TiO₂ nanoparticles induce dysfunction and activation of human endothelial cells

Nanoparticles can reach the blood and cause inflammation, suggesting that nanoparticles-endothelial cells interactions may be pathogenically relevant. We evaluated the effect of titanium dioxide nanoparticles (TiO?) on proliferation, death, and responses related with inflammatory processes such as monocytic adhesion and expression of adhesion molecules (E- and P-selectins, ICAM-1, VCAM-1, and PECAM-1) and with inflammatory molecules (tissue factor, angiotensin-II, VEGF, and oxidized LDL receptor-1) on human umbilical vein endothelial cells (HUVEC). We also evaluated the production of reactive oxygen species, nitric oxide production, and NF-κB pathway activation. Aggregates of TiO? of 300 nm or smaller and individual nanoparticles internalized into HUVEC inhibited proliferation strongly and induced apoptotic and necrotic death starting at 5 μg/cm2. Besides, TiO? induced activation of HUVEC through an increase in adhesion and in expression of adhesion molecules and other molecules involved with the inflammatory process. These effects were associated with oxidative stress and NF-κB pathway activation. In conclusion, TiO? induced HUVEC activation, inhibition of cell proliferation with increased cell death, and oxidative stress.     

Comparative uptake and impact of TiO₂ nanoparticles in wheat and rapeseed

Up to 2 million tons per year of titanium dioxide (TiO?) nanoparticles (NP) are produced worldwide. This extensive production is postulated to result in release into the environment with subsequent contamination of soils and plants; however, few studies have examined TiO?-NP uptake and impact on plants. In this study, wheat and rapeseed plantlets were exposed to 14 nm or 25 nm anatase TiO?-NP in hydroponics conditions, either through root or leaf exposure. Microparticle-induced x-ray emission (μPIXE) coupled with Rutherford backscattering spectroscopy (RBS) was used to quantify absorbed titanium (Ti). Micro x-ray fluorescence (μXRF) based on synchrotron radiation was used to evaluate Ti distribution in roots and leaves. Our results show that both TiO?-NP are accumulated in these plantlets upon root exposure and that Ti content is higher in rapeseed than wheat. Ti distribution in root cross sections depended on NP agglomeration state. NP are also accumulated in plantlets upon leaf exposure. Finally, it was found that TiO?-NP exposure induced increased root elongation but did not affect germination, evapotranspiration, and plant biomass. Taken together, these results confirm that TiO?-NP may be accumulated in plant crops but may only moderately impact plant development.     

Toxicity of TiO2 nanoparticles on soil nitrification at environmentally relevant concentrations: Lack of classical dose–response relationships

Titanium-dioxide nanoparticles (TiO₂-NPs) are increasingly released in agricultural soils through, e.g. biosolids, irrigation or nanoagrochemicals. Soils are submitted to a wide range of concentrations of TiO₂-NPs depending on the type of exposure. However, most studies have assessed the effects of unrealistically high concentrations, and the dose–response relationships are not well characterized for soil microbial communities. Here, using soil microcosms, we assessed the impact of TiO₂-NPs at concentrations ranging from 0.05 to 500?mg kg^?1?dry-soil, on the activity and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB), and nitrite-oxidizing bacteria (Nitrobacter and Nitrospira). In addition, aggregation and oxidative potential of TiO₂-NPs were measured in the spiking suspensions, as they can be important drivers of TiO₂-NPs toxicity. After 90?days of exposure, non-classical dose–response relationships were observed for nitrifier abundance or activity, making threshold concentrations impossible to compute. Indeed, AOA abundance was reduced by 40% by TiO₂-NPs whatever the concentration, while Nitrospira was never affected. Moreover, AOB and Nitrobacter abundances were decreased mainly at intermediate concentrations nitrification was reduced by 25% at the lowest (0.05?mg?kg^?1) and the highest (100 and 500?mg?kg^?1) TiO₂-NPs concentrations. Path analyses indicated that TiO₂-NPs affected nitrification through an effect on the specific activity of nitrifiers, in addition to indirect effects on nitrifier abundances. Altogether these results point out the need to include very low concentrations of NPs in soil toxicological studies, and the lack of relevance of classical dose–response tests and ecotoxicological dose metrics (EC50, IC50…) for TiO₂-NPs impact on soil microorganisms.     

