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1.
Eur J Pharm Sci ; 166: 105985, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34455087

RESUMO

Non-ideal behaviour of mixed ions is disclosed in skin absorption experiments of mixed halide anions in excised pig skin. Comparison of skin absorption of pure and mixed ions shows enhanced penetration of chaotropic ions from mixed solutions. An experimental design and statistical analysis using a Scheffé {3,2} simplex-lattice allows investigating the full ternary diagram of anion mixtures of fluoride, bromide and iodide. Synergism in mixed absorption is observed for chaotropic bromide and iodide anions. A refined analysis highlighting specific interactions is made by considering the ratio of the absorbed amount to the ion activity instead of the directly measured absorbed amount. Statistical analysis discards non-significant effects and discloses specific interactions. Such interactions between bromide and iodide cause an absorption enhancement of their partner by a factor of 2-3 with respect to the case of ideal mixing. It is proposed that enhanced absorption from mixed solution involves the formation of neutral complex species of mixed bromide and iodide with endogenous magnesium or calcium inside stratum corneum.


Assuntos
Absorção Cutânea , Água , Animais , Ânions/metabolismo , Fluoretos/metabolismo , Pele/metabolismo , Soluções , Suínos , Água/metabolismo
2.
Int J Cosmet Sci ; 43(4): 432-445, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33964042

RESUMO

OBJECTIVE: Pickering emulsions are increasingly used in the pharmaceutical and cosmetic fields, especially for topical applications, since these systems require solid particles as emulsifiers instead of surfactants which are known to cause skin irritation. The solid inorganic nanoparticles (TiO2 and ZnO) used as UV filters in sunscreen formulations may also stabilize emulsion droplets, so that the utility of surfactants may be questioned. Surfactant-free sunscreen emulsions solely stabilized by such nanoparticles (NPs) have been studied. METHODS: The ability of these NPs to stabilize o/w emulsions containing a 'model' oil phase, the C12 -C15 alkylbenzoate, has been assessed. ZnO and hydrophilic silica-coated TiO2 NPs widely used in sunscreen products were used together with their mixtures. The emulsification efficiency, the control of droplet size and the stability of o/w Pickering emulsions solely stabilized by NPs were investigated. A ZnO/TiO2 NPs mixture characterized by a theoretical SPF of 45 was finally used as unique emulsifiers to develop a surfactant-free sunscreen emulsion. RESULTS: Stable Pickering emulsions containing 10 up to 60 wt% of C12 -C15 alkyl benzoate were formulated with 2 wt% ZnO in the aqueous phase. The droplet size was controlled by the solid NPs content with respect to oil and the emulsification process. Hydrophilic TiO2 NPs did not allow the stabilization of emulsions. The substitution of TiO2 for ZnO up to 60-70 wt% in a 20/80 o/w emulsion was successfully performed. Finally, a ZnO/TiO2 NP mixture was tested as unique emulsifier system for the formulation of a sunscreen cream. Despite a lower viscosity, the obtained Pickering emulsion was stable and exhibited a photoprotective effect similar to the corresponding surfactant-based sunscreen cream with an in vitro SPF of about 45. CONCLUSION: Surfactant-free Pickering emulsions can be stabilized by the UV-filter nanoparticles for the manufacture of sunscreen products.

3.
Drug Deliv Transl Res ; 11(2): 675-691, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33738676

RESUMO

This study explored the design of supersaturable self-microemulsifying drug delivery systems (S-SMEDDS) to address poor solubility and oral bioavailability of a novel benzimidazole derivative anticancer drug (BI). Firstly, self-microemulsifying drug delivery systems SMEDDS made of Miglyol® 812, Kolliphor® RH40, Transcutol® HP, and ethanol were prepared and loaded with the BI drug. Upon dispersion, the systems formed neutrally charged droplets of around 20 nm. However, drug precipitation was observed following incubation with simulated gastric fluid (pH 1.2). Aiming at reducing this precipitation and enhancing drug payload, supersaturable systems were then prepared by adding 1% hydroxypropyl cellulose as precipitation inhibitor. Supersaturable systems maintained a higher amount of drug in a supersaturated state in gastric medium compared with conventional formulations and were stable in simulated intestinal medium (pH 6.8). In vitro cell studies using Caco-2 cell line showed that these formulations reduced in a transient manner the transepithelial electrical resistance of the monolayers without toxicity. Accordingly, confocal images revealed that the systems accumulated at tight junctions after a 2 h exposure. In vivo pharmacokinetic studies carried out following oral administration of BI-loaded S-SMEDDS, SMEDDS, and free drug to healthy mice showed that supersaturable systems promoted drug absorption compared with the other formulations. Overall, these data highlight the potential of using the supersaturable approach as an alternative to conventional SMEDDS for improving oral systemic absorption of lipophilic drugs.

