The prostate-specific antigen (PSA) found in blood samples is a well-known biomarker for prostate cancer. The functionalization of a gold sensor with a thiolated-DNA aptamer allowed for the detection of PSA using a quartz crystal microbalance in dissipation mode (QCM-D) with an affinity constant of 37 nM. These studies revealed not only the amount of PSA bound to the sensor, but also the structure and hydration of the aptamer layer (Formisano et al., 2015). The gene discussed is KLK3; the disease is Familial prostate cancer.