TiO2 nanoparticles induce endothelial cell activation in a pneumocyte–endothelial co-culture model

The effects of particulate matter (PM) on endothelial cells have been evaluated in vitro by exposing isolated endothelial cells to different types of PM. Although some of the findings from these experiments have been corroborated by in vivo studies, an in vitro model that assesses the interaction among different cell types is necessary to achieve more realistic assays. We developed an in vitro model that mimics the alveolar–capillary interface, and we challenged the model using TiO₂ nanoparticles (TiO₂-NPs). Human umbilical endothelial cells (HUVECs) were cultured on the basolateral side of a membrane and pneumocytes (A549) on the apical side. Confluent co-cultures were exposed on the apical side to 10 μg/cm² of TiO₂-NPs or 10 ng/mL of TNFα for 24 h. Unexposed cultures were used as negative controls. We evaluated monocyte adhesion to HUVECs, adhesion molecule expression, nitric oxide concentration and proinflammatory cytokine release. The TiO₂-NPs added to the pneumocytes induced a 3- to 4-fold increase in monocyte adhesion to the HUVECs and significant increases in the expression of adhesion molecules (4-fold for P-selectin at 8 h, and about 8- and 10-fold for E-selectin, ICAM-1, VCAM-1 and PECAM-1 at 24 h). Nitric oxide production also increased significantly (2-fold). These results indicate that exposing pneumocytes to TiO₂-NPs causes endothelial cell activation.     

Evaluation of photodynamic activity of C60/2-hydroxypropyl-β-cyclodextrin nanoparticles

The objective of this study is to evaluate the ability of C(60)/2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) naonparticles to generate reactive oxygen species (ROS) and to induce cell toxicity by the photoirradiation. C(60) nanoparticles were prepared by cogrinding with HP-β-CyD for 3 h at 4°C under reduced pressure. The photodynamic activity of C(60)/HP-β-CyD nanoparticles was evaluated by spectroscopic methods, including the electron spin resonance spin-trapping method, and by the cell viability test using Hela cells. C(60)/HP-β-CyD nanoparticles efficiently generated not only superoxide anion radical (O(2)(·-)) and hydroxyl radical (·OH), but also singlet oxygen ((1)O(2)) through photoirradiation. The ROS generation was enhanced by decreasing the mean particle diameter of C(60) nanoparticles, and the particle size smaller than 90 nm showed a high generation of ·OH and (1)O(2). In addition, HP-β-CyD enhanced the generation of (1)O(2), compared with polyvinylpyrrolidone (an effective solubillizer for C(60)), due to partial disposition of C(60) in the hydrophobic CyD cavity. Furthermore, C(60) /HP-β-CyD nanoparticles showed cell toxicity after the light irradiation, but no toxicity was observed without the light irradiation. Therefore, HP-β-CyD is useful for the preparation of stable C(60) nanoparticles with high ROS generation ability, and C(60)/HP-β-CyD nanoparticles are a promising photosensitizer for photodynamic therapy.     

Potential of nanoparticles for allergen-specific immunotherapy – use of silica nanoparticles as vaccination platform

ABSTRACT

Introduction: Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field.

Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized.

Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.     

Stability of paclitaxel-loaded solid lipid nanoparticles in the presence of 2-hydoxypropyl-β-cyclodextrin

Paclitaxel (PTX)-loaded solid lipid nanoparticles without hydroxyl-β-cyclodextrin (PS) or with hydroxypropyl-β-cyclodextrin (PSC) were prepared by hot-melted sonication. Biocompatible and biodegradable stearic acid was used to produce the solid matrix. The stability of PS and PSC was assessed at different temperatures. Drug stability, as assessed by encapsulation efficiency (EE; %), particle size, and the polydispersity index (PDI), was examined and in vitro release of PTX from PS or PSC for up to 180 days was assessed. After 180 days of storage at 25 °C, no significant change in particle size, PDI, or EE of PS or PSC was observed. PS and PSC displayed similar sustained PTX release patterns. The particle size, PDI, EE, PTX release profile, and cytotoxicity of PS changed significantly with increasing incubation time, whereas those of PSC showed no significant change, when samples were stored at 40 ± 2 °C. PSC was more stable than PS in plasma with regard to particle size and PDI. These results demonstrate that PSC could be a promising formulation to increase drug stability.     

