Microemulsions and nanoemulsions modified with cationic surfactants for improving the solubility and therapeutic efficacy of loaded drug indomethacin

In this work, a noncovalent strategy was successfully used to modify colloidal stability andin vitroandin vivoefficacy of two amphiphilic formulations of the anti-inflammatory drug indomethacin. Namely, nanoemulsions and microemulsions based on oleic acid and nonionic surfactants have been produced and compared. The influence of cationic surfactants cetyltrimethylammonium bromide and its carbamate bearing analogue on the size characteristics, stability and ability to provide prolonged action of loaded drug indomethacin has been evaluated. Adding the positively charged molecules in the surface layer of nanoemulsions and microemulsions has shown the stability increase along with maintaining the size characteristics and homogeneity in time. Moreover, the carbamate modified analogue demonstrated beneficial behavior. Indomethacin loaded in microemulsions and nanoemulsions showed prolonged-release (10%-15% release for 5 h) compared to a free drug (complete release for 5 h). The rate of release of indomethacin from nanoemulsions was slightly higher than from microemulsions and insignificantly decreased with an increase in the concentration of the cationic surfactant. For carbamate surfactant nanocarrier loaded with fluorescence probe Nile Red, the ability to penetrate into the cell was supported by flow cytometry study and visualized by fluorescence microscopy.In vitrotests on anti-inflammatory activity of the systems demonstrated that the blood cell membrane stabilization increased in the case of modified microemulsion. The anti-inflammatory activity of the encapsulated drug was tested in rats using a carrageenan-induced edema model. Nanoemulsions without cationic surfactants appeared more efficient compared to microemulsions. Indomethacin emulsion formulations with carbamate surfactant added showed slower carrageenan-induced edema progression compared to unmodified compositions. Meanwhile, the edema completely disappeared upon treatment with emulsion loaded indomethacin after 4 h in the case of microemulsions versus 5 h in the case of nanoemulsions.

Nanoemulsions containing Garcinia mangostana L. pericarp extract for topical applications: Development, characterization, and in vitro percutaneous penetration assay

A highly stable oil-in-water nanoemulsion for topical applications, containing mangostins extracted from the pericarp of mangosteen (Garcinia mangostana L.), is a promising strategy to protect mangostins as well as to improve penetration of these important antioxidants through the skins. Nanoemulsions consisted of virgin coconut oil as the oil phase, Tween-80 and Span-80 as surfactants, and xanthan gum as the thickening agent, were prepared using the high-energy and low-energy emulsification methods. The nanoemulsions that were stable up to 28 days had oil droplet diameter of 220 nm to 353 nm and zeta potential of -46.9 mV to -63.7 mV. The accelerated stability test showed that the most stable nanoemulsions were those prepared using the low-energy emulsification method with an estimated shelf life of eleven months, composed of 11% oil phase, 17% surfactant, and 72% aqueous phase. The in vitro percutaneous penetration test for the nanoemulsion with added xanthan gum provided high cumulative skin penetration of mangostins of up to 114 μg/cm². The results of this study indicate that virgin coconut oil-based nanoemulsions containing mangostins, prepared using the low-energy emulsification method, stabilized by xanthan gum and mixed at 40°C can prospectively be used for topical applications.

Safety Assessment of PEGylated Alkyl Glycerides as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 60 PEGylated alkyl glycerides. PEGylated alkyl glycerides are mono-, di-, and/or triglycerides that have been modified with ethylene glycol repeat units (in the starting material form as epoxide). Most of the PEGylated alkyl glycerides are reported to function as skin-conditioning agents or surfactants. The Panel reviewed the available animal and clinical data as well as data from the 1999 report for the 5 polyethylene glycol (PEG) glyceryl cocoates and the 2012 report of PEGylated oils, to determine the safety of these ingredients. The Panel concluded these ingredients are safe in the current practices of use and concentration when formulated to be nonirritating; this conclusion supersedes the 1999 conclusion issued on 5 PEG glyceryl cocoate ingredients.

Preparation and in vitro evaluation of amphiphilic paclitaxel small molecule prodrugs and enhancement of oral absorption

A series of novel amphiphilic paclitaxel (PTX) small molecule prodrugs, PTX-succinic anhydride-cystamine (PTX-Cys), PTX-dithiodipropionic anhydride (PTX-SS-COOH) and PTX-succinic anhydride-cystamine-valine (PTX-SS-Val) were designed, synthesized and evaluated against cancer cell lines. Compared with paclitaxel, these prodrugs contained water-soluble groups such as amino, carboxyl and amino acid, which improved the aqueous solubility of the prodrugs. More importantly, the valine was introduced in PTX-SS-Val molecule and made the molecule conform to the structural characteristics of intestinal oligopeptide transporter PEPT1 substrate. Thus the oral bioavailability of prodrug could be improved because of the mediation of PEPT1 transporter. These small molecule paclitaxel prodrugs could self-assemble into nanoparticles in aqueous solution, which effectively improved the solubility of paclitaxel, and had certain stability in pH 6.5, pH 7.4 buffer solutions and simulated gastrointestinal fluids. Some of these prodrugs, especially for PTX-Cys and PTX-SS-Val, exhibited nearly equal or slightly better anticancer activity when compared to paclitaxel. Further studies on PTX-Cys and PTX-SS-Val showed that both had good intestinal absorption in the rat single-pass intestinal perfusion (SPIP) experiments. Oral pharmacokinetic experiments showed that PTX-SS-Val could effectively improve the oral bioavailability of PTX.

Bile Acid Tethered Docetaxel-Based Nanomicelles Mitigate Tumor Progression through Epigenetic Changes

In this study, we describe the engineering of sub-100 nm nanomicelles (DTX-PC NMs) derived from phosphocholine derivative of docetaxel (DTX)-conjugated lithocholic acid (DTX-PC) and poly(ethylene glycol)-tethered lithocholic acid. Administration of DTX-PC NMs decelerate tumor progression and increase the mice survivability compared to Taxotere (DTX-TS), the FDA-approved formulation of DTX. Unlike DTX-TS, DTX-PC NMs do not cause any systemic toxicity and slow the decay rate of plasma DTX concentration in rodents and non-rodent species including non-human primates. We further demonstrate that DTX-PC NMs target demethylation of CpG islands of Sparcl1 (a tumor suppressor gene) by suppressing DNA methyltransferase activity and increase the expression of Sparcl1 that leads to tumor regression. Therefore, this unique system has the potential to improve the quality of life in cancer patients and can be translated as a next-generation chemotherapeutic.

Highly Biocompatible Nanoparticles of Au@Fluorescent Polymers as Novel Contrast Agent for In Vivo Bimodality NIR Fluorescence/CT Imaging

In this work, one kind of biocompatible and all-in-one dual-modal nanoprobe, based on Au nanoparticles and NIR emissive semiconducting fluorescence polymers, was developed by the one-step solvent-mediated self-assembly method for in vivo X-ray computed tomography (CT) and fluorescence bioimaging for the first time. After preparation, a series of comprehensive evaluations were performed, and the nanoprobe exhibited smart size and modification, good compatibility, inducement of autophagy, long blood circulation, unconspicuous in vivo toxicity, and excellent fluorescence/CT imaging effects. Overall, the studies in this work assuredly indicate that the synthesized Au@FP nanoparticles as a noninvasive contrast agent is suitable for in vivo fluorescence/X-ray CT bimodality biomedical imaging and diagnosis.

Toxicity mitigation and bioaccessibility of the cationic surfactant cetyltrimethylammonium bromide in a sorbent-modified biodegradation study

Biodegradation potential of cationic surfactants may be hampered by inhibition of inoculum at concentrations required to accurately measure inorganic carbon. At >0.3 mg/L cetyltrimethylammonium bromide (CTAB) negatively impacted degradation of the reference compound aniline. We used silicon dioxide (SiO₂) and illite as inorganic sorbents to mitigate toxicity of CTAB by lowering freely dissolved concentrations. In an OECD Headspace Test we tested whether 16.8 mg/L CTAB was readily biodegradable in presence of two concentrations of SiO₂ and illite. SiO₂ adsorbed 85% and 98% CTAB, resulting in concentrations of 2.5 and 0.34 mg/L, mineralized to CO₂ >60% within 16 and 23 d, respectively. With 89% and 99% sorbed to illite, 60% mineralization was reached within 9 and 23 d, respectively. However, higher sorbent concentrations increased time needed to reach >60% mineralization. Thus, desorption kinetics likely decreased bioaccessibility. It is therefore essential to determine appropriate concentrations of mitigating sorbents to render a Headspace Test based on carbon analysis suitable to determine ready biodegradability of compounds which might inhibit inoculum. This would avoid use of expensive radiolabeled compounds. However, high sorbent concentrations can reduce bioaccessibility and limit degradation kinetics, particularly for relatively toxic substances that require strong mitigation.

