Chemically based devices that are able to detect and/or measure the presence of certain molecules (e.g., DNA, antigens, pesticides, etc.). These devices are currently created in the following forms:
- A two-part diagnostic test that can detect the presence of trace amounts of specific chemicals (e.g., pesticides). The (chemical) biosensor consists of an immobilized enzyme (to bind the trace chemical) combined with a color reagent (to indicate visually the presence of the trace chemical).
- (2) A one-part test that can detect specific DNA segments in complex (“dirty,” multiple component) samples. The biosensor consists of 13-nm gold particles onto which are attached numerous nucleotide “molecular chains.” Each “nucleotide chain” contains twenty-eight nucleotides. The thirteen nucleotides that are closest to each gold particle serve as a “spacer,” and solutions containing such (spaced) randomly distributed gold particles appear red in color when illuminated by light. The fifteen nucleotides that are farthest from each gold particle are chosen to be complementary to, and thus bind to (complementary), nucleotide sequences in the target (e.g., DNA) molecule. In the presence of the specific target molecule, a closely linked network of gold particles and double-stranded nucleotide molecular chains forms (overcoming the 13-nucleotide “spacer” which previously held apart the gold particles). When double-stranded chains form (i.e., target molecule is present), the distance between gold particles becomes less than the size of those particles, which makes the solution containing (bound) particles appear blue in color when illuminated by light.