Influence of hydrophilic polymers on mechanical property and wound recovery of hybrid bilayer wound dressing system for delivering thermally unstable probiotic

In this study, a novel hybrid bilayer wound dressing (HBD) has been developed for delivering a thermally unstable probiotic, Lactobacillus brevis. The HBD was composed of two layer, a hydrocolloid layer and a Lactobacillus brevis-loaded hydrogel layer as a block supporter and drug carrier, respectively. Moreover, various probiotic-loaded hydrogel layers in HBD were prepared with polyvinyl alcohol (PVA) and numerous hydrophilic polymers via a freezing and thawing method, and their mechanical property, release and wound recovery were assessed. Among the hydrophilic polymers investigated, copovidone most improved the mechanical strength, swelling ability, and release properties; and thus, copovidone/PVA (ratio of 1.0/10) was determined as an appropriate composition of hydrogel layer in HBD. The selected HBD exhibited superior stability than conventional dressing, maintaining approximately 90% of Lactobacillus brevis (9.0 × 10⁸ CFU) during the preparation and storage process. Moreover, the HBD had about 5- and 4-fold better swelling ability and elasticity compared to the conventional dressing. Additionally, it exhibited superior recovery efficacy than the commercial dressing in the animal study. Therefore, this HBD system for delivering a thermally unstable Lactobacillus brevis would be a promising wound dressing with excellent mechanical property and wound recovery.