title: Reversible Inter- and Intra-Microgel Cross-Linking using Disulfides.
abstract: Thermoresponsive hydrogel nanoparticles composed of poly(N-isopropylmethacrylamide) (pNIPMAm) and the disulfide-based cross-linker N,N'-bis(acryloyl)cystamine (BAC) have been prepared using a redox-initiated, aqueous precipitation polymerization approach, leading to improved stability of the disulfide bond compared to traditional thermally-initiated methods. The resultant particles demonstrate complete erosion in response to reducing conditions or thiol competition. This stands in contrast to the behavior of thermally-initiated particles, which retain a cross-linked network following disulfide cleavage due to uncontrolled chain-branching and self-cross-linking side reactions. The synthetic strategy has also been combined with the non-degradable cross-linker N,N-methylenebisacrylamide (BIS) to generate "co-cross-linked" pNIPMAm-BAC-BIS microgels. These particles are redox-responsive, swell upon BAC cross-link scission and present reactive thiols. This pendant thiol functionality was demonstrated to be useful for conjugation of thiol-reactive probes and in reversible network formation by assembling particles cross-linked by disulfide linkages.
authors.affiliation: School of Chemistry & Biochemistry and the Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, United States.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Gaulding
authors.forename: Michael H
authors.initials: MH
authors.lastname: Smith
authors.forename: John S
authors.initials: JS
authors.lastname: Hyatt
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernandez-Nieves
authors.forename: L Andrew
authors.initials: LA
authors.lastname: Lyon