4.
Int J Pharm ; 584: 119414, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32438040

RESUMO

Antibiotics are well-known disruptive elements of the intestinal microbiota and antibiotic-associated diarrhea appeared as the most common complication related with post-antibiotic dysbiosis. Lactobacillus rhamnosus GG (LGG) strain is very effective in preventing antibiotic-associated diarrhea in children and adults. However, as any probiotics, it is concerned by the loss of viability during storage and gastrointestinal transit. The aim of this study was to develop an encapsulation system suitable for the specific colonic delivery of LGG strain after oral administration. For this purpose, spray-dried Eudragit® S100 microparticles encapsulating LGG bacteria were developed by using an aqueous based spray-drying approach, avoiding the use of organic solvents. Carbohydrates were added to the formulation since they are widely used as protective agents of bacteria against the harmful effect of dehydration stress. Here, both Surface Enhanced Raman Scattering (SERS) and conventional plate count methods showed that carbohydrates increased the survival ratio of bacteria after spray-drying from 3 to more than 50%. Moreover, these protective agents ensured low residual moisture content thus providing great stability of the cells in the spray-dried powder during storage. Significant improvement of the cell viability in simulated gastro intestinal fluid (SGIF) was observed for encapsulated cells as compared with free LGG bacteria for which no viable cell was detectable after 1 h incubation in gastric fluid only. As a consequence, 4.5 × 107 CFU/g of encapsulated LGG were found viable after incubation of microparticles 1 h in Simulated Gastric Fluid followed by 6 h in Simulated Intestinal Fluid, corresponding to less than 3 log reduction of viable cells during the 7 h incubation in Simulated Gastro Intestinal Fluid. These results attested that the developed encapsulation system is suitable for its use as a bacteria carrier for specific colonic delivery.


Assuntos
Dessecação/métodos , Lactobacillus rhamnosus , Microesferas , Probióticos/administração & dosagem , Tecnologia Farmacêutica/métodos , Administração Oral , Carboidratos/química , Colo , Contagem de Colônia Microbiana , Liberação Controlada de Fármacos , Concentração de Íons de Hidrogênio , Viabilidade Microbiana , Ácidos Polimetacrílicos/química , Análise Espectral Raman
5.
Bioorg Chem ; 89: 103009, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31158579

RESUMO

A new series of 3-hydroxyflavones (1-46) were synthesized according to the Claisen-Schmidt followed by Algar-Flynn-Oyamada reactions (AFO) in one step. The synthesized flavonoids were characterized by 1H NMR, 13C NMR and DCI-HRMS. All the synthesized compounds were tested in vitro for their 15-lipoxygenase inhibitory and cytotoxic activity against the human cell lines HCT-116 (Human colon carcinoma), IGROV-1 and OVCAR-3 (human ovarian carcinoma). It has been found that the derivatives 25, 37 and 45 were the most actives against HCT-116 (IC50 = 8.0, 9.0 and 9.0 µM, respectively) and against IGROV-1 (IC50 = 2.4, 5.0 and 6.0 µM, respectively). The derivatives 14 and 21 exhibited the higher anti-inflammatory activity at 100 µM with PI values of 76.50 and 72.70%, respectively. Molecule description was performed with DFT calculations, the drug likeness and bioactivity scores. The results exhibted that some compounds are in linear correlation with Lipinski's rule of five showing good drug likeness and bioactivity score for drug targets.


Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Antineoplásicos/farmacologia , Araquidonato 15-Lipoxigenase/metabolismo , Flavonoides/farmacologia , Inibidores de Lipoxigenase/farmacologia , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Teoria da Densidade Funcional , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Flavonoides/síntese química , Flavonoides/química , Células HCT116 , Humanos , Inibidores de Lipoxigenase/síntese química , Inibidores de Lipoxigenase/química , Estrutura Molecular , Relação Estrutura-Atividade
6.
Anal Bioanal Chem ; 411(21): 5563-5576, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31209547

RESUMO

The Surface-enhanced Raman spectroscopy (SERS) method based on gold nanoparticles as SERS substrate was investigated for the label-free detection and quantification of probiotic bacteria that are widely used in various pharmaceutical formulations. Indeed, the development of a simple and fast SERS method dedicated to the quantification of bacteria should be very useful for the characterization of such formulations in a more convenient way than the usually performed tedious and time-consuming conventional counting method. For this purpose, uncoated near-spherical gold nanoparticles were developed at room temperature by acidic treatment of star-like gold nanoparticle precursors. In this study, we first investigated the influence of acidic treatment conditions on both the nanoparticle physicochemical properties and SERS efficiency using Rhodamine 6G (R6G) as "model" analyte. Results highlighted that an effective R6G Raman signal enhancement was obtained by promoting chemical effect through R6G-anion interactions and by obtaining a suitable aggregation state of the nanoparticles. Depending on the nanoparticle synthesis conditions, R6G SERS signals were up to 102-103-fold greater than those obtained with star-like gold nanoparticles. The synthesized spherical gold nanoparticles were then successfully applied for the detection and quantification of Lactobacillus rhamnosus GG (LGG). In that case, the signal enhancement was especially due to the combination of anion-induced chemical enhancement and nanoparticle aggregation on LGG cell wall consecutive to non-specific interactions. Both the simplicity and speed of the procedure, achieved under 30 min, including nanoparticle synthesis, sample preparation, and acquisition of SERS spectra, appeared as very relevant for the characterization of pharmaceutical formulations incorporating probiotics. Graphical abstract.


Assuntos
Ouro/química , Lactobacillus rhamnosus/isolamento & purificação , Nanopartículas Metálicas/química , Análise Espectral Raman/métodos , Probióticos , Rodaminas/química , Espectrofotometria Ultravioleta
7.
Front Microbiol ; 10: 829, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31057527

RESUMO

Besides their established antioxidant activity, many phenolic compounds may exhibit significant antibacterial activity. Here, the effect of a large dataset of 35 polyphenols on the growth of 6 foodborne pathogenic or food-spoiling bacterial strains, three Gram-positive ones (Staphylococcus aureus, Bacillus subtilis, and Listeria monocytogenes) and three Gram-negative ones (Escherichia coli, Pseudomonas aeruginosa, and Salmonella Enteritidis), have been characterized. As expected, the effects of phenolic compounds were highly heterogeneous ranging from bacterial growth stimulation to antibacterial activity and depended on bacterial strains. The effect on bacterial growth of each of the polyphenols was expressed as relative Bacterial Load Difference (BLD) between a culture with and without (control) polyphenols at a 1 g L-1 concentration after 24 h incubation at 37°C. Reliable Quantitative Structure-Activity Relationship (QSAR) models were developed (regardless of polyphenol class or the mechanism of action involved) to predict BLD for E. coli, S. Enteritidis, S. aureus, and B. subtilis, unlike for L. monocytogenes and P. aeruginosa. L. monocytogenes was generally sensitive to polyphenols whereas P. aeruginosa was not. No satisfactory models predicting the BLD of P. aeruginosa and L. monocytogenes were obtained due to their specific and quite constant behavior toward polyphenols. The main descriptors involved in reliable QSAR models were the lipophilicity and the electronic and charge properties of the polyphenols. The models developed for the two Gram-negative bacteria (E. coli, S. Enteritidis) were comparable suggesting similar mechanisms of toxic action. This was not clearly observed for the two Gram-positive bacteria (S. aureus and B. subtilis). Interestingly, a preliminary evaluation by Microbial Adhesion To Solvents (MATS) measurements of surface properties of the two Gram-negative bacteria for which QSAR models were based on similar physico-chemical descriptors, revealed that MATS results were also quite similar. Moreover, the MATS results of the two Gram-positive bacterial strains S. aureus and B. subtilis for which QSARs were not based on similar physico-chemical descriptors also strongly differed. These observations suggest that the antibacterial activity of most of polyphenols likely depends on interactions between polyphenols and bacterial cells surface, although the surface properties of the bacterial strains should be further investigated with other techniques than MATS.