Formation of stable hydrophilic C60 nanoparticles by 2-hydroxypropyl-β-cyclodextrin

A number of papers have reported that the large cavity of γ-CyD is favorable for inclusion of C(60) and forms a 1:2 (C(60):γ-CyD) complex, whereas it is thought to be difficult for β-CyD to form a complex at the molecular level. This is because the cavity size of β-CyD (0.78 nm) is smaller than the van der Waals diameter of C(60) (1.0 nm). In this paper, we will report on the formation of the stable C(60) nanoparticles by the hydrophilic 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) layer through weak interaction on the surface of the nanoparticles. C(60) was coground with β-CyD, γ-CyD or HP-β-CyD mainly in a 1:2 molar ratio by an automatic magnetic agitating mortar, the coground powders were dispersed in water, and the resulting solutions were filtered through a pore size of 0.8 μm filter. The γ-CyD and HP-β-CyD systems gave transparent colloidal solutions consisting of C(60)/CyD nanoparticles with the size lower than 100 nm, with high yields (about 100%). The C(60)/HP-β-CyD nanoparticles are physically stable, keeping a small size for more than 28 days, whereas the γ-CyD nanoparticles are readily aggregated to form large particles (>800 nm). Solid and liquid NMR spectroscopic studies including measurements of spin-lattice relaxation times indicated that C(60) interacted with γ-CyD and HP-β-CyD in the solid and colloidal solutions. When compared with the γ-CyD nanoparticles, adsorption studies of a hydrophobic dye on the surface of C(60)/CyD nanoparticles indicated that the surface of the HP-β-CyD nanoparticles is largely covered by HP-β-CyD molecules forming hydrophilic hydration layers. The present results suggest that HP-β-CyD is useful for the preparation of C(60) nanoparticles and medical applications such as photodynamic therapy, in spite of having a cavity size smaller than that of γ-CyD.     

Antibacterial effect of novel synthesized sulfated β-cyclodextrin crosslinked cotton fabric and its improved antibacterial activities with ZnO, TiO2 and Ag nanoparticles coating

Sulfated β-cyclodextrin was synthesized from sulfonation of β-cyclodextrin and sulfated polymer was crosslinked with cotton fabric using ethylenediaminetetraacetic acid as crosslinker. ZnO, TiO(2) and Ag nanoparticles were prepared and characterized by XRD, UV, DLS, SEM and PSA. The prepared nanoparticles were coated on crosslinked cotton fabric. The crosslinking and nanoparticles coating effects of cotton fabrics were studied by FTIR and SEM analysis. The antibacterial test was done against gram positive Staphylococcus aureus and gram negative Escherichia coli bacterium.     

Development of noncytotoxic PLGA nanoparticles to improve the effect of a new inhibitor of p53–MDM2 interaction

One possible approach to overcome solubility complications and enhance the biological activity of drugs is their incorporation into drug delivery systems. Within this scope, several nanosphere and nanocapsule formulations of a new inhibitor of p53–MDM2 interaction (xanthone 1) were developed and their physicochemical properties analyzed. Through the investigation of the effect of several empty nanoparticles on the growth of MCF-7 cells, it was possible to observe that four out of five formulations were cytotoxic and that some correlations between the toxic potential of these polymeric nanoparticles and their properties/composition could be extrapolated. One empty formulation of nanocapsules developed by emulsification/solvent evaporation and containing PLGA, PVA and Mygliol^® 812 was found to be noncytotoxic to this cell line. The corresponding compound 1-loaded nanocapsules showed an incorporation efficiency of 77% and revealed to be more potent than the free drug against cell growth inhibition, which may be related to the enhancement in its intracellular delivery. In an integrative study, the intracellular uptake of nanocapsules was confirmed using fluorescent 6-coumarin and well as compound 1 release from nanocapsules. Overall, it was possible to enhance the effect of the hit inhibitor of p53–MDM2 interaction through the development of suitable noncytotoxic polymeric nanoparticles.     

