Silibinin solubilization: combined effect of co-solvency and inclusion complex formation

Belonging to the class II drugs according to the biopharmaceutics classification system, silibinin (SLB) benefits from high permeability but suffers poor solubility that negatively affects the development of any delivery system. This research aimed to improve SLB solubility by combined use of co-solvency and complexation phenomena. Solubility studies were performed using the phase solubility analysis according to the shake-flask method in the presence of ethanol and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as a co-solvent and inclusion complexing agent, respectively. SLB release studies from chitosan nanoparticles were carried out in double-wall, diffusion cells using the optimized drug release medium. SLB solubility was mathematically optimized constraining to using the lowest concentrations of ethanol and HP-β-CD. SLB solubility increased linearly with the increase of HP-β-CD concentration. The solubility in PBS-ethanol mixtures followed a log-linear model. SLB solubility in the presence of the ethanol co-solvent and HP-β-CD complexing agent was optimized by adopting a genetic algorithm suggesting the phosphate buffer saline solution supplemented by 6%v/v ethanol and 8 mM HP-β-CD as an optimized medium. The optimized solution was examined to study SLB release from chitosan nanoparticles (4.5 ± 0.2% drug loading) at 37 °C under static conditions. The sigmoidal release profile of SLB from the particles indicated a combination of erosion and diffusion mechanisms governing drug release from the nanoparticles. SLB solubility in a buffered solution supplemented by ethanol co-solvent and HP-β-CD complexing agent is a function of free drug present in the semi-aqueous media, the drug-ligand binary complex, and the drug/ligand/co-solvent ternary complex.</p

Superabsorbent Microparticles for Production of Concrete Using Ultrasound: A Performance Study

Hypothesis: Superabsorbent polymers are modifiers that have broad applications. One of their applications is in concrete production industry. The use of these materials for supplying water to cement materials and their curing process has attracted the attention of researchers. Using SAPs in concrete is a valuable tool for areas where conventional curing is very difficult, such as extreme weather conditions that can lead to excessive evaporation and freezing. It also saves water.Methods: Modified carbopol was prepared using poly(ethylene glycol) methyl ether methacrylate as a monomer with a molecular weight of 300 in amounts of 1, 2 and 3 g and with azobisisobutyronitrile (AIBN) as the initiator by ultrasound method. The properties of the prepared microgel and its effect on the properties of cement paste are investigated. The prepared microgel has been studied using FTIR analysis, scanning electron microscopy, particle size determination and swelling properties. In addition, the effect of prepared microgel on different properties of cement paste, such as rheology, compressive and flexural strength and hydration, is investigated.Findings: The results of FTIR and microscopic images showed that the monomer was modified. According to the swelling results, it was observed that carbopol has no absorption and it is dissolved. After modification, the swelling and absorption properties are obtained. The swelling capacity in water and saline solution has increased first and then decreased with increasing monomer concentration. The resultant cement pastes show that the compressive strength of samples is decreased in the presence of modified carbopol. In addition, the strength of the cement paste prepared with commercial superabsorbent (polyacrylic acid sodium salt) has increased with the same water:cement ratio. The flexural strength is reduced in all samples compared to the reference. According to the results, the modified carbopol has increased the viscosity of the cement pastes. According to the XRD results, hydration and curing of samples with superabsorbent have completed within 28 days compared to the control cement. Therefore, it can be concluded that superabsorbents generally cause a delay in hydration, and besides the hydration of the superabsorbent-cement specimens is decreased by reducing the monomer

Experimental study and numerical modelling of rheological and flow behaviour of xanthan gum solutions using artificial neural network

Δημοσίευση σε επιστημονικό περιοδικόSummarization: This study investigated effect of temperature, concentration, and shear rate on rheological properties of xanthan gum aqueous solutions using a Couette viscometer at temperatures between 25°C and 55°C and concentrations of 0.25 wt% to 1.0 wt%. The Herschel–Bulkley model described very well the non-Newtonian behavior of xanthan gum solutions. Shear rate, temperature, and concentration affected apparent viscosity and an equation was proposed for the temperature and concentration effect valid for each shear rate. This article also presents an artificial neural network (ANN) model to predict apparent viscosity. Based on statistical analysis, the ANN method estimated viscosity with high accuracy and low error.Presented on: Journal of Dispersion Science and Technolog