β-Carotene has been established as a known free radical scavenger with chain-breaking antioxidant properties. It has been documented for the treatment of epileptic convulsions at a 200 mg/kg body weight dose. The reported pathogenesis for epileptic convulsions is oxidative stress. Hence, experimental epileptic convulsions via oxidative stress was induced in albino mice epileptic models (maximal electroshock seizure and pentylenetetrazole [PTZ]). A dose concentration equivalent to 2 mg/kg was efficaciously administered in the form of brain-targeted polysorbate-80-coated poly(d,l-lactide-co-glycolide) nanoparticles. The nanoparticles were prepared by solvent evaporation technique and further characterized for their physical parameters, in-vitro release kinetics, and in-vivo brain release via various standard methods. Normal β-carotene nanoparticles (BCNP) and polysorbate-80-coated β-carotene nanoparticles (P-80-BCNP) of 169.8 ± 4.8 nm and 176.3 ± 3.2 nm in size, respectively, were formulated and characterized. Their zeta potential and polydispersity index were subsequently evaluated after 5 months of storage to confirm stability. In vivo activity results showed that a 2 mg unformulated β-carotene dose was ineffective as an anticonvulsant. However, salutary response was reported from BCNP at the same dose, as the hind limb duration decreased significantly in maximal electroshock seizure to 9.30 ± 0.86 seconds, which further decreased with polysorbate-80 coating to 2.10 ± 1.16 seconds as compared to normal control (15.8 ± 1.49 seconds) and placebo control (16.50 ± 1.43 seconds). In the PTZ model, the duration of general tonic–clonic seizures reduced significantly to 2.90 ± 0.98 seconds by the use of BCNP and was further reduced on P-80-BCNP to 1.20 ± 0.20 seconds as compared to PTZ control and PTZ-placebo control (8.09 ± 0.26 seconds). General tonic–clonic seizures latency was increased significantly to 191.0 ± 9.80 seconds in BCNP and was further increased in P-80-BCNP to 231.0 ± 16.30 seconds, as compared to PTZ (120.10 ± 4.50 seconds) and placebo control (120.30 ± 7.4 seconds). The results of this study demonstrate a plausible novel anticonvulsant activity of β-carotene at a low dose of 2 mg/kg, with brain-targeted nanodelivery, thus increasing its bioavailability and stability.
anticonvulsant; blood–brain barrier (BBB); targeted brain delivery; polysorbate-80-coated β-carotene nanoparticles (P-80-BCNP); maximal electroshock seizure (MES); pentylenetetrazole (PTZ)
Polybutylcyanoacrylate (PBCA) nanoparticles coated with polysorbate-80 have been extensively proposed for delivering drugs into the animal brain and have shown great potential for therapeutic applications. In this study, we made an attempt to deliver the chemotherapeutic drug, temozolomide, into the brain by using PBCA nanoparticles. The physicochemical characteristics, in vitro release, and brain targeting ability of the drug-loaded nanoparticles were investigated.
Our results show that a significantly higher concentration of temozolomide in the form of polysorbate-80-coated PBCA nanoparticles was observed in the brain (P < 0.05) in comparison with the free drug.
This study indicates that polysorbate-80 coated PBCA nanoparticles could be a feasible carrier for temozolomide delivery to the brain. It is anticipated that the developed formulation may improve on targeted therapy for malignant brain tumors in the future.
temozolomide; polybutylcyanoacrylate; nanoparticles; polysorbate-80; brain targeting
The article of Gasser et al. [Part Fibre Toxicol. 24; 9:17, 2012] describes the interaction of carbon nanotubes with cells within a complex cell culture model. Besides various toxicity parameters, the influence of coating with pulmonary surfactant was investigated. Pulmonary surfactant covers the entire alveolar region with the main function of decreasing the surface tension in the alveoli to prevent alveolar collapse. Although each inhaled nanoparticle, reaching the alveoli, will come into contact with pulmonary surfactant which will probably lead to a surfactant coating, pulmonary surfactant components are not commonly integrated in in vitro systems. Gasser and co-workers have shown that this surfactant coating is able to influence the further interaction with cellular systems. Hence, each scientist, working with in vitro systems and nanoparticles, should think of integrating pulmonary surfactant structures in order to harmonize the in vitro systems with the in vivo situation. In the present commentary we discuss the most important points of the manuscript of Gasser et al. and discuss where the usage of pulmonary surfactant can be further optimized.