Dendritic nanoparticles: the next generation of nanocarriers?

Dendritic polymers have attracted a great deal of scientific interest due to their well-defined unique structure and capability to be multifunctionalized. Here we present a comprehensive overview of various dendrimer-based nanomaterials that are currently being investigated for therapeutic delivery and diagnostic applications. Through a critical review of the old and new dendritic designs, we highlight the advantages and disadvantages of these systems and their structure-biological property relationships. This article also focuses on the major challenges facing the clinical translation of these nanomaterials and how these challenges are being (or should be) addressed, which will greatly benefit the overall progress of dendritic materials for theranostics.     

Engineering of polymer–surfactant nanoparticles of doxycycline hydrochloride for ocular drug delivery

Abstract

Context: Physiologic barriers of the eye, short precorneal drug residence time and poor corneal penetration are the few reasons for reduced ocular bioavailability.

Objective: This study was aimed to develop novel polymer–surfactant nanoparticles of hydrophilic drug doxycycline hydrochloride (DXY) to improve precorneal residence time and drug penetration.

Materials and methods: Nanoparticles were formulated using emulsion cross-linking method and the formulation was optimized using factorial design. The prepared formulation was characterized for particle size, ζ potential, encapsulation efficiency, in vitro drug release and ex vivo drug diffusion studies. The antibacterial activity studies were also carried out against Escherichia coli and Staphylococcus aureus using the cup-plate method. In vivo eye irritation study was carried out by a modified Draize test in rabbits.

Results and discussion: The particle size was found to be in the range of 331–850?nm. About 45–80% of the drug was found to be encapsulated in the nanoparticles. In vitro release demonstrated sustained release profile. Lower flux values in case of nanoparticles as compared to DXY pure drug solution in ex vivo diffusion studies confirmed the sustained release. The nanoparticles were found to be significantly effective (p?<?0.001) than DXY aqueous solution due to sustained release of doxycycline from nanoparticles in both the E. coli and S. aureus strains. The formulation was found to be stable over entire stability period.

Conclusion: The developed formulation is safe and suitable for sustained ocular drug delivery.     

Toxicity of silver nanoparticles - nanoparticle or silver ion?

The toxicity of silver nanoparticles (AgNPs) has been shown in many publications. Here we investigated to which degree the silver ion fraction of AgNP suspensions, contribute to the toxicity of AgNPs in A549 lung cells. Cell viability assays revealed that AgNP suspensions were more toxic when the initial silver ion fraction was higher. At 1.5 μg/ml total silver, A549 cells exposed to an AgNP suspension containing 39% silver ion fraction showed a cell viability of 92%, whereas cells exposed to an AgNP suspension containing 69% silver ion fraction had a cell viability of 54% as measured by the MTT assay. In addition, at initial silver ion fractions of 5.5% and above, AgNP-free supernatant had the same toxicity as AgNP suspensions. Flow-cytometric analyses of cell cycle and apoptosis confirmed that there is no significant difference between the treatment with AgNP suspension and AgNP supernatant. Only AgNP suspensions with silver ion fraction of 2.6% or less were significantly more toxic than their supernatant as measured by MTT assays. From our data we conclude that at high silver ion fractions (≥5.5%) the AgNPs did not add measurable additional toxicity to the AgNP suspension, whereas at low silver ion fractions (≤2.6%) AgNP suspensions are more toxic than their supernatant.     

Silver and fullerene nanoparticles’ effect on interleukin-2-dependent proliferation of CD4 (+) T cells

