Self‐Assembled DNA Nanospheres Driven by Carbon Dots for MicroRNAs Imaging in Tumor via Logic Circuit

Abstract DNA nanostructures with diverse biological functions have made significant advancements in biomedical applications. However, a universal strategy for the efficient production of DNA nanostructures is still lacking. In this work, a facile and mild method is presented for self‐assembling polyethylenimine‐modified carbon dots (PEI‐CDs) and DNA into nanospheres called CANs at room temperature. This makes CANs universally applicable to multiple biological applications involving various types of DNA. Due to the ultra‐small size and strong cationic charge of PEI‐CDs, CANs exhibit a dense structure with high loading capacity for encapsulated DNA while providing excellent stability by protecting DNA from enzymatic hydrolysis. Additionally, Mg 2+ is incorporated into CANs to form Mg@CANs which enriches the performance of CANs and enables subsequent biological imaging applications by providing exogenous Mg 2+ . Especially, a DNAzyme logic gate system that contains AND and OR Mg@CANs is constructed and successfully delivered to tumor cells in vitro and in vivo. They can be specifically activated by endogenic human apurinic/apyrimidinic endonuclease 1 and recognize the expression levels of miRNA‐21 and miRNA‐155 at tumor sites by logic biocomputing. A versatile pattern for delivery of diverse DNA and flexible logic circuits for multiple miRNAs imaging are developed.