Xanthan and Poly(vinyl alcohol) - Based Composite Films, as Supports for Chloramphenicol Immobilization

The paper discusses a method for the realization of some polymer - drug systems in which the macromolecular support is represented by a three-dimensional network based on xanthan and poly(vinyl alcohol). Knowing that the drug (chloramphenicol) was to be inserted through a diffusion process, the support – selected according to an experimental program – had the highest degree of swelling. Several variants of chloramphenicol inclusion into the synthesized support are analyzed by studying the process kinetics. The study of chloramphenicol release from the inclusion products, in the form of films, indicated the installation of a “zero order” kinetics. The tests devoted to the system’s antimicrobial activity evidenced their biological action

Chemically modified xanthan and gellan for preparation of biomaterials for ophthalmic applications

International audienceGellan and xanthan are extracellular polysaccharides with very interesting rheological or gelling properties. They are esterified with acrylic acid, acryloyl chloride or maleic anhydride. Consequently, due to the presence of carbon double bonds, hydrogels are obtained using a grafting–crosslinking process with N-isopropylacrylamide and N′-bisacrylamide. Such hydrogels, due to the presence of poly(N-isopropylacrylamide), are thermosensitive and present drug release properties which can be adjusted through the reaction conditions. This concept was demonstrated for ophthalmic applications

Thermo-sensitive gellan maleate/N-isopropylacrylamide hydrogels: initial “in vitro” and “in vivo” evaluation as ocular inserts

International audienceHydrogels are among the most used polymer–drug systems, polysaccharide-based materials presenting many advantages to be used for controlled release applications. Gellan maleate/NIPAm hydrogels are hydrophilic swelling matrixes that were originally developed for biomedical applications as controlled release dosage forms. The purpose of this study is to explore the ability of gellan maleate/NIPAm thermoreversible hydrogels for ophthalmic applications as ocular inserts. Studied hydrogels were synthesized by free radical grafting/polymerization of unsaturated esters (gellan maleate) with N-isopropylacrylamide (NIPAm) and N,N′-methylenebisacrylamide as cross-linker. They are evaluated for swelling degree, in vitro inclusion and release of drugs (adrenaline and chloramphenicol) and in vivo biocompatibility. The hydrogel is shown to be a temperature-responsive material with a LCST close to 36 °C. The swelling properties and the release of biologically active compounds occur when polymer conformation changes determining phase transition at LCST. Gellan-based hydrogels present reproducible responses to alternation between ambient temperature and human body one. The stability and biocompatibility were evaluated in vitro and in vivo. Tissue response to implantation of hydrogel was determined by histological analysis (haematoxylin–eosin–methylene blue and periodic acid–Schiff). A thin fibrous capsule was observed around the implanted hydrogels. No necrosis, calcification and acute inflammatory reaction were noted. Successful preliminary results were obtained for ophthalmic applications

Superparamagnetic Hybrid Nanospheres Based on Chitosan Obtained by Double Crosslinking in a Reverse Emulsion for Cancer Treatment

Nowadays, the Magnetically Targeted Drug Delivery System (MTDDS) is among the most attractive and promising strategies for delivering drugs to the target site. The present study aimed to obtain a biopolymer–magnetite–drug nanosystem via a double crosslinking (ionic and covalent) technique in reverse emulsion, which ensures the mechanical stability of the polymer support in the form of original hybrid nanospheres (NSMs) loaded with biologically active principles (the 5-Fluorouracil (5-FU)) as a potential treatment for cancer. Obtained NSMs were characterized in terms of structure (FT-IR), size (DLS), morphology (SEM), swelling, and 5-FU entrapment/release properties, which were dependent on the synthesis parameters (polymer concentration, dispersion speed, and amount of ionic crosslinking agent). SEM analysis results revealed that NSMs presented a spherical shape and are homogeneous and separated. Moreover, NSMs’ ability to load/release 5-FU was tested in vitro, the results confirming, as expected, their dependence on the varied synthesis process and NSM swelling ability in physiological liquids. The drug transport mechanism through the polymer matrix of its release is the Fickian type. The morphological, bio-material characteristics and the ability to include and release an antitumor drug highlight the utility of the NSMs obtained for targeting and treating some tumor diseases

An Interpenetrating Polymer Network Hydrogel Based on Cellulose, Applied to Remove Colorant Traces from the Water Medium: Electrostatic Interactions Analysis

The main objective of this work was the removal of eosin Y and green malachite from an aqueous medium by using a cellulose-based biodegradable interpenetrated network (IPN). The IPN was obtained by the sequenced synthesis method. In the first step, cellulose was crosslinked with epichlorohydrin (ECH). In the second step, the obtained gels were swollen in a reactive mixture solution, which was based on the monomers 2-hydroxyethyl methacrylate (HEMA) and 1,6- hexanediol diacrylate (HDDA). After this, swelling equilibrium was reached through the gels’ exposition to UV radiation. An infrared spectroscopy (FTIR) was used to analyze the bond stretching, which confirmed the IPN’s formation. The swelling kinetics in aqueous mediums with different pH values showed a high swelling at a basic pH value and a low response in neutral and acidic media. The IPNs showed an improvement in water uptake, compared to the networks based on PHEMA or cellulose. The IPN was used to remove dyes from the water. The results showed that a high percentage of green malachite was removed by the IPN in six minutes of contact time. The experimental results were confirmed by the docking/modeling method of the system (IPN/Dye). The different physical interactions between the IPN and the dyes’ molecules were investigated. The interactions of the hydrogen bonds with malachite green were stronger than those with eosin Y, which was in good agreement with the experimental results