Enhanced Solubility and Permeability of Salicis cortex Extract by Formulating as a Microemulsion

A microemulsion system was developed and investigated as a novel oral formulation to increase the solubility and absorption of Salicis cortex extract. This extract possesses many pharmacological activities, in particular, it is beneficial for back pain and osteoarthritic and rheumatic complaints. In this work, after qualitative and quantitative characterization of the extract and the validation of an HPLC/diode array detector analytical method, solubility studies were performed to choose the best components for microemulsion formulation. The optimized microemulsion consisted of 2.5 g of triacetin, as the oil phase, 2.5 g of Tween 20 as the surfactant, 2.5 g of labrasol as the cosurfactant, and 5 g of water. The microemulsion was visually checked, characterized by light scattering techniques and morphological observations. The developed formulation appeared transparent, the droplet size was around 40 nm, and the ζ-potential result was negative. The maximum loading content of Salicis cortex extract resulted in 40 mg/mL. Furthermore, storage stability studies and an in vitro digestion assay were performed. The advantages offered by microemulsion were evaluated in vitro using artificial membranes and cells, i.e., parallel artificial membrane permeability assay and a Caco-2 model. Both studies proved that the microemulsion was successful in enhancing the permeation of extract compounds, so it could be useful to ameliorate the bioefficacy of Salicis cortex.

CO2-based amphiphilic polycarbonate micelles enable a reliable and efficient platform for tumor imaging

Biodegradable polymeric nanomaterials can be directly broken down by intracellular processes, offering a desirable way to solve toxicity issues for cancer diagnosis and treatment. Among them, aliphatic polycarbonates are approved for application in biological fields by the United States Food and Drug Administration (FDA), however, high hydrophobicity, deficient functionality and improper degradation offer significant room for improvement in these materials.

METHODS

To achieve progress in this direction, herein, we demonstrate that CO2-based amphiphilic polycarbonates (APC) with improved hydrophilicity and processability can be used as a reliable and efficient platform for tumor imaging. To better investigate their potential, we devised a convenient strategy through conjugation of APC with gadolinium (Gd).

RESULTS

The resulting polymeric micelles (APC-DTPA/Gd) exhibit excellent magnetic resonance imaging performance, simultaneously enabling real-time visualization of bioaccumulation and decomposition of polymeric micelles in vivo. Importantly, these micelles can be degraded to renally cleared products within a reasonable timescale without evidence of toxicity.

CONCLUSION

Our findings may help the development of CO2-based amphiphilic polycarbonate for cancer diagnosis and treatment, accompanied by their low-toxicity degradation pathway.

Transformative Nanomedicine of an Amphiphilic Camptothecin Prodrug for Long Circulation and High Tumor Uptake in Cancer Therapy

We report a camptothecin (CPT) prodrug that was well formulated in solution and rapidly transformed into long-circulating nanocomplexes in vivo for highly efficient drug delivery and effective cancer therapy. Specifically, using a redox-responsive disulfide linker, CPT was conjugated with an albumin-binding Evans blue (EB) derivative; the resulting amphiphilic CPT-ss-EB prodrug self-assembled into nanostructures in aqueous solution, thus conferring high solubility and stability. By binding CPT-ss-EB to endogenous albumin, the 80 nm CPT-ss-EB nanoparticles rapidly transformed into 7 nm albumin/prodrug nanocomplexes. CPT-ss-EB was efficient at intracellular delivery into cancer cells, released intact CPT in a redox-responsive manner, and exhibited cytotoxicity as potent as CPT. In mice, the albumin/CPT-ss-EB nanocomplex exhibited remarkably long blood circulation (130-fold greater than CPT) and efficient tumor accumulation (30-fold of CPT), which consequently contributed to excellent therapeutic efficacy. Overall, this strategy of transformative nanomedicine is promising for efficient drug delivery.

Phospholipid based self-nanoemulsifying self-nanosuspension (p-SNESNS) as a dual solubilization approach for development of formulation with diminished food effect: Fast/fed in vivo pharmacokinetics study in human

The novel self- nanoemulsifying self-nanosuspension (SNESNS) combines the advantages of two efficient solubilization technologies; the nanoemulsion and the nanosuspension. The aim of this study is to test the efficiency of phospholipid based self-nanoemulsifying self-nanosuspension (p-SNESNS) formulation as a powerful tool to diminish the food effect on bioavailability of lurasidone hydrochloride as BCS Class II model drug. Phospholipid was incorporated into SNESNS to increase the solubilization power of the in-situ formed nanoemulsion and facilitate the dispersion of the in-situ formed nanosized drug particles. P-SNESNS was evaluated for particle size, Polydispersity index, in vitro dissolution and transmission electron microscopy (TEM). The drug amount dissolved after water dilution of LSD p-SNESNS was ~2 folds that dissolved after dilution of non-phospholipid SNESNS. The self-nanosuspension obtained by aqueous dilution of p-SNESNS kept the cubic morphology of LSD macroparticles. The high in vitro dissolution of LSD in the non-sink dissolution media (water and Phosphate buffer pH6.8) indicated that the p-SNESNS formulation had successfully increased the drug solubility irrespective of pH of the medium. The pharmacokinetics parameters of LSD p-SNESNS in humans were the same in both the fasted and fed states and were similar to those of LSD capsules in the fed state. Our results propose that p-SNESNS could be promising to increase patient compliance and drug efficiency of BCS class II antipsychotics by diminishing the food effect on their oral absorption and preventing the necessity to administer them with food.

Final Report on the Safety Assessment of Octoxynol-1, Octoxynol-3, Octoxynol-5, Octoxynol- 6, Octoxynol-7, Octoxynol-8, Octoxynol-9, Octoxynol-10, Octoxynol-11, Octoxynol-12, Octoxynol-13, Octoxynol-16, Octoxynol-20, Octoxynol-25, Octoxynol-30, Octoxynol-33, Octoxynol-40, Octoxynol-70, Octoxynol-9 Carboxylic Acid, Octoxynol-20 Carboxylic Acid, Potassium Octoxynol-12 Phosphate, Sodium Octoxynol-2 Ethane Sulfonate, Sodium Octoxynol-2 Sulfate, Sodium Octoxynol-6 Sulfate, and Sodium Octoxynol-9 Sulfate1

Octoxynols are ethoxylated alkylphenols in which the size of the molecule is related to the number of moles of ethylene oxide used in synthesis. Reactions are performed at elevated temperature, under pressure, and in the presence of NaOH. It is possible that the synthesis may leave trace amounts of ethylene oxide, 1,4-dioxane, and unreacted C9 phenols. Octoxynols of various chain lengths as well as octoxynol salts and organic acids function in cosmetics either as surfactants—emulsifying agents, surfactants—cleansing agents, surfactant—solubilizing agents, or surfactants—hydrotropes in a wide variety of cosmetic products at concentrations ranging from 0.0008% to 25%, with most less than 5.0%. The octoxynols are chemically similar to nonoxynols, the safety of which were previously considered. Long-chain nonoxynols (9 and above) were considered safe as used, whereas short-chain nonoxynols (8 and below) were considered safe as used in rinse-off products and safe at concentrations less than 5% in leave-on formulations.

Preparation and Evaluation of a Novel Class of Amphiphilic Amines as Antitumor Agents and Nanocarriers for Bioactive Molecules

Purpose

We describe a novel class of antitumor amphiphilic amines (RCn) based on a tricyclic amine hydrophilic head and a hydrophobic linear alkyl tail of variable length.

Methods

We tested the lead compound, RC16, for cytotoxicity and mechanism of cell death in several cancer cell lines, anti tumor efficacy in mouse tumor models, and ability to encapsulate chemotherapy drugs.