Nanoparticle; Lung; Pulmonary surfactant; Coating
To investigate a nuclear factor-kappa B decoy oligonucleotides strategy on the inhibition of tissue factor (TF) expression in cultured rat brain microvascular endothelial cells (BMECs) by polylactic acid (PLA) nanoparticles delivery system and to evaluate this new vector for in vitro gene therapy. Nanoparticles were formulated using poly D,L-polylactic acid with surface modifying by polysorbates 80. 3-[4,5-Dimethylthiazol-2,5-diphenyl-2H-tetrazolium bromide] (MTT) assays showed that PLA nanoparticles were not toxic to the cultured BMECs.The decoy oligonuceotides (ODNs) loaded within nanoparticles was 6 μg/mg, encapsulation efficacy was (60.5±1.5)%. It was observed by flow cytometry that the cellular uptake of nanoparticles depended on the time of incubation and the concentration of nanoparticles in the medium. And confocal microscopy demonstrated that nanoparticles localized mostly in the BMECs cytoplasm. The released decoy oligonuceotides (ODNs) uptaked by BMECs retained their biologic activity and led to reduced level of tissue factor expression as compared to control cultures. These findings offer a potential therapeutic strategy in the control of TF expression in BMECs in vitro and suggest that PLA nanoparticles may be appropriate as delivery vehicles for decoy strategy in the gene therapy of cerebral thrombosis.
Tissue factor; decoy oligonucleotides; nanoparticles; nuclear factor-kappaB; polylactic acid
This study evaluated the use of isothermal microcalorimetry (ITMC) to detect macrophage–nanoparticle interactions. Four different nanoparticle (NP) formulations were prepared: uncoated poly(isobutyl cyanoacrylate) (PIBCA), polysorbate-80-coated PIBCA, gelatin, and mannosylated gelatin NPs. Changes in NP formulations were aimed to either enhance or decrease macrophage–NP interactions via phagocytosis. Alveolar macrophages were cultured on glass slabs and inserted in the ITMC instrument. Thermal activities of the macrophages alone and after titration of 100 μL of NP suspensions were compared. The relative interactive coefficients of macrophage–NP interactions were calculated using the heat exchange observed after NP titration. Control experiments were performed using cytochalasin B (Cyto B), a known phagocytosis inhibitor. The results of NP titration showed that the total thermal activity produced by macrophages changed according to the NP formulation. Mannosylated gelatin NPs were associated with the highest heat exchange, 75.4 ± 7.5 J, and thus the highest relative interactive coefficient, 9,269 ± 630 M-1. Polysorbate-80-coated NPs were associated with the lowest heat exchange, 15.2 ± 3.4 J, and the lowest interactive coefficient, 890 ± 120 M-1. Cyto B inhibited macrophage response to NPs, indicating a connection between the thermal activity recorded and NP phagocytosis. These results are in agreement with flow cytometry results. ITMC is a valuable tool to monitor the biological responses to nano-sized dosage forms such as NPs. Since the thermal activity of macrophage–NP interactions differed according to the type of NPs used, ITMC may provide a method to better understand phagocytosis and further the development of colloidal dosage forms.
Electronic supplementary material
The online version of this article (doi:10.1208/s12248-010-9240-y) contains supplementary material, which is available to authorized users.
flow cytometry; isothermal microcalorimetry; macrophages; nanoparticles; phagocytosis
Despite recent advances in nonsteroidal anti-inflammatory drug (NSAID) formulations, the design of targeted delivery systems to improve the efficacy and reduce side effects of NSAIDs continues to be a focus of much research. Enteric nanoparticles have been recognized as a potential system to reduce gastrointestinal irritations caused by NSAIDs. The aim of this study was to evaluate the effect of EUDRAGIT® L100, polyethylene glycol, and polysorbate 80 on encapsulation efficiency of indomethacin within enteric nanoparticles. Formulations were developed based on a multilevel factorial design (three factors, two levels). The amount of polyethylene glycol was shown to be the factor that had the greatest influence on the encapsulation efficiency (evaluated response) at 95% confidence level. Some properties of nanoparticles like process yield, drug–polymer interaction, particle morphology, and in vitro dissolution profile, which could affect biological performance, have also been evaluated.
nonsteroidal anti-inflammatory; indomethacin; enteric polymer; polyethylene glycol; nanoparticles
Because of the described hazards related to inhalation of manufactured nanoparticles, we investigated the lung toxicity of biodegradable poly (lactide-co-glycolide) (PLGA) nanoparticles displaying various surface properties on human bronchial Calu-3 cells.
