DNA Aptamers That Bind to Alginate Hydrogels

Hydrogels have become common in wound treatment because they form very stable and biocompatible environments that promote healing. However, due to the highly porous hydrogel structure, any therapeutic added to these gels tends to diffuse quickly and impact delivery to the target site. Aptamers are short, single-stranded DNA or RNA sequences that bind specifically to a target, so aptamers that bind to hydrogels could serve as tags for therapeutics to prevent rapid diffusion and allow for extended delivery. An in vitro selection approach was developed to identify DNA aptamers for alginate hydrogels. Two DNA aptamers were shown to bind hydrogels ranging from 0.5 to 2% alginate and could be either encapsulated during gelation or introduced to preformed gels. Both aptamers also showed specificity for binding to alginate compared to agarose. To demonstrate the functional aspect of the aptamers as tethers for other biomolecules, both aptamers were conjugated to BSA. Aptamer-conjugated BSA was retained longer in the hydrogel during week-long diffusion studies both when encapsulated or introduced to preformed gels, which adds flexibility to how these aptamers can be deployed in a clinical setting.