Results

These compounds displayed strong cytotoxic activity against cell lines derived from both pediatric and adult cancers. The IC50 of the lead compound, RC16, for normal cells including human keratinocytes, human fibroblasts and human umbilical vein endothelial cells was tenfold higher than for tumor cells. RC16 exhibited significant antitumor effects in vivo using several human xenografts and a metastatic model of murine neuroblastoma by both intravenous and oral administration routes. The amphiphilic character of RC16 triggered a spontaneous molecular self-assembling in water with formation of micelles allowing complexation of Doxorubicin, Etoposide and Paclitaxel. These micelles significantly improved the in vitro antitumor activity of these drugs as the enhancement of their aqueous solubility also improved their biologic availability.

Conclusions

RC16 and related amphiphilic amines may be useful as a novel cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s11095-016-1999-9) contains supplementary material, which is available to authorized users.

Physicochemical determinants of linear alkylbenzene sulfonate (LAS) disposition in skin exposed to aqueous cutting fluid mixtures

Linear alkylbenzene sulfonate (LAS) is added to cutting fluid formulations to enhance the performance of metal machining operations, but this surfactant can cause contact dermatitis in workers involved in these operations. The purpose of this study was to determine how cutting fluid additives influence dermal disposition of 14C-LAS in mineral oil-or polyethylene glycol 200 (PEG)-based mixtures when topically applied to silastic membranes and porcine skin in an in vitroflow-through diffusion cell system. 14C-LAS mixtures were formulated with three commonly used cutting fluid additives; 0 or 2% triazine (TRI), 0 or 5% triethanolamine (TEA), and 0 or 5% sulfurized ricinoleic acid (SRA). LAS absorption was limited to less than a 0.5% dose and the additives in various combinations influenced the physicochemical characteristics of the dosing mixture. LAS was more likely to partition into the stratum corneum (SC) in mineral oil mixtures, and LAS absorption was significantly greater in the complete mixture. TRI enhanced LAS transport, and the presence of SRA decreased LAS critical micelle concentration (CMC) which reduced LAS monomers available for transport. TEA increased mixture viscosity, and this may have negated the apparent enhancing properties of TRI in several mixtures. In summary, physicochemical interactions in these mixtures influenced availability of LAS for absorption and distribution in skin, and could ultimately influence toxicological responses in skin.

Bioremediation of Crude Oil Contaminated Desert Soil: Effect of Biostimulation, Bioaugmentation and Bioavailability in Biopile Treatment Systems

This work was aimed at evaluating the relative merits of bioaugmentation, biostimulation and surfactant-enhanced bioavailability of a desert soil contaminated by crude oil through biopile treatment. The results show that the desert soil required bioaugmentation and biostimulation for bioremediation of crude oil. The bioaugmented biopile system led to a total petroleum hydrocarbon (TPH) reduction of 77% over 156 days while the system with polyoxyethylene (20) sorbitan monooleate (Tween 80) gave a 56% decrease in TPH. The biostimulated system with indigenous micro-organisms gave 23% reduction in TPH. The control system gave 4% TPH reduction. The addition of Tween 80 led to a respiration rate that peaked in 48 days compared to 88 days for the bioaugmented system and respiration declined rapidly due to nitrogen depletion. The residual hydrocarbon in the biopile systems studied contained polyaromatics (PAH) in quantities that may be considered as hazardous. Nitrogen was found to be a limiting nutrient in desert soil bioremediation.

The unique ligand binding features of subfamily-II iLBPs with respect to bile salts and related drugs

Intracellular lipid binding proteins (iLBPs) are a family of evolutionarily related small cytoplasmic proteins implicated in the transcellular transport of lipophilic ligands. Subfamily-II iLBPs include the liver fatty acid binding protein (L-FABP), and the ileal and the liver and ileal bile acid binding proteins (L-BABP and I-BABP). Atomic-level investigations during the past 15-20 years have delivered relevant information on bile acid binding by this protein group, revealing unique features including binding cooperativity, promiscuity, and site selectivity. Using NMR spectroscopy and other biophysical techniques, our laboratories have contributed to an understanding of the molecular determinants of some of these properties and their generality among proteins from different animal species. We focused especially on formation of heterotypic complexes, considering the mixed compositions of physiological bile acid pools. Experiments performed with synthetic bile acid derivatives showed that iLBPs could act as targets for cell-specific contrast agents and, more generally, as effective carriers of amphiphilic drugs. This review collects the major findings related to bile salt interactions with iLBPs aiming to provide keys for a deeper understanding of protein-mediated intracellular bile salt trafficking.

Comparative in vitro properties and clinical pharmacokinetics of paclitaxel following the administration of Taxol® and Paxene®

PURPOSE

Taxol contains paclitaxel formulated in Cremophor EL-P (CrEL-P) and ethanol. Paxene is similar to Taxol, except for the use of Cremophor EL (CrEL) and the addition of citric acid. Here, we investigated the physicochemical properties and clinical pharmacokinetics of the two paclitaxel formulations.

EXPERIMENTAL DESIGN

The size and modality of distribution of CrEL-P and CrEL micelles was determined by dynamic-light scattering. The effect of vehicle composition on the fraction unbound paclitaxel in vitro was determined by equilibrium dialysis. Paclitaxel pharmacokinetics were studied in 61 cancer patients receiving Taxol and 26 patients receiving Paxene. Comparative pharmacokinetics of CrEL-P and CrEL were obtained in 14 and 6 patients, respectively.

RESULTS

The size of micelles present in Taxol was slightly smaller (9 to 13%) than those present in Paxene. Surface tension and critical micellar concentration were also similar for the two formulations, with mean values of 37.0 and 38.1 mN/m and 0.0387 and 0.0307 mg/mL, respectively. The fraction unbound paclitaxel was not significantly different for Taxol and Paxene (p > 0.05). Over the tested dose range, the mean clearance of paclitaxel decreased from 45.1 to 16.9 L/h for Taxol, and from 50.7 to 16.4 L/h for Paxene (p > 0.05). Concentrations of the excipient following the administration of CrEL-P or CrEL were also similar.

CONCLUSION

The differences in formulation between Taxol and Paxene do not significantly affect micelle formation and/or quantitative aspects of the vehicle-paclitaxel interaction in vitro and in vivo.

Cardiomyopathy of Duchenne muscular dystrophy: pathogenesis and prospect of membrane sealants as a new therapeutic approach

Duchenne muscular dystrophy (DMD) is a devastating progressive disease of striated muscle deterioration. This fatal X-linked disorder results from the loss of the protein dystrophin, which in turn causes striated muscle membrane instability. Cardiac dysfunction is a growing problem in patients with DMD, but relatively little is known about the pathophysiology of the dystrophic heart. At present, there is no effective treatment for DMD and the current clinical approaches are primarily supportive in nature. This review will discuss the pathogenesis of DMD in the heart and discuss how these pathogenic processes have led to a new class of agents directed specifically at restoring membrane integrity to dystrophic myocardium. The tri-block poloxamers, specifically poloxamer 188 (P188), are able to stabilize the membranes of dystrophic myocardium in animal models and may offer a new therapeutic approach for cardiac disease in DMD.

[Effects of sub-micro emulsion composition on cellular disposition of incorporated lipophilic drug]

OBJECTIVE

To investigate the effects of sub-micro emulsion composition on cellular uptake and disposition of incorporated lipophilic drug.

METHODS

Sub-micro emulsions containing 10 % oil, 1.2 % lecithin and 2.25 % glycerol were prepared, and the fluorescent agent coumarin 6 was used as a model drug. The effects of oil types, co-surfactants and cationic lipid on uptake and elimination kinetics of 6-coumarin in HeLa cells were studied. The uptake mechanism of sub-micro emulsions was further investigated.

