Apparatus and method for detecting zinc ions

A method for determining the presence of prostate cancer or the risk for prostate cancer in an individual, said method comprising:

• determining an amount of free zinc in a fluid sample of an individual using a zinc ion detection apparatus, wherein the fluid sample comprises semen, expressed prostatic fluid, VB3 urine, or a mixture thereof;
• and
• determining the presence of prostate cancer or the risk for prostate cancer in the individual using the amount of free zinc determined from the fluid sample of the individual,
• wherein the zinc ion detection apparatus determines the zinc ion concentration in the fluid sample excluding zinc ions bound to proteins, peptides, amino acids and the zinc ions in spermatozoa or endothelial cells that maybe present in the fluid sample, and wherein the zinc ion detection apparatus comprises:
• 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;
• at least one sample-holding component adapted to hold a liquid sample in a pathway of the excitatory light;
• a photodetector for measuring fluorescent emission intensity generated by fluorescent reporter probe bound to zinc ion within the liquid sample;
• and
• 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.