Study On Preparation Of Antimicrobial Starch-PVA Hydrogel Dressings And Their Properties

Skin damage often causes body fluid loss and wound infection. It is necessary to cover the wounds with dressings to protect them and promote their healing. Hydrogel dressings are a kind of new wound dressings with excellent performance. They can absorb wound exudate, provide a moisturized wound healing environment and they are removable without causing trauma to the wound. But the antibacterial functions need to be strengthened.Polyhexamethylene guanidine hydrochloride (PHMG) is an efficient and broad-spectrum oligoguanidine antimicrobial agent. Starch and polyvinyl alcohol (PVA) are two polymers with good biocompatibility. In this paper, a kind of long lasting antimicrobial starch-PVA hydrogels have been prepared from starch, PVA and starch grafted PHMG by chemical crosslinking technique. The properties of the resulting hydrogels were investigated.First, PHMG was prepared by polycondensation of hexamethylenediamine and guanidine hydrochloride. Electrospray ionization time of flight mass spectrometry (ESI-TOF-MS) showed that the linear type condensation products formed the majority of the oligomers, and linear structure molecular is required for the grafting reaction. Minimum growth inhibitory concentration (MIC) and hemolytic activity (HC50) against human red blood cells tests showed that PHMG has a high antibacterial activity and low toxicity to human body, so it can be used in wound dressings.Then, respectively, epichlorohydrin and glycol diglycidyl ether as bonding agents, the effects of reaction time, temperature and pH on the PHMG grafting efficiency were investigated. The results show that the grafting efficiency was higher with glycol diglycidyl ether as a bonding agent, when the reaction time is 2h, temperature is 70℃, pH is 11, grafting efficiency could reach 49.73%.Finally, antimicrobial starch-PVA hydrogels were prepared from chemical crosslinking of potato starch, PVA and starch grafted PHMG. The effects of crosslinker type and amount, raw materials ratio, reaction time, temperature and pH on swelling behavior and dehydration performance of the hydrogels were investigated. PVA was helpful to increase the gel strength, but it also reduced the reswelling rate of hydrogels and accelerate the dewatering rate. Hydrogels prepared with epichlorohydrin as the crosslinking agent have a higher reswelling rate, while the reaction time, temperature and pH have different effects on the swelling properties. Starch-PVA hydrogels exhibited high antibacterial activites against both Escherichia coli and Staphylococcus aureus. The results of shaking flask method showed that when the concentration of PHMG in the hydrogel was 1.0%, and shaking time was 40min, the growth inhibition against Escherichia coli and Staphylococcus aureus can reach 100%.