Swelling properties of bioresponsive hydrogels: Swelling kinetics, and transport mechanisms in a hydrogel for signal transducing
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An oligonucleotide grafted acrylamide-bis-acrylamide based hydrogel was tested as a signal transducer. The sensing strand was conjugated with Iowa black that quenched the signal from the Alexa fluor 488 conjugated at the blocking strand within a distance that made Förster resonance energy transfer possible. The hydrogel was tested with oligonucleotide probes with toeholds of 2 and 10. The kinetics of the gel swelling was investigated using confocal laser scanning microscopy(CLSM) and interferometry. The interferometric data gave the change of optical length over time. The CLSM time frames imaged the gel swelling process, and is presented as mean frame intensity profiles and snapshots. The CLSM time frames shows that diffusion is faster than DNA displacement reactions, hence the DNA displacement reaction is likely the rate limiting factor of gel swelling. The difference in diffusion rate and DNA displacement reaction rate is less for T10 than for T2, probably due to the increased toehold length of T10. The interferometry data suggests that the increasing concentration of Iowa black also contributes to an increase in equilibrium gel radius in probe solutions, may be due to Iowa black hydrophobicity attracting the hydrophobe fluorophore probes and increasing osmotic pressure of the gel.