RESULTS

Oil type and Tweens had no influence on the cellular uptake. Modifications of surfactants with Span series increased the cellular influx, among which Span 20 with hydrophilic-lipophilic balance (HLB) value of 8.6 was the best enhancer. The intracellular drug level reached up to (46.09 ± 1.98)ng/μg protein which had significant difference with control group [(38.54 ± 0.34)ng/μg protein]. The positively charged emulsions significantly increased the uptake rate constant and elimination rate constant which were 4 times and 1.5 times of those in anionic groups, respectively. The uptake enhancement was also observed in cationic emulsions, cellular concentrations at plateau were (42.73 ± 0.84)ng/μg protein, which was about 3 times of that in anionic emulsions [(15.71 ± 0.74)ng/μg protein], when extracellular drug concentration kept at 100 ng/ml. Cationic emulsions delivered the payload mainly by direct drug transfer to contacted cells, while the negative ones depended on both drug passive diffusion and clathrin-mediated endocytosis of drug containing oil droplets which accounted for 20% of the intracellular drug.

CONCLUSION

Interfacial characteristic of sub-micro emulsions such as co-surfactants HLB as well as zeta potentials can influence lipophilic drug both in cellular uptake and elimination.

Treatment with a novel topical nanoemulsion (NB-001) speeds time to healing of recurrent cold sores

BACKGROUND

Current topical therapies for cold sores are only marginally beneficial due to poor skin penetration. We assessed the safety and efficacy of a novel topical antiviral nanoemulsion (NB-001) with high tissue bioavailability.

OBJECTIVES

The primary endpoint was the time to lesion healing.

METHODS

482 subjects with recurrent cold sores were randomized to self-initiate treatment with either vehicle or NB-001 (0.1%, 0.3% or 0.5%) at the first signs or symptoms of a cold sore episode. Lotion was applied 5 times per day, approximately 3 to 4 hours apart, for 4 days. Time to lesion healing was correlated with NB-001 bioavailability determined in human cadaver skin.

RESULTS

Subjects treated with 0.3% NB-001 showed a 1.3-day improvement in the mean time to healing compared to vehicle (P=0.006). This was consistent with human cadaver skin data indicating that the 0.3% nanoemulsion had the highest bioavailability, compared to 0.1% and 0.5% emulsions. No significant safety or dermal irritation concerns or systemic absorption were noted with any of the doses.

CONCLUSIONS

Topical NB-001 (0.3%) was well tolerated and highly efficacious in shortening the time to healing of cold sores. The improvement in time to healing was similar to that reported for oral nucleoside analogues, but without systemic exposure. Topical agents for recurrent herpes labialis (cold sores) reduce healing time by one half day, compared to oral therapies that speed healing by a day or more. A topical antiviral nanoemulsion was well tolerated and improved cold sore healing time by over a day compared to vehicle control. Nanoemulsion (NB-001) could represent a more efficacious topical treatment for recurrent cold sores.

A facile, one-step nanocarbon functionalization for biomedical applications

Despite their immense potential in biomedicine, carbon nanomaterials suffer from inefficient dispersion and biological activity in vivo. Here we utilize a single, yet multifunctional, hyaluronic acid-based biosurfactant to simultaneously disperse nanocarbons and target single-walled carbon nanotubes (SWCNTs) to CD44 receptor positive tumor cells with prompt uptake. Cellular uptake was monitored by intracellular enzyme-activated fluorescence, and localization of SWCNTs within cells was further confirmed by Raman mapping. In vivo photoacoustic, fluorescence, and positron emission tomography imaging of coated SWCNTs display high tumor targeting capability while providing long-term, fluorescence molecular imaging of targeted enzyme events. By utilizing a single biomaterial surfactant for SWCNT dispersion without additional bioconjugation, we designed a facile technique that brings nanocarbons closer to their biomedical potential.

Synthesis of amphiphilic [PEO(PCL)₂] triarm star-shaped block copolymers: a promising system for in cell delivery

The paper reports on a simple method of synthesizing [PEO(PCL)(2)] triarm star-shaped copolymers by a combination of Michael-addition type reaction and ring-opening polymerization. A Michael-addition reaction yielded a PEO end-capped by two hydroxyl groups-a [PEO(OH)(2)] macroinitiator-which was used for sequential building of PCL blocks. The macroinitiator and copolymers were analyzed by FTIR, (1)H NMR spectroscopy and SEC. The self-assembly behavior of the copolymers in aqueous media was studied by UV-Vis spectroscopy. The size and morphology of the obtained micelles were determined by TEM. None of the polymers had cytotoxic effects in vitro. Cellular uptake studies showed the accumulation of neutral red loaded micelles in the perinuclear area of human hepatocellular carcinoma cells revealing a cellular uptake associated with macropinocytosis and caveolae mediated endocytosis. The accumulation had a sustained effect over 3 days pointing at the potential application of the copolymers micelles as a drug delivery system.

Synthesis of three novel anionic gemini surfactants and comparative studies of their assemble behavior in the presence of bovine serum albumin

Three novel anionic sulfonate gemini surfactants, sodium 4,4'-(10,19-dioxo-9,11,18,20-tetraazaoctacosane-9,20-diyl) dibenzenesulfonate (Surfactant I), sodium 4,4'-(12,21-dioxo-11,13,20,22-tetraazadotriacontane-11,22-diyl) dibenzenesulfonate (Surfactant II), and sodium 4,4'-(14,23-dioxo-13,15,22,24-tetraazahezatriacontane-13,24-diyl) dibenzenesulfonate (Surfactant III), with different lengths of hydrophobic tail have been synthesized, and their assembly behavior in the presence of bovine serum albumin (BSA) has been studied using spectral methods and molecular modeling methods at physiological pH and 298 K. Critical micelle concentrations (CMCs) of the three surfactants have been determined by surface tension measurements. Despite the obvious decrease of CMC with the increase of tail length, fluorescence spectra have shown much closer CAC in the presence of BSA. Surfactant II shows the highest CAC of 3.19 × 10(-5) mol L(-1) compared with the other two. The polarity of the microenvironment in BSA-surfactant systems has been investigated using pyrene as the probe. In addition, far-UV CD spectra studied the change of the secondary structure content of BSA caused by the three surfactants. The features of the assembly behavior were discussed by three concentration regions. Surfactant II could unfold the protein much more efficiently than the other two surfactants at low concentration, but at high concentration, the change of the secondary structure and the formation of hydrophobic microenvironment show a direct relationship to the length of the hydrophobic tail with the increase of the surfactant concentration.

PEGylated liposomal doxorubicin targeted to α5β1-expressing MDA-MB-231 breast cancer cells

Targeting drugs selectively to cancer cells can potentially benefit cancer patients by avoiding side effects generally associated with several cancer therapies. One of the attractive approaches to direct the drug cargo to specific sites is to incorporate ligands at the surface of the delivery systems. Integrin α(5)β(1) is overexpressed in tumor vasculature and cancer cells, thus making it an attractive target for use in drug delivery. Our group has developed a fibronectin-mimetic peptide, PR_b, which has been shown to bind specifically to integrin α(5)β(1), thereby providing a tool to target α(5)β(1)-expressing cancer cells in vitro as well as in vivo. Our current work focuses on designing modified stealth liposomes (liposomes functionalized with polyethylene glycol, PEG) for combining the benefits associated with PEGylation, as well as imparting specific targeting properties to the liposomes. We have designed PEGylated liposomes that incorporate in their bilayer the fibronectin-mimetic peptide-amphiphile PR_b that can target several cancer cells that overexpress α(5)β(1), including the MDA-MB-231 breast cancer cells used in this study. We have encapsulated doxorubicin inside the liposomes to enhance its therapeutic potential via PEGylation as well as active targeting to the cancer cells. Our results show that PR_b-functionalized stealth liposomes were able to specifically bind to MDA-MB-231 cells, and the binding could be controlled by varying the peptide concentration. The intracellular trafficking of the doxorubicin liposomes was examined, and within minutes after delivery the majority of them were found to be in the early endosomes, whereas after a longer period of time they had accumulated in the late endosomes and lysosomes. The functionalized liposomes were found to be equally cytotoxic as the free doxorubicin, especially at higher doxorubicin concentrations, and provided higher cytotoxicity than the nontargeted and GRGDSP-functionalized stealth liposomes. Thus, the PR_b-functionalized PEGylated nanoparticles examined in this study offer a promising strategy to deliver their therapeutic payload directly to the breast cancer cells, in an efficient and specific manner.

