to combat against ongoing global health threats such as malaria, hepatitis C, universal influenza, and human immunodeficiency virus. This review also highlights the interaction of adjuvants with the delivery of antigens to cells and unfolds mechanism of actions. In addition, this review discusses the physicochemical factors responsible for the efficient interaction of nanoadjuvants with antigen receptors to develop more effective, less reactogenic, and multifunctional systems for the next generation vaccines.

Metal-Based Nanoparticles and the Immune System: Activation, Inflammation, and Potential Applications

Nanomaterials, including metal-based nanoparticles, are used for various biological and medical applications. However, metals affect immune functions in many animal species including humans. Different physical and chemical properties induce different cellular responses, such as cellular uptake and intracellular biodistribution, leading to the different immune responses. The goals of this review are to summarize and discuss the innate and adaptive immune responses triggered by metal-based nanoparticles in a variety of immune system models.

Inhaled Titanium Dioxide Nanoparticles: A Review of Their Pulmonary Responses with Particular Focus on the Agglomeration State

Nanotechnology represents major scientific and economic issues for the future. TiO 2 is used as a reference nanoparticle (NP) for research and workplace exposure assessments due to its important industrial production. However, to date little consistent information exists about its human health effects. Approximately 50% of all TiO 2in vivo studies targeting the respiratory tract have been by inhalation and these exposures are often in the form of agglomerates rather than as individual NPs. Therefore, the size of the NP agglomerates represents the effective size interacting with the biological material and could thereby influence the NP mechanisms of action. Thus, interpretation of nanotoxicological data without considering the agglomeration state could partly explain the heterogeneous results found in the scientific literature for TiO 2 NPs. The objective of this review is to examine the literature concerning the importance of TiO 2 aerosol characterization in the assessment of pulmonary toxicity in rodents. In this way, this review reveals that the pulmonary responses following inhalation of TiO 2 NPs might not depend solely on the primary NP size, but also on the crystal phase, the NP agglomerate size, its structure and the mass concentration. It also shows that TiO 2 NPs may exert their toxicity mechanisms specifically because of the size of their agglomerates in aerosols, thus supporting the concept that aerosols composed essentially of small (< 100 nm) or large (> 100 nm) NP agglomerates do not seem to follow the same pulmonary toxicity mechanisms.

Silica nanoparticles induce autophagy and endothelial dysfunction via the PI3K/Akt/mTOR signaling pathway

Although nanoparticles have a great potential for biomedical applications, there is still a lack of a correlative safety evaluation on the cardiovascular system. This study is aimed to clarify the biological behavior and influence of silica nanoparticles (Nano-SiO₂) on endothelial cell function. The results showed that the Nano-SiO₂ were internalized into endothelial cells in a dose-dependent manner. Monodansylcadaverine staining, autophagic ultrastructural observation, and LC3-I/LC3-II conversion were employed to verify autophagy activation induced by Nano-SiO₂, and the whole autophagic process was also observed in endothelial cells. In addition, the level of nitric oxide (NO), the activities of NO synthase (NOS) and endothelial (e)NOS were significantly decreased in a dose-dependent way, while the activity of inducible (i)NOS was markedly increased. The expression of C-reactive protein, as well as the production of proinflammatory cytokines (tumor necrosis factor α, interleukin [IL]-1β, and IL-6) were significantly elevated. Moreover, Nano-SiO₂ had an inhibitory effect on the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. Our findings demonstrated that Nano-SiO₂ could disturb the NO/NOS system, induce inflammatory response, activate autophagy, and eventually lead to endothelial dysfunction via the PI3K/Akt/mTOR pathway. This indicates that exposure to Nano-SiO₂ is a potential risk factor for cardiovascular diseases.

Carbon black and titanium dioxide nanoparticles induce distinct molecular mechanisms of toxicity

Increasing evidence link nanomaterials with adverse biological outcomes and due to the variety of applications and potential human exposures to nanoparticles, it is thus important to evaluate their toxicity for the risk assessment of workers and consumers. It is crucial to understand the underlying mechanisms of their toxicity as observation of similar effects after different nanomaterial exposures does not reflect similar intracellular processing and organelle interactions. A thorough understanding of mechanisms is needed not only for accurate prediction of potential toxicological impacts but also for the development of safer nanoapplications by modulating the physicochemical characteristics. Furthermore biomedical applications may also take advantage of an in depth knowledge about the mode of action of nanotoxicity to design new nanoparticle-derived drugs. In the present manuscript we discuss the similarities and differences in molecular pathways of toxicity after carbon black (CB) and titanium dioxide (TiO₂) nanoparticle exposures and identify the main toxicity mechanisms induced by these two nanoparticles which may also be indicative for the mode of action of other insoluble nanomaterials. We address the translocation, cell death induction, genotoxicity, and inflammation induced by TiO₂ and CB nanoparticles which depend on their internalization, reactive oxygen species (ROS) production capacities and/or protein interactions. We summarize their distinct cellular mechanisms of toxicity and the crucial steps which may be targeted to avoid adverse effects or to induce them for nanomedical purposes. Several physicochemical characteristics could influence these general toxicity pathways depicted here and the identification of common toxicity pathways could support the grouping of nanomaterials in terms of toxicity.

