title: Simultaneous Measurement of the Dissolution Kinetics of Responsive DNA Hydrogels at Multiple Length Scales.
abstract: Recent years have seen increasing study of stimulus-responsive hydrogels constructed from aptamer-connected DNA building blocks. Presumably due to a lack of simple, quantitative tools with which to measure gel responsiveness, however, the literature describing these materials is largely qualitative. In response, we demonstrate here simple, time-resolved, multiscale methods for measuring the response kinetics of these materials. Specifically, by employing trace amounts of fluorophore-quencher labeled cross-linkers and the rheology of entrapped fluorescent particles, we simultaneously measure dissolution at molecular, hundred-nanometer, and hundred-micron length-scales. For our test-bed system, an adenine-responsive hydrogel, we find biphasic response kinetics dependent on both effector concentration and depth within the gel and a dissolution pattern uniform at scales longer than a few times the monomer-monomer distance. Likewise, we find that, in agreement with theoretical predictions, dissolution kinetics over the hundred nanometer length scale exhibit a power-law-like dependence on the fraction of disrupted cross-links before a distinct crossover from solid-like to liquid-like behavior.
authors.forename: Anna J
authors.identifier: 0000-0002-1879-5628
authors.initials: AJ
authors.lastname: Simon
authors.forename: Luke T
authors.initials: LT
authors.lastname: Walls-Smith
authors.affiliation: Medway School of Pharmacy, University of Kent , Central Avenue, Chatham Maritime, Chatham, ME4 4TB Kent, U.K.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Freddi
authors.forename: Faye Yi
authors.initials: FY
authors.lastname: Fong
authors.affiliation: Medway School of Pharmacy, University of Kent , Central Avenue, Chatham Maritime, Chatham, ME4 4TB Kent, U.K.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Gubala
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Plaxco
mesh_terms: D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D007700:Kinetics; D010316:Particle Size; D012212:Rheology; D013499:Surface Properties
chemical_list: D005456:Fluorescent Dyes; D020100:Hydrogels; D004247:DNA
keywords: aptamers; gels; macromolecular assemblies; rheology; smart materials; soft matter