Electrochemical and Spectroscopic Studies Performed for Indomethacin and 1-Naphthol Incorporated in 1-Butyl-3-methyl-imidazolium Bis(2-ethylhexyl) Sulfosuccinate Vesicles to Investigate Them as a Potentially pH-Sensitive Nanocarrier.

Characterization studies of 1-butyl-3-methyl-imidazolium bis(2-ethylhexyl) sulfosuccinate vesicles at different pH values have been carried out by using liquid surface tension, transmission electron microscopy, and dynamic light scattering. The results show that there are no vesicle changes in its size and negative Z potential at pH 3, 6, and 10. Furthermore, indomethacin and 1-naphthol, both pH-dependent, electroactive, and fluorescence probes, were used to further characterize the bilayer employing electrochemical and emission techniques. The partition of indomethacin and 1-naphthol between the water and bilayer pseudophases only occurs for the neutral species and does not happen for the anionic species because the highly negative Z bilayer potential prevents incorporation due to negative repulsion. For the neutral species, the partition constant values were evaluated by square wave voltammetry and emission spectroscopy. Finally, for the indomethacin incorporated into the vesicle bilayer at pH 3, the release profile was monitored over time at pH 6. It was found that a change in the pH values causes the complete release of indomethacin after 25 min, which led us to think that the vesicles presented in this work can be used as a pH-sensitive nanocarrier for neutral pH-sensitive drugs.

PRODAN Photophysics as a Tool to Determine the Bilayer Properties of Different Unilamellar Vesicles Composed of Phospholipids.

Vesicles formed by phospholipids are promising candidates for drug delivery. It is known that the lipid composition affects properties such as the rigidity-fluidity of the membrane and that it influences the bilayer permeability, but sometimes sophisticated techniques are selected to monitor them. In this work, we study the bilayer of different unilamellar vesicles composed of different lipids (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC, and lecithin) and diverse techniques such as extruder and electrospun templates and using 6-propionyl-2-(N,N-dimethyl) aminonaphthalene (PRODAN) and its photophysics. Moreover, we were able to monitor the influence of cholesterol on the bilayers. We demonstrate that the bilayer properties can be evaluated using the emission feature of the molecular probe PRODAN. This fluorescent probe gives relevant information on the polarity and fluidity of the microenvironment for unilamellar vesicles formed by two different methods. The PRODAN emission at 434 nm suggests that the bilayer properties significantly change if DOPC or lecithin is used in the vesicle preparation especially in their fluidity. Moreover, cholesterol induces alterations in the bilayer's structural and microenvironmental properties to a greater or lesser degree in both vesicles. Thus, we propose an easy and elegant way to evaluate physicochemical properties, which is fundamental for manufacturing vesicles as a drug delivery system, simply by monitoring the molecular probe emission band centered at 434 nm, which corresponds to the PRODAN species deep inside the bilayer.

Foliar application of silicon sources and shading levels in Peltophorum dubium (Spreng.) Taub.

Depending on the intensity and ecological successional classification of plants, light availability can become an unfavorable condition for producing high-quality seedlings. We hypothesized that applying silicon sources might contribute to inducing tolerance to different shading levels for Peltophorum dubium (Spreng.) Taub. seedlings. Two independent experiments were developed: I) the application of five doses of silicon oxide (SiO2: 0.0; 1.0; 2.0; 4.0; and 6.0 g L-1); and II) the application of five doses of potassium silicate (K2SiO3: 0.0; 5.0; 10.0; 15.0; and 20.0 mL L-1 of water). Both were associated with three shading levels: 0% (direct sunlight), 30%, and 50%. In experiment I, we observed that seedlings were more responsive to shading levels and had little influence from foliar application of SiO2, with higher growth, biomass, and quality values when grown under direct sunlight (0% shading). In experiment II, the foliar application of 20.0 mL L-1 of K2SiO3 contributed to greater heights under 0% and 30% shading. Meanwhile, under 50% shading, the dose of 5.0 K2SiO3 favored the species' growth. The application of K2SiO3 favored the increase in the dry mass of the aerial part (DMAP). The highest biomass production and seedling quality occurred under 0% and 30% shading. The 50% shaded environment was most unfavorable to the growth and quality of P. dubium seedlings. Even though the seedlings were not very responsive to silicon sources, K2SiO3 provided a greater response than SiO2. High-quality seedling production is favored when the seedlings are grown under direct sunlight (0% shading).