Health risk assessments of lithium titanate nanoparticles in rat liver cell model for its safe applications in nanopharmacology and nanomedicine

Due to their high chemical stability, lithium titanate (Li2TiO3) nanoparticles (LTT NPs) now are projected to be transferred into different nanotechnology areas like nano pharmacology and nano medicine. With the increased applications of LTT NPs for numerous purposes, the concerns about their potential human toxicity effects and their environmental impact are also increased. However, toxicity data for LTT NPs related to human health are very limited. Therefore we aimed to investigate toxicity potentials of various concentrations (0-1,000 ppm) of LTT NPs (<100 nm) in cultured primary rat hepatocytes. Cell viability was detected by [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide] (MTT) assay and lactate dehydrogenase (LDH) release, while total antioxidant capacity (TAC) and total oxidative stress (TOS) levels were determined to evaluate the oxidative injury. DNA damage was analyzed by scoring liver micronuclei rates and by determining 8-oxo-2-deoxyguanosine (8-OH-dG) levels. The results of MTT and LDH assays showed that higher concentrations of dispersed LTT NPs (500 and 1,000 ppm) decreased cell viability. Also, LTT NPs increased TOS (300, 500 and 1,000 ppm) levels and decreased TAC (300, 500 and 1,000 ppm) levels in cultured hepatocytes. The results of genotoxicity tests revealed that LTT NPs did not cause significant increases of micronucleated hepatocytes and 8-OH-dG as compared to control culture. In conclusion, the obtained results showed for the first time that LTT NPs had dose dependent effects on oxidative damage and cytotoxicity but not genotoxicity in cultured primary rat hepatocytes for the first time.

Characterization of food-grade titanium dioxide: the presence of nanosized particles

Titanium dioxide (TiO2) is widely used in food products, which will eventually enter wastewater treatment plants and terrestrial or aquatic environments, yet little is known about the fraction of this TiO2 that is nanoscale, or the physical and chemical properties of TiO2 that influence its human and environmental fate or toxicity. Instead of analyzing TiO2 properties in complex food or environmental samples, we procured samples of food-grade TiO2 obtained from global food suppliers and then, using spectroscopic and other analytical techniques, quantified several parameters (elemental composition, crystal structure, size, and surface composition) that are reported to influence environmental fate and toxicity. Another sample of nano-TiO2 that is generally sold for catalytic applications (P25) and widely used in toxicity studies, was analyzed for comparison. Food-grade and P25 TiO2 are engineered products, frequently synthesized from purified titanium precursors, and not milled from bulk scale minerals. Nanosized materials were present in all of the food-grade TiO2 samples, and transmission electron microscopy showed that samples 1-5 contained 35, 23, 21, 17, and 19% of nanosized primary particles (<100 nm in diameter) by number, respectively (all primary P25 particles were <100 nm in diameter). Both types of TiO2 aggregated in water with an average hydrodynamic diameter of >100 nm. Food-grade samples contained phosphorus (P), with concentrations ranging from 0.5 to 1.8 mg of P/g of TiO2. The phosphorus content of P25 was below inductively coupled plasma mass spectrometry detection limits. Presumably because of a P-based coating detected by X-ray photoelectron spectroscopy, the ζ potential of the food-grade TiO2 suspension in deionized water ranged from -10 to -45 mV around pH 7, and the iso-electric point for food-grade TiO2 (<pH 4) was significantly lower than that for P25. The presence of other elements in or on the TiO2 (Si content of 0.026-0.062% and Al content of 0.0006-0.810%) was also different from the case for P25 and would influence the environmental fate of TiO2. X-ray diffraction analysis confirmed the presence of anatase and/or rutile in the food-grade materials, and although the presence of amorphous TiO2 could not be ruled out, it is unlikely on the basis of Raman analysis. The food-grade TiO2 was solar photoactive. Cationic dyes adsorbed more readily to food-grade TiO2 than P25, indicating very different potentials for interaction with organics in the environment. This research shows that food-grade TiO2 contains engineered nanomaterials with properties quite different from those of P25, which has previously been used in many ecotoxicity studies, and because food-grade TiO2 is more likely than P25 to enter the environment (i.e., potentially higher exposure levels), there is a need to design environmental (and human) fate and toxicity studies comparing food-grade to catalytic TiO2.

