Spatially Constrained DNA Nanomachines To Accelerate Kinetics in Response to External Input: Design and Bioanalysis

Cells take advantage of the spatial organization to accelerate the reaction kinetics of diverse components within a crowded intracellular environment. Inspired by this, we hereby designed a principle of spatial constraint to overcome limitations of response kinetics in DNAzyme-powered DNA nanomachines. First, we proposed the type-1 of spatially constrained DNA nanomachines (scDN-1) by co-localizing the aptamer probe and power unit (DNAzyme), allowing the DNA nanomachines to accomplish faster cyclic cleavage of DNAzyme as intramolecular reactions. To expand the scDN into the clinical practice, Type 2 spatially constrained DNA nanomachines (scDN-2) with constrained antibody probes were then constructed through Holliday junction assembly, which increased the effective local concentration to obtain the improved kinetics. With an accelerated response kinetics, this design principle allows DNA nanomachines to accomplish the response to tumor markers in real patients' samples within 30 min, significantly broadening the bioanalytical applications of DNA nanomachines to clinical practice.