Evaluation of the Effect of Crosslinking Method of Poly(Vinyl Alcohol) Hydrogels on Thrombogenicity.

PURPOSE: Crosslinked poly(vinyl alcohol) (PVA) is a biomaterial that can be used for multiple cardiovascular applications. The success of implanted biomaterials is contingent on the properties of the material. A crucial consideration for blood-contacting devices is their potential to incite thrombus formation, which is dependent on the material surface properties. The goal of this study was to quantify the effect of different crosslinking methods of PVA hydrogels on in vitro thrombogenicity. METHODS: PVA was manufactured using three different crosslinking methods: 30% sodium trimetaphosphate (STMP), three 24 h freeze-thaw cycles (FT), and 2% glutaraldehyde-crosslinked (GA) to produce STMP-PVA, FT-PVA and GA-PVA, respectively. Expanded polytetrafluoroethylene (ePTFE) was used as a clinical control. As markers of thrombus formation, the degree of coagulation factor (F) XII activation, fibrin formation, and platelet adhesion were measured. RESULTS: The GA-PVA material increased FXII activation in the presence of cofactors compared to vehicle and increase platelet adhesion compared to other PVA surfaces. The STMP-PVA and FT-PVA materials had equivalent degrees of FXII activation, fibrin formation and platelet adhesion. CONCLUSION: This work supports crosslinker dependent thrombogenicity of PVA hydrogels and advances our understanding of how the manufacturing of a PVA hydrogel affects its hemocompatibility.

Factor XII Activation Promotes Platelet Consumption in the Presence of Bacterial-Type Long-Chain Polyphosphate In Vitro and In Vivo.

Objective- Terminal complications of bacterial sepsis include development of disseminated intravascular consumptive coagulopathy. Bacterial constituents, including long-chain polyphosphates (polyP), have been shown to activate the contact pathway of coagulation in plasma. Recent work shows that activation of the contact pathway in flowing whole blood promotes thrombin generation and platelet activation and consumption distal to thrombus formation ex vivo and in vivo. Here, we sought to determine whether presence of long-chain polyP or bacteria in the bloodstream promotes platelet activation and consumption in a coagulation factor (F)XII-dependent manner. Approach and Results- Long-chain polyP promoted platelet P-selectin expression, microaggregate formation, and platelet consumption in flowing whole blood in a contact activation pathway-dependent manner. Moreover, long-chain polyP promoted local fibrin formation on collagen under shear flow in a FXI-dependent manner. Distal to the site of thrombus formation, platelet consumption was dramatically enhanced in the presence of long-chain polyP in the blood flow in a FXI- and FXII-dependent manner. In a murine model, long-chain polyP promoted platelet deposition and fibrin generation in lungs in a FXII-dependent manner. In a nonhuman primate model of bacterial sepsis, pre-treatment of animals with an antibody blocking FXI activation by FXIIa reduced lethal dose100 Staphylococcus aureus-induced platelet and fibrinogen consumption. Conclusions- This study demonstrates that bacterial-type long-chain polyP promotes platelet activation in a FXII-dependent manner in flowing blood, which may contribute to sepsis-associated thrombotic processes, consumptive coagulopathy, and thrombocytopenia.

Impact of surface modification on the toxicity of zerovalent iron nanoparticles in aquatic and terrestrial organisms.

Nanoscale zerovalent iron (nZVI)-based materials are increasingly being applied in environmental remediation, thereby lead to their exposure to aquatic and terrestrial biota. However, little is known regarding the toxic effects of surface-modified nZVI on multiple species in the ecosystem. In this study, we systematically compared the toxicities of different forms of nZVIs, such as bare nZVI, carboxymethyl cellulose (CMC)-stabilized nZVI, tetrapolyphosphate (TPP)-coated nZVI and bismuth (Bi)-doped nZVI, on a range of aquatic and terrestrial organisms, including bacteria (Escherichia coli and Bacillus subtilis), plant (Arabidopsis thaliana), water flea (Daphnia magna) and earthworm (Eisenia fetida). The Bi- and CMC-nZVI induced adverse biological responses across all the test systems, except E. fetida, varying from cell death in E. coli and B. subtilis to inhibition of the physiological states in D. magna and A. thaliana. The particle characterization under exposure conditions indicated that the surface modification of nZVI played a significant role in their toxicities by changing their physicochemical properties. The underlying mechanisms by which nZVI induces toxicity might be a combination of oxidative stress and another mechanism such as cell membrane disruption, chlorosis and hypoxia. Overall, our findings could provide important implications for the development of environment-friendly nanomaterials and direct further ecotoxicological researches regarding interspecies exploration.