Green AOT reverse micelles as nanoreactors for alkaline phosphatase. The hydrogen bond "dances" between water and the enzyme, the reaction product, and the reverse micelles interface.

In this work, we present an investigation of the influence of water encapsulated in 1,4-bis-2-ethylhexylsulfosuccinate/methyl laurate and 1,4-bis-2-ethylhexylsulfosuccinate/isopropyl myristate reverse micelles on the enzymatic hydrolysis of 1-naphthyl phosphate by alkaline phosphatase. Our results show that the enzyme is active in the biocompatible reverse micelles studied and that the Michaelis-Menten kinetic model is valid in all systems. We found that both micellar systems studied have a particular behavior toward pH and that the penetration of external solvents into the interfaces is crucial to understanding the effect. Methyl laurate does not disrupt the interface and is not necessary to control the pH value since alkaline phosphatase in the center of the micelles is always solvated similarly. In contrast, isopropyl myristate disrupts the interfaces so that the water and 1-naphthol molecules cannot form hydrogen bond interactions with the polar head of the surfactant. Then, when the water is at pH = 7, the 1-naphthol moves away to the interfaces inhibiting alkaline phosphatase which is not observable when the water is at pH = 10. Our study shows that the concept of pH cannot be used directly in a confined environment. In addition, our research is of great importance in the field of reactions that occur in reverse micelles, catalyzed by enzymes.

Topical systems for the controlled release of antineoplastic Drugs: Oxidized Alginate-Gelatin Hydrogel/Unilamellar vesicles.

The efficacy of chemotherapeutic procedures relies on delivering proper concentrations of anti-cancer drugs in the tumor surroundings, so as to prevent potential side effects on healthy tissues. Novel drug carrier platforms should not just be able to deliver anticancer molecules, but also allow for adjustements in the way these drugs are administered to the patients. We developed a system for delivering water-insoluble drugs, based on the use of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), or bis(2-ethylhexyl) sulfosuccinate benzyl-n-hexadecyldimethylammonium (BHD-AOT), embedded into oxidized alginate-gelatin (ADA/Gel) hydrogel, emulating a patch for topic applications. After being loaded with curcumin, cancer cells such as human colorectal adenocarcinoma (HCT116 and DLD-1) and melanoma cell lines (MEL501), and non-malignant cells such as mammary epithelial cell lines (NMuMG) and embryonal fibroblasts (NIH 3T3 or NEO cells) were analyzed for biocompatibility and cytotoxic effects. The results show that the proposed system can load comparatively higher concentrations of the drug (with respect to other nano/microcarriers in the literature), and that it can enhance the likelihood of the drug being uptaken by cancer cells instead of non-malignant cells. These assays were complemented by diffusion studies across the stratum corneum of rat skin, with the aim of determining the system's efficiency during topical application. Finally, the stability of the patch was tested after lyophilization to determine its potential pharmaceutical use. As a whole, the combined system represents a highly reliable and robust method for embedding and delivering complex insoluble chemotherapeutical molecules, and it is less invasive than other alternative methods in the literature.

Low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope: Monte Carlo treatment planning and dose measurements in a postmortem subject.

Objective.The goal of this study was to use Monte Carlo (MC) simulations and measurements to investigate the dosimetric suitability of an interventional radiology (IR) c-arm fluoroscope to deliver low-dose radiotherapy to the lungs.Approach.A previously-validated MC model of an IR fluoroscope was used to calculate the dose distributions in a COVID-19-infected patient, 20 non-infected patients of varying sizes, and a postmortem subject. Dose distributions for PA, AP/PA, 3-field and 4-field treatments irradiating 95% of the lungs to a 0.5 Gy dose were calculated. An algorithm was created to calculate skin entrance dose as a function of patient thickness for treatment planning purposes. Treatments were experimentally validated in a postmortem subject by using implanted dosimeters to capture organ doses.Main results.Mean doses to the left/right lungs for the COVID-19 CT data were 1.2/1.3 Gy, 0.8/0.9 Gy, 0.8/0.8 Gy and 0.6/0.6 Gy for the PA, AP/PA, 3-field, and 4-field configurations, respectively. Skin dose toxicity was the highest probability for the PA and lowest for the 4-field configuration. Dose to the heart slightly exceeded the ICRP tolerance; all other organ doses were below published tolerances. The AP/PA configuration provided the best fit for entrance skin dose as a function of patient thickness (R2 = 0.8). The average dose difference between simulation and measurement in the postmortem subject was 5%.Significance.An IR fluoroscope should be capable of delivering low-dose radiotherapy to the lungs with tolerable collateral dose to nearby organs.