Positively and negatively charged as well as neutral nanoparticles were tailored by coating their surface with chitosan, Poloxamer, or poly (vinyl alcohol), respectively. Nanoparticles were characterized in terms of size, zeta potential, and surface chemical composition, confirming modifications provided by hydrophilic polymers.
Although nanoparticle internalization by lung cells was clearly demonstrated, the cytotoxicity of the nanoparticles was very limited, with an absence of inflammatory response, regardless of the surface properties of the PLGA nanoparticles.
These in vitro results highlight the safety of biodegradable PLGA nanoparticles in the bronchial epithelium and provide initial data on their potential effects and the risks associated with their use as nanomedicines.
nanoparticles; PLGA; surface properties; Calu-3; toxicity; inflammation
There is increasing interest in the environmental and health consequences of silver nanoparticles as the use of this material becomes widespread. Although human exposure to nanosilver is increasing, only a few studies address possible toxic effect of inhaled nanosilver. The objective of this study was to determine whether very small commercially available nanosilver induces pulmonary toxicity in mice following inhalation exposure.
In this study, mice were exposed sub-acutely by inhalation to well-characterized nanosilver (3.3 mg/m3, 4 hours/day, 10 days, 5 ± 2 nm primary size). Toxicity was assessed by enumeration of total and differential cells, determination of total protein, lactate dehydrogenase activity and inflammatory cytokines in bronchoalveolar lavage fluid. Lungs were evaluated for histopathologic changes and the presence of silver. In contrast to published in vitro studies, minimal inflammatory response or toxicity was found following exposure to nanosilver in our in vivo study. The median retained dose of nanosilver in the lungs measured by inductively coupled plasma - optical emission spectroscopy (ICP-OES) was 31 μg/g lung (dry weight) immediately after the final exposure, 10 μg/g following exposure and a 3-wk rest period and zero in sham-exposed controls. Dissolution studies showed that nanosilver did not dissolve in solutions mimicking the intracellular or extracellular milieu.
Mice exposed to nanosilver showed minimal pulmonary inflammation or cytotoxicity following sub-acute exposures. However, longer term exposures with higher lung burdens of nanosilver are needed to ensure that there are no chronic effects and to evaluate possible translocation to other organs.
Iron oxide nanoparticles with unique magnetic properties have a high potential for use in several biomedical, bioengineering and in vivo applications, including tissue repair, magnetic resonance imaging, immunoassay, drug delivery, detoxification of biologic fluids, cell sorting, and hyperthermia. Although various surface modifications are being done for making these nonbiodegradable nanoparticles more biocompatible, their toxic potential is still a major concern. The current in vitro study of the interaction of superparamagnetic iron oxide nanoparticles of mean diameter 30 nm coated with Tween 80 and murine macrophage (J774) cells was undertaken to evaluate the dose- and time-dependent toxic potential, as well as investigate the role of oxidative stress in the toxicity. A 15–30 nm size range of spherical nanoparticles were characterized by transmission electron microscopy and zeta sizer. MTT assay showed >95% viability of cells in lower concentrations (25–200 μg/mL) and up to three hours of exposure, whereas at higher concentrations (300–500 μg/mL) and prolonged (six hours) exposure viability reduced to 55%–65%. Necrosis-apoptosis assay by propidium iodide and Hoechst-33342 staining revealed loss of the majority of the cells by apoptosis. H2DCFDDA assay to quantify generation of intracellular reactive oxygen species (ROS) indicated that exposure to a higher concentration of nanoparticles resulted in enhanced ROS generation, leading to cell injury and death. The cell membrane injury induced by nanoparticles studied using the lactate dehydrogenase assay, showed both concentration- and time-dependent damage. Thus, this study concluded that use of a low optimum concentration of superparamagnetic iron oxide nanoparticles is important for avoidance of oxidative stress-induced cell injury and death.
