Antibacterial Polyacrylamide and Dextran-Graft-Polyacrylamide Hydrogels for the Treatment of Open Wounds

Abstract

Background. Open wound treatment requires a use of bandage material to prevent the development of pathogenic microflora and to provide the necessary conditions for tissue regeneration. The aim of the study was to compare the effectiveness of polyacrylamide (PAA) and dextran-graft-polyacrylamide (D-PAA) hydrogels loaded with silver nanoparticles (AgNPs), antibiotics, and photosensitizers for the treatment of bacterial infection of open wounds. Materials and Methods. PAA and D-PAA hydrogels with AgNPs, methylene blue (0.001%) without (MB) and with red light irradiation (660 nm) (MB+L), chlorhexidine (0.05%) and cefuroxime (0.1%) were used. There were tested in vitro and in vivo (a rat model) antibacterial activities against wild-type Staphylococcus aureus, Escherichia coli, antibiotic-resistant Escherichia coli and Klebsiella pneumoniae strains obtained from the wound. Clinical investigations were performed in patients with chronic venous ulcers of the lower extremities with no response to traditional treatments. Results. S. aureus, E. coli, and K. pneumoniae strains were sensitive to PAA and D-PAA hydrogels with AgNPs, chlorhexidine, and cefuroxime. Antibiotic-resistant E. coli was not inhibited by the hydrogels with cefuroxime. This strain was less sensitive to chlorhexidine and MB+L. There were no differences between unloaded PAA and D-PAA hydrogels; the antibacterial properties of the dressing were determined by an antibacterial component loaded into the hydrogel. The use of unloaded D-PAA hydrogels in vivo helped reduce the size of the wound by 28.6% and 42.8% three and five days after wound modeling, respectively. Similar results were obtained for D-PAA hydrogels loaded with cefuroxime, chlorhexidine, and MB+L. D-PAA hydrogel with AgNPs reduced wound size by 50% and 62.5% three and five days after wound induction, respectively, demonstrated greater antibacterial activity and was selected for clinical investigations. In a patient, 14 days after bandage application, the fibrin membrane disappeared, the ulcers were covered with pink granulations, marginal epithelialization appeared. Conclusions. PAA and D-PAA hydrogels can be loaded with the antibacterial compounds of various types. The type of polymer does not affect the antibacterial properties of the final hydrogels. The hydrogels with chlorhexidine and MB+L can be potentially used to treat bacterial contamination of wounds and ulcers. Nevertheless, their disadvantage is the inability to absorb or precipitate tissue breakdown products that interfere with normal regeneration and inflammation. D-PAA/AgNPs are the best option for treating ulcers due to the ability to control the properties of the hydrogels and nanoparticles, as well as multiple mechanisms of antibacterial action.