[Blood plasma protein adsorption capacity of perfluorocarbon emulsion stabilized by proxanol 268 (in vitro and in vivo studies)]

The adsorption abilities of the perfluorocarbon emulsion stabilized by Proxanol 268 were investigated in vitro and in vivo. In vitro, the saturation point for the blood plasma proteins was nearly reached after five minutes of incubation of the emulsion with human/rabbit blood plasma and was stable for all incubation periods studied. The decrease in volume ratio (emulsion/plasma) was accompanied by the increase in the adsorptive capacity of the emulsion with maximal values at 1/10 (3.2 and 1.5 mg of proteins per 1 ml of the emulsion, for human and rabbit blood plasma, respectively) that was unchanged at lower ratios. In vivo, in rabbits, intravenously injected with the emulsion, the proteins with molecular masses of 12, 25, 32, 44, 55, 70, and 200 kDa were adsorbed by the emulsion (as in vitro) if it was used 6 hours or less before testing. More delayed testing (6 h) revealed elimination of proteins with molecular masses of 25 and 44 kDa and an additional pool of adsorpted new ones of 27, 50, and 150 kDa. Specific adsorptive capacity of the emulsion enhanced gradually after emulsion injection and reached its maximum (3.5-5 mg of proteins per 1 ml of the emulsion) after 24 hours.

Levels, temporal trends, and tissue distribution of perfluorinated surfactants in freshwater fish from Asian countries

Perfluorinated surfactants (PFSs) in Asian freshwater fish species were analyzed to investigate tissue distribution, temporal trends, extent of pollution, and level of PFS exposure through food intake. Freshwater fish species, namely carp, snakehead, and catfish, were collected in Japan, Vietnam, India, Malaysia, and Thailand, and 10 PFSs, including perfluorooctanesulfonate (PFOS) and perfluorooctanoate, were analyzed by liquid chromatography-tandem mass spectrometry. PFSs in carp in Tokyo were more concentrated in kidneys (Σ10 PFSs = 257 ± 95 ng/g wet weight [ww]) and livers (119 ± 36 ng/g ww) than in ovaries (43 ± 2 ng/g ww) and muscles (24 ± 17 ng/g ww). Concentrations of PFOS and its precursor, perfluorooctane sulfonamide, in livers of carp and in waters in Tokyo showed a dramatic decrease during the last decade, probably because of 3 M's phasing-out of the manufacture of perfluorooctanesulfonyl-fluoride-based products in 2000. In contrast, continuing contamination by long-chain perfluorocarboxylates (PFCAs) with ≥ 9 fluorinated carbons was seen in multiple media, suggesting that these compounds continue to be emitted. PFS concentrations in freshwater fish species in tropical Asian countries were generally lower than those in developed countries, such as Japan, e.g., for PFOS in muscle, Vietnam < 0.05-0.3 ng/g ww; India < 0.05-0.2 ng/g ww; Malaysia < 0.05-0.2 ng/g ww; Thailand < 0.05 ng/g ww; and Japan (Tokyo) = 5.1-22 ng/g ww. Daily intake of short-chain PFCAs with ≤ 8 fluorinated carbons from freshwater fish species in Japan was approximately one order of magnitude lower than that from drinking water, whereas daily intake of PFOS and long-chain PFCAs with ≥ 9 fluorinated carbons from freshwater fish species was comparable with or greater than that from drinking water. Because the risk posed by exposure to these compounds through intake of fish species is a matter of concern, we recommend the continued monitoring of PFS levels in Asian developing countries.

Uptake and elimination of perfluorinated phosphonic acids in the rat

The mono- and di-substituted perfluorinated phosphonic acids (mono-PFPAs and di-PFPAs) are high production volume fluorinated surfactants. Mono-PFPAs have been observed in Canadian surface waters and wastewater treatment plant (WWTP) effluent. The first observation of the di-PFPAs in the environment is reported here, with the observation of the C6/C6 and C6/C8 di-PFPAs in the National Institute for Standards and Technology (NIST) WWTP sludge standard reference material (SRM) 2781. To characterize the risk associated with human exposure to the mono-PFPAs and di-PFPAs, we determined uptake and elimination parameters in the rat. After oral gavage all of the mono-PFPA and di-PFPA congeners were observed in the blood of the dosed animals. Half-lives after intraperitoneal dosing ranged from 0.96 +/- 0.11 to 2.8 +/- 0.5 days for the mono-PFPAs and 1.8 +/- 0.1 to 9.3 +/- 1.5 days for the di-PFPAs. These half-lives are of similar magnitude to those for perfluorooctane sulfonate (PFOS, 8 to 30 days in male rats) and perfluorooctanoate (PFOA, 6 days in male rats and 1 hour in female rats). Both PFOS and PFOA have human half-lives on the order of years, and so the mono-PFPAs and di-PFPAs may also have significant lifetimes in the human body. The analysis of paired whole blood and plasma samples demonstrated that the mono-PFPAs may bind to blood cells underestimating their concentration in plasma and sera samples. The biological fate of the mono-PFPAs and di-PFPAs determined here suggest there is the potential for human exposure and that if exposure does occur, they may be long-lived in the body.

Nanostructured chitosan-surfactant matrices as polyphenols nanocapsules template with zero order release kinetics

Nanostructured membranes and films of cationic surfactant-chitosan with tannic acid as polyphenol model were obtained by phase inversion method. The membranes were investigated by Attenuated Total Reflectance Fourier Transform InfraRred, X-Ray Diffraction, Scanning Electron Microscopy and Thermogravimetry, and the films topography was analysed by Atomic Force Microscopy. The analysis reveals that the interactions at the molecular level between cationic CTAB surfactant and cationic chitosan polymer strive to weaken membrane stability, whereas, the tannic acid is favoured to cluster with CTAB and diminish the membrane thermodynamic instability. The nanocapsules formed, with dimensions in the range of 16.35-27.68 nm, are congregating in clusters having dimensions in the domain of 50-300 nm. The layers resulted from these nanostructures arrangement constitute a surfactant-chitosan matrix with tannic acid suitable for drug controlled release with zero order kinetics.

Fast-dissolving microparticles fail to show improved oral bioavailability

Oral dosage forms are the preferred means of delivering drugs for systemic absorption. However, development problems occur for drugs with poor water solubility and/or gastrointestinal permeability. It is generally believed that the in-vivo bioavailability of poorly water-soluble drugs from Class II of the Biopharmaceutics Classification System can be improved by increasing the dissolution rate. We have attempted to increase the in-vivo oral bioavailability of a model Class II drug (griseofulvin) by preparing rapidly-dissolving particles. The solvent-diffusion method was used to prepare particles with hydrophilic surfactants (Brij 76/Tween 80 surfactant blend) and in-vivo studies were conducted in rats. The griseofulvin particles produced were bipyramidal in habit with a particle size of 2.18 ± 0.12 mm; they contained crystalline drug and a relatively large proportion (12% w/w) of hydrophilic surfactant. The latter and the small particle size ensured rapid particle dispersion and dissolution in-vitro. Thus, within 30 min of the in-vitro dissolution test, the bipyramidal particles had released ∼70% of drug compared with ∼10% from the starting material (particle size 12.61 ± 1.11 μm). However, the rapid and increased drug dissolution in-vitro was not translated to rapid and enhanced absorption in-vivo, and the oral bioavailability of the model drug was found to be the same from the control and from the bipyramidal particles. The poor in-vivo performance of the bipyramidal particles showed that although the dissolution rate of a Class II drug is thought to be a good indicator of its in-vivo bioavailability, this is not always the case.

Interfacial properties and in vitro cytotoxic effects of surface-modified near infrared absorbing Au-Au(2)S nanoparticles

Near infrared (NIR) absorbing Au-Au(2)S nanoparticles were modified with surfactants of different hydrocarbon chain lengths to allow loading of anticancer drug, cisplatin. The interfacial interactions and surfactant chain length effects on drug loading, optical properties and cytotoxicity were discussed in this work. Short-chain surfactants were oriented closer to the surface normal and were adsorbed at higher densities. Surface modification also changed the optical properties of the particles. Notably, particles modified with short-chain surfactants exhibited a red shift, whereas particles modified with long-chain surfactants showed a blue shift. The in vitro cytotoxicity of drug-loaded surface-modified particles was dependent on the surfactants' chain length. Significant cytotoxicity was observed for 1 mg/ml of drug-loaded particles using surfactants with the shortest chain length. After NIR triggered drug release, the released Pt compounds were observed to be cytotoxic, while remaining nanoparticles did not exhibit any cytotoxicity. Also, the released Pt compounds upon NIR irradiation of drug-loaded particles were observed to be more toxic and had a different molecular structure from cisplatin.

