Sol gel method performed for biomedical products implementation

Sol-gel technology is an impressive and instructive innovation in science that necessitates a multidisciplinary approach for its important applications in the practice. An important peculiarity of the sol gel technology is the possibility to control the mechanism and kinetics of the chemical reactions, thus monitoring the final structure (particle size, porosity, thin layer thickness) of the materials. The low processing temperature combined with the intrinsic bio-compatibility and environmental friendliness of the implied components makes it an ideal method applied in different biomedical purposes: the synthesis of porous matrices for entrapping of organic and inorganic compounds, sensor molecules, enzymes and many other biological molecules, selective coatings for optical and electrochemical biosensors, stationary phases for chromatography, immunoadsorbent and solid-phase extraction materials, controlled release agents, solid-phase biosynthesis, and unique matrices for biophysical studies. It is therefore the scope of this review to provide a few insights of the recent progresses made in sol-gel-based materials for biomedical applications.

An in vitro release study of indomethacin from nanoparticles based on methyl methacrylate/glycidyl methacrylate copolymers

Indomethacin was coupled onto some macromolecular nanostructures based on methyl methacrylate copolymers with glycidyl methacrylate and tested as a model drug. The polymeric matrices were synthesized by radical emulsion copolymerization with and without the presence of a continuous external magnetic field of 1500 Gs intensity. Mathematical analysis of the release data was performed using Higuchi, Peppas-Korsmeyer equations. NIR chemical imaging (NIR-CI) was used to provide information about the spatial distribution of the components in the studied nanostructures. This opportunity was used to visualize the spatial distribution of bioactive substances (indomethacin) into the polymeric matrix, as well as to evaluate the degree of chemical and/or physical heterogeneity of the bioactive samples. The release rate dependence on the synthesis conditions as well as on the chemical compositions of the tested polymeric systems, it was also evidenced.

Effect of emulsion polymerization and magnetic field on the adsorption of albumin on poly(methyl methacrylate)-based biomaterial surfaces

The adsorption of bovine serum albumin (BSA) onto the surfaces of poly(methyl methacrylate) (PMMA) and of methyl methacrylate copolymer with 2,3-epoxypropyl methacrylate, it was investigated. The polymeric matrices were obtained through radical emulsion polymerization with and without the presence of a continuous external magnetic field (MF) of 1,500 Gs intensity. Two types of surfactant agents were used for polymers' synthesis: a classic one sodium lauryl sulphate (SLS) and beta-cyclodextrin (CD). The protein adsorption was conducted in the presence as well as in the absence of MF, by varying the coupling conditions, respectively, the temperature, pH and albumin/polymer ratio. The study underlines the assistance of MF during the adsorption process, materialized into growth of the BSA adsorbed quantity. Thus, MF presence during adsorption determines the doubling of the BSA adsorbed quantity onto the surface of polymers prepared in the MF. The adsorption process was also related to the tensioactive used for the synthesis of polymeric matrices. The higher content of the adsorbed BSA corresponds to the polymers with CD instead of SLS. The fact was attributed to the catalytic activity of the MF, which determines the molecules distortions, the growth of distance interactions and the modifications of the angles between bonds, with benefit effect upon adsorption.

Study of a binary interpenetrated polymeric complex by correlation of rheological parameters with zeta potential and conductivity

The interpenetrated macromolecular chains complexation between poly(aspartic acid) and poly(vinyl alcohol) in aqueous solution it was investigated. The interpolymer complexation process was evaluated through dynamic rheology. The aspects concerning the stability of the tested homopolymers and the prepared interpolymeric complex there were achieved from the evaluation of the aqueous solutions'zeta potential and also by determining the pH influence upon the zeta potential and the conductivity. The data obtained through the rheological dynamic measurements were correlated with the composition of the polymeric mixture, the dependence of zeta potential and conductivity. The study reveals the conditions for the formation of interpenetrated polymeric complex as being a ratio of 70wt.% PAS to 30wt.% PVA at 22 degrees C and 50/50 PAS/PVA ratio at 37 degrees C temperature. From the pH influence upon the zeta potential values it was evidenced the PAS aqueous solution does not reach the isoelectric point. At the same time, PVA solution and the complex PAS/PVA reaches the isoelectric point at strongly acid pH. The better stability of PAS, PVA and their mixture in solution is recorded in the alkaline domain (7.5<or=pH>or=12). The conductivity increases with the rising of the PAS content, pH and temperature. Other characteristics of the prepared interpenetrated polymeric structure, as for example thermal stability, there are also presented.

Biocompatibilizing possibilities of some vinylic functionalized structures

The paper presents a study concerning the capacity of albumin coupling by conventional method and through a procedure in the magnetic field presence onto pre-formed vinylic matrices in order to obtain biocompatible structure. The increase of the coupling yield of the protein structure onto functionalized polymeric matrix via acetylation with acidic halogenic chlorides was evidenced, too.

Synthesis and characterization of a hydrogel with therapeutic applications

The study presents the synthesis of an acrylamide polymeric hydrogel in aqueous solution by copolymerization concomitant with a crosslinking process using a bifunctional co-monomer with a redox initiation system--potassium peroxo-disulphate/ascorbic acid. The swelling kinetics as well the characterization of structure through optical microscopy was performed. The synthesized polymeric gel shows temperature sensitivity, maintaining low temperatures for a prolonged period of time. Thus, the material is assessed as an inner material in thermo sensitive packs to be applied in pain therapy.