Polymer Gels

The development of synthetic hydrogels for biomedical use as well as contact and intraocular lenses is the characteristic  topic for this department. The research has been advanced continuously from the period of the eighties when our department was closely associated with  Academician Otto Wichterle, D.Sc, one of the leading pioneers of polymer science.

 

 

 

New polymeric materials are tested using physical and chemical methods. The material properties (swelling, mechanical, transport and optical properties) are studied, including their biocompatibility and interaction with living tissue.

 During the last year we developed polymer materials facilitating wound healing, which are capable of removing reactive oxygen and nitrogen species. The wound-cover material is characteristic in that it consists of a polymer carrier based on slightly crosslinked hydrophilic polymers or copolymers and physiologically bioactive substances with radical-scavenger properties, selected from the group of vitamins A, carotenoids, vitamins E, ubiquinones, flavonoids, nicotin­amide, uric acid, bilirubin, lipoic acid, glutathione, and melatonin. The material is successfully used in veterinary medicine.

 

New hydrophilic polymer supports for the cultivation and subsequent transplantation of keratinocytes designed for treatment of burns and large skin defects have also been prepared. We continued the research by testing low-hydrated materials containing ether groupings. We prepared copolymers of glycerol monomethacrylate and 2-ethoxy­ethyl methacrylate cross­linked with glycerol dimethacrylate and compared them with copolymers of glycerol monomethacrylate and dimeth­acrylate. Following our present and previous results, it is evident that one of the main factors determining keratinocyte adhesion is the equilibrium swelling of the hydrogel. Low-hydrated hydrogels show the enhanced sorption of proteins important for cell adhesion (e.g. fibronectin and its active adhesive sequences). Thus, we started preparation of polymer carriers based on 2-ethoxyethyl methacrylate (possibly with a low admixture of 2-hydroxyethyl meth­acrylate) crosslinked with hexane-1,6-diyl dimeth­acrylate and containing modified adhesive amino-acid sequences derived from fibronectin (e.g. RGD with synergic sequence PHSRN). We prepared 6-meth­acryl­amidohexanoyl-PHSRN­amide and 6-methacryl­amido­hexanoyl-RGD-amide by  solid-phase synthesis of peptides. Both the prepared amides were copolymerized with 2-ethoxy­ethyl meth­acrylate. Now we are working on optimization of the length and type of flexible spacer between the methacrylate chain and the adhesive sequences.

 

In the framework of the research on implants for the central nervous system, we continued  research  on  macroporous hydrogels based on copolymers of 2-hydroxyethyl meth­acrylate, methacrylic acid and [2-(meth­acryloyloxy)ethyl]tri­methyl­amonium chloride and their polyelectrolyte complexes. Previous results have demonstrated the possibility of obtaining controlled pore size, pore communication, and suitable biological response. Our hydrogels show predominantly communicating pores and quite a narrow pore-size distribution as follows from confocal and electron microscopy.

 

From the viewpoint of mechanical properties, the 10 mol% concentration of ionic monomers is an optimum (properties of the resulting polymer are similar to those of  nervous tissue). As most polymer - living tissue interactions are localized in the protein layer at the interface, we prepared a layer of selected proteins on the surfaces of the materials. The described macroporous hydrogels were used for the immobilization of the model proteins: albumin (low pI, 4.9) and avidin (high pI, 10.5). The protein adsorption capacity was measured and kinetic studies were carried out. The protein - polymer complex is stable, desorption of proteins is minimal.

 

 

In the framework of  research on new hydrogel materials for contact lenses, we prepared copolymers of diethylene glycol methacrylate with new types of perfluorinated vinyl monomers. They are transparent gels with promising properties. The mentioned structures enhance the oxygen permeability of the resulting hydrophilic gels.

 

We also participate in the development of novel separation techniques, e.g. in the syntheses of imprinted polymers for high-performance liquid chromatography or capillary electro­chromatography, and in the study of permanent hydrogel coatings of fused-silica columns for capillary electrophoresis. 

 

The biomedical properties of the prepared polymers are evaluated by a long-standing and successful collaboration with the teams of co-workers at the Institute of Anatomy, the First Faculty of Medicine at the Charles University, Prague, and the Burn Centre , the Third Faculty of Medicine at the Charles University, Prague, as well as at the Department of Eye Histochemistry, and the Institute of Experimental Medicine, Academy of Sciences, Prague.

 

In cooperation with the Charles University of Prague, the Institute of Chemical Technology of Prague, our department educates several PhD. and diploma students and generates the opportunity to evolve both pure and applied research. 

 

Further our department makes use of the long tradition of collaboration  with the Czech Contact Lens Society, and we teach  at the Second Faculty of Medicine at the Charles University, Prague as external lecturers.