RESUMO
The aim of this work was to evaluate the influence of US on the properties of the fluconazole emulsions prepared using imidazolium-based ILs ([Cn C1im]Br). The effects of the preparation method (mechanical stirring or US), US amplitude, alkyl chain length (of [C12C1im]Br or [C16C1im]Br), and IL concentration on the physicochemical properties were evaluated. Properties such as droplet size, span index, morphology, viscosity encapsulation efficiency, and drug release profile were determined. The results showed that US-prepared emulsions had a smaller droplet size and smaller polydispersity (Span) than those prepared by mechanical stirring. Additionally, the results showed that emulsions prepared with [C16C1im]Br and US had spherical shapes and increased stability compared to emulsions prepared by MS, and also depended on the IL concentration. The emulsion prepared by US at 40% amplitude had increased encapsulation efficiency. US provided a decrease in the viscosity of emulsions containing [C12C1im]Br; however, in general, all emulsions had viscosity close to that of water. Emulsions containing [C16C1im]Br had the lowest viscosities of all the emulsions. The emulsions containing the IL [C16C1im]Br had more controlled release and a lower cumulative percentage of drug release. The IL concentration required to prepare these emulsions was lower than the amount of conventional surfactant required, which highlights the potential synergic effects of ILs and US in preparing emulsions of hydrophobic drugs.
Assuntos
Fluconazol/química , Líquidos Iônicos/química , Ondas Ultrassônicas , Emulsões , Interações Hidrofóbicas e Hidrofílicas , Imidazóis/química , Cinética , Fenômenos Mecânicos , Tamanho da Partícula , ViscosidadeRESUMO
Carbon-like materials from pyrolysis (<500°C) of agricultural leftovers (rice husks, eucalyptus sawdust and peach stones) were submitted to steam activation and the expected adsorbent properties evaluated by means of a chemical method (methylene blue) and physically characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and surface area (BET). Batch experiments were carried out to check the pH effect on the adsorption of methylene blue, by evaluating the respective equilibrium isotherms (Langmuir, Freundlich and Temkin). The steam-activated biocarbons showed significant adsorbent capacity, which increased along with pH. The best performance was achieved by the activated biocarbon from peach stones, which showed adsorptive properties similar to activated carbon market. The suitable detoxification efficiency of untreated broths with activated biocarbon, and an increase in the required fermentability, supports the potential use of these adsorptive bioproducts from agricultural leftovers. The profitable use of agricultural waste materials is actually a welcome strategy for consolidating the biorefinery concept as well as ensuring planetary sustainability. PRACTITIONER POINTS: Use of biomass residues for detoxification of fermentable broth. The activated biocarbons showed significant adsorbent capacity similar to activated carbon market. The results revealed the potential of the biomass residues as a promising source within bio-refineries.
Assuntos
Carvão Vegetal , Pirólise , Adsorção , Biomassa , Azul de MetilenoRESUMO
The thermal, physical, and morphological properties of diphenhydraminium ibuprofenate ([DIP][IBU]) adsorbed onto mesoporous silica (SiO2-60â¯Å and SiO2-90â¯Å) from solution were determined. The thermal, physical, and morphological properties of [DIP][IBU] supported on silica were determined. The adsorption of [DIP][IBU] on the pores and surface of silica was proven by N2 adsorption/desorption isotherms. Additionally, release profiles were determined for all systems, and the antinociceptive activity of neat [DIP][IBU] and [DIP][IBU] supported on silica were determined. The interaction of [DIP][IBU] and silica was dependent on pore size, with the formation of a [DIP][IBU] monolayer on SiO2-60 and a multilayer on SiO2-90. The release profile was sustained and slow and dependent on the pore size of the silica, in which the smaller the pore size, the faster the release. The nociceptive evaluation showed that [DIP][IBU] presents a greater (99.21⯱â¯0.85%) antinociceptive effect than the ibuprofen (46⯱â¯4.3%). Additionally, [DIP][IBU] on SiO2-60 (90⯱â¯5.8%) had a greater antinociceptive effect than on SiO2-90 (73⯱â¯13.2%), which indicates that in vivo tests are in accordance with the in vitro experiments.
Assuntos
Analgésicos , Ibuprofeno , Dor/tratamento farmacológico , Dióxido de Silício , Analgésicos/química , Analgésicos/farmacocinética , Analgésicos/farmacologia , Animais , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Preparações de Ação Retardada/farmacologia , Avaliação Pré-Clínica de Medicamentos , Ibuprofeno/análogos & derivados , Ibuprofeno/química , Ibuprofeno/farmacocinética , Ibuprofeno/farmacologia , Masculino , Camundongos , Dor/metabolismo , Dor/fisiopatologia , Porosidade , Dióxido de Silício/química , Dióxido de Silício/farmacocinética , Dióxido de Silício/farmacologiaRESUMO
A water-soluble carboxymethylchitosan (CMC) was prepared in water/isopropanol (2/8) medium, at 10 °C, and characterized by UV-vis, FT-IR and NMR techniques. Its performance as an environmentally friendly scale inhibitor in oil wells was evaluated under the physicochemical conditions of oil wells in northeast of Brazil, by using SEM, visual compatibility and dynamic tube blocking test. The synthesis conditions led to a degree of carboxymethylation of 0.45 and water-solubility in all pH range studied (1-11). CMC acted as a scale inhibitor of CaCO3 under synthetic brine medium, presenting a minimum inhibitor concentration (MIC) of 170 ppm (1000 psi, T = 70 °C). SEM images showed that CaCO3 crystals were deformed by CMC, which was attributed to effective interactions of CMC through its carboxylate ions and lone pair of electrons on OH and NH2 groups with calcium ions, preventing scale deposition.