Effect of a 2-step probiotic program on digestive health and performance of Holstein heifer calves.

Managing the composition of the bacterial communities in the digestive tract with the use of probiotics that enhance protective microflora could result in positive effects on health and performance of calves. The objective of this study was to evaluate a 2-step probiotic program (added to colostrum and milk) on the digestive health and growth of preweaning Holstein heifers. A randomized clinical trial was conducted from July to October 2020 in a calf rearing facility in Colorado. Calves were housed in pairs sharing the same treatment in 2 polyethylene hutches within a common area of 4.50 m2. A total of 232 calves were enrolled at birth and randomly allocated into 2 treatment groups [control (CTR) = 116; treatment (PB) = 116] and followed until weaning (64 ± 3 d). Treatment consisted of 2 formulations of a multistrain bacterial-based probiotic added in colostrum (PBF1) and milk (PBF2). Treatment calves received 2 g of PBF1 added to each colostrum feeding, and 1 g of PBF2 added to the milk at the morning feeding 3 times per week up to weaning. Calf weight was collected at birth, at 30 d of age, and at weaning. Serum total protein was determined at age 3 ± 1 d and a health assessment was completed 3 times per week. Statistical analyses were performed using SAS, with calf considered the experimental unit clustered by housing pair. Cox proportional hazard analysis and time to event analysis were used to compare time to the first diarrhea event and time to recovery between treatment groups. The total number of diarrhea events and culling were assessed by Poisson regression and logistic regression analysis, respectively. Linear regression was performed to evaluate differences in average daily gain by treatment group. Overall, the mean (± standard error) temperature humidity index (THI) was 75 (± 0.44) units during the study period, which resulted in continuous exposure to heat stress in the day hours. No difference between treatment groups was observed in serum total protein. The overall incidence of diarrhea was 96.6% (CTR = 99%, PB = 95%); no differences were determined in the hazard of a first diarrhea episode or in the median time to the first diarrhea event (11 d in both groups). Similarly, no differences were found in the likelihood of recovery or in the median time to recovery from diarrhea (7 d in both groups). Likewise, treatment group was not associated with the number of diarrhea events, mean (± standard error, g/d) average daily gain from birth to weaning [CTR = 562.5 (13.9); PB = 570.8 (13.5)], or with the odds of culling. The most prevalent pathogen isolated from feces was Clostridium, which tended to be more frequent in CTR calves than PB calves. In conclusion, the probiotic program did not affect the incidence of enteric disease or the growth of preweaning heifer calves.

Can Pediatric Primary Care Practices Afford Integrated Behavioral Health? A Comparison of 5 Pediatric Practices.

Licensed behavioral health providers (LBHPs) were integrated into 5 pediatric primary care practices in southeast and east Texas from October 2018 through March 2020. LBHPs Licensed behavioral health providers across the sites were 3 licensed clinical social workers (LCSW), 1 psychologist, and 1 nurse practitioner (NP). Practices provided data for 6 to 15 months. Overall, 2769 units of behavioral health services were provided to 746 children over 2243 hours. Across 4 sites, 44.3% of behavioral health patients were diagnosed with trauma disorders, 22.1% with anxiety, 19.3% with attention-deficit hyperactivity disorder, 15.1% with depression, and 10.9% with disruptive behavior disorders. Overall, the model was financially successful at 2 sites (LCSWs) and unsuccessful at 1 site (NP). The other 2 sites demonstrated potential for financial sustainability with increased behavioral health patient volume. Overall, this model is a financially viable option for pediatric primary care practices with adequate patient volumes to provide integrated behavioral health services.

Amphiphilic Ionic Liquids Capable to Formulate Organized Systems in an Aqueous Solution, Designed by a Combination of Traditional Surfactants and Commercial Drugs.