Equilibrium partitioning theory to predict the sediment toxicity of the anionic surfactant C(12)-2-LAS to Corophium volutator

The study of the effect of the sorption of linear alkylbenzene sulfonates (LAS) on the bioavailability to marine benthic organisms is essential to refine the environmental risk assessment of these compounds. According to the equilibrium partitioning theory (EqP), the effect concentration in water-only exposure will be similar to the effect concentration in the sediment pore water. In this work, sorption and desorption experiments with two marine sediments were carried out using the compound C(12)-2-LAS. The effect of the sediment sorption on the toxicity of benthic organisms was studied in water-only and in sediment bioassays with the marine mud shrimp Corophium volutator. In addition, three common spiking methods were tested for its application in the toxicity tests, as well as the stability of the surfactant during the water-only and sediment-water test duration. LC50 values obtained from water-only exposure showed a good correspondence with the pore water concentrations calculated from the sorption and desorption isotherms in the spiked sediments.

Does sodium dodecyl sulfate wash out of detergent-treated bovine pericardium at cytotoxic concentrations?

BACKGROUND AND AIM OF THE STUDY

The ionic detergent sodium dodecyl sulfate (SDS) is a proposed treatment for the removal of antigenic proteins from unfixed biological scaffolds used in tissue engineering. However, questions remain about possible cytotoxic effects of SDS-treated tissues. The study aims were to: (i) develop a sensitive SDS assay for physiological solutions; (ii) measure SDS concentrations in the washing media of SDS-treated tissue; and (iii) determine cytotoxic SDS concentrations in cultured ovine vascular cells.

METHODS

An assay was developed to monitor SDS concentrations at microM levels, based on attenuated total reflectance infrared spectroscopy. Bovine pericardium was treated with SDS (1.0 to 0.01%) and washed for 96 h. The SDS concentration in the washing media was measured at 24-h intervals; data were expressed as microM/g tissue. Ovine vascular cells were cultured in DME media at 37 degrees C for 48 h in various SDS concentrations (10 to 1000 microM). The cells were then counted, and the percentage live cells expressed, based on trypan blue exclusion (n=5).

RESULTS

SDS concentrations > or =10 microM significantly reduced (p < 0.05) the total cell number, while concentrations > or =100 microM reduced (p < 0.05) the percentage live cells of ovine vascular cell cultures. SDS was present in the washing media of SDS-treated bovine pericardium. SDS leaching from bovine pericardium was found to depend on the SDS concentration used for the treatment, and diminished with time.

CONCLUSION

SDS leaches from SDS-treated bovine pericardium at concentrations that are potentially cytotoxic. An understanding of the dynamics of SDS washout, based on a sensitive SDS assay, may lead to the creation of protocols for the preparation of biological scaffolds that are free from cytotoxic leaching.

Toxicokinetics of p-tert-octylphenol in male and female Sprague-Dawley rats after intravenous, oral, or subcutaneous exposures

This study was undertaken to characterize the toxicokinetics of p-tert-octylphenol (OP), a weak estrogenic compound, in male and female rats. Male and female Sprague-Dawley rats were given a single dose of OP either by oral gavage (50, 125 or 250 mg/kg), by intravenous (iv) injection (2, 4, or 8 mg/kg), or by subcutaneous (sc) injection (125 mg/kg). In a repeated dosing experiment, rats were given OP (oral) daily (25, 50, or 125 mg/kg) for 35 d (female) or 60 d (male). Blood and tissue samples were collected and analyzed for OP content using gas chromatography with detection by mass spectrometry. Blood OP concentrations were generally higher in female than male rats following a single oral or sc administration but were similar following a single iv injection. Tissue OP concentrations were also higher in female than male rats following oral exposure, consistent with the faster metabolism of OP observed in male rat liver microsomes. After subchronic administration, blood OP concentrations were higher at the end of exposure for female (33 d) (2.26-fold, not significant) and male (57 d) (3.47-fold) rats than single dosing but there was no change in the tissue OP concentrations. Gender differences in tissue OP concentrations may contribute, in part, to gender differences in the toxicity of OP in rats. The fact that OP was found in all reproductive tissues confirms its potential for direct endocrine-like effects.

Moisturizing Lotions can Increase Transdermal Absorption of the Herbicide 2,4-Dichlorophenoxacetic Acid Across Hairless Mouse Skin

Moisturizing lotions can be an effective treatment for occupationally induced dry skin. These compounds are designed to be hygroscopic and retain water to keep the stratum corneum hydrated, while at the same time enhancing the horny layer to prevent increases in transepidermal water loss (TEWL). Skin hydration levels, however, are known to influence barrier properties. The purpose of this work was to compare skin moisture levels induced by four commercially available moisturizing lotions with their capacity as transdermal penetration enhancers using the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) as a model chemical. Further, the effect of moisturizing the skin after washing with sodium lauryl sulfate (SLS) on transdermal absorption was determined. Skin moisture levels were also measured noninvasively and were correlated to penetration enhancement. Hairless mouse skin was pretreated with commercially available moisturizing lotions either with or without SLS washing and in vitro permeability studies were performed with the herbicide 2,4-D. The data demonstrate that pretreatment with three of the four lotions tested increased the transdermal absorption of 2,4-D as evidenced by cumulative penetration or faster lag times (p < 0.05). Skin moisture levels correlated with the penetration enhancement capabilities of the lotion. Washing the skin with 5% SDS increased the transdermal absorption of 2,4-D (p < 0.05) and application of moisturizing lotions increased the absorption further. In summary moisturizing lotions may influence transdermal penetration of the skin, with the more effective moisturizers having a greater effect on 2,4-D absorption.

In vitro biotransformation of surfactants in fish. Part I: linear alkylbenzene sulfonate (C12-LAS) and alcohol ethoxylate (C13EO8)

Developing regulatory activities (e.g., REACh, [DGEE. 2003. Directorates General Enterprise and Environment. The new EU chemicals legislation REACH. DG Enterprise, Brussels, Belgium. (http://www.europa.eu.int/comm/enterprise/reach/index_en.htm)]) will require bioaccumulation to be assessed for thousands of chemicals. Further, there is increasing pressure to reduce, refine or replace animal tests. Given this scenario, there is an urgent need to evaluate the feasibility of in vitro systems to supply data useful for bioaccumulation estimation. Subcellular and cellular hepatic systems were tested to determine the biotransformation of two surfactants: C12-2-LAS (2-phenyl dodecane p-sulfonate) and an alcohol ethoxylate C13EO8 (Octaethylene glycol monotridecyl ether). The subcellular systems tested were liver homogenates and microsomes from the common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss). Cellular systems consisted of primary hepatocytes from the common carp (Cyprinus carpio) and PLHC-1 cells, hepatocarcinoma cells from the desert topminnow (Poeciliopsis lucida). All in vitro systems were exposed to radiolabeled test compounds and assayed for biotransformation using liquid scintillation and thin layer chromatographic methods. First-order kinetics were used to estimate rates of biotransformation. Bioconcentration of test materials in fish were predicted using an in vitro to in vivo metabolic rate extrapolation model linked to a mass-balance model commonly used to predict bioaccumulation in fish. Subcellular biotransformation rates for each of the surfactants were greatest with microsomes. Cellular loss rates exceeded subcellular rates, leading to lower predicted BCF values. Predicted BCFs corresponded closely to measured values in several fish species, verifying the utility of in vitro systems in refining Kow-only-based BCFs via the inclusion of biotransformation rates.