8.
Carbohydr Polym ; 150: 159-65, 2016 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-27312625

RESUMO

Low methoxyl pectin is known to gel with divalent cations (e.g. Ca(2+), Zn(2+)). In this study, a new way of pectin gelation in the presence of an active pharmaceutical ingredient, chlorhexidine (CX), was highlighted. Thus chlorhexidine interactions with pectin were investigated and compared with the well-known pectin/Ca(2+) binding model. Gelation mechanisms were studied by several physico-chemical methods such as zeta potential, viscosity, size measurements and binding isotherm was determined by Proton Nuclear Magnetic Resonance Spectroscopy ((1)H NMR). The binding process exhibited similar first two steps for both divalent ions: a stoichiometric monocomplexation of the polymer followed by a dimerization step. However, stronger interactions were observed between pectin and chlorhexidine. Moreover, the dimerization step occurred under stoichiometric conditions with chlorhexidine whereas non-stoichiometric conditions were involved with calcium ions. In the case of chlorhexidine, an additional intermolecular binding occurred in a third step.


Assuntos
Fenômenos Químicos , Clorexidina/química , Pectinas/química , Cálcio/química , Géis , Soluções , Viscosidade
10.
Anal Bioanal Chem ; 408(17): 4669-81, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27098933

RESUMO

In a stricter legislative context, greener detergent formulations are developed. In this way, synthetic surfactants are frequently replaced by bio-sourced surfactants and/or used at lower concentrations in combination with enzymes. In this paper, a LC-MS/MS method was developed for the identification and quantification of enzymes in laundry detergents. Prior to the LC-MS/MS analyses, a specific sample preparation protocol was developed due to matrix complexity (high surfactant percentages). Then for each enzyme family mainly used in detergent formulations (protease, amylase, cellulase, and lipase), specific peptides were identified on a high resolution platform. A LC-MS/MS method was then developed in selected reaction monitoring (SRM) MS mode for the light and corresponding heavy peptides. The method was linear on the peptide concentration ranges 25-1000 ng/mL for protease, lipase, and cellulase; 50-1000 ng/mL for amylase; and 5-1000 ng/mL for cellulase in both water and laundry detergent matrices. The application of the developed analytical strategy to real commercial laundry detergents enabled enzyme identification and absolute quantification. For the first time, identification and absolute quantification of enzymes in laundry detergent was realized by LC-MS/MS in a single run. Graphical Abstract Identification and quantification of enzymes by LC-MS/MS.


Assuntos
Cromatografia Líquida/métodos , Detergentes/química , Enzimas/análise , Lavanderia , Espectrometria de Massas em Tandem/métodos , Sequência de Aminoácidos , Limite de Detecção , Reprodutibilidade dos Testes , Extração em Fase Sólida
11.
Rapid Commun Mass Spectrom ; 30(9): 1108-14, 2016 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-27060838

RESUMO

RATIONALE: To develop more eco-friendly laundry detergents, renewable surfactants synthesized from vegetal sources are increasingly being used. In a more stringent regulation context, the determination of bio-sourced surfactant origin thus appears essential to assess the claims of detergent manufacturers. Radiocarbon determination, the standard method for the analysis of bio-sourced materials, is an expensive technique, so there is a need for a cheaper method. METHODS: Here, the use of an elemental analyzer linked to isotope-ratio mass spectrometry (EA/IRMS) is evaluated as an alternative approach to the official method. The δ(18) O, δ(13) C and δ(2) H isotope-ratio values were determined to investigate the bio-sourced origin of surfactant raw materials and mixtures. RESULTS: A sample library of 26 commercial surfactants representative of detergent raw materials was first analyzed by EA/IRMS. The δ(18) O, δ(13) C and δ(2) H values allowed discrimination of synthetic and bio-sourced surfactants. Moreover, in this latter group, C4 plant-derived surfactants were distinguished by their δ(13) C values. Binary and ternary mixtures made of synthetic and bio-sourced surfactants were also analyzed and indicated a linear relationship between mixture isotope-ratio values and surfactant proportions. CONCLUSIONS: IRMS represents a viable alternative to radiocarbon determination for the evaluation of surfactant bio-sourced origin. It is a faster and cheaper technique, allowing discrimination of petroleum- and biomass-derived surfactants and identification of their carbon sources (C4 or C3 plants).