The present review describes the state of the art in the conversion of pharmaceutically active ingredients (API) in amphiphilic Ionic Liquids (ILs) as alternative drug delivery systems. In particular, we focus our attention on the compounds generated by ionic exchange and without original counterions which generate different systems in comparison with the simple mixtures. In water, these new amphiphiles show similar or even better properties as surfactants in comparison with their precursors. Cations such as 1-alkyl-3-methyl-imidazolium and anions such as dioctyl sulfosuccinate or sodium dodecyl sulfate appear as the amphiphilic components most studied. In conclusion, this work shows interesting information on several promissory compounds and they appear as an interesting challenge to extend the application of ILs in the medical field.

Monte Carlo simulations and phantom validation of low-dose radiotherapy to the lungs using an interventional radiology C-arm fluoroscope.

PURPOSE: To use MC simulations and phantom measurements to investigate the dosimetry of a kilovoltage x-ray beam from an IR fluoroscope to deliver low-dose (0.3-1.0 Gy) radiotherapy to the lungs. MATERIALS AND METHODS: PENELOPE was used to model a 125 kV, 5.94 mm Al HVL x-ray beam produced by a fluoroscope. The model was validated through depth-dose, in-plane/cross-plane profiles and absorbed dose at 2.5-, 5.1-, 10.2- and 15.2-cm depths against the measured beam in an acrylic phantom. CT images of an anthropomorphic phantom thorax/lungs were used to simulate 0.5 Gy dose distributions for PA, AP/PA, 3-field and 4-field treatments. DVHs were generated to assess the dose to the lungs and nearby organs. Gafchromic film was used to measure doses in the phantom exposed to PA and 4-field treatments, and compared to the MC simulations. RESULTS: Depth-dose and profile results were within 3.2% and 7.8% of the MC data uncertainty, respectively, while dose gamma analysis ranged from 0.7 to 1.0. Mean dose to the lungs were 1.1-, 0.8-, 0.9-, and 0.8- Gy for the PA, AP/PA, 3-field, and 4-field after isodose normalization to cover âˆ¼ 95% of each lung volume. Skin dose toxicity was highest for the PA and lowest for the 4-field, and both arrangements successfully delivered the treatment on the phantom. However, the dose distribution for the PA was highly non-uniform and produced skin doses up to 4 Gy. The dose distribution for the 4-field produced a uniform 0.6 Gy dose throughout the lungs, with a maximum dose of 0.73 Gy. The average percent difference between experimental and Monte Carlo values were -0.1% (range -3% to +4%) for the PA treatment and 0.3% (range -10.3% to +15.2%) for the 4-field treatment. CONCLUSION: A 125 kV x-ray beam from an IR fluoroscope delivered through two or more fields can deliver an effective low-dose radiotherapy treatment to the lungs. The 4-field arrangement not only provides an effective treatment, but also significant dose sparing to healthy organs, including skin, compared to the PA treatment. Use of fluoroscopy appears to be a viable alternative to megavoltage radiation therapy equipment for delivering low-dose radiotherapy to the lungs.

A simple electrochemical immunosensor for sensitive detection of transgenic soybean protein CP4-EPSPS in seeds.

Soybean is the most produced crop in Argentina, and 99 % corresponds to genetically modified soybean. One of the main produced varieties is Roundup Ready® soybean (RR), which was modified to express the enzyme CP4 5-enolpyruvylshikimate 3-phosphate synthase (CP4 EPSPS), which confers resistance to glyphosate, the main herbicide worldwide used. The possible impact of genetically modified organisms (GMO) has generated public concerns, thus increasing interest in the development of GMOs detection devices. In this work, an electrochemical immunosensor for CP4 EPSPS detection in soybean seeds was obtained, by using a gold electrode modified with an anti-CP4 EPSPS polyclonal antibody produced in our laboratory. The presented immunosensor resulted in a simple, low-cost, fast, and reproducible device. Also, labeling and/or signal amplification system was not necessary, since the sensor showed high sensibility with a low detection limit (lower at 0,038 % RR soybean, 38 ng mL-1 CP4 EPSPS).

Trends in maternal mortality in India over two decades in nationally representative surveys.

