Multifunctional hybrid 3D network based on hyaluronic acid and a copolymer containing pendant spiroacetal moieties.

The elasticity, soft consistency and similarity to the human body are important characteristics of the gels. Such similarities allow the hydrogels to be biocompatible and, as a consequence, they are very attractive to be applied as biomaterials. This study presents a new strategy for developing a biohybrid complex based on a natural/synthetic polymer conjugate as gel type structure enriched with quercetin, which can be a relevant biomaterial for its antimicrobial properties. There are evidenced the preparation possibilities for the natural/synthetic structure as complex gel based on hyaluronic acid conjugated with poly(itaconic anhydride­co­3,9­divinyl­2,4,8,10­tetraoxaspiro[5.5] undecane) copolymer decorated with quercetin. The effects of the composition on various properties were assessed. The chemical composition of bioconjugate gels was confirmed by FTIR spectroscopy. It was established that the new gel structures have enhanced swelling capacity and a typical gel-like behavior. The investigations evidenced the gels responsiveness to stimuli and their high elasticity. The new structures were tested as drug delivery systems. The in vitro release shows the dependence of the mechanism of release on the composition of the gels, evidencing a transport behavior which varies from the Fickian to super case II. In vivo investigations demonstrated a good biocompatibility after systemic administration in mice.

Investigation of the magnetic field effect upon interpolymeric complexes formation based on bovine serum albumin and poly(aspartic acid).

The study presents a novel strategy for obtaining highly ordered interpolymeric complexes based on a protein, bovine serum albumin and a synthetic polymer, poly(aspartic acid). In this approach, experimental tests were carried out in the presence of a magnetic field of different intensities, namely 0.11 T and 0.3 T produced by permanent magnets. The influence of the magnetic force on the complexation process and the resulted self-assembled structures were studied by means of FTIR spectroscopy, X-ray diffraction, DLS, SEM microscopy and in vitro assay. The changes in the FTIR spectra acquired after 24 h of exposure were connected with conformational changes in the secondary structure and increased interactions between polymers, particularly when a higher intensity field was used. Due to a large anisotropy of magnetic susceptibility characteristic to both proteins and polypeptides, the magnetic field generated ordered assemblies consisting in globular structures of nanometric dimensions. This assembly strategy using magnets, along with remote manipulation capability can provide a versatile, contact-free, and inexpensive tool to create new, complex materials with tailorable characteristics.

Self-assembling of poly(aspartic acid) with bovine serum albumin in aqueous solutions.

Macromolecular co-assemblies built up in aqueous solutions, by using a linear polypeptide, poly(aspartic acid) (PAS), and a globular protein, bovine serum albumin (BSA), have been studied. The main interest was to identify the optimum conditions for an interpenetrated complex formation in order to design materials suitable for biomedical applications, such as drug delivery systems. BSA surface possesses several amino- and carboxylic groups available for covalent modification, and/or bioactive substances attachment. In the present study, mixtures between PAS and BSA were investigated at 37°C in dilute aqueous solution by viscometry, dynamic light scattering and zeta potential determination, as well as in solid state by AFM microscopy and dielectric spectroscopy. The experimental data have shown that the interpolymer complex formation occurs for a PAS/BSA molar ratio around 0.541.

Current concepts on cardiovascular stent devices.

Coronary artery stents used for the treatment of patients with coronary artery disease develop the practice of interventional cardiology after they were first introduced in the mid-1980s. Since then, with dozens of companies involved in the development of new and innovative anti-restenotic drugs, polymeric coatings and stent platforms has made significant progress in this area. Today, the challenge is the conception of the "ideal" coronary stent designed to respond to the patient health difficulty. In this context, the literature in the field is quite dynamic and successful. The aim of this article is to provide a systematic review on the interdisciplinary field literature of the evolution of these medical devices by describing the current status, importance and different types of stents used in clinical practice. After the presentation of cardiovascular problems associated to stenting therapy, the authors describe the bare metal stents, the generations of drug eluting stents and the future in progress directions regarding: the stents based on biodegradable/bioresorbable polymers, polymer-free metal platforms, fully biodegradable scaffolds, as well as drug delivery mediated by stent-targeted magnetic nanoparticles.

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.

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.