Human immunity in vitro - solving immunogenicity and more

It has been widely recognised that the phylogenetic distance between laboratory animals and humans limits the former's predictive value for immunogenicity testing of biopharmaceuticals and nanostructure-based drug delivery and adjuvant systems. 2D in vitro assays have been established in conventional culture plates with little success so far. Here, we detail the status of various 3D approaches to emulate innate immunity in non-lymphoid organs and adaptive immune response in human professional lymphoid immune organs in vitro. We stress the tight relationship between the necessarily changing architecture of professional lymphoid organs at rest and when activated by pathogens, and match it with the immunity identified in vitro. Recommendations for further improvements of lymphoid tissue architecture relevant to the development of a sustainable adaptive immune response in vitro are summarized. In the end, we sketch a forecast of translational innovations in the field to model systemic innate and adaptive immunity in vitro.

Purinergic signaling via P2X7 receptor mediates IL-1β production in Kupffer cells exposed to silica nanoparticle

There is extensive evidence that nanoparticles (NPs) cause adverse effects in multiple organs, including liver, though the mechanisms involved remain to be fully established. Kupffer cells are macrophages resident in the liver, and play important roles in liver inflammation induced by various toxic agents, including lipopolysaccharide (LPS). Interleukin-1 (IL-1) family members IL-1α,β are released from LPS-primed macrophages exposed to NPs, including silica NPs (SNPs), via activation of nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 inflammasomes. Here, we investigated the mechanism of production of IL-1β via activation of inflammasomes in mouse Kupffer cell line KUP5, focusing on the role of purinergic signaling via P2X7 receptor. IL-1β production by LPS-primed KUP5 cells exposed to SNPs was increased dose-dependently, and was greatest in response to SNPs with a diameter of 30 nm (SNP30), as compared with 70-nm and 300-nm SNPs (SNP70 and SNP300). ATP release was also highest in cells exposed to SNP30. Treatment of LPS-primed KUP5 cells with ATP also induced a high level of IL-1β production, similar to that induced by SNP30. IL-1β production was significantly inhibited by apyrase (an ecto-nucleotidase) and A438079 (a P2X7 antagonist/ATP-release inhibitor). Production of reactive oxygen species (ROS) was confirmed in cells exposed to SNP30. In conclusion, ATP released from P2X7 receptor in response to stimulation of KUP5 cells with SNP30 induces ROS production via cell-membrane NADPH oxidase. The ROS causes activation of inflammasomes, leading to caspase-1-dependent processing of IL-1β.

Protein corona fingerprinting predicts the cellular interaction of gold and silver nanoparticles

Using quantitative models to predict the biological interactions of nanoparticles will accelerate the translation of nanotechnology. Here, we characterized the serum protein corona 'fingerprint' formed around a library of 105 surface-modified gold nanoparticles. Applying a bioinformatics-inspired approach, we developed a multivariate model that uses the protein corona fingerprint to predict cell association 50% more accurately than a model that uses parameters describing nanoparticle size, aggregation state, and surface charge. Our model implicates a set of hyaluronan-binding proteins as mediators of nanoparticle-cell interactions. This study establishes a framework for developing a comprehensive database of protein corona fingerprints and biological responses for multiple nanoparticle types. Such a database can be used to develop quantitative relationships that predict the biological responses to nanoparticles and will aid in uncovering the fundamental mechanisms of nano-bio interactions.

The induction of maturation on dendritic cells by TiO2 and Fe(3)O(4)@TiO(2) nanoparticles via NF-κB signaling pathway