OBJECTIVE: To assess national and regional trends and causes-specific distribution of maternal mortality in India. DESIGN: Nationally representative cross-sectional surveys. SETTING: All of India from 1997 to 2020. SAMPLE: About 10 000 maternal deaths among 4.3 million live births over two decades. METHODS: We analysed trends in the maternal mortality ratio (MMR) from 1997 through 2020, estimated absolute maternal deaths and examined the causes of maternal death using nationally representative data sources. We partitioned female deaths (aged 15-49 years) and live birth totals, based on the 2001-2014 Million Death Study to United Nations (UN) demographic totals for the country. MAIN OUTCOME MEASURES: Maternal mortality burden and distribution of causes. RESULTS: The MMR declined in India by about 70% from 398/100 000 live births (95% CI 378-417) in 1997-98 to 99/100 000 (90-108) in 2020. About 1.30 million (95% CI 1.26-1.35 million) maternal deaths occurred between 1997 and 2020, with about 23 800 (95% CI 21 700-26 000) in 2020, with most occurring in poorer states (63%) and among women aged 20-29 years (58%). The MMRs for Assam (215), Uttar Pradesh/Uttarakhand (192) and Madhya Pradesh/Chhattisgarh (170) were highest, surpassing India's 2016-2018 estimate of 113 (95% CI 103-123). After adjustment for education and other variables, the risks of maternal death were highest in rural and tribal areas of north-eastern and northern states. The leading causes of maternal death were obstetric haemorrhage (47%; higher in poorer states), pregnancy-related infection (12%) and hypertensive disorders of pregnancy (7%). CONCLUSIONS: India could achieve the UN 2030 MMR goals if the average rate of reduction is maintained. However, without further intervention, the poorer states will not. TWEETABLE ABSTRACT: We estimated that 1.3 million Indian women died from maternal causes over the last two decades. Although maternal mortality rates have fallen by 70% overall, the poorer states lag behind.

Deciphering Solvation Effects in Aqueous Binary Mixtures by Fluorescence Behavior of 4-Aminophthalimide: The Comparison Between Ionic Liquids and Alcohols as Cosolvents.

Ionic liquids (ILs) have received attention for many years due to them being very promising as green solvent substitutes, but they are not fully understood, especially their behavior dissolved in other solvents, for example, water. Thus, the goal of this contribution is to show insight into the different IL-water mixtures interaction. In this way, two protic ILs (PILs), ethylammonium nitrate (EAN) and 1-methylimidazolium acetate (MIA), mixed with water were investigated. To study the PILs-water interaction, the unique spectroscopical behavior in water of the molecular probe 4-aminophthalimide (4-AP) was used. 4-AP emission spectra show hypsochromic shifting by changing the excitation wavelength and, using time-resolved spectroscopy, can be detected by a blue shifting with time. Also, the water mixture of an aprotic IL, 1-methyl-3-butylimidazolium tetrafluoroborate (bmimBF4), and three alcohols, methanol (MeOH), 2-propanol (2-PrOH), and t-butanol (t-BOH), were investigated for comparison. Our results show that the water-ILs interaction is dominated by the size of the IL components, in particular, the cation size. Thus, in MIA-water and bmimBF4-water mixtures, 4-AP is mostly solvated by the IL, even at a low IL molar fraction, as in the t-BOH-water mixture. This finding is especially interesting when ILs-water mixtures are used as a solvent in an organic reaction, where it may call attention to water probably not being the solvent that is interacting with the reactants.

How the external solvent in biocompatible reverse micelles can improve the alkaline phosphatase behavior.

In the last decade, the nature of the nonpolar solvents that can be part of reverse micelles (RMs) has been the topic of several investigations to improve their applications. In this sense, the hydrolysis of 1-naphthyl phosphate catalyzed by the enzyme alkaline phosphatase (AP) was used as a probe to investigate the effect of the change of the external solvent on RMs formulated with the anionic surfactant sodium diethylhexyl sulfosuccinate (AOT). As external nonpolar solvents, two biocompatible lipophilic esters, isopropyl myristate and methyl laurate, and the traditional nonpolar solvents, n-heptane and benzene, were used. The results were compared among the RMs investigated and with the reaction in homogeneous media. Thus, the effect of the nanoconfinement as well as the impact of the replacement of a conventional external nonpolar solvent by biocompatible solvents were analyzed. The results indicate that the catalytic efficiency in the AOT RMs is larger than that in homogeneous media, denoting a different hydration level over the AP enzyme, which is directly related to the different degrees of nonpolar solvent penetration to the RM interface. Our findings demonstrated that toxic solvents such as n-heptane and benzene can be replaced by nontoxic ones (isopropyl myristate or methyl laurate) in AOT RMs without affecting the performance of micellar systems as nanoreactors, making them a green and promising alternative toward efficient and sustainable chemistry.

