Patent ID: 8642260

Claim:
A signal-off-quantum-dot-based sensor for detecting the presence of a target entity comprising: an aptamer probe having a nucleotide sequence which specifically interacts with the target entity, wherein the aptamer probe is sandwiched between (a) a tagged-oligonucleotide which is capable of being immobilized on the surface of a quantum dot (QD), and (b) an oligonucleotide labeled with a fluorophore, designated as “FP-oligonucleotide,” wherein when the sensor is excited by an energy source: (i) in the absence of specific interaction between the target entity and the aptamer probe, a baseline signal is emitted, and (ii) in the presence of specific interaction between the target entity and the aptamer probe, a detection signal is emitted, wherein if the baseline signal is a stronger fluorescence signal than the detection signal, the presence of the target entity is detected.