Nanomaterials are increasingly used in many fields, including drug vectors and vaccine formulation. In this study, nano-TiO(2) and magnetic Fe(3)O(4)@TiO(2) were synthesized and their abilities to activate dendritic cells were investigated. The signaling pathway involved in their effects on the cellular functions was also explored. First, nano-TiO(2) and Fe(3)O(4)@TiO(2) were prepared with diameters of 82nm and 63nm, and zeta potentials of 41.5mV and 30.2mV, respectively. The magnetic property of Fe(3)O(4)@TiO(2) was detected to be 12.9emu/g. Both kinds of nanoparticles were proved to have good biocompatibility in vitro. Second, the exposure of nano-TiO2 and Fe(3)O(4)@TiO(2)caused an increased expression of TNF-α, CD86 and CD80, and besides, Fe(3)O(4)@TiO(2)showed a certain up-regulation on MHC-II. The cellular uptake of Ovalbumin on BMDCs could be strongly improved by nano-TiO2 and Fe(3)O(4)@TiO(2)as detected via flow cytometer and confocal observation. Further investigation revealed that nano-TiO(2) and Fe(3)O(4)@TiO(2)significantly increased the NF-κB expression in the nucleus, indicating that the NF-κB signaling pathway was involved in the dendritic cell maturation. Our results suggested that nano-TiO(2) and Fe(3)O(4)@TiO(2)may function as a useful vector to promote vaccine delivery in immune cells, and Fe(3)O(4)@TiO(2)provided a possibility to deliver and track vaccines via its magnetofection.

Potential proinflammatory effects of hydroxyapatite nanoparticles on endothelial cells in a monocyte-endothelial cell coculture model

Currently, synthetic hydroxyapatite nanoparticles (HANPs) are used in nanomedicine fields. The delivery of nanomedicine to the bloodstream exposes the cardiovascular system to a potential threat. However, the possible adverse cardiovascular effects of HANPs remain unclear. Current observations using coculture models of endothelial cells and monocytes with HANPs to mimic the complex physiological functionality of the vascular system demonstrate that monocytes could play an important role in the mechanisms of endothelium dysfunction induced by the exposure to HANPs. Our transmission electron microscopy analysis revealed that both monocytes and endothelial cells could take up HANPs. Moreover, our findings demonstrated that at a subcytotoxic dose, HANPs alone did not cause direct endothelial cell injury, but they did induce an indirect activation of endothelial cells, resulting in increased interleukin-6 production and elevated adhesion molecule expression after coculture with monocytes. The potential proinflammatory effect of HANPs is largely mediated by the release of soluble factors from the activated monocytes, leading to an inflammatory response of the endothelium, which is possibly dependent on p38/c-Jun N-terminal kinase, and nuclear factor-kappa B signaling activation. The use of in vitro monocyte–endothelial cell coculture models for the biocompatibility assessment of HANPs could reveal their potential proinflammatory effects on endothelial cells, suggesting that exposure to HANPs possibly increases the risk of cardiovascular disease.

Alterations of intestinal serotonin following nanoparticle exposure in embryonic zebrafish

The increased use of engineered nanoparticles (NPs) in manufacturing and consumer products raises concerns about the potential environmental and health implications on the ecosystem and living organisms. Organs initially and more heavily affected by environmental NPs exposure in whole organisms are the skin and digestive system. We investigate the toxic effect of two types of NPs, nickel (Ni) and copper oxide (CuO), on the physiology of the intestine of a living aquatic system, zebrafish embryos. Embryos were exposed to a range of Ni and CuO NP concentrations at different stages of embryonic development. We use changes in the physiological serotonin (5HT) concentrations, determined electrochemically with carbon fiber microelectrodes inserted in the live embryo, to assess this organ dysfunction due to NP exposure. We find that exposure to both Ni and CuO NPs induces changes in the physiological 5HT concentration that varies with the type, exposure period and concentration of NPs, as well as with the developmental stage during which the embryo is exposed. These data suggest that exposure to NPs might alter development and physiological processes in living organisms and provide evidence of the effect of NPs on the physiology of the intestine.

Rat pulmonary responses to inhaled nano-TiO₂: effect of primary particle size and agglomeration state

Background

The exact role of primary nanoparticle (NP) size and their degree of agglomeration in aerosols on the determination of pulmonary effects is still poorly understood. Smaller NP are thought to have greater biological reactivity, but their level of agglomeration in an aerosol may also have an impact on pulmonary response. The aim of this study was to investigate the role of primary NP size and the agglomeration state in aerosols, using well-characterized TiO₂ NP, on their relative pulmonary toxicity, through inflammatory, cytotoxic and oxidative stress effects in Fisher 344 male rats.

Methods

Three different sizes of TiO₂ NP, i.e., 5, 10–30 or 50 nm, were inhaled as small (SA) (< 100 nm) or large agglomerates (LA) (> 100 nm) at 20 mg/m³ for 6 hours.

