Dosing potent drugs is still largely guesswork refined by occasional blood tests, each giving a single snapshot of a constantly changing system. For medicines with a narrow therapeutic window, such as the antibiotic vancomycin, the gap between an effective dose and a harmful one can be small and varies between patients. KAUST engineers have built a wearable alternative: a microneedle patch that reads drug levels continuously from dermal interstitial fluid.
Each needle in the array lightly penetrates the outer skin and is coated with a DNA aptamer that changes shape when vancomycin binds, producing an electrochemical signal. A miniature potentiostat designed by the team converts the signal into a concentration estimate and streams it wirelessly to a smartphone app. In mouse experiments reported in the journal Device, the sensor tracked drug levels through repeated dosing over four hours, and bench tests in artificial interstitial fluid showed stability for up to ten hours.
Tellingly, vancomycin levels differed clearly between individual animals, precisely the variation that sporadic blood draws miss. The platform, developed in Khaled Salama's Sensors Lab, is not yet ready for the clinic: longer-term stability and biocompatibility studies remain. But the aptamer chemistry can in principle be swapped for other drugs, suggesting a general route to minimally invasive therapeutic monitoring at the bedside or at home.