Abstract: The present invention provides apparatuses and methods for determining zinc ion concentration in a fluid sample. Some apparatuses of the invention include (i) a light source designed to emit an excitatory light at a first known wavelength that activates a fluorescent emission having a second and different wavelength by at least one selected fluorescent reporter probe that generates a different fluorescent response when bound to zinc ion; (ii) at least one sample-holding component adapted to hold a liquid sample in a pathway of the excitatory light; (iii) a photodetector for measuring fluorescent emission intensity generated by fluorescent reporter probe bound to zinc ion within the liquid sample; and (iv) electronic means for creating a data signal that correlates with fluorescent emission intensity generated by fluorescent reporter probe bound to zinc ion in the liquid sample to the free zinc ion concentration.

Abstract: The present invention provides devices, kits, and methods for determining the zinc level in a fluid sample of a subject. Such determination is useful in screening for the presence of or the increased risk of having prostate cancer.