Constructing Mg-phytic acid enhanced hydrogel patch with janus structure for antibacterial and angiogenic urethral repair

Abstract

Due to bacteria in urine and inadequate blood supply, urethral defect repair faces great clinical difficulties. Inspired by the natural structure of the urethra, in this study, we designed a multifunctional hydrogel urethral patch with a Janus structure. The inner layer was a double-network hydrogel of polyvinyl alcohol/carboxymethyl chitosan (PVA/CMCS) enhanced by natural phytic acid (PA) and Mg2+ (Mg2+-PA/PVA/CMCS). The outer layer was composed of poly (L-lactic acid) (PLLA) nanofibers to form a hydrophobic barrier, coupling via a micelle layer to ensure interfacial bonding. The patch exhibited mechanical properties matching soft tissues, with maximum tensile strength and toughness of 1.69±0.13 MPa and 24.7±0.9 MJ/m3, respectively, under the strengthening effect of Mg2+-PA chelation. Therein, the 4 % Mg2+-PA/PVA/CMCS composite patch could maintain unilateral hydrophobicity for at least 14 days and demonstrated an antibacterial rate of 99.0 %±0.1 % against E. coli. In PBS, the patch could deliver Mg2+ for at least 7 days and stabilize the surrounding pH environment for up to 28 days. In vitro cell experiments indicated that the 4 % Mg2+-PA/PVA/CMCS composite patch could promote the human umbilical vein endothelial cell (HUVEC) proliferation and migration, with the angiogenic protein expression enhanced more than 1.2 times compared with the Control group. In conclusion, the patch constructed in this study may provide a new approach to clinical urethral injury repair.