Inorganic Polyphosphate Amplifies High Mobility Group Box 1-Mediated Von Willebrand Factor Release and Platelet String Formation on Endothelial Cells.

Objective- Inorganic polyphosphate (polyP) is known to modulate coagulation, inflammation, and metabolic pathways. It also amplifies inflammatory responses of HMGB1 (high mobility group box 1) in endothelial cells. The objective of this study was to evaluate the effect of polyP on von Willebrand factor (VWF) release from endothelial cells with or without HMGB1. Approach and Results- EA.hy926 endothelial cells were treated with different concentrations of polyP70 alone or in combination with different concentrations of HMGB1. VWF release was measured by an ELISA assay in the absence or presence of pharmacological inhibitors of the receptor for advanced glycation end products, P2Y1, and Ca2+. A flow chamber assay was used to monitor polyP70-mediated platelet recruitment and VWF-platelet string formation. PolyP70 and HMGB1 induced VWF release from endothelial cells by a concentration-dependent manner. PolyP70 amplified HMGB1-mediated VWF release from endothelial cells. This was also true if boiled platelet releasate was used as the source of polyP. Gene silencing or pharmacological inhibitors of receptor for advanced glycation end products, P2Y1, and Ca2+ significantly inhibited VWF release. PolyP70 and HMGB1 synergistically promoted VWF-platelet string formation in the flow chamber assay, which was inhibited by the anti-GPIbα (glycoprotein Ib alpha) antibody. VWF release by polyP70-HMGB1 complex required phosphorylation of Src and phospholipase C because inhibitors of Src, phospholipase C, and Ca2+ signaling significantly decreased VWF secretion. The polyP70-HMGB1 complex also increased angiopoietin-2 release, indicating that Weibel-Palade body exocytosis is involved in the VWF release. Conclusions- PolyP70 can promote thrombotic and inflammatory pathways by inducing VWF release and platelet string formation on endothelial cells.

Effect of mercury on the polyphosphate level of alga Chlamydomonas reinhardtii.

In this study, the accumulation and toxicity effect of 1-7 µM of Hg was determined during 24-72 h on two strains of Chlamydomonas reinhardtii, CC-125 and CC-503 as a cell wall-deficient mutant, by monitoring the growth rate and the maximum quantum yield of Photosystem II. In addition, the level of extracytoplasmic polyphosphates (polyP related to the cell wall) was determined to understand the polyP physiological role in Hg-treated algal cells. The results showed that the polyP level was higher in the strain CC-125 compared to CC-503. When algal cells were exposed to 1 and 3 µM of Hg, the accumulation of Hg was correlated with the degradation of polyP for both strains. These results suggested that the degradation of polyP participated in the sequestration of Hg. In fact, this mechanism might explain at 72 h the recovery of the polyP level, the efficiency of maximum PSII quantum yield, the low inhibition of growth rate, and the low accumulated Hg in algal biomass. Under the effect of 5 and 7 µM of Hg, the degradation of polyP was complete and could not be recovered, which was caused by a high accumulation and toxicity of Hg already at 24 h. Our results demonstrated that the change of polyP level was correlated with the accumulation and effect of Hg on algal cells during 24-72 h, which can be used as a biomarker of Hg toxicity. Therefore, this study suggested that extracytoplasmic polyP in C. reinhardtii contributed to the cellular tolerance for Hg.

Evaluation of the effects of polymeric chitosan/tripolyphosphate and solid lipid nanoparticles on germination of Zea mays, Brassica rapa and Pisum sativum.