Results

Compared to the controls, bronchoalveolar lavage fluids (BALF) showed that LA aerosols induced an acute inflammatory response, characterized by a significant increase in the number of neutrophils, while SA aerosols produced significant oxidative stress damages and cytotoxicity. Data also demonstrate that for an agglomeration state smaller than 100 nm, the 5 nm particles caused a significant increase in cytotoxic effects compared to controls (assessed by an increase in LDH activity), while oxidative damage measured by 8-isoprostane concentration was less when compared to 10–30 and 50 nm particles. In both SA and LA aerosols, the 10–30 nm TiO₂ NP size induced the most pronounced pro-inflammatory effects compared to controls.

Conclusions

Overall, this study showed that initial NP size and agglomeration state are key determinants of nano-TiO₂ lung inflammatory reaction, cytotoxic and oxidative stress induced effects.

A framework for grouping nanoparticles based on their measurable characteristics

Background

There is a need to take a broader look at nanotoxicological studies. Eventually, the field will demand that some generalizations be made. To begin to address this issue, we posed a question: are metal colloids on the nanometer-size scale a homogeneous group? In general, most people can agree that the physicochemical properties of nanomaterials can be linked and related to their induced toxicological responses.

Methods

The focus of this study was to determine how a set of selected physicochemical properties of five specific metal-based colloidal materials on the nanometer-size scale – silver, copper, nickel, iron, and zinc – could be used as nanodescriptors that facilitate the grouping of these metal-based colloids.

Results

The example of the framework pipeline processing provided in this paper shows the utility of specific statistical and pattern recognition techniques in grouping nanoparticles based on experimental data about their physicochemical properties. Interestingly, the results of the analyses suggest that a seemingly homogeneous group of nanoparticles could be separated into sub-groups depending on interdependencies observed in their nanodescriptors.

Conclusion

These particles represent an important category of nanomaterials that are currently mass produced. Each has been reputed to induce toxicological and/or cytotoxicological effects. Here, we propose an experimental methodology coupled with mathematical and statistical modeling that can serve as a prototype for a rigorous framework that aids in the ability to group nanomaterials together and to facilitate the subsequent analysis of trends in data based on quantitative modeling of nanoparticle-specific structure–activity relationships. The computational part of the proposed framework is rather general and can be applied to other groups of nanomaterials as well.

Cytokines as biomarkers of nanoparticle immunotoxicity

Nanoscale objects, whether of biologic origin or synthetically created, are being developed into devices for a variety of bionanotechnology diagnostic and pharmaceutical applications. However, the potential immunotoxicity of these nanomaterials and mechanisms by which they may induce adverse reactions have not received sufficient attention. Nanomaterials, depending on their characteristics and compositions, can interact with the immune system in several ways and either enhance or suppress immune system function. Cytokines perform pleiotropic functions to mediate and regulate the immune response and are generally recognized as biomarkers of immunotoxicity. While the specificity and validity of certain cytokines as markers of adverse immune response has been established for chemicals, small and macromolecular drugs, research on their applicability for predicting and monitoring the immunotoxicity of engineered nanomaterials is still ongoing. The goal of this review is to provide guidelines as to important cytokines that can be utilized for evaluating the immunotoxicity of nanomaterials and to highlight the role of those cytokines in mediating adverse reactions, which is of particular importance for the clinical development of nanopharmaceuticals and other nanotechnology-based products. Importantly, the rational design of nanomaterials of low immunotoxicity will be discussed, focusing on synthetic nanodevices, with emphasis on both the nanoparticle-forming materials and the embedded cargoes.

Cytokines as biomarkers of nanoparticle immunotoxicity

Nanoscale objects, whether of biologic origin or synthetically created, are being developed into devices for a variety of bionanotechnology diagnostic and pharmaceutical applications. However, the potential immunotoxicity of these nanomaterials and mechanisms by which they may induce adverse reactions have not received sufficient attention. Nanomaterials, depending on their characteristics and compositions, can interact with the immune system in several ways and either enhance or suppress immune system function. Cytokines perform pleiotropic functions to mediate and regulate the immune response and are generally recognized as biomarkers of immunotoxicity. While the specificity and validity of certain cytokines as markers of adverse immune response has been established for chemicals, small and macromolecular drugs, research on their applicability for predicting and monitoring the immunotoxicity of engineered nanomaterials is still ongoing. The goal of this review is to provide guidelines as to important cytokines that can be utilized for evaluating the immunotoxicity of nanomaterials and to highlight the role of those cytokines in mediating adverse reactions, which is of particular importance for the clinical development of nanopharmaceuticals and other nanotechnology-based products. Importantly, the rational design of nanomaterials of low immunotoxicity will be discussed, focusing on synthetic nanodevices, with emphasis on both the nanoparticle-forming materials and the embedded cargoes.

