Covalent segmented polymer networks composed of poly(2-isopropenyl-2-oxazoline) and selected aliphatic polyesters: designing biocompatible amphiphilic materials containing degradable blocks.

To promote facile and efficient synthesis of segmented covalent networks, we developed a cross-linking process with reactive polymeric components in a system without catalysts or side products. To achieve the direct formation of amphiphilic networks, an addition reaction was performed between the polyesters containing carboxyl terminal groups with pendant groups distributed along poly(2-isopropenyl-2-oxazoline) chains. Covalent cross-linking was achieved from predetermined amounts of components dissolved in DMSO at 140 °C. To tune the properties of the resulting networks, the composition and length of the polyester segments and the degree of cross-linking were changed in the feed. The chemical structure of the networks was characterized using Fourier transform infrared-attenuated total reflection spectroscopy and 13C magic-angle spinning NMR. The swelling ability of the formed networks was investigated in aqueous and organic media. Moreover, mechanical properties were tested during uniaxial compression. The cytocompatibility of the scaffolds was confirmed by MTT assay. Through the results obtained, the first report describing the cross-linking of polyesters on hydrophilic PiPOx was provided to prepare new, biocompatible materials with tuneable properties that are promising for potential biomedical applications.

A simple strategy for efficient preparation of networks based on poly(2-isopropenyl-2-oxazoline), poly(ethylene oxide), and selected biologically active compounds: Novel hydrogels with antibacterial properties.

Novel polymer networks composed of biocompatible, hydrophilic poly(2-isopropenyl-2-oxazoline) (PiPOx), poly(ethylene oxide) (PEO), and selected biologically active compounds (cinnamic acid, benzoic acid or eugenol) were developed for potential antimicrobial applications. The applied crosslinking method, based on the addition reaction between oxazoline pendant groups and chosen reagents containing carboxyl functions, is relatively facile, free from by-products, and thus well suited for biomaterial preparation. The one-step synthesis enabled efficient network formation with high gel contents (>90%). The chemical structure of the newly synthesized networks was characterized using Fourier Transform Infrared-attenuated Total Reflection spectroscopy (FTIR-ATR) and 13C Magic-Angle Spinning (MAS) NMR. To evaluate the suitability for biomedical applications, swelling in water and the mechanical properties of the networks were investigated. The antimicrobial efficacy of the prepared hydrogels was tested in neutral medium both by the agar diffusion method and in the liquid culture against Gram-positive and Gram-negative strains: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloaceae. All the tested hydrogels showed an antimicrobial effect in the direct contact zone. Moreover, the eugenol loaded hydrogel expressed a broader bacteriostatic effect inhibiting microorganism growth beyond the contact zone. These form-stable hydrogels with antibacterial properties may be of interest for designing materials dedicated to biomedical applications.