A hydrogel capsule could improve diagnosis of prostate cancer, according to Japanese researchers. Itaru Hamachi and colleagues at Kyoto University, have developed a robust hydrogel that can selectively detect prostate cancer cells as well as releasing a fluorescent drug into those cells upon binding. The mode of action is based on cleavage of the hydrogel capsule by an enzyme produced only by the cancerous tissue. Prostate cancer is a slow-developing disease that remains symptom-free in the early stages. Current diagnostics are not considered entirely reliable. The hydrogel has advantages over conventional polymer capsules because it is biodegradable and so holds much greater promise as a potential diagnostic and drug delivery vehicle.