A Novel Acid-Degradable PEG Crosslinker for the Fabrication of pH-Responsive Soft Materials

The design and synthesis of a novel acid-degradable polyethylene glycol-based N-hydroxysuccinimide (NHS) ester-activated crosslinker is reported. The crosslinker is reactive towards nucleophiles and features a central ketal functional group that is stable at pH > 7.5 and rapidly hydrolyses at pH > 6.0. The crosslinker is used to (i) fabricate acid-degradable polysaccharide hydrogels that exhibit controlled degradation upon exposure to an acidic environment or via endogenous enzyme activity; and (ii) construct hydrogel-filled protein-polymer microcompartments (termed proteinosomes) capable of pH-dependent membrane disassembly. Taken together the results provide new opportunities for the fabrication of pH-responsive soft materials with potential applications in drug delivery, tissue engineering, and soft-matter bioengineering.