Although the potential toxicity of many metallic and carbon nanoparticles to plants has been reported, few studies have evaluated the phytotoxic effects of polymeric and solid lipid nanoparticles. The present work described the preparation and characterization of chitosan/tripolyphosphate (CS/TPP) nanoparticles and solid lipid nanoparticles (SLN) and evaluated the effects of different concentrations of these nanoparticles on germination of Zea mays, Brassica rapa, and Pisum sativum. CS/TPP nanoparticles presented an average size of 233.6±12.1nm, polydispersity index (PDI) of 0.30±0.02, and zeta potential of +21.4±1.7mV. SLN showed an average size of 323.25±41.4nm, PDI of 0.23±0.103, and zeta potential of -13.25±3.2mV. Nanotracking analysis enabled determination of concentrations of 1.33×1010 (CS/TPP) and 3.64×1012 (SLN) nanoparticles per mL. At high concentrations, CS/TPP nanoparticles caused complete inhibition of germination, and thus negatively affected the initial growth of all tested species. Differently, SLN presented no phytotoxic effects. The different size and composition and the opposite charges of SLN and CS/TPP nanoparticles could be associated with the differential phytotoxicity of these nanomaterials. The present study reports the phytotoxic potential of polymeric CS/TPP nanoparticles towards plants, indicating that further investigation is needed on the effects of such formulations intended for future use in agricultural systems, in order to avoid damage to the environment.

Safety assessment of nanopesticides using the roundworm Caenorhabditis elegans.

The extensive use of pesticides is causing environmental pollution, affecting animal organisms in different habitats and also leading human health at risk. In this study, we present as an alternative the use of nanoparticles loaded with pesticides and report their toxicological assessment to a soil organism, Caenorhabditis elegans. Three nanoparticle formulations were analyzed: solid lipid nanoparticles loaded or not with atrazine and simazine, SLN; polymeric nanoparticles, NC_PCL loaded with atrazine; and chitosan/tripolyphosphate, CS/TPP, loaded or not with paraquat. All formulations, loaded or not with pesticides, increased lethality in a dose- dependent manner with similar LC50. Both loaded and unloaded NC_PCL were the most toxic formulations to developmental rate, significantly reducing worms length, even at low concentrations. In contrast, both CS/TPP nanoparticles were the least toxic, not affecting reproduction and body length at higher concentrations, probably due to the biocompatibility of chitosan. The physico-chemical characterization of nanoparticles after incubation in saline solution (used in exposure of organisms) has shown that these colloidal systems are stable and remain with the same initial characteristics, even in the presence of saline environment. Notably, our results indicate that the observed effects were caused by the nanoparticles per se. These results suggest that the development of nanoparticles aiming agriculture applications needs more studies in order to optimize the composition and then reduce their toxicity to non-target organisms.

Acute Corneal Toxicity of Diquas.

AIM: This study aimed to investigate acute corneal toxicity of commercially available diquafosol 3% ophthalmic solution (Diquas®), which contains C12 benzalkonium chloride (BAC) as a preservative. METHODS: Corneal transepithelial electrical resistance (TER) changes after a 60-second exposure to Diquas® (diquafosol 3% preserved with 0.0075% C12 BAC); 0.0075% C12 BAC and 0.0075% C12, C14, C16 BAC mixture were measured in living rabbits. Corneal damage was also examined by scanning electron microscopy (SEM). Hank's balanced salt solution (HBSS) was used as a control. RESULTS: Diquas® and 0.0075% C12 BAC did not produce any significant decrease in the corneal TER as compared to the HBSS control eyes. There was a significant decrease in the corneal TER after exposure of the cornea to the 0.0075% C12, C14, C16 BAC mixture (p < 0.01). SEM revealed that the superficial cells of the corneas exposed to the 0.0075% BAC mixture were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to Diquas® or 0.0075% C12 BAC appeared normal and had normal microvilli under SEM examinations. CONCLUSION: The acute corneal toxicity of Diquas® is less than that of the 0.0075% BAC mixture. Diquas® preserved with 0.0075% C12 BAC did not show acute corneal toxicity.

Design and evaluation of novel pH-sensitive ureido-conjugated chitosan/TPP nanoparticles targeted to Helicobacter pylori.