Bioaccumulation and toxicity of a cationic surfactant (DODMAC) in sediment dwelling freshwater invertebrates

Dimethyldioctadecylammonium chloride (DODMAC, CAS No. 107-64-2) is the principal active component of Di(hydrogenated tallow alkyl) dimethylammonium chloride (DHTDMAC, CAS No. 61789-80-8), a cationic surfactant formerly used principally in laundry fabric softeners. After discharge to water, DODMAC partitions strongly to sediment, therefore the assessment of the effects of DODMAC to benthic organisms is essential in any risk assessment. Chronic toxicity studies were conducted with Lumbriculus variegatus (Oligochaete), Tubifex tubifex (Oligochaete) and Caenorhabditis elegans (Nematode). NOECs were greater than 5738, 1515 and 1351 mg/kg dw, respectively, even for sub-lethal effects. Measurement of the route of uptake of DODMAC by L. variegatus demonstrated the relative importance of uptake via ingestion (86%) compared with direct contact with the sediment and via pore water (14%). The overall tendency of DODMAC to bioaccumulate, however, was low with measured accumulation factors of 0.22 and 0.78 for L. variegatus and T. tubifex, respectively.

Experimental determination of bioconcentration, biotransformation, and elimination of linear alkylbenzene sulfonates in Solea senegalensis

The bioconcentration, biotransformation, and elimination of anionic surfactants, linear alkylbenzene sulfonates (LAS), specifically 2ØC(10) and 2ØC(12) LAS, which are pure isomers from two different homologues, have been characterized in Solea senegalensis using an experimental flow-through system with environmental exposure levels. The LAS and their carboxylated metabolites, sulfophenylcarboxylic acids (SPCs), were analyzed by pressurized liquid extraction, followed by solid-phase extraction, liquid chromatography with fluorescence detection, and mass spectrometry. The bioconcentration factors obtained in the steady state were 17.2 +/- 1.2 L/kg for 2ØC(10) LAS and 386.5 +/- 31.5 L/kg for 2ØC(12) LAS. A kinetic study also was performed with 2ØC(12) LAS, and the rate constants of uptake and elimination were K(1) = 177.04 L/kg d and K(2) = 0.92/d, respectively. The formation of the intermediate degradation products was monitored during the 2ØC(10) LAS experiment, thus allowing, to our knowledge for the first time, the identification and quantification of SPCs from 5ØC(6) to 9ØC(10) in marine organisms and in the depuration water as a result of biotransformation by the organisms, diffusive elimination, and excretion. The elimination percentage of the surfactants is both time- and concentration-dependent, and this suggests the existence of a concentration limit for the surfactant in the fish below which the elimination processes are slow. Overall, LAS are not persistent bioaccumulative compounds at environmental exposure levels.

Biodistribution of intravenously administered amphiphilic β-cyclodextrin nanospheres

Amphiphilic beta-cyclodextrin (betaCDa) nanospheres (mean diameter 90-110 nm) prepared by the solvent displacement method were developed as a colloidal drug delivery system. In order to survey the fate of these nanoparticles, the amphiphilic beta-cyclodextrin was first iodinated by a two-step procedure involving iodination of the primary face followed by an acylation of the secondary face. After radiolabeling of this derivative with (125)I, nanospheres made of betaCDa/betaCDa (125)I were formulated. After a single intravenous injection of labeled nanoparticles in mice, the organ distribution was analyzed from 10 min to 6 days. A rapid clearance of (125)I-labeled betaCDa nanospheres from the blood circulation to the mononuclear phagocyte system was visualized by non-invasive planar imaging study. Radioactivity measurements in organs showed that the nanospheres mainly concentrated in the liver and the spleen where 28 and 24% of the radioactivity per gram of organ was, respectively, found 10 min after injection. At the opposite, the blood activity was low at that time and become negligible thereafter. Finally, the fact that no particular sign of toxicity is observed in injected animals should be emphasized since it is the first report on intravenous administration of betaCDa nanoparticles.

Ranking of aqueous surfactant-humectant systems based on an analysis of in vitro and in vivo skin barrier perturbation measurements

We propose that skin electrical current measurements can be used in vitro to effectively rank aqueous solutions containing surfactants and humectants (the enhancer) contacting the skin, relative to a PBS aqueous solution (the control) contacting the skin, based on their ability to perturb the skin aqueous pores. Specifically, we develop an in vitro ranking metric using the increase in the skin electrical current induced by an enhancer relative to the control. Aqueous contacting solutions containing (i) surfactants [SDS (sodium dodecyl sulfate)] and C(12)E(6) [dodecyl hexa (ethylene oxide)], (ii) humectants (glycerol and propylene glycol), and (iii) a control (PBS) were studied. Utilizing the new in vitro ranking metric, these aqueous contacting solutions were ranked as follows (from the mildest to the harshest): glycerol < propylene glycol < PBS < C(12)E(6) < SDS. In order to further develop this ranking methodology, which can potentially lead to the reduction, or elimination, of costly and time-consuming procedures, such as human and animal testing and trial-and-error screening in vivo, it was important to correlate the findings of the in vitro ranking metric with direct in vivo skin barrier measurements. For this purpose, in vivo soap chamber measurements, including transepidermal water loss, visual skin dryness, and chromameter erythema measurements, were carried out on human volunteers using the aqueous surfactant-humectant solutions described above. The results of these in vivo measurements were found to be consistent with the ranking results obtained using the in vitro ranking metric. To further explore the validity of our model and to verify the skin barrier mitigating effect of glycerol, in vivo soap chamber measurements were carried out for aqueous SDS solutions containing 10 wt% added glycerol. These in vivo measurements support our recent in vitro finding that glycerol reduces the average radius and the pore number density of the skin aqueous pores, such that SDS micelles are hindered from penetrating into the skin and inducing skin barrier perturbation.

Transport properties and aggregation phenomena of polyoxyethylene sorbitane monooleate (polysorbate 80) in pig gastrointestinal mucin and mucus

The aqueous environment in the gastrointestinal tract frequently requires solubilization of hydrophobic drug molecules in appropriate drug delivery vehicles. An effective uptake/absorption and systemic exposure of a drug molecule entails many processes, one being transport properties of the vehicles through the mucus layer. The mucus layer is a complex mixture of biological molecules. Among them, mucin is responsible of the gel properties of this layer. In this study, we have investigated the diffusion of polyoxyethylene sorbitane monooleate (polysorbate 80), a commonly used nonionic surfactant, in aqueous solution, in mucin solutions at 0.25 and 5 wt %, and in mucus. These measurements were done by using the pulsed field gradient spin echo nuclear magnetic resonance (PGSE-NMR) technique. We conclude that polysorbate 80 is a mixture of non-surface-active molecules that can diffuse freely through all the systems investigated and of surface-active molecules that form micellar structures with transport properties strongly dependent on the environment. Polysorbate 80 micelles do not interact with mucin even though their diffusion is hindered by obstruction of the large mucin molecules. On the other hand, the transport is slowed down in mucus due to interactions with other components such as lipids depots. In the last part of this study, a hydrophobic NMR probe molecule has been included in the systems to mimic a hydrophobic drug molecule. The measurements done in aqueous solution revealed that the probe molecules were transported in a closely similar way as the polysorbate 80 micelles, indicating that they were dissolved in the micellar core. The situation was more complex in mucus. The probe molecules seem to dissolve in the lipid depots at low concentrations of polysorbate 80, which slows down their transport. At increasing concentration of polysorbate 80, the diffusion of the probe molecules increases indicating a continuous dissolution of hexamethyldisilane in the core of polysorbate 80 micelles.

A comparative human health risk assessment of p-dichlorobenzene-based toilet rimblock products versus fragrance/surfactant-based alternatives

A comparison of the human health risk to consumers using one of two types of toilet rimblock products, either a p-dichlorobenzene-based rimblock or two newer fragrance/surfactant-based alternatives, was conducted. Rimblock products are designed for global use by consumers worldwide and function by releasing volatile compounds into indoor air with subsequent exposure presumed to be mainly by inhalation of indoor air. Using the THERdbASE exposure model and experimentally determined emission data, indoor air concentrations and daily intake values were determined for both types of rimblock products. Modeled exposure concentrations from a representative p-dichlorobenzene rimblock product are an order of magnitude higher than those from the alternative rimblock products due to its nearly pure composition and high sublimation rate. Lifetime exposure to p-dichlorobenzene or the subset of fragrance components with available RfD values is not expected to lead to non-cancer-based adverse health effects based on the exposure concentrations estimated using the THERdbASE model. A similar comparison of cancer-based effects was not possible as insufficient data were available for the fragrance components.