Characterization and preliminary toxicity assay of nano-titanium dioxide additive in sugar-coated chewing gum

Nanotechnology shows great potential for producing food with higher quality and better taste through including new additives, improving nutrient delivery, and using better packaging. However, lack of investigations on safety issues of nanofood has resulted in public fears. How to characterize engineered nanomaterials in food and assess the toxicity and health impact of nanofood remains a big challenge. Herein, a facile and highly reliable separation method of TiO2 particles from food products (focusing on sugar-coated chewing gum) is reported, and the first comprehensive characterization study on food nanoparticles by multiple qualitative and quantitative methods is provided. The detailed information on nanoparticles in gum includes chemical composition, morphology, size distribution, crystalline phase, particle and mass concentration, surface charge, and aggregation state. Surprisingly, the results show that the number of food products containing nano-TiO2 (<200 nm) is much larger than known, and consumers have already often been exposed to engineered nanoparticles in daily life. Over 93% of TiO2 in gum is nano-TiO2 , and it is unexpectedly easy to come out and be swallowed by a person who chews gum. Preliminary cytotoxicity assays show that the gum nano-TiO2 particles are relatively safe for gastrointestinal cells within 24 h even at a concentration of 200 μg mL(-1) . This comprehensive study demonstrates accurate physicochemical property, exposure, and cytotoxicity information on engineered nanoparticles in food, which is a prerequisite for the successful safety assessment of nanofood products.

Immunomodulation and T helper TH₁/TH₂ response polarization by CeO₂ and TiO₂ nanoparticles

Immunomodulation by nanoparticles, especially as related to the biochemical properties of these unique materials, has scarcely been explored. In an in vitro model of human immunity, we demonstrate two catalytic nanoparticles, TiO₂ (oxidant) and CeO₂ (antioxidant), have nearly opposite effects on human dendritic cells and T helper (T_H) cells. For example, whereas TiO₂ nanoparticles potentiated DC maturation that led towards T_H1-biased responses, treatment with antioxidant CeO₂ nanoparticles induced APCs to secrete the anti-inflammatory cytokine, IL-10, and induce a T_H2-dominated T cell profile. In subsequent studies, we demonstrate these results are likely explained by the disparate capacities of the nanoparticles to modulate ROS, since TiO₂, but not CeO₂ NPs, induced inflammatory responses through an ROS/inflammasome/IL-1β pathway. This novel capacity of metallic NPs to regulate innate and adaptive immunity in profoundly different directions via their ability to modulate dendritic cell function has strong implications for human health since unintentional exposure to these materials is common in modern societies.

Immunotoxicological impact of engineered nanomaterial exposure: mechanisms of immune cell modulation

Abstract Engineered nanomaterials (ENMs) are increasingly being utilized in many consumer products and various medical applications, thereby leading to the potentiality of increased human exposures. Assessment of the adverse effects on the immune system is an important component for evaluating the overall health and safety of ENM. Tasked with eliminating pathogens and removing cancerous cells, the immune system is constantly functioning to maintain homeostasis. Small modifications to the immune system, which may occur following ENM exposure, could lead to impaired protection or an inappropriate immune response resulting in autoimmunity and damage to the host. This review seeks to survey and evaluate the current literature to better understand the impact of ENM exposure on cells critical to the innate and adaptive immune systems.

Retinyl palmitate–loaded poly(lactide-co-glycolide) nanoparticles for the topical treatment of skin diseases

Nanoparticles were prepared with poly(lactide- co-glycolide), Pluronic F127, and phospholipids and loaded with retinyl palmitate. Morphology and physicochemical properties of these nanoparticles were determined by atomic force microscopy, light scattering, and zeta potential. The elasticity and deformability of the nanoparticles were correlated to Tg values measured by differential scanning calorimetry. The in vitro cytotoxicity and genotoxicity of the nanosystems were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell membrane asymmetry, and Ames tests with BALB/3T3 mouse embryo fibroblasts and HaCaT human keratinocytes cell lines. The reactive oxygen species levels and cytokine production in response to the exposure of cells to these nanoparticles were investigated, as well as the penetration in human skin culture.