The covalently modified ureido-conjugated chitosan/TPP multifunctional nanoparticles have been developed as targeted nanomedicine delivery system for eradication of Helicobacter pylori. H. pylori can specifically express the urea transport protein on its membrane to transport urea into cytoplasm for urease to produce ammonia, which protects the bacterium in the acid milieu of stomach. The clinical applicability of topical antimicrobial agent is needed to eradicate H. pylori in the infected fundal area. In this study, we designed and synthesized two ureido-conjugated chitosan derivatives UCCs-1 and UCCs-2 for preparation of multifunctional nanoparticles. The process was optimized in order to prepare UCCs/TPP nanoparticles for encapsulation of amoxicillin. The results showed that the amoxicillin-UCCs/TPP nanoparticles exhibited favorable pH-sensitive characteristics, which could procrastinate the release of amoxicillin at gastric acids and enable the drug to deliver and target to H. pylori at its survival region effectively. Compared with unmodified amoxicillin-chitosan/TPP nanoparticles, a more specific and effective H. pylori growth inhibition was observed for amoxicillin-UCCs/TPP nanoparticles. Drug uptake analysis tested by flow cytometry and confocal laser scanning microscopy verified that the uptake of FITC-UCCs-2/TPP nanoparticles was associated with urea transport protein on the membrane of H. pylori and reduced with the addition of urea as competitive transport substrate. These findings suggest that the multifunctional amoxicillin-loaded nanoparticles have great potential for effective therapy of H. pylori infection. They may also serve as pharmacologically effective nanocarriers for oral targeted delivery of other therapeutic drugs to treat H. pylori.

Chitosan nanoparticles loaded the herbicide paraquat: the influence of the aquatic humic substances on the colloidal stability and toxicity.

Polymeric nanoparticles have been developed for several applications, among them as carrier system of pesticides. However, few studies have investigated the fate of these materials in the environment in relation to colloidal stability and toxicity. In nature, humic substances are the main agents responsible for complexation with metals and organic compounds, as well as responsible for the dynamics of these nanoparticles in aquatic and terrestrial environments. In this context, the evaluation of the influence of aquatic humic substances (AHS) on the colloidal stability and toxicity of polymeric nanoparticles of chitosan/tripolyphosphate with or without paraquat was performed. In this study, the nanoparticles were prepared by the ionic gelation method and characterized by size distribution measurements (DLS and NTA), zeta potential, infrared and fluorescence spectroscopy. Allium cepa genotoxicity studies and ecotoxicity assays with the alga Pseudokirchneriella subcapitata were used to investigate the effect of aquatic humic substances (AHS) on the toxicity of this delivery system. No changes were observed in the physical-chemical stability of the nanoparticles due to the presence of AHS using DLS and NTA techniques. However some evidence of interaction between the nanoparticles and AHS was observed by infrared and fluorescence spectroscopies. The ecotoxicity and genotoxicity assays showed that humic substances can decrease the toxic effects of nanoparticles containing paraquat. These results are interesting because they are important for understanding the interaction of these nanostructured carrier systems with species present in aquatic ecosystems such as humic substances, and in this way, opening new perspectives for studies on the dynamics of these carrier systems in the ecosystem.

Cross-linked polyethylenimine-tripolyphosphate nanoparticles for gene delivery.

The high transfection efficiency of polyethylenimine (PEI) makes it an attractive potential nonviral genetic vector for gene delivery and therapy. However, the highly positive charge of PEI leads to cytotoxicity and limits its application. To reduce the cytotoxicity of PEI, we prepared anion-enriched nanoparticles that combined PEI with tripolyphosphate (TPP). We then characterized the PEI-TPP nanoparticles in terms of size, zeta potential, and Fourier-transform infrared (FTIR) spectra, and assessed their transfection efficiency, cytotoxicity, and ability to resist deoxyribonuclease (DNase) I digestion. The cellular uptake of PEI-TPP with phosphorylated internal ribosome entry site-enhanced green fluorescent protein C1 or FAM (fluorouracil, Adriamycin [doxorubicin] and mitomycin)-labeled small interfering ribonucleic acids (siRNAs) was monitored by fluorescence microscopy and confocal laser microscopy. The efficiency of transfected delivery of plasmid deoxyribonucleic acid (DNA) and siRNA in vitro was 1.11- to 4.20-fold higher with the PEI-TPP particles (7.6% cross-linked) than with the PEI, at all N:P ratios (nitrogen in PEI to phosphorus in DNA) tested. The cell viability of different cell lines was more than 90% at the chosen N:P ratios of PEI-TPP/DNA complexes. Moreover, PEI-TPP nanoparticles resisted digestion by DNase I for more than 2 hours. The time-dependent absorption experiment showed that 7.6% of cross-linked PEI-TPP particles were internalized by 293T cells within 1 hour. In summary, PEI-TPP nanoparticles effectively transfected cells while conferring little or no toxicity, and thus have potential application in gene delivery.