12.
Anal Chim Acta ; 915: 36-48, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-26995638

RESUMO

This paper presents the analysis of surfactants in complex mixtures using Raman spectroscopy combined with signal extraction (SE) methods. Surfactants are the most important component in laundry detergents. Both their identification and quantification are required for quality control and regulation purposes. Several synthetic mixtures of four surfactants contained in an Ecolabel laundry detergent were prepared and analyzed by Raman spectroscopy. SE methods, Independent Component Analysis and Multivariate Curve Resolution, were then applied to spectral data for surfactant identification and quantification. The influence of several pre-processing treatments (normalization, baseline correction, scatter correction and smoothing) on SE performances were evaluated by experimental design. By using optimal pre-processing strategy, SE methods allowed satisfactorily both identifying and quantifying the four surfactants. When applied to the pre-processed Raman spectrum of the Ecolabel laundry detergent sample, SE models remained robust enough to predict the surfactant concentrations with sufficient precision for deformulation purpose. Comparatively, a supervised modeling technique (PLS regression) was very efficient to quantify the four surfactants in synthetic mixtures but appeared less effective than SE methods when applied to the Raman spectrum of the detergent sample. PLS seemed too sensitive to the other components contained in the laundry detergent while SE methods were more robust. The results obtained demonstrated the interest of SE methods in the context of deformulation.

13.
Sci Total Environ ; 532: 80-90, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-26057727

RESUMO

In urbanized areas, small streams can be greatly damaged by urban inflows and combined sewer overflows. These polluted inputs can be several times higher than the natural stream flow over short time periods. Sound knowledge of the spatial distribution of the discharged pollutants in sediments is therefore crucial for designing monitoring strategies and suitable remediation operations. This field study combines geomorphic characterization, hydraulic conductivity measurement and pollutant assays in sediments of a small suburban river. The study site was divided up into geomorphic units: riffles, pools and runs. The last two were grouped into one class named "pool-runs" owing to their closely similar open channel flow hydraulics. Benthic and hyporheic sediments were sampled at 2m intervals. Conventional particulate pollutants (Cr, Pb, N(org), P(tot) & C(org)) were assayed in samples. The main result was: pollutants were not randomly distributed in the stream sediments, but their location showed clear concentration differences by geomorphic units, with preferential accumulation in the hyporheic zones of riffle units and a lesser one in the hyporheic zones of pools. A decrease in hydraulic conductivity was significantly correlated with an increase in pollutant concentration. This occurred mainly at the transition between riffles and pool units. The down-welling water fluxes in the sediment calculated using Darcy's formula reflect this slowdown. Our findings highlight the need to take into account the geomorphological and hydrological functioning of a stream to accurately locate the biogeochemical hotspots to be treated and thereby develop more relevant monitoring and remediation methodologies.


Assuntos
Monitoramento Ambiental , Rios/química , Poluentes Químicos da Água/análise , França , Movimentos da Água
14.
J Chromatogr A ; 1405: 116-25, 2015 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-26094139