superparamagnetic iron oxide nanoparticles; cytotoxicity; MTT assay; J774 cell line
Titanium dioxide nanoparticles (nanoTiO2) are used in various applications including in paints. NanoTiO2 inhalation may induce pulmonary toxicity and systemic effects. However, the underlying molecular mechanisms are poorly understood. In this study, the effects of inhaled surface-coated nanoTiO2 on pulmonary global messenger RNA (mRNA) and microRNA (miRNA) expression in mouse were characterized to provide insight into the molecular response. Female C57BL/6BomTac mice were exposed for 1 hr daily to 42.4 ± 2.9 (SEM) mg surface-coated nanoTiO2/m3 for 11 consecutive days by inhalation and were sacrificed 5 days following the last exposure. Physicochemical properties of the particles were determined. Pulmonary response to nanoTiO2 was characterized using DNA microarrays and pathway-specific PCR arrays and related to data on pulmonary inflammation from bronchial lavages. NanoTiO2 exposure resulted in increased levels of mRNA for acute phase markers serum amyloid A-1 (Saa1) and serum amyloid A-3 (Saa3), several C-X-C and C-C motif chemokines, and cytokine tumor necrosis factor genes. Protein analysis of Saa1 and 3 showed selective upregulation of Saa3 in lung tissues. Sixteen miRNAs were induced by more than 1.2-fold (adjusted P-value < 0.05) following exposure. Real time polymerase chain reaction confirmed the upregulation of miR-1, miR-449a and revealed dramatic induction of miR-135b (60-fold). Thus, inhalation of surface-coated nanoTiO2 results in changes in the expression of genes associated with acute phase, inflammation and immune response 5 days post exposure with concomitant changes in several miRNAs. The role of these miRNAs in pulmonary response to inhaled particles is unknown and warrants further research. Environ. Mol. Mutagen., 2011. © 2011 Wiley-Liss, Inc.†
nanotitanium dioxide; gene expression; microRNA; inflammation
Convection-enhanced delivery (CED) is a novel approach for delivering drugs directly into brain tumors by intracranial infusion, enabling the distribution of high drug concentrations over large tissue volumes. This study was designed to present a method for binding methotrexate (MTX) to unique crystalline, highly ordered and superparamagnetic maghemite nanoparticles via human serum albumin (HSA) coating, optimized for CED treatments of gliomas. Naked nanoparticles and HSA- or polyethylene glycol (PEG)-coated nanoparticles with/without MTX were studied. In vitro results showed no toxicity and a similar cell-kill efficacy of the MTX-loaded particles via HSA coating to that of free MTX, while MTX-loaded particles via PEG coating showed low efficacy. In vivo, the PEG-coated nanoparticles provided the largest distributions in normal rat brain and long clearance times, but due to their low efficacy in vitro, were not considered optimal. The naked nanoparticles provided the smallest distributions and shortest clearance times. The HSA-coated nanoparticles (with/without MTX) provided good distributions and long clearance times (nearly 50% of the distribution volume remained in the brain 3 weeks post treatment). No MTX-related toxicity was noted. These results suggest that the formulation in which HSA was bound to our nanoparticles via a unique precipitation method, and MTX was bound covalently to the HSA, could enable efficient and stable drug loading with no apparent toxicity. The cell-kill efficacy of the bound MTX remained similar to that of free MTX, and the nanoparticles presented efficient distribution volumes and slow clearance times in vivo, suggesting that these particles are optimal for CED.
convection-enhanced delivery; nanoparticles; methotrexate; magnetic resonance imaging; rat brain
This study tests the hypothesis that large porous poly (lactic-co-glycolic acid) (PLGA) microparticles modified with polyethyleneimine (PEI) are viable carriers for pulmonary delivery of prostaglandin E1 (PGE1) used in the treatment of pulmonary arterial hypertension (PAH), a pulmonary vascular disorder. The particles were prepared by a double-emulsion solvent evaporation method with PEI-25 kDa in the internal aqueous phase to produce an osmotic pressure gradient. Polyvinyl alcohol (PVA) was used for external coating of the particles. The particles were examined for morphology, size, aerodynamic diameter, surface area, pore volume and in-vitro release profiles. Particles with optimal properties for inhalation were tested for in-vivo pulmonary absorption, metabolic stability in rat lung homogenates, and acute toxicity in rat bronchoalveolar lavage fluid and respiratory epithelial cells, Calu-3. The micromeritic data indicated that the PEI-modified particles of PGE1 are optimal for inhalation. Incorporation of PEI in the formulations resulted in an increased entrapment efficiency–83.26±3.04% for particles with 1% PVA and 95.48±0.46% for particles with 2% PVA. The amount of cumulative drug released into the simulated interstitial lung fluid was between 50.8±0.76% and 55.36±0.06%. A remarkable extension of the circulation half-life up to 6.0–6.5 hours was observed when the formulations were administered via the lungs. The metabolic stability and toxicity studies showed that the optimized formulations were stable at physiological conditions and relatively safe to the lungs and respiratory epithelium. Overall, this study demonstrates that large porous inhalable polymeric microparticles can be a feasible option for non-invasive and controlled release of PGE1 for treatment of PAH.
