A straightforward process manipulates dramatic morphology change of DNA rolling circle amplification products

Abstract

Rolling circle amplification (RCA) is a widely used method for the synthesis of DNA nanoparticles and macro hydrogels. Several strategies, including oscillation-promoted entanglement of DNA chains, multi-round chain amplification, hybridization between DNA chains, and hybridization with functional moieties, are applied to synthesize DNA macro hydrogels; alternatively, flower-like nanoparticles are also produced. Here we report a straightforward yet effective method to manipulate the morphology of RCA products from nanoparticles to 3D hydrogels by an additional cold treatment step of the circular DNA template prior to elongation using phi29 DNA polymerase. This process induces a minor aggregation of the circular DNA template, significantly enhancing the entanglement of DNA chains in subsequent steps. Compared to contemporary synthesis methods for RCA-based macro hydrogels, our technique provides milder reaction conditions, shorter reaction time, and a more straightforward system. Notably, our method eliminates the need for oscillation during amplification and requires only a single round of RCA with a single type of circular DNA, thereby simplifying the synthesis process.