Coupled synthesis and translocation restrains polyphosphate to acidocalcisome-like vacuoles and prevents its toxicity.

Eukaryotes contain inorganic polyphosphate (polyP) and acidocalcisomes, which sequester polyP and store amino acids and divalent cations. Why polyP is sequestered in dedicated organelles is not known. We show that polyP produced in the cytosol of yeast becomes toxic. Reconstitution of polyP translocation with purified vacuoles, the acidocalcisomes of yeast, shows that cytosolic polyP cannot be imported, whereas polyP produced by the vacuolar transporter chaperone (VTC) complex, an endogenous vacuolar polyP polymerase, is efficiently imported and does not interfere with growth. PolyP synthesis and import require an electrochemical gradient, probably as a driving force for polyP translocation. VTC exposes its catalytic domain to the cytosol and carries nine vacuolar transmembrane domains. Mutations in the VTC transmembrane regions, which are likely to constitute the translocation channel, block not only polyP translocation but also synthesis. Given that they are far from the cytosolic catalytic domain of VTC, this suggests that the VTC complex obligatorily couples synthesis of polyP to its import in order to avoid toxic intermediates in the cytosol. Sequestration of otherwise toxic polyP might be one reason for the existence of acidocalcisomes in eukaryotes.

Stabilization and cellular delivery of chitosan-polyphosphate nanoparticles by incorporation of iron.

Chitosan (CS) nanoparticles are typically obtained by complexation with tripolyphosphate (TPP) ions, or more recently using triphosphate group-containing drugs such as adenosine triphosphate (ATP). ATP is an active molecule we aim to deliver in order to restore its depletion in macrophages, when associated with their death leading to plaque rupture in atherosclerotic lesions. Despite high interest in CS nanoparticles for drug delivery, due to the biodegradability of CS and to the ease of the preparation process, these systems tend to readily disintegrate when diluted in physiological media. Some stabilization strategies have been proposed so far but they typically involve the addition of a coating agent or chemical cross-linkers. In this study, we propose the complexation of CS with iron ions prior to nanoparticle formation as a strategy to improve the carrier stability. This can be achieved thanks to the ability of iron to strongly bind both chitosan and phosphate groups. Nanoparticles were obtained from either TPP or ATP and chitosan-iron (CS-Fe) complexes containing 3 to 12% w/w iron. Isothermal titration calorimetry showed that the binding affinity of TPP and ATP to CS-Fe increased with the iron content of CS-Fe complexes. The stability of these nanoparticles in physiological conditions was evaluated by turbidity and by fluorescence fluctuation in real time upon dilution by electrolytes, and revealed an important stabilization effect of CS-Fe compared to CS, increasing with the iron content. Furthermore, in vitro studies on two macrophage cell lines (J774A.1 and THP-1) revealed that ATP uptake is improved consistently with the iron content of CS-Fe/ATP nanoparticles, and correlated to their lower dissociation in biological medium, allowing interesting perspectives for the intracellular delivery of ATP.

Chitosan/tripolyphosphate nanoparticles loaded with paraquat herbicide: an environmentally safer alternative for weed control.

Paraquat is a fast acting nonselective contact herbicide that is extensively used worldwide. However, the aqueous solubility and soil sorption of this compound can cause problems of toxicity in nontarget organisms. This work investigates the preparation and characterization of nanoparticles composed of chitosan and sodium tripolyphosphate (TPP) to produce an efficient herbicidal formulation that was less toxic and could be used for safer control of weeds in agriculture. The toxicities of the formulations were evaluated using cell culture viability assays and the Allium cepa chromosome aberration test. The herbicidal activity was investigated in cultivations of maize (Zea mays) and mustard (Brassica sp.), and soil sorption of the nanoencapsulated herbicide was measured. The efficiency association of paraquat with the nanoparticles was 62.6 ± 0.7%. Encapsulation of the herbicide resulted in changes in its diffusion and release as well as its sorption by soil. Cytotoxicity and genotoxicity assays showed that the nanoencapsulated herbicide was less toxic than the pure compound, indicating its potential to control weeds while at the same time reducing environmental impacts. Measurements of herbicidal activity showed that the effectiveness of paraquat was preserved after encapsulation. It was concluded that the encapsulation of paraquat in nanoparticles can provide a useful means of reducing adverse impacts on human health and the environment, and that the formulation therefore has potential for use in agriculture.