Immunotoxicity studies of nanoparticles on T cells addressed their effects on activation by T antigen receptor, but have neglected the regulation of proliferation by IL-2. In this study, the IL-2-dependent T lymphoblastoid WE17/10 cell line was used to compare silver (Ag-NPs) and fullerene (C₆₀-NPs) nanoparticles’ toxicity and evaluate whether these NPs could interfere with IL-2-dependent proliferation. Results have shown that Ag-NPs are more toxic, as they reduced cell viability at the highest concentration tested (100 μg/ml), while C₆₀-NPs have shown good biocompatibility. Characterization of NP suspensions by dynamic light scattering measured large aggregates for C₆₀-NPs, whereas Ag-NPs were relatively stable and well dispersed. This translated into a much larger uptake of Ag-NPs compared to C₆₀-NPs, as measured by flow cytometry. Proliferation measurements by CFSE following 72 h incubation have shown that Ag-NPs decrease cell proliferation and C₆₀-NPs slightly increase proliferation. CD25 expression was unchanged following exposure to C₆₀-NPs, but was significantly increased by Ag-NPs’ presence for short and long-term incubations. Analyses of three key signaling proteins activated by IL-2 receptor (Stat5, JNK and ERK1/2) by western immunoblotting have shown no effects from either NPs on Stat5 and JNK phosphorylation. ERK1/2 was slightly activated following a short exposure to Ag-NPs, while C₆₀-NPs had no effect. Our results show that C₆₀-NPs have good biocompatibility and do not interfere with IL-2-dependent proliferation. A deeper investigation would be needed for the case of Ag-NPs, since the mechanism of their action is still unclear.     

Targeting the resolution pathway of inflammation using Ac2–26 peptide-loaded PEGylated lipid nanoparticles for the remission of rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease characterized by joint inflammation and immune dysfunction. Although various therapeutic approaches have been utilized for the treatment of RA in clinical applications, the low responsiveness of RA patients and undesired systemic toxicity are still unresolved problems. Targeting the resolution pathway of inflammation with pro-resolving mediators would evoke the protective actions of patient for combating the inflammation. Ac2–26, a 25-amino acid peptide derived from Annexin A (a pro-resolving mediator), has shown good efficacy in the treatment of inflammatory disorders. However, the low bioavailability of Ac2–26 peptides hinders their efficacy in vivo. In this paper, we formed PEGylated lipid nanoparticles (LDNPs) by the co-assembly of l-ascorbyl palmitate (L-AP) and N-(carbonyl methoxypolyethylene glycol-2000)-1,2-distearoyl-sn‑glycero-3-phosphoethanolamine (DSPE-PEG_2k) to encapsulate and deliver Ac2–26 peptides to the arthritic rats. They showed good stability and biocompatibility. After being intravenously administrated, Ac2–26 peptide-loaded PEGylated lipid nanoparticles (ADNPs) showed the prolonged in vivo circulation time and enhanced accumulation in inflamed sites. In vivo therapeutic evaluations revealed that ADNPs could attenuate synovial inflammation and improve joint pathology. Therefore, the pro-resolving therapeutic strategy using ADNPs is effective in RA treatment.     

Mathematical modelling of the transport of hydroxypropyl-β-cyclodextrin inclusion complexes of ranitidine hydrochloride and furosemide loaded chitosan nanoparticles across a Caco-2 cell monolayer

Chitosan nanoparticles (CS-NPs) have been used to enhance the permeability of furosemide and ranitidine hydrochloride (ranitidine HCl) which were selected as candidates for two different biopharmaceutical drug classes having low permeability across Caco-2 cell monolayers. Drugs loaded CS-NPs were prepared by ionic gelation of CS and pentasodium tripolyphosphate (TPP) which added to the drugs inclusion complexes with hydroxypropyl-β-cyclodextrin (HP-βCD). The stability constants for furosemide/HP-βCD and ranitidine HCl/HP-βCD were calculated as 335 M(-1) and 410 M(-1), whereas the association efficiencies (AE%) of the drugs/HP-βCD inclusion complexes with CS-NPs were determined to be 23.0 and 19.5%, respectively. Zetasizer and scanning electron microscopy (SEM) were used to characterise drugs/HP-βCD-NPs size and morphology. Transport of both nano and non-nano formulations of drugs/HP-βCD complexes across a Caco-2 cell monolayer was assessed and fitted to mathematical models. Furosemide/HP-βCD-NPs demonstrated transport kinetics best suited for the Higuchi model, whereas other drug formulations demonstrated power law transportation behaviour. Permeability experiments revealed that furosemide/HP-βCD and ranitidine HCl/HP-βCD nano formulations greatly induce the opening of tight junctions and enhance drug transition through Caco-2 monolayers.