Engineering Logic DNA Nanoprobes on Live Cell Membranes for Simultaneously Monitoring Extracellular pH and Precise Drug Delivery.

It remains a challenge to use a single probe to simultaneously detect extracellular pH fluctuations and specifically recognize cancer cells for precise drug delivery. Here, we engineered a tetrahedral framework nucleic acid-based logic nanoprobe (isgc8-tFNA) on live cell membranes for simultaneously monitoring extracellular pH and targeted drug delivery. Isgc8-tFNA was anchored stably on the cell surface through three cholesterol molecules inserting into the bilayer of the cell membrane. Once responding to the acidic tumor microenvironment, isgc8-tFNA formed an i-motif structure, leading to turn-on FRET signals for monitoring changes of extracellular pH. The nanoprobe exhibited a narrow pH-response window and excellent reversibility. Moreover, the nanoprobe could execute logic identification on the cell surface for precise drug delivery. Only if both in the acidic microenvironment and aptamer-targeting marker are present on the cell surface, the sgc8-ASO-chimera strand, carrying an antisense oligonucleotide drug, was released from the nanoprobe and entered into targeted cancer cells for gene silence. Additionally, the in situ drug release facilitated the uptake of drugs mediated by the interaction between sgc8 aptamer and membrane proteins, resulting in enhanced inhibition of cancer cell migration and proliferation. This logic nanoprobe will provide inspiration for designing smart devices for diagnosis of pH-related diseases and targeted drug delivery.