Rationally designed aberrant kinase-targeted endogenous protein nanomedicine against oncogene mutated/amplified refractory chronic myeloid leukemia

Deregulated protein kinases play a very critical role in tumorigenesis, metastasis, and drug resistance of cancer. Although molecularly targeted small molecule kinase inhibitors (SMI) are effective against many types of cancer, point mutations in the kinase domain impart drug resistance, a major challenge in the clinic. A classic example is chronic myeloid leukemia (CML) caused by BCR-ABL fusion protein, wherein a BCR-ABL kinase inhibitor, imatinib (IM), was highly successful in the early chronic phase of the disease, but failed in the advanced stages due to amplification of oncogene or point mutations in the drug-binding site of kinase domain. Here, by identifying critical molecular pathways responsible for the drug-resistance in refractory CML patient samples and a model cell line, we have rationally designed an endogenous protein nanomedicine targeted to both cell surface receptors and aberrantly activated secondary kinase in the oncogenic network. Molecular diagnosis revealed that, in addition to point mutations and amplification of oncogenic BCR-ABL kinase, relapsed/refractory patients exhibited significant activation of STAT5 signaling with correlative overexpression of transferrin receptors (TfR) on the cell membrane. Accordingly, we have developed a human serum albumin (HSA) based nanomedicine, loaded with STAT5 inhibitor (sorafenib), and surface conjugated the same with holo-transferrin (Tf) ligands for TfR specific delivery. This dual-targeted "transferrin conjugated albumin bound sorafenib" nanomedicine (Tf-nAlb-Soraf), prepared using aqueous nanoprecipitation method, displayed uniform spherical morphology with average size of ∼150 nm and drug encapsulation efficiency of ∼74%. TfR specific uptake and enhanced antileukemic activity of the nanomedicine was found maximum in the most drug resistant patient sample having the highest level of STAT5 and TfR expression, thereby confirming the accuracy of our rational design and potential of dual-targeting approach. The nanomedicine induced downregulation of key survival pathways such as pSTAT5 and antiapoptotic protein MCL-1 was demonstrated using immunoblotting. This study reveals that, by implementing molecular diagnosis, personalized nanomedicines can be rationally designed and nanoengineered by imparting therapeutic functionality to endogenous proteins to overcome clinically important challenges like molecular drug resistance.

Titanium dioxide induced inflammation in the small intestine

AIM: To investigate the effects of titanium dioxide (TiO₂) nanoparticles (NPTiO₂) and microparticles (MPTiO₂) on the inflammatory response in the small intestine of mice.

METHODS: Bl 57/6 male mice received distilled water suspensions containing TiO₂ (100 mg/kg body weight) as NPTiO₂ (66 nm), or MPTiO₂ (260 nm) by gavage for 10 d, once a day; the control group received only distilled water. At the end of the treatment the duodenum, jejunum and ileum were extracted for assessment of cytokines, inflammatory cells and titanium content. The cytokines interleukin (IL)-1b, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-23, tumor necrosis factor-α (TNF-α), intracellular interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) were evaluated by enzyme-linked immunosorbent assay in segments of jejunum and ileum (mucosa and underlying muscular tissue). CD4⁺ and CD8⁺ T cells, natural killer cells, and dendritic cells were evaluated in duodenum, jejunum and ileum samples fixed in 10% formalin by immunohistochemistry. The titanium content was determined by inductively coupled plasma atomic emission spectrometry.

RESULTS: We found increased levels of T CD4⁺ cells (cells/mm²) in duodenum: NP 1240 ± 139.4, MP 1070 ± 154.7 vs 458 ± 50.39 (P < 0.01); jejunum: NP 908.4 ± 130.3, MP 813.8 ± 103.8 vs 526.6 ± 61.43 (P < 0.05); and ileum: NP 818.60 ± 123.0, MP 640.1 ± 32.75 vs 466.9 ± 22.4 (P < 0.05). In comparison to the control group, the groups receiving TiO₂ showed a statistically significant increase in the levels of the inflammatory cytokines IL-12, IL-4, IL-23, TNF-α, IFN-γ and TGF-β. The cytokine production was more pronounced in the ileum (mean ± SE): IL-12: NP 33.98 ± 11.76, MP 74.11 ± 25.65 vs 19.06 ± 3.92 (P < 0.05); IL-4: NP 17.36 ± 9.96, MP 22.94 ± 7.47 vs 2.19 ± 0.65 (P < 0.05); IL-23: NP 157.20 ± 75.80, MP 134.50 ± 38.31 vs 22.34 ± 5.81 (P < 0.05); TNFα: NP 3.71 ± 1.33, MP 5.44 ± 1.67 vs 0.99 ± 019 (P < 0.05); IFNγ: NP 15.85 ± 9.99, MP 34.08 ± 11.44 vs 2.81 ± 0.69 (P < 0.05); and TGF-α: NP 780.70 ± 318.50, MP 1409.00 ± 502.20 vs 205.50 ± 63.93 (P < 0.05).