RESUMO

The present study is focused on the development of a pre-analytical strategy for the quantification of intracellular nucleotides from cultured cell lines. Different protocols, including cell recovery, nucleotide extraction and purification, were compared on a panel of nucleoside mono-, di- and triphosphates from four cell lines (adherent and suspension cells). The quantification of nucleotides was performed using a validated technique with on-line solid-phase extraction coupled with liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS). Designed experiments were implemented to investigate, in a rigorous and limited-testing experimental approach, the influence of several operating parameters. Results showed that the technique used to harvest adherent cells drastically affected the amounts of intracellular nucleotides. Scraping cells was deleterious because of a major leakage (more than 70%) of intracellular nucleotides during scraping. Moreover, some other tested conditions should be avoided, such as using pure methanol as extraction solvent (decrease over 50% of intracellular nucleotides extracted from NCI-H292 cells) or adding a purification step with chloroform. Designed experiments allowed identifying an interaction between the percentage of methanol and the presence of chloroform. The mixture methanol/water (70/30, v/v) was considered as the best compromise according to the nucleoside mono-, di-, or triphosphates and the four cell lines studied. This work highlights the importance of pre-analytical step combined with the cell lines studied associated to sensitive and validated assay for the quantification of nucleotides in biological matrices.


Assuntos
Nucleotídeos/análise , Animais , Linhagem Celular Tumoral , Clorofórmio , Cromatografia Líquida/métodos , Humanos , Metanol , Camundongos , Extração em Fase Sólida , Solventes , Espectrometria de Massas em Tandem/métodos , Água/química
15.
Anal Bioanal Chem ; 406(4): 1209-19, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23900670

RESUMO

Metabonomics has become a very valuable tool and many research fields rely on results coming out from this combination of analytical techniques, chemometric strategies, and biological interpretation. Moreover, the matrices are more and more complex and the implications of the results are often of major importance. In this context, the need for pertinent validation strategies comes naturally. The choice of the appropriate chemometric method remains nevertheless a difficult task due to particularities such as: the number of measured variables, the complexity of the matrix and the purposes of the study. Consequently, this paper presents a detailed metabonomic study on human urine with a special emphasis on the importance of assessing the data's quality. It also describes, step by step, the statistical tools currently used and offers a critical view on some of their limits. In this work, 29 urine samples among which 15 samples obtained from tetrahydrocannabinol (delta-9-tetrahydrocannabinol)-consuming athletes, 5 samples provided by volunteers, and 9 samples obtained from athletes were submitted to untargeted analysis by means of ultra high-pressure liquid chromatography-electrospray ionization-time-of-flight mass spectrometry. Next, the quality of the obtained data was assessed and the results were compared to those found in databases. Then, unsupervised (principal component analysis (PCA)) and supervised (ANOVA/PCA, partial least-square-discriminant analysis (PLS-DA), orthogonal PLS-DA) univariate and multivariate statistical methods were applied.


Assuntos
Mineração de Dados/estatística & dados numéricos , Dronabinol/urina , Metabolômica , Cromatografia Líquida de Alta Pressão , Doping nos Esportes , Dronabinol/metabolismo , Humanos , Análise de Componente Principal , Espectrometria de Massas por Ionização por Electrospray
16.
Langmuir ; 29(46): 14074-81, 2013 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-24144015

RESUMO

The relationship between the effective charge of polymer nanoparticles (PNP) in solution and the charge states of ionized particles produced in the gas phase by electrospray ionization was investigated. Charge detection mass spectrometry was used to measure both the mass and charge of individual electrosprayed ions. The effective charges extracted from the measured zeta-potential of PNPs in solution are partially correlated with the average values of charge of PNPs in the gas phase. The correlation between the magnitude of charging of PNPs ions produced in the gas phase with the PNPs surface charge in solution demonstrates that the mass spectrometry-based analysis described in this work is an alternative and promising way for a fast and systematic characterization of charges on colloidal particles.


Assuntos
Gases/química , Nanopartículas/química , Polimetil Metacrilato/química , Espectrometria de Massas por Ionização por Electrospray , Soluções
17.
Anal Bioanal Chem ; 403(4): 1145-55, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22286081