Prostaglandin E1; Pulmonary Arterial Hypertension; PLGA microparticles; Core modifying polyethyleneimine; pulmonary delivery
The antimicrobial activity of silver nanoparticles has resulted in their widespread use in many consumer products. Yet, despite their many advantages, it is also important to determine whether silver nanoparticles may represent a hazard to the environment and human health.
Thus, to evaluate the genotoxic potential of silver nanoparticles, in vivo genotoxicity testing (OECD 474, in vivo micronuclei test) was conducted after exposing male and female Sprague-Dawley rats to silver nanoparticles by inhalation for 90 days according to OECD test guideline 413 (Subchronic Inhalation Toxicity: 90 Day Study) with a good laboratory practice system. The rats were exposed to silver nanoparticles (18 nm diameter) at concentrations of 0.7 × 106 particles/cm3 (low dose), 1.4 × 106 particles/cm3 (middle dose), and 2.9 × 106 particles/cm3 (high dose) for 6 hr/day in an inhalation chamber for 90 days. The rats were killed 24 hr after the last administration, then the femurs were removed and the bone marrow collected and evaluated for micronucleus induction.
There were no statistically significant differences in the micronucleated polychromatic erythrocytes or in the ratio of polychromatic erythrocytes among the total erythrocytes after silver nanoparticle exposure when compared with the control.
The present results suggest that exposure to silver nanoparticles by inhalation for 90 days does not induce genetic toxicity in male and female rat bone marrow in vivo.
Silver nanoparticles; Genotoxicity; OECD test guidelines; In vivo micronuclei test; Good laboratory practice; Inhalation toxicity
The inhalation of combustion-derived nanoparticles (CDNPs) is believed to cause an oxidative stress response, which in turn may lead to pulmonary or even systemic inflammation.
Objective and Methods
In this study we assessed whether the in vivo inflammatory response—which is generally referred to as particle toxicity—of mice to CDNPs can be predicted in vitro by a cell-free ascorbate test for the surface reactivity or, more precisely, oxidative potency (OxPot) of particles.
For six types of CDNPs with widely varying particle diameter (10–50 nm), organic content (OC; 1–20%), and specific Brunauer, Emmett, and Teller (BET) surface area (43–800 m2/g), OxPot correlated strongly with the in vivo inflammatory response (pulmonary polymorphonuclear neutrophil influx 24 hr after intratracheal particle instillation). However, for CDNPs with high organic content, OxPot could not explain the observed inflammatory response, possibly due to shielding of the OxPot of the carbon core of CDNPs by an organic coating. On the other hand, a pathway-specific gene expression screen indicated that, for particles rich in polycyclic aromatic hydrocarbon (PAHs), cytochrome P450 1A1 (CYP1A1) enzyme-mediated biotransformation of bio-available organics may generate oxidative stress and thus enhance the in vivo inflammatory response.
The compensatory nature of both effects (shielding of carbon core and biotransformation of PAHs) results in a good correlation between inflammatory response and BET surface area for all CDNPs. Hence, the in vivo inflammatory response can either be predicted by BET surface area or by a simple quantitative model, based on in vitro OxPot and Cyp1a1 induction.
air pollution; BET; biotransformation; carbonaceous particles; Cyp1a1; dose response; nanoparticles; nanotoxicity; organic compounds; oxidative stress; particle toxicity; soot particles; specific surface area; surface toxicity; ultrafine particles
With the increase in production and use of engineered nanoparticles (NP; ≤ 100 nm), safety concerns have risen about the potential health effects of occupational or environmental NP exposure. Results of animal toxicology studies suggest that inhalation of NP may cause pulmonary injury with subsequent acute or chronic inflammation. People with chronic respiratory diseases like asthma or allergic rhinitis may be even more susceptible to toxic effects of inhaled NP. Few studies, however, have investigated adverse effects of inhaled NP that may enhance the development of allergic airway disease.
We investigated the potential of polyethylene glycol coated amorphous silica NP (SNP; 90 nm diameter) to promote allergic airway disease when co-exposed during sensitization with an allergen. BALB/c mice were sensitized by intranasal instillation with 0.02% ovalbumin (OVA; allergen) or saline (control), and co-exposed to 0, 10, 100, or 400 μg of SNP. OVA-sensitized mice were then challenged intranasally with 0.5% OVA 14 and 15 days after sensitization, and all animals were sacrificed a day after the last OVA challenge. Blood and bronchoalveolar lavage fluid (BALF) were collected, and pulmonary tissue was processed for histopathology and biochemical and molecular analyses.
