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Molecular computing holds great promise for diagnosis and treatment of diseases at the molecular level; nevertheless, designing molecular logic gates to operate programmably and autonomously for molecular diagnostics still remains challenging. We designed logic gates on DNA Origami for microRNA analysis. As a demonstration, two indicators of heart failure, microRNA-21 and microRNA-195, were selected as the logic inputs. The logic gates contain two main modules: computation module and output module, performing in a single DNA Origami nanostructure. The computation module recognizes disease indicators, while the output module display different nanoscale symbols, "+" (positive) or "-" (negative), depending on the computing results. We demonstrated that the molecular logic gates worked well with single and two input combinations. [ABSTRACT FROM AUTHOR]

Self-assembled DNA origami nanostructures have shown great promise for bottom-up construction of complex objects with nanoscale addressability. Here we show that DNA origami-based 1D nanoribbons and nanotubes are one-pot assembled with controllable sizes and nanoscale addressability with high speed (within only 10-20 min), exhibiting extraordinarily high cooperativity that is often observed in assembly of natural molecular machines in cells (e.g. ribosome). By exploiting the high specificity of DNA-based self-assembly, we can precisely anchor proteins on these DNA origami nanostructures with sub-10 nm resolution and at the single-molecule level. We attach a pair of enzymes (horseradish peroxidase and glucose oxidase) at the inner side of DNA nanotubes and observe high coupling efficiency of enzyme cascade within this confined nanospace. Hence, DNA nanostructures with such unprecedented properties shed new light on the design of nanoscale bioreactors and nanomedicine and provide an artificial system for studying enzyme activities and cascade in highly organized and crowded cell-mimicking environments. [ABSTRACT FROM AUTHOR]