Activating a DNA Nanomachine via Computation across Cancer Cell Membranes for Precise Therapy of Solid Tumors.

Taking advantage of cancer cells' endogenous characters, the responsive activation of DNA nanomachines has achieved great success in tumor therapy. Combining with extra stimuli such as external light irradiation provided spatiotemporal control of DNA nanomachine activation. However, specific activation at the cellular level is still challenging considering the macroscopic-scale exposure area of usual light sources. DNA logic gates located at the cell membrane contributed to cellular specificity, but the free diffusion of input DNA strands during the operation process would impair efficiency and result in side effects to circumjacent normal cells in solid tumors. Here we design a transmembrane DNA logical computation strategy to activate a DNA nanomachine only in cancer cells from a complex solid tumor microenvironment. The DNA nanomachine multishell UCNPs-DNA is prepared by modifying DNA strands on upconversion nanoparticles. LA-apt, a DNA strand anchoring to a cancer cell membrane overexpressed receptor, and intracellular miRNA-21 served as inputs 1 and 2, respectively. Hybridization with input 1 at the cell membrane not only exposes the miRNA-21 recognition region at the DNA nanomachine, but also delivers it into cancer cells. The cascade hybridization with intracellular input 2 completes the "AND" gate operation and releases a DNA strand L2 as output. L2 acts as the trigger to operate the DNA nanomachine and correspondingly activates the photosensitizer Rose Bengal for reactive oxygen species generation. Through the "AND" gate operation of the DNA nanomachine across the cancer cell membrane, highly precise therapy only to cancer cells is achieved in a complex solid tumor microenvironment, which could become a promising modality for precise therapy of solid tumors.