This is interesting. Sure it has only been tested on mice, but interesting none the less.
Earlier detection of disease could help improve response to therapy. Blood calcium concentrations are elevated in several types of cancer, in addition to other diseases. Here, Tastanova et al. used synthetic biology and cell engineering to develop a sensor that detects hypercalcemia. Their implantable sensor consists of cells that express the calcium-sensing receptor and produce melanin in response to sustained elevated calcium in the blood.