MicroRNAs (miRs) are frequently found to be deregulated in bodily fluids of cancer patients and have great potential for early-stage diagnosis. Surprisingly, there is currently no cancer diagnostic test based on miR detection. Here, we will apply DNA nanotechnology to build “artificial cells” for multiplexed detection and quantitation of cancer-related miRs in patient samples. The technology will be tested in vitro on miRs overexpressed in prostate cancer, and then with cancer-patient serum or plasma, potentially unlocking a new non-invasive diagnostic route for a disease where early detection is particularly critical. The biocompatible artificial cells will then be further engineered to release therapeutic payloads upon miR detection, thus laying the foundations for a future therapeutic platform where ACs could be deployed in vivo as a targeted, low-toxicity cancer treatment activated by local miR upregulation.