Biocompatible Solvents and Ionic Liquid-Based Surfactants as Sustainable Components to Formulate Environmentally Friendly Organized Systems.

In this review, we deal with the formation and application of biocompatible water-in-oil microemulsions commonly known as reverse micelles (RMs). These RMs are extremely important to facilitate the dissolution of hydrophilic and hydrophobic compounds for biocompatibility in applications in drug delivery, food science, and nanomedicine. The combination of two wisely chosen types of compounds such as biocompatible non-polar solvents and ionic liquids (ILs) with amphiphilic character (surface-active ionic liquids, SAILs) can be used to generate organized systems that perfectly align with the Green Chemistry concepts. Thus, we describe the current state of SAILs (protic and aprotic) to prepare RMs using non-polar but safe solvents such as esters derived from fatty acids, among others. Moreover, the use of the biocompatible solvents as the external phase in RMs and microemulsions/nanoemulsions with the other commonly used biocompatible surfactants is detailed showing the diversity of preparations and important applications. As shown by multiple examples, the properties of the RMs can be modified by changes in the type of surfactant and/or external solvents but a key fact to note is that all these modifications generate novel systems with dissimilar properties. These interesting properties cannot be anticipated or extrapolated, and deep analysis is always required. Finally, the works presented provide valuable information about the use of biocompatible RMs, making them a green and promising alternative toward efficient and sustainable chemistry.

Extract from Arrabidaea chica (Fridericia chica) leaves show preventive action for the mitigation of doxorubicin-induced cardiotoxicity / [Extrato das folhas de Arrabidaea chica (Fridericia chica) mostrou potencial ação no combate à cardiotoxicidade induzida pela doxorrubicina]

A doxorrubicina (dox) é um medicamento antineoplásico que induz cardiotoxicidade por estresse oxidativo. Os flavonoides são antioxidantes extraídos de plantas como Camellia sinensis e Arrabidaea chica (Fridericia chica). Esta pesquisa objetivou avaliar efeitos protetores do extrato de A. chica (AC), comparado ao de C. sinensis (CS), frente ao estresse oxidativo induzido pela dox, no coração. Cardiomiócitos e células neoplásicas MDA-MB 231 foram incubados com AC e CS. Depois, adicionou-se dox e avaliaram-se taxas de viabilidade e morte celular. A citometria de fluxo para o ensaio de iodeto de propídeo (IP) em cardiomiócitos mostrou as seguintes taxas de morte celular: controle 53%; dox 78% (maior que controle, P=0,015); AC_12,5µg/mL + dox 65% (menor que dox, P=0,031); AC_25µg/mL + dox 62% (menor que dox, P=0,028); AC_50µg/mL + dox 63% (menor que dox, P=0,030); CS_12,5µg/mL + dox 71% (menor que dox, P=0,040); CS_25µg/ml + dox 69% (menor que dox, P=0,037); CS_50µg/mL + dox 74% (menor que dox, P=0,044). Resultados das células MDA-MB 231 mostraram que nenhum extrato interferiu na atividade antitumoral da dox. Os dados de IP foram corroborados pelos de MTT. Este estudo reporta promissora utilização de A. chica na prevenção da cardiotoxicidade induzida pela dox.(AU)

Is it Necessary for the Use of Fluorinated Compounds to Formulate Reverse Micelles in a Supercritical Fluid? Searching the Best Cosurfactant to Create "Green" AOT Reverse Micelle Media.