Co-exposure to SNP during OVA sensitization caused a dose-dependent enhancement of allergic airway disease upon challenge with OVA alone. This adjuvant-like effect was manifested by significantly greater OVA-specific serum IgE, airway eosinophil infiltration, mucous cell metaplasia, and Th2 and Th17 cytokine gene and protein expression, as compared to mice that were sensitized to OVA without SNP. In saline controls, SNP exposure did cause a moderate increase in airway neutrophils at the highest doses.
These results suggest that airway exposure to engineered SNP could enhance allergen sensitization and foster greater manifestation of allergic airway disease upon secondary allergen exposures. Whereas SNP caused innate immune responses at high doses in non-allergic mice, the adjuvant effects of SNP were found at lower doses in allergic mice and were Th2/Th17 related. In conclusion, these findings in mice suggest that individuals exposed to SNP might be more prone to manifest allergic airway disease, due to adjuvant-like properties of SNP.
Silica nanoparticles; Adjuvant potential; Allergic airway disease; Th2/Th17 response; Murine ovalbumin model
Hydroxypropyl-sulfobutyl-β-cyclodextrin (HP-SBE-β-CD) inclusion complex was developed and used as a drug delivery system for DTX (DTX/HP-SBE-β-CD). The objective of the present study was to evaluate and compare the biological properties of DTX/HP-SBE-Β-CD with Taxotere®. The pharmacokinetics, biodistribution, antitumor efficacy in vivo and in vitro, and safety evaluation of DTX/HP-SBE-β-CD were studied. The most significant finding was that it was possible to prepare a Polysorbate-80-free inclusion complex for DTX. Studies based on pharmacokinetics, biodistribution, and antitumor efficacy indicated that DTX/HP-SBE-β-CD had similar pharmacokinetic properties and antitumor efficacy both in vitro and in vivo as Taxotere®. Fortunately, this new drug delivery system attenuated the side effects when used in vivo. As a consequence, DTX/HP-SBE-β-CD may be a promising alternative to Taxotere® for cancer chemotherapy treatment with reduced side effects. The therapeutic potential against a variety of human tumors and low toxicity demonstrated in a stringent study clearly warrant clinical investigation of DTX/HP-SBE-β-CD for possible use against human tumors.
antitumor efficacy; biodistribution; DTX/HP-SBE-β-CD; pharmacokinetics; safety evaluation
The use of nanoparticles (NPs) has increased in the past few years in various fields, including defence, aerospace, electronics, biology, medicine, and so forth. and in applications such as diagnostic technology, bioimaging, and drug/gene delivery. Thus, human exposure to NPs and nanomaterials is unavoidable and will certainly expand in the future resulting in a growing interest in nanotoxicology, the study of toxicity of nanomaterials. A number of studies have reported the effects of NPs in respect to pulmonary inflammation by investigating in vitro activation of pulmonary cells with NPs and in vivo in a variety of models in which neutrophils appear to be the predominant leukocyte cell type in lungs and in bronchoalveolar lavages following inhalation or intratracheal instillation of NPs. Despite the fact that several studies have reported an increased number of neutrophils, the literature dealing with the direct activation of neutrophils by a given NP is poorly documented. This paper will summarize the current literature in this latter area of research and will end with a perspective view in which our laboratory will be involved in the following years.
inflammation; nanotoxicology; neutrophils; nanoparticles
We have shown that pulmonary exposure to fine particulate matter (PM) impairs endothelium dependent dilation in systemic arterioles. Ultrafine PM has been suggested to be inherently more toxic by virtue of its increased surface area. The purpose of this study was to determine if ultrafine PM (or nanoparticle) inhalation produces greater microvascular dysfunction than fine PM. Rats were exposed to fine or ultrafine TiO2 aerosols (primary particle diameters of ~1 μm and ~21 nm, respectively) at concentrations which do not alter bronchoalveolar lavage markers of pulmonary inflammation or lung damage.
By histopathologic evaluation, no significant inflammatory changes were seen in the lung. However, particle-containing macrophages were frequently seen in intimate contact with the alveolar wall. The spinotrapezius muscle was prepared for in vivo microscopy 24 hours after inhalation exposures. Intraluminal infusion of the Ca2+ ionophore A23187 was used to evaluate endothelium-dependent arteriolar dilation. In control rats, A23187 infusion produced dose-dependent arteriolar dilations. In rats exposed to fine TiO2, A23187 infusion elicited vasodilations that were blunted in proportion to pulmonary particle deposition. In rats exposed to ultrafine TiO2, A23187 infusion produced arteriolar constrictions or significantly impaired vasodilator responses as compared to the responses observed in control rats or those exposed to a similar pulmonary load of fine particles.