RESUMO

A design of experiement approach is described for the optimization of the microscopic morphology of macro-mesoporous titania monoliths that were elaborated for the chromatographic enrichment of phosphorylated compounds. The monolithic titania gels were formed via an alkoxy-derived sol-gel route in association with a phase separation mechanism. The synthesis was performed at mild temperatures of gelation using starting mixtures of titanium n-propoxide, hydrochloric acid, N-methylformamide, water, and poly (ethylene oxide). The gelation temperature and the chemical compositions of N-methylformamide, water, and poly (ethylene oxide) were chosen as the most relevant experimental factors of the sol­gel process. Using the sizes of the skeletons and macropores as morphological descriptors of the dried porous monoliths, the statistical analyses simultaneously revealed the effects and interactions between the different factors. Crack-free TiO2 monolithic rods of 8 to 10 cm long with well-defined co-continuous macropores and micro-structured skeletons were obtained after selection of the sol-gel parameters and optimization of the drying and heat-treatment steps of the gels. The bimodal texture of the rods exhibited macropores of 1.5 µm and mesopores centered at 5.2 nm with a total surface area of 140 m2 g(-1). The ability of the macro-mesoporous titania rods to selectively bind phosphorylated compounds was demonstrated for O-phosphoamino acids (P-Ser, P-Thr, P-Tyr).

18.
Talanta ; 83(5): 1769-73, 2011 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-21238782

RESUMO

A metabonomic strategy based on LC-MS was employed to investigate the metabolic profile of urine samples from 20 athletes who had been tested positive for corticoids and anabolic steroids and 29 controls. In this aim, different sample preparations and chromatographic conditions were compared. The acquired LC-MS data of doped athletes and controls were subjected to analysis of variance (ANOVA) and principal component analysis (PCA). Using this approach, molecular signature of human urine was obtained showing that metabonomics could be a complementary tool to discriminate different urinary profiles and to track down metabolic changes in humans.


Assuntos
Anabolizantes/urina , Glucocorticoides/urina , Esteroides/urina , Cromatografia Líquida/métodos , Humanos , Metabolômica , Espectrometria de Massas em Tandem/métodos
19.
J Phys Chem A ; 113(22): 6365-74, 2009 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-19425570

RESUMO

The photocatalytic oxidation of diuron has been performed in presence of TiO(2) suspensions. To better understand the mechanistic details of the hydroxyl radical attack on diuron, computational methods were carried out. The combination of experimental and computational methods has been employed to establish the main degradation pathways of diuron. After identification of the majority of first byproduct, the experimental study underlined that substitution of chlorines and hydroxylation by hydroxyl radicals are the main diuron degradation pathways, in agreement with MOPAC and DFT simulations carried out in the gas phase. In addition, these calculations revealed that the aromatic ring attack is led by a HO degrees addition and not a hydrogen abstraction and the main first byproduct, monochlorohydroxylated compounds, are obtained by concerted reactions.


Assuntos
Diurona/química , Radical Hidroxila/química , Processos Fotoquímicos , Teoria Quântica , Carbono/química , Ácidos Carboxílicos/química , Catálise , Cromatografia Líquida , Espectrometria de Massas , Minerais/química , Modelos Moleculares , Conformação Molecular , Superóxidos/química , Termodinâmica
20.
Pharm Res ; 24(4): 650-61, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17318421

RESUMO

PURPOSE: Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them. MATERIALS AND METHODS: Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent. The interactions among the formulation parameters and process variables were also studied. Responses analyzed for computing these effects and interactions were outlet temperature, moisture content, operation yield, particles size, and particulate density. Additional qualitative responses (particles morphology, powder behavior) were also considered. RESULTS: Nanocapsules and silica concentrations were the main factors influencing the yield, particulate density and particle size. In addition, they were concerned for the only significant interactions occurring among two different variables. None of the studied variables had major effect on the moisture content while the interaction between nanocapsules and silica in the feed was of first interest and determinant for both the qualitative and quantitative responses. The particles morphology depended on the feed formulation but was unaffected by the process conditions. CONCLUSION: This study demonstrated that drying nanocapsules using silica as auxiliary agent by spray drying process enables the obtaining of dried micronic particle size. The optimization of the process and the formulation variables resulted in a considerable improvement of product yield while minimizing the moisture content.


Assuntos
Coloides , Nanocápsulas , Poliésteres/química , Projetos de Pesquisa , Dióxido de Silício/química , Tecnologia Farmacêutica/métodos , Química Farmacêutica , Densitometria , Dessecação/métodos , Composição de Medicamentos , Microscopia Eletrônica de Varredura , Modelos Estatísticos , Tamanho da Partícula , Pós , Propriedades de Superfície , Temperatura , Água/química
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