Characterization of Hydrogel Made by pH-responsive Polymer and Alginate

4-Vinylphenylboronic acid (VPBA) and N,N'-dimethylaminoethyl methacrylate (DMAEMA) are pH-sensitive compounds; VPBA can bind to cis-diol compounds above pH 8 to form covalent bonds, while DMAEMA unit is activated to quaternary ammonium through ionization below pH 7. In this study, a phospholipid polymer (PMDV) composed of VPBA, DMAEMA, and 2-methacryloylphosphorycholin was synthesized and reacted with alginate (ALG) to form a hydrogel, which is a polysaccharide comprising two repeating carboxylated monosaccharide units. The hydrogel was characterized using a rheometer (for gelation and gel dissociation), FTIR, and SEM. Furthermore, multilayered hydrogel was fabricated by PMDV and ALG via layer-by-layer (LbL) method. The affinity between ALG and vascular endothelial growth factor (VEGF) was exploited to load VEGF into ALG layer through LbL method, which was confirmed by SPR analysis. The driving force can be controlled by changing the pH for the fabrication of PMDV/ALG hydrogel for application in drug delivery system.