Dynamically Programmed Switchable DNA Hydrogels Based on a DNA Circuit Mechanism.

Abstract

Biological stimuli-responsive DNA hydrogels have attracted much attention in the field of medical engineering owing to their unique phase transitions from gel to sol through cleavage of DNA cross-linking points in response to specific biomolecular inputs. In this paper, a new class of biological stimuli-responsive DNA hydrogels with a dynamically programmed DNA system that relies on a DNA circuit system through cascading toehold-mediated DNA displacement reactions is constructed, allowing the catalytic cleavage of cross-linking points and main chains in response to an appropriate DNA input. The dynamically programmed DNA hydrogels exhibit a significant sharp phase transition from gel to sol in comparison to another DNA hydrogel showing noncatalytic cleavage of cross-linking points due to synchronization of the catalytic cleavage of cross-linking points and the main chains. Further, the sol-gel phase transitions of the DNA hydrogels in response to the DNA input are easily tunable by changing the cross-linking density. Additionally, with a structure-switching aptamer, DNA hydrogels encapsulating PEGylated gold nanoparticles can be used as enzyme-free signal amplifiers for the colorimetric detection of adenosine 5 -triphosphate (ATP); this detection system provides simplicity and higher sensitivity (limit of detection: 5.6 × 10-6 m at 30 min) compared to other DNA hydrogel-based ATP detection systems.