These observations suggest that at equivalent pulmonary loads, as compared to fine TiO2, ultrafine TiO2 inhalation produces greater remote microvascular dysfunction.
Imaging sentinel lymph nodes (SLN) could provide us with critical information about the progression of a cancerous disease. Real-time high-resolution intraoperative photoacoustic imaging (PAI) in conjunction with a near infrared (NIR) probe may offer the opportunities for the immediate imaging for direct identification and resection of SLN or collecting tissue samples. In this work a commercially amenable synthetic methodology is revealed for developing luminescent carbon nanoparticles with rapid clearance properties. A one-pot “green” technique is pursued, which involved rapid surface passivation of carbon nanoparticles with organic macromolecules (e.g. polysorbate, polyethyleneglycol) in a solvent free condition. Interestingly, the naked carbon nanoparticles are derived for the first time, from commercial food grade honey. Surface coated particles are markedly smaller (~7 nm) than the previously explored particles (gold, SWNT, copper) for SLN imaging. Results indicate an exceptionally rapid signal enhancement (~2 min) of the SLN. Owing to their strong optical absorption in the near infrared region, tiny size and rapid lymphatic transport, this platform offers great potential for faster resection of SLN and may lower complications caused by axillary investigation for mismarking with dyes or low-resolution imaging techniques.
Carbon nanoparticle; honey; contrast agents; photoacoustic tomography; real-time imaging
The majority of studies on the effect of nanomaterials on biological function involves either isolated in vitro cell systems or are concerned with in vivo effects after inhalational or dermal exposure. The present work reports on an intriguing observation of the vascular effects seen in an ex vivo perfused tissue preparation, the isolated perfused porcine skin flap (IPPSF), in studies conducted to assess nanomaterial biodistribution. Compared to a relatively large dataset involving organic chemical infusions (n=53), infusion of six different nanoparticles of diverse sizes and composition (silica or dextran coated Fe2O3, silica or citrate coated silver, PEG or carboxylated quantum dots (QD)) resulted in statistically significant post-infusion flap weight gain and an increase in arterial perfusion pressure (especially with QD-PEG). In contrast, infusion with nC60 nanoparticles did not produce these effects. These observations suggest certain nanoparticle infusions may be associated with acute vascular physiological effects which merit further attention.
Nanoparticles; vascular toxicity; in vitro; biodistribution
The assessment of macrophage response to nanoparticles is a central component in the evaluation of new nanoparticle designs for future in vivo application. This work investigates which feature, nanoparticle size or charge, is more predictive of non-specific uptake of nanoparticles by macrophages. This was investigated by synthesizing a library of polymer-coated iron oxide micelles, spanning a range of 30–100 nm in diameter and −23 mV to +9 mV, and measuring internalization into macrophages in vitro. Nanoparticle size and charge both contributed towards non-specific uptake, but within the ranges investigated, size appears to be a more dominant predictor of uptake. Based on these results, a protease-responsive nanoparticle was synthesized, displaying a matrix metalloproteinase-9 (MMP-9)-cleavable polymeric corona. These nanoparticles are able to respond to MMP-9 activity through the shedding of 10–20 nm of hydrodynamic diameter. This MMP-9-triggered decrease in nanoparticle size also led to up to a six-fold decrease in nanoparticle internalization by macrophages and is observable by T2-weighted magnetic resonance imaging. These findings guide the design of imaging or therapeutic nanoparticles for in vivo targeting of macrophage activity in pathologic states.
macrophage targeting; poly(ethylene glycol) (PEG); poly(propylene sulfide) (PPS); iron oxides; opsonization
Solid lipid nanoparticles (SLNs) are colloidal carrier systems which provide controlled-release profiles for many substances. In this study, we prepared aqueous dispersions of lipid nanoparticles using a modified, pH-sensitive derivative of phosphatidylethanolamine.
SLNs were prepared using polysorbate 80 as the surfactant and tripalmitin glyceride and N-glutaryl phosphatidylethanolamine as the lipid components. Particle size, polydispersity index, and zeta potential were examined by photon correlation spectroscopy. Morphological evaluation was performed using scanning electron microscopy, atomic force microscopy, and differential scanning calorimetry.
