Fluidic Spatial-Confinement Scaffold Affords a Multicomponent DNA Reaction with Improved Efficiency and Accelerated Kinetics.

Enzyme-free nucleic acid amplification reactions with the capability of signal catalytic amplification have been widely used in biosensors. However, these multicomponent, multistep nucleic acid amplification systems often suffer from low reaction efficiency and kinetics. Herein, inspired by the natural cell membrane system, we utilized the red blood cell membrane as a fluidic spatial-confinement scaffold to construct a novel accelerated reaction platform. By simply modifying with cholesterol, DNA components can be efficiently integrated into the red blood cell membrane through hydrophobic interactions, which greatly increases the local concentration of DNA strands. Moreover, the fluidity of the erythrocyte membrane improves the collision efficiency of DNA components in the amplification system. Based on the increased local concentration and improved collision efficiency, the fluidic spatial-confinement scaffold significantly improved the reaction efficiency and kinetics. Taking catalytic hairpin assembly (CHA) as a model reaction, an RBC-CHA probe based on the erythrocyte membrane platform enables a more sensitive detection of miR-21 with a sensitivity that is 2 orders of magnitude higher than the free CHA probe and a fast reaction rate (about 3.3-fold). The proposed strategy provides a new idea for the construction of a novel spatial-confinement accelerated DNA reaction platform.