CONCLUSION: Our findings indicate that TiO₂ particles induce a Th1-mediated inflammatory response in the small bowel in mice.

Immunotoxicology of non-functionalized engineered nanoparticles in aquatic organisms with special emphasis on fish--review of current knowledge, gap identification, and call for further research

The rapid increase in use of nanotechnology products is increasing the presence of metal, metal-oxide and carbon-based nanoparticles in the aquatic environment. These non-functionalized engineered nanoparticles can interact with the immune system of fish and invertebrates, and tip the ecological balance of population sustainability. Most nanoparticle types present in the aquatic environment, such as titanium dioxide, do not exhibit or have very low direct toxicity, but instead display silent or concealed sub-lethal effects on the immune system with serious implications. There is a gap in current available information regarding the immunotoxic potential of engineered nanoparticles toward aquatic organisms. Therefore, there is a critical need to provide the first comprehensive review of the effects of engineered non-functionalized nanoparticles on the immune system of aquatic animals, address the major gaps in current existing information, and recommend the future focus of research. This manuscript identifies cell mediated immunity and the phagocytic cells as the primary target of nanoparticle immunotoxicity. The immunotoxicity is primarily govern by lysosomal destabilization, frustrated phagocytosis, and change in function of the phagocytic cells, which decrease the ability of animals to defend themselves against pathogens and infectious diseases. Humoral immune system is a lesser target of direct immunotoxicity, but plays a critical role in dissemination of the nanoparticles through the body and their presentation to the phagocytic cells. The external innate immunity and the acquired immunity have not been connected with overly important and direct immunotoxic effects, but instead a big gap in current targeted research has been acknowledged.

Adjuvant properties of mesoporous silica particles tune the development of effector T cells

Alum is the most frequently used adjuvant today, primarily inducing Th2 responses. However, Th1-type responses are often desirable within immune therapy, and therefore the development of new adjuvants is greatly needed. Mesoporous silica particles with a highly ordered pore structure have properties that make them very interesting for future controlled drug delivery systems, such as controllable particle and pore size; they also have the ability to induce minor immune modulatory effects, as previously demonstrated on human-monocyte-derived dendritic cells (MDDCs). In this study, mesoporous silica particles are shown to be efficiently engulfed by MDDCs within 2 h, probably by phagocytic uptake, as seen by confocal microscopy and transmission electron microscopy. A co-culture protocol is developed to evaluate the capability of MDDCs to stimulate the development of naïve CD4(+) T cells in different directions. The method, involving ELISpot as a readout system, demonstrates that MDDCs, after exposure to mesoporous silica particles (AMS-6 and SBA-15), are capable of tuning autologous naïve T cells into different effector cells. Depending on the size and functionalization of the particles added to the cells, different cytokine patterns are detected. This suggests that mesoporous silica particles can be used as delivery vehicles with tunable adjuvant properties, which may be of importance for several medical applications, such as immune therapy and vaccination.

A cerium oxide nanoparticle-based device for the detection of chronic inflammation via optical and magnetic resonance imaging

Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues.

Transport of two metal oxide nanoparticles in saturated granular porous media: role of water chemistry and particle coating

The growing use of nanosized titanium dioxide (nTiO2) and zinc oxide (nZnO) in a large number of commercial products raises concerns regarding their release and subsequent mobility in natural aquatic environments. Laboratory-scale sand-packed column experiments were conducted with bare and polymer-coated nTiO2 and nZnO to improve our understanding of the mobility of these nanoparticles in natural or engineered water saturated granular systems. The nanoparticles are characterized over a range of environmentally relevant water chemistries using multiple complimentary techniques: dynamic light scattering, nanoparticle tracking analysis, transmission electron microscopy, and scanning electron microscopy. Overall, bare (uncoated) nanoparticles exhibit high retention within the water saturated granular matrix at solution ionic strengths (IS) as low as 0.1 mM NaNO3 for bare nTiO2 and 0.01 mM NaNO3 for bare nZnO. Bare nTiO2 and nZnO also display dynamic (time-dependent) deposition behaviors under selected conditions. In contrast, the polymer-coated nanoparticles are much less likely to aggregate and exhibit significant transport potential at IS as high as 100 mM NaNO3 or 3 mM CaCl2. These findings illustrate the importance of considering the extent and type of surface modification when evaluating metal oxide contamination potential in granular aquatic environments.