Photon correlation spectroscopy revealed a particle hydrodynamic diameter of 165.8 nm and zeta potential of −41.6.0 mV for the drug-loaded nanoparticles. Atomic force microscopy investigation showed the nanoparticles to be 50–600 nm in length and 66.5 nm in height. Differential scanning calorimetry indicated that the majority of SLNs possessed less ordered arrangements of crystals compared with corresponding bulk lipids, which is favorable for improving drug-loading capacity. Drug-loading capacity and drug entrapment efficiency values for the SLNs were 25.32% and 94.32%, respectively.
The SLNs prepared in this study were able to control the release of triamcinolone acetonide under acidic conditions.
solid lipid nanoparticles; high-shear homogenization; triamcinolone acetonide; tripalmitin; phosphatidylethanolamine
Previously uncharacterized poly(N-isopropylacrylamide-acrylamide-allylamine)-coated magnetic nanoparticles (MNPs) were synthesized using silane-coated MNPs as a template for radical polymerization of N-isopropylacrylamide, acrylamide, and allylamine. Properties of these nanoparticles such as size, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery. Spherical core-shell nanoparticles with a diameter of 100 nm showed significantly lower systemic toxicity than did bare MNPs, as well as doxorubicin encapsulation efficiency of 72%, and significantly higher doxorubicin release at 41°C compared with 37°C, demonstrating their temperature sensitivity. Released drugs were also active in destroying prostate cancer cells (JHU31). Furthermore, the nanoparticle uptake by JHU31 cells was dependent on dose and incubation time, reaching saturation at 500 μg/mL and 4 hours, respectively. In addition, magnetic resonance imaging capabilities of the particles were observed using agarose platforms containing cells incubated with nanoparticles. Future work includes investigation of targeting capability and effectiveness of these nanoparticles in vivo using animal models.
Magnetic nanoparticles; Temperature-responsive polymers; Prostate cancer; Doxorubicin
Magnetic fluids containing superparamagnetic iron oxide nanoparticles represent an attractive platform as nanocarriers in chemotherapy. Recently, we developed a formulation of maghemite nanoparticles coated with rhodium (II) citrate, which resulted in in vitro cytotoxicity enhanced up to 4.6 times when compared to free rhodium (II) citrate formulation on breast carcinoma cells. In this work, we evaluate the antitumor activity and toxicity induced by these formulations in Balb/c mice bearing orthotopic 4T1 breast carcinoma.
Mice were evaluated with regard to the treatments’ toxicity through analyses of hemogram, serum levels of alanine aminotransferase, iron, and creatinine; DNA fragmentation and cell cycle of bone marrow cells; and liver, kidney and lung histology. In addition, the antitumor activity of rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate was verified by tumor volume reduction, histology and immunohistochemistry.
Regarding the treatments’ toxicity, no experimental groups had alterations in levels of serum ALT or creatinine, and this suggestion was corroborated by the histopathologic examination of liver and kidney of mice. Moreover, DNA fragmentation frequency of bone marrow cells was lower than 15% in all experimental groups. On the other hand, the complexes rhodium (II) citrate-functionalized maghemite and free rhodium (II) citrate led to a marked growth inhibition of tumor and decrease in CD31 and Ki-67 staining.
In summary, we demonstrated that both rhodium (II) citrate and maghemite nanoparticles coated with rhodium (II) citrate formulations exhibited antitumor effects against 4T1 metastatic breast cancer cell line following intratumoral administration. This antitumor effect was followed by inhibition of both cell proliferation and microvascularization and by tumor tissue injury characterized as necrosis and fibrosis. Remarkably, this is the first published report demonstrating the therapeutic efficacy of maghemite nanoparticles coated with rhodium (II) citrate. This treatment prolonged the survival period of treated mice without inducing apparent systemic toxicity, which strengthens its use for future breast cancer therapeutic applications.
Using nanoparticles for therapy and imaging holds tremendous promise for the treatment of major diseases such as cancer. However, their translation into the clinic has been slow because it remains difficult to produce nanoparticles that are consistent ‘batch-to-batch’, and in sufficient quantities for clinical research. Moreover, platforms for rapid screening of nanoparticles are still lacking. Recent microfluidic technologies can tackle some of these issues, and offer a way to accelerate the clinical translation of nanoparticles. In this Progress Article, we highlight the advances in microfluidic systems that can synthesize libraries of nanoparticles in a well-controlled, reproducible and high-throughput manner. We also discuss the use of microfluidics for rapidly evaluating nanoparticles in vitro under microenvironments that mimic the in vivo conditions. Furthermore, we highlight some systems that can manipulate small organisms, which could be used for evaluating the in vivo toxicity of nanoparticles or for drug screening. We conclude with a critical assessment of the near- and long-term impact of microfluidics in the field of nanomedicine.