Herein, we report the effect of employing two different alcohols, such as n-pentanol and 2,2,3,3,4,4,5,5-octafluoro pentanol (from now on F-pentanol), into 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs), to determine the interfacial activity and establish the best candidate to act as a cosurfactant in supercritical RMs. Dynamic light scattering (DLS), Fourier transform infrared (FT-IR), and fluorescence emission spectroscopy allowed us to determine and understand the behavior of alkanols in RMs. As a result, we found interesting displacements of alkanol molecules within the RMs, suggesting that the electrostatic interaction between SO3- and Na+ weakens because of new interactions of n-pentanol with SO3- through H-bonds, changing the curvature of the micellar interface. According to FT-IR and DLS studies, F-pentanol forms a RM polar core interacting through intermolecular H-bonds, suggesting no perturbations of the AOT RM interface. Hence, n-pentanol was selected as a cosurfactant to form supercritical RMs, which is confirmed by red edge excitation shift studies, using C343 as a molecular probe. Herein, we were able to create RMs under supercritical conditions without the presence of modified surfactants, fluorinated or multitailed compounds, which, to the best of our knowledge, was not shown before.

Influence of the AOT Counterion Chemical Structure on the Generation of Organized Systems.

The impact of the imidazolium counterion structure on the organized systems formed by the surfactant 1,4-bis-2-ethylhexylsulfosuccinate, AOT, both in aqueous solutions and in nonpolar solvents is investigated. With this in mind, we investigated if the ionic liquid-like (IL-like) surfactant 1-ethyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, emim-AOT, forms direct micelles or vesicles in water. Dynamic light scattering, zeta potential, conductivity, fluorescence spectroscopy, and UV-visible spectroscopy measurements were performed to characterize the organized systems in aqueous solutions. We also studied the self-aggregation of emim-AOT, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, bmim-AOT, and of 1-hexyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate, hmim-AOT, in nonpolar solvents. The results obtained showed that the IL-like surfactant emim-AOT forms direct micelles in water, as sodium 1,4-bis-2-ethylhexylsulfosuccinate (Na-AOT) does. However, emim-AOT aggregates are larger, have a lower surface charge, are more stable, and have a more polar and less fluid micellar interface than Na-AOT micelles. It was also observed that emim-AOT and hmim-AOT form reverse micelles in nonpolar solvents. The size of the imidazolium cations dramatically influences the size of the reverse micelles and their ability to solubilize water.

Water-soluble gold nanoparticles: recyclable catalysts for the reduction of aromatic nitro compounds in water.

A structure/catalytic activity study of water-soluble gold nanoparticles, stabilized by zwitterionic ligands derived from imidazolium salts, in the reduction of aromatic nitro compounds in pure water at different temperature, as well as their recyclability, was performed. Our studies indicate that the nanoparticles synthesized by an easy, fast and reproducible process, need a short characteristic induction time to restructure the surfaces and make them active. The differences observed in the catalytic activity of the nanoparticles, determined by using the typical Langmuir-Hinshelwood model, are strongly based on the degree of coverage and spatial arrangement of the imidazolium salts on them. Finally, we demonstrate that gold nanoparticles stabilized by non-traditional ligands can be an excellent choice for nitro compound degradation.

Catanionic nanocarriers as a potential vehicle for insulin delivery.

Diabetes is a disease that affects millions of people in the World, constituting a global problem. Patients are administered insulin subcutaneous injections, resulting in high costs and frequent infections in the injection site. A possible solution to this problem may be the use of nanotechnology. Nanotransporters can act as specific release systems able to overcome the current limitations to drug delivery. Liposomes and vesicles can deliver drugs directly and efficiently to the site of action, decreasing toxicity and adverse effects. In previous studies, we demonstrated the biocompatibility and safety of catanionic benzyl n-hexadecyldimethylammonium 1,4 -bis-2-ethylhexylsulfosuccinate (BHD-AOT) vesicles using both in vitro and in vivo tests. Thus, the aims of this work were to evaluate the ability of the BHD-AOT vesicles to encapsulate insulin; to analyze the structural properties and stability of the system, vesicle-Insulin (VIn), at different pH conditions; and to study the ability of VIn to decrease the glycemia in miceby different administration routes. Our results showed that 2 and 5 mg mL-1 of vesicles were able to encapsulate about 55 % and 73 % of insulin, respectively. The system VIn showed a significant increase in size from 120 to 350 nm, changes in the surface zeta potential value, and high stability to different pH conditions. A significant decrease of the glycemia after VIn administration was demonstrated in in vivo assays, including the oral route. Our results reveal that BHD-AOT vesicles may be an appropriate system to encapsulate and protect insulin, and may be a potential system to be administrated in different ways as an alternative strategy to conventional therapy.