Toxicity of PHOS-CHEK LC-95A and 259F fire retardants to ocean- and stream-type Chinook salmon and their potential to recover before seawater entry.

Long-term fire retardants are used to prevent the spread of wildland fire, but have inadvertently entered aquatic habitats and resulted in fish kills. We examined the toxicity of two fire retardant products; PHOS-CHEK 259F and LC-95A, on Chinook salmon with two different life histories, ocean-type and stream-type, at different stages of their development. Ocean-type Chinook outmigrate to the ocean as subyearlings; while, stream-type salmon overwinter in freshwater and outmigrate as yearlings. Ocean-type and stream-type salmon were exposed to the fire retardants prior to their parr to smolt transition (presmolts) as subyearlings (stream-type and ocean-type) and yearlings (stream-type only), as well as during their transition (smolts). The salmon were exposed to eight concentrations of each retardant and a control for 96h to determine acute toxicity. Lethal concentration curves were modeled by logistic regression for each life history and life stage exposed to the two fire retardants. Among all life histories and life stages tested, PHOS-CHEK 259F was most toxic to stream-type salmon at smolt stage and PHOS-CHEK LC-95A was most toxic to ocean-type salmon at smolt stage. To determine the delayed effects of product exposures on fish health as well as for the potential of recovery, 24-hour seawater challenges were performed immediately after fire retardant exposure, as well as after a recovery period. Previous PHOS-CHEK exposure reduced survival during seawater challenge among salmon from both life histories undergoing the parr-smolt transition and was more pronounced after PHOS-CHEK LC-95A exposure. However, this delayed effect was not observed 34 or more days after either PHOS-CHEK exposure. We conclude that accidental PHOS-CHEK LC-95A or 259F drops during salmon outmigration would have adverse impacts that extend beyond the acute mortality that occurs within the immediate drop and dilution areas.

Chitosan tripolyphosphate (CS/TPP) nanoparticles: preparation, characterization and application for gene delivery in shrimp.

The present study examines the use of CS/TPP nanoparticles for gene delivery in different tissues of shrimp through oral route. The viral gene of WSSV was used to construct DNA vaccines using pcDNA 3.1, a eukaryotic expression vector and the constructs were named as pVP28. The CS/TPP nanoparticles were synthesized by ionic gelation process and these particles were characterized. The structure and morphology of the nanoparticles were studied by field emission scanning electron microscopy (FE-SEM) and FTIR (Fourier Transform Infrared Spectra). The cytotoxicity of CS/TPP nanoparticles was evaluated by MTT assay using fish cell line. The expression of gene was confirmed by Immuno-dot blot, ELISA and RT-PCR analyses. The results indicate that DNA can be easily delivered into shrimp by feeding with CS/TPP nanoparticles.

Emergency do not consume/do not use concentrations for blended phosphates in drinking water.

The U.S. Congress [PL 107-188] amended the Safe Drinking Water Act and required each community water system serving more than 3,000 people to conduct vulnerability assessments. These assessments address potential circumstances that could compromise the safety and reliability of municipal water. The present evaluation concerns the concentrations of the blended phosphates (also known as polyphosphates, condensed complex phosphates, polyphosphate glassy balls, and pyrophosphates) intended to aid regulatory agencies in decisions to avoid contact with affected water. Polyphosphates are direct food additives and they are used to treat municipal drinking water, but depending upon the concentration and duration of exposure these substances can induce chemical burns. Ingested polyphosphates are degraded by phosphatase enzymes to monophosphates, substances that are over-the-counter bowel purgatives. High oral doses of the monophosphates can induce transient hyperphosphatemia in older and susceptible young people, which can lead to acute phosphate nephropathy. In some patients, the condition is fatal. Based on the acute diarrhea after the ingestion of a single oral dose of monobasic (NaH2PO(4)) and dibasic (Na2HPO(4)) monophosphates in adults, a do not consume concentration of 600 mg PO(4)/L can be derived. Based on mild local irritation after topical application of 1.0% sodium metaphosphate [(NaPO(3))6 • H2O] to intact skin of sensitive volunteers, a do not use concentration of 8,000 mg PO4/L can be assigned. Given the lack of eye irritation in rabbits after direct instillation of 0.2% (NaPO(3))6 • H2O, an acute ocular contact limit of 50 mg PO4/L serves as the overall do not use level.

