Cross-linked chitosan-epichlorohydrin/bentonite composite for reactive orange 16 dye removal: Experimental study and molecular dynamic simulation.

Chitosan/bentonite beads (CsB) composites were prepared from chitosan (Cs) and bentonite (B) and cross-linked with epichlorohydrin for removal of reactive orange 16 (RO16) and methylene blue (MB). The adsorption results have shown that the (Cs20B80), 20 % wt of (Cs) and 80 % (B), was selected as the best adsorbent for (MB) and (RO16) dyes. SEM, EDX, FTIR, BET, and pHpzc were implemented to investigate the features of Cs, B, and Cs20B80 samples. The influence of contact time (0-72 h), initial RO16 concentration (15-300 mg/L), temperature (30, 40, and 50 °C), the quantity of adsorbent (1-4 g/L), ion strength (0.1-1 M), and solution pH (3-10) on RO16 adsorption onto Cs20B80 were explored. The pseudo-second-order and the Langmuir models fit adequately the adsorption kinetic results and the isotherms ones respectively. Also, the maximal monolayer capacities calculated using the non-linear form of the Langmuir isotherm are 55.27, 55.29, and 70.80 mg/g, at 30, 40 and 50 °C. Based to the statistical physics model, the RO16 could be retained on the surface of Cs20B80 through a non-parallel orientation. The RO16 adsorption process is endothermic and natural, as demonstrated by thermodynamic studies. After three regeneration cycles, the Cs20B80 composite has shown an adsorption capacity of around 20 % compared to the initial one. The adsorption energy of RO16 onto Cs, B, and Cs20B80 examined using the Monte Carlo simulation method (MC) ranged from -164.8 to -303.7 (kcal/mol), showing the potential of the three adsorbants for RO16 dye. Also, the process of adsorption of RO16 dye on the surface of Cs20B80 composite indicates several kinds of physical interactions, involving electrostatic interaction, hydrogen bonding, and π-π interactions, this finding was proved theoretically via molecular dynamic simulations.

Conception of Cellulose/Alginate/Mesalazine microspheres by solvent evaporation technique for drug release: Experimental and theoretical investigations.

Preparation of microspheres containing Mesalazine referred to as 5-aminosalicylic acid (5-ASA) for colon targeting drug was carried out using the emulsion solvent evaporation technique. The formulation was based on 5-ASA as the active agent, sodium Alginate (SA) andEthylcellulose (EC) as encapsulating agents, with polyvinyl alcohol (PVA) as emulsifier. The effects ofthe following processing parameters, 5-ASA %, EC:SA ratio and stirring rate on the properties of the resulting products in the form microspheres were considered. The samples were characterized using Optical microscopy, SEM, PXRD, FTIR, TGA, and DTG. In vitro release of 5-ASA from the different batches of microspheres was tested in biologically simulated fluids, (gastric; SGF, pH 1.2 for 2 h), then (intestinal fluid SIF, pH 7.4for 12 h) at 37 °C. The release kinetic results have been treated mathematically relaying on Higuchi's and Korsmeyer-Peppas' models for drug liberation. DOE study was performed to evaluate the interactive effects of variables on the drug entrapment and microparticle sizes. Molecular chemical interactions in structures were optimized using DFT analysis.

Solubility enhancement of mefenamic acid by inclusion complex with ß-cyclodextrin: in silico modelling, formulation, characterisation, and in vitro studies.

The aim of this study was to prepare and characterise inclusion complexes of a low water-soluble drug, mefenamic acid (MA), with ß-cyclodextrin (ß-CD). First, the phase solubility diagram of MA in ß-CD was drawn from 0 to 21 × 10-3 M of ß-CD concentration. A job's plot experiment was used to determine the stoichiometry of the MA:ß-CD complex (2:1). The stability of this complex was confirmed by molecular modelling simulation. Three methods, namely solvent co-evaporation (CE), kneading (KN), and physical mixture (PM), were used to prepare the (2:1) MA:ß-CD complexes. All complexes were fully characterised. The drug dissolution tests were established in simulated liquid gastric and the MA water solubility at pH 1.2 from complexes was significantly improved. The mechanism of MA released from the ß-CD complexes was illustrated through a mathematical treatment. Finally, two in vitro experiments confirmed the interest to use a (2:1) MA:ß-CD complex.