Oleic acid and docosahexaenoic acid cause an increase in the paracellular absorption of hydrophilic compounds in an experimental model of human absorptive enterocytes

Surface active compounds present in food possibly have the ability to enhance the absorption of water soluble toxic agents. Therefore, we investigated whether fatty acids such as oleic acid and docosahexaenoic acid (DHA), both commonly present in food, negatively affect the integrity of tight junctions (TJ) in the intestinal epithelium and thereby increase the absorption of poorly absorbed hydrophilic substances. Caco-2 cells, which are derived from human absorptive enterocytes, were grown on permeable filters for 20-25 days. Differentiated cell monolayers were apically exposed for 90min to mannitol in emulsions of oleic acid (5, 15 or 30mM) or DHA (5, 15 or 30mM) in an experimental medium with or without Ca(2+) and Mg(2+). Absorption of (14)C-mannitol increased and trans-epithelial electrical resistance (TEER) decreased in cell monolayers exposed to oleic acid and DHA, compared to controls. Cytotoxicity, measured as leakage of LDH, was higher in groups exposed to 30mM oleic acid and all concentrations of DHA. Morphology of the cell monolayers was studied by using fluorescence microscopy. Exposure of cell monolayers to 5mM DHA for 90min resulted in a profound alteration of the cell-cell contacts as detected by staining the cells for beta-catenin. Oleic acid (30mM) treatment also induced dissolution of the cell-cell contacts but the effect was not as pronounced as with DHA. Cell monolayers were also exposed for 180min to 250nM cadmium (Cd) in emulsions of oleic acid (5 or 30mM) or DHA (1 or 5mM), in an experimental medium with Ca(2+) and Mg(2+). Retention of Cd in Caco-2 cells was higher after exposure to 5mM oleic acid but lower after exposure to 30mM oleic acid and DHA. Absorption of Cd through the monolayers increased after DHA exposure but not after exposure to oleic acid. Our results indicate that fatty acids may compromise the integrity of the intestinal epithelium and that certain lipids in food may enhance the paracellular absorption of poorly absorbed hydrophilic substances.

Production of perfluorinated carboxylic acids (PFCAs) from the biotransformation of polyfluoroalkyl phosphate surfactants (PAPS): exploring routes of human contamination

Perfluorinated acids are detected in human blood world-wide, with increased levels observed in industrialized areas. The origin of this contamination is not well understood. A possible route of exposure, which has received little attention experimentally, is indirect exposure to perfluorinated acids through ingestion of chemicals applied to food contact paper packaging. The current investigation quantified the load of perfluorinated acids to Sprague-Dawley rats upon exposure to polyfluoroalkyl phosphate surfactants (PAPS), nonpolymeric fluorinated surfactants approved for application to food contact paper products. The animals were administered a single dose at 200 mg/kg by oral gavage of 8:2 fluorotelomer alcohol (8:2 FTOH) mono-phosphate (8:2 monoPAPS), or the corresponding di-phosphate (8:2 diPAPS), with blood taken over 15 days post-dosing to monitor uptake, biotransformation, and elimination. Upon completion of the time-course study the animals were redosed using an identical dosing procedure, with sacrifice and necropsy 24 h after the second dosing. Increased levels of perfluorooctanoic acid (PFOA), along with both 8:2 PAPS congeners, were observed in the blood of the dosed animals. In the 8:2 monoPAPS-dosed animals, 8:2 monoPAPS and PFOA blood concentrations peaked at 7900 +/- 1200 ng/g and 34 +/- 4 ng/g respectively. In the 8:2 diPAPS-dosed animals, 8:2 diPAPS peaked in concentration at 32 +/- 6 ng/g, and 8:2 monoPAPS and PFOA peaked at 900 +/- 200 ng/g and 3.8 +/- 0.3 ng/g, respectively. Several established polyfluorinated metabolites previously identified in 8:2 FTOH metabolism studies were also observed in the dosed animals. Consistent with other fluorinated contaminants, the tissue distributions showed increased levels of both PFOA and the 8:2 PAPS congeners in the liver relative to the other tissues measured. Previous investigations have found that PAPS can migrate into food from paper packaging. Here we link ingestion of PAPS with in vivo production of perfluorinated acids.

Multiphasic kinetics of myoglobin/sodium dodecyl sulfate complex formation

We have carried out a kinetic analysis of the conformational changes that myoglobin (Mb) undergoes in the presence of the anionic surfactant sodium dodecyl sulfate (SDS). The time-resolved results have been combined with steady-state circular dichroism (CD) and resonance Raman (RR) spectroscopy. Time-resolved absorption spectra indicate that SDS induces changes in the heme coordination with the formation of three different Mb species, depending on SDS concentration. The formation of the Mb/SDS complex involves three or four phases, depending on surfactant concentration. The kinetic data are analyzed assuming two modes of interaction according to whether SDS is monomeric or micellar. The two pathways are separated but interconnected through free Mb. At the lowest concentrations a six-coordinated, low-spin form dominates. Two distinct five-coordinated species are formed at higher SDS concentrations: one is a protein-free heme and the other reequilibrates slowly with the six-coordinated, low-spin form. The resulting complexes have been characterized by CD and RR. In addition, CD spectra show that the local changes in the heme environment are coupled to changes in the protein structure.

[The deleterious effect of certain surface active agents on the ocular surface]

Most ocular solutions enter the eye through the corneal epithelial barrier. In order to pass through this barrier, these hydrosoluble drugs require to be associated with a detergent agent to increase topical efficiency. Although these agents have a preservative action, it was recently demonstrated that, after short or long term use, toxic side effects on the ocular surface will occur.

Specific Determination of Linear Alkylbenzenesulfonates (LAS) in Commercial Detergents and Whole Blood by High-Performance Liquid Chromatography with Solid-Phase Extraction

This paper presents the extraction and analysis of linear alkylbenzenesulfonates (LAS) from whole blood using solid-phase extraction (SPE) together with high-performance liquid chromatography (HPLC). The sample was buffered with extraction solution and purified with Bakerbond C(18) SPE columns. The columns were washed, dried, and eluted with experimental optimized solvent systems. HPLC was performed using a Wakopak) WS AS-Aqua column (4.6 * 250-mm) and monitored at 228 nm using a UV detector. A mobile phase consisting of acetonitrile/water (60:40, v/v) and containing 1.2% (w/v) of sodium perchlorate was employed. Good separation was achieved for the five homologues of LAS (C(10) approximately C(14)) eluted at 6.85 and 13.79 min. The linearity range for this analysis was found to be from 10.0 to 100.0 ng/g and the limit of detection was 4.0-5.0 ng/g in blood for each homologue. The recovery of each homologue in blood ranged from 76 to 107%. The LAS in commercial detergents could be extracted and the homologues of C(10) approximately C(13) were detected. Blood samples of rats, which were administered a commercial detergent orally, were determined by the present method, and C(14) was used as an internal standard. The method was simple and reliable for the determination of LAS in blood samples and could be expected to apply to the forensic and clinical specimens.

Hyperlipidemia and surfactants: The liver sieve is a link

Poloxamer 407 is a ubiquitous synthetic surfactant that causes massive hyperlipidemia and atherosclerosis in the rodent. The initial step in hepatic metabolism of lipoproteins is their transfer through 100-200 nm pores (fenestrations) in the liver sinusoidal endothelial cell, prior to receptor-mediated uptake. The 'liver sieve hypothesis' emphasizes the role of these fenestrations in the regulation of lipoprotein disposition. Here we show that P407 causes dramatic defenestration of the liver sinusoidal endothelium in vivo. By 24h after intraperitoneal administration in mice, fenestrations were reduced by approximately 80% coincident with a 10-fold increase in plasma lipids. Moreover impulse-response experiments in the perfused rat liver showed that P407 prevented the passage of small chylomicrons across the liver sinusoidal endothelium. Defenestration was also induced acutely with P407 in isolated liver sinusoidal endothelial cells, indicating this is a direct effect of P407 on fenestrations. The results establish the role of the porosity of the liver sinusoidal endothelial cell as a pivotal yet relatively unrecognised mechanism for hyperlipidemia. Furthermore, the results establish an intriguing mechanism for surfactant-induced hyperlipidemia. Thus the liver sieve is a new and untapped target for the treatment and prevention of hyperlipidemia.