Upon some multi-membrane hydrogels based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane): preparation, characterization and in vivo tests

The study presents the possibility of preparation of multi-membrane gel systems with different morphologies and properties, based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) copolymer and crosslinked with N,N'-methylene-bis-acrylamide. The basic copolymer has dual thermo- and pH sensitive character. After the core hydrogel is realized, the preformed gel is immersed in the aqueous solutions of ammonia, sodium chloride and sodium citrate for further edge constructing of the supramolecular assemblies. Then, the new layers by adding new sets of gelifying components are realized. The new multi-membrane gel systems are intended to be used as matrix for bioactive substances embedding. In this context the systems were loaded with norfloxacin as drug model. The in vivo tests show good biocompatibility for the implants based on multi-membrane gel structures loaded with drug.

Semi-imprinting quercetin into poly[N,N-dimethylacrylamide-co-3, 9-divinyl-2, 4, 8, 10-tetraoxaspiro (5.5) undecane] network: evaluation of the antioxidant character

A responsive antioxidant system constituted from quercetin inserted into poly[N,N-dimethylacrylamide-co-3, 9-divinyl-2, 4, 8, 10-tetraoxaspiro (5.5) undecane] through a semi-imprinted procedure was evaluated. A continuous magnetic field (MF) was used during supramolecular structure preparation. The strength of coupling quercetin was evaluated based on the template release from the polymeric matrices, as well as to what extent quercetin reloaded into the polymer matrix in prescribed conditions--with or without the MF presence--shows antioxidant properties. The antioxidant activity of the complex was investigated by radical inhibitor activity method using 2, 2-diphenyl-l-picrylhydrazyl. The evaluation of the homogeneity distribution of the quercetin inside the polymeric network was made by near-infrared chemical imaging and correspondingly statistical analysis. For in vivo biocompatibility investigation, granuloma test in rats was performed correlated with the activity of enzymes involved in oxidative stress as well as immunologic effects of tested supramolecular complexes that include quercetin as therapeutic agent.

Biocompatibility, biodegradability, and drug carrier ability of hybrid collagen-based hydrogel nanocomposites

The biocompatibility, biodegradability, and drug carrier capacity of new types of hybrid hydrogels were evaluated for potential medical applications. The effects of swelling and deswelling of the hybrid hydrogels on drug loading and release capacity were evaluated. The hybrid hydrogels with Dellite® 67G and Cloisite® 93A had superior collagenase resistance compared to hydrogels without the inorganic nanoparticles. The effect of the hybrid hydrogels on the immune response parameters was followed by evaluating the chronic inflammation in rats. These hybrid hydrogels have the potential for medical and pharmaceutical applications as well as for scaffolds production in the reconstruction and regeneration of burned tissues with control of inflammatory processes.

Evaluation of the controlled release ability from the poly(2-hydroxyethyl methacrylate-co-3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane) polymer network synthesized in the presence of β-cyclodextrin

The study presents the possibility to use the 2-hydroxyethyl methacrylate--HEMA copolymer with a comonomer with spiroacetal moiety, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane)-U, as polymer network for loading the indomethacin--INN as drug model, and also, the controlled release evaluation of the prepared bioactive system. The macromolecular compounds were prepared by radical dispersion polymerization in the presence of a pair of surfactants. The use of cyclodextrin as surfactant allowed the building of the host-guest complexes by inclusion of hydrophobic molecules. Also, the cyclodextrin supplemented the hydrogen bonds and the hydrophobic interactions responsible for the stability of the achieved complexes. The copolymers composition and the INN inclusion onto the polymeric matrix were confirmed by FTIR analysis. The porous structure of the lyophilized P(HEMA-U) samples was illustrated by SEM images. The swelling studies evidenced the interdependence between P(HEMA-U) network properties and the spiroacetal moiety amount. Thus, the copolymers presented the increase of the equilibrium swelling degree with pH and temperature. Also, the polymeric matrices manifested dual sensitivity with pH and temperature. The in vitro release of the INN drug from the polymeric network as well as the in vivo experimental studies evidenced the benefit consequence of the spiroacetal compound presence. The clinical observation of the experimental groups does not show any behavioral modifications to suggest a possible toxic effect of these polymeric formulations with and without INN.

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.