RESUMO
Supramolecular gels present several applications in which the gelator properties are closely dependent on their structure and solvent. Despite this, there are few studies on the effect of the gelation ability of gelators with slight molecular changes. Therefore, N-arylestearamides (in which aryl = phenyl (1), 4-tolyl (2) and 4-acetylphenyl (3)) were evaluated in different solvents. The critical gelefication concentration (CGC) values indicated that the substituents can significantly affect the concentration at which the supramolecular gels are formed, mainly in non-aromatic solvents (e.g. cyclohexane, acetonitrile and DMSO). From UV-Vis and DSC data, we verified that the gel-sol and sol-gel transitions (Tgel-sol and Tsol-gel) increase in the order of 1 < 2 < 3. Organogel strength was evaluated for 1-3 as a function of concentration and solvent type using rheology data. Gel strength is concentration-dependent and a strength order was found in acetonitrile, cyclohexane and DMSO, in which: 1 â¼ 2 > 3. Dynamic viscoelastic measurements as a function of temperature sweeps indicate a predominantly enthalpic contribution to the elasticity of the organogels formed from 1-3. Temperature-dependent 1H NMR indicates that NHO interactions may be responsible for the molecular association of molecules into 1D fibers, while 3D fibers were formed from van der Waals interactions.
RESUMO
Partition constants (KD°), molecular dynamics (T1, T2, and DOSY measurements), thermal stability, and toxicity of dicationic ionic liquids (ILs) were determined. The dicationic ILs derived from 1,n-bis(3-methylimidazolim-1-yl)octane, [BisOct(MIM)2][2X] (in which X = Cl, Br, NO3, SCN, BF4, and NTf2), were evaluated to verify the influence of anion structure on the IL properties. A monocationic IL [Oct(MIM)][Br] was also monitored for comparison. In general, the solubility of the ILs followed the anion free energy of hydration (ΔG°hyd). The thermokinetic and thermodynamic functions of activation of the ILs were determined via thermogravimetric data, and it was observed that polyatomic anions influence the decomposition mechanism of these IL structures. Furthermore, [Oct(MIM)][Br] had a decomposition rate greater than that of the dicationic analogue, and the thermodynamic parameters of activation data corroborate these results. Finally, the dicationic ILs did not indicate toxic effects (LD50 > 40 mM).
RESUMO
Extensive investigation of interactions and aggregation properties of IL + API systems is necessary to apply ionic liquids (ILs) with different hydrophobic characteristics to drug delivery or in active pharmaceutical ingredient (API) formulations. Therefore, this study aims to investigate the heteroassembly between dicationic ILs ([BisOct(MIM)2][2X], in which X is Br or BF4, and [BisOct(BnIM)2][2Br]), both in the absence and the presence of neutral APIs (salicylic acid, ibuprofen, and paracetamol) with different functional groups. Isothermal titration calorimetry results demonstrate that IL-API associations occur at very low concentrations of IL. These results were reinforced by electrospray ionization mass spectrometry with variable collision-induced dissociation, in which the IL dication interactions with APIs were detected. The strength of the dication-API interaction was determined from E cm,1/2 data. The aggregation parameters (cac, ΔG agg °, and K) between ILs and APIs were evaluated by conductivity. The 1H NMR data showed that differences in chemical shifts provided relevant insights about interaction sites in both components.
RESUMO
Interactions between uncharged polymers and cationic surfactants are considered weaker than interactions with the anionic analogues. This work describes the binding occurring between methylcellulose (MC) and the cationic surfactant DTAB in aqueous medium. In the absence of salt, MC-DTAB exhibits a maximum in hydrodynamic radius, R(h,slow), with the increase in the surfactant concentration. Otherwise, in presence of salt the MC-DTAB system shows only a linear increase of R(h,slow). CAC is lower than the CMC, which is taken as an evidence of binding between the cationic surfactant and neutral polymer that induces the aggregation process. Static light scattering, rheology and micro-DSC results highlight the hydrophobic MC-DTAB association. Salt-out and the salt-in effects were observed in presence of DTAB, with a clear transition at concentration values close to the CMC, as judged from rheological and micro DSC measurements. Indeed, DTAB affects both the pattern of the sol-gel transition and the gel strength.