Human health risks from mercury exposure from broken compact fluorescent lamps (CFLs).

Human health risk to infants/toddlers and adults was evaluated based on two exposure scenarios from compact fluorescent lamp (CFL) breakage; first in a room with no ventilation and no clean-up, and second in a room with adequate ventilation and clean-up. Concentration data from multiple exposure scenarios tested in a study by Stahler et al. (2008) were compared to human toxicity benchmarks to calculate hazard quotients. For the no clean-up scenario, hazard quotients were generally less than 1, suggesting an unlikely health risk. When the room was ventilated and the broken CFL was cleaned-up, mercury concentrations were generally lower. A review of release scenarios, along with duration-adjusted toxicity benchmarks, indicated that few releases produced levels of concern, but some scenarios resulted in exceedance of risk targets and require further study. Uncertainties in this screening characterization include assumptions about room size, ventilation, age of lamp, the distribution of mercury in the room, and also the choice of the toxicity benchmarks used to develop the hazard quotients.

Hyperbranched polyphosphates for drug delivery application: design, synthesis, and in vitro evaluation.

A water-soluble hyperbranched polyphosphate (HPHEEP) was synthesized through the self-condensation ring-opening polymerization (SCROP) of 2-(2-hydroxyethoxy)ethoxy-2-oxo-1,3,2-dioxaphospholane (HEEP), and its suitability as a drug carrier was then evaluated in vitro. Methyl tetrazolium (MTT) and live/dead staining assays indicated that HPHEEP had excellent biocompatibility against COS-7 cells. The good biodegradability of HPHEEP was observed by NMR analysis, and the degradation products were nontoxic to COS-7 cells. Flow cytometry and confocal laser scanning microscopy analyses suggested that HPHEEP could be easily internalized by vivid cells and preferentially accumulated in the perinuclear region. Furthermore, a hydrophobic anticancer drug, chlorambucil, was used as a model drug and covalently bound to HPHEEP. The chlorambucil dose of the conjugate and free drug required for 50% cellular growth inhibition were 75 and 50 microg/mL, respectively, according to MTT assay against an MCF-7 breast cancer cell line in vitro. This high activity of the conjugate may be attributed to the biodegradability of HPHEEP so as to release the chlorambucil in cells. Therefore, on the basis of its biocompatibility and biodegradability, HPHEEP could provide a charming opportunity to design some excellent drug delivery systems for therapeutic applications.

Ionically crosslinked chitosan/tripolyphosphate nanoparticles for oligonucleotide and plasmid DNA delivery.

Ionically crosslinked nanoparticles based on high and low molecular weight chitosans (CS) were formulated with plasmid DNA or dsDNA oligomers using the ionic gelation technique with pentasodium tripolyphospate (TPP) as crosslinking agent. The resulting CS/TPP nanoparticles were investigated with regard to their physical-chemical properties, in vitro transfection efficiency, toxicity, cellular uptake, and in vivo gene expression following intratracheal administration to mice. The effects of co-formulating the nanoparticles with a model protein, BSA, were also studied. CS/TPP nanoparticles showed high encapsulation efficiencies both for plasmid DNA and dsDNA oligomers (20-mers), independent of CS molecular weight. TEM images revealed a spherical shape of the CS/TPP nanoparticles in contrast to the heterogeneous and irregular morphology displayed by conventional chitosan polyplexes. The nanoparticles showed high physical stability and no DNA release could be detected in diverse release media, nor even after incubation with heparin. Low molecular weight (LMW) CS/TPP nanoparticles gave high gene expression levels in HEK 293 cells already 2 days after transfection, reaching a plateau of sustained and high gene expression between 4 and 10 days. The inclusion of BSA into the nanostructures did not alter the inherent transfection efficiency of the nanoparticles. Confocal studies suggest endocytotic cellular uptake of the nanoparticles and a subsequent release into the cytoplasm within 14 h. LMW CS/TPP nanoparticles mediated a strong beta-galactosidase expression in vivo after intratracheal administration. The results of this study forward ionically crosslinked CS/TPP nanoparticles as a biocompatible non-viral gene delivery system and generate a solid ground for further optimization studies, for example with regard to steric stabilization and targeting.