Use of quantum dots in the development of assays for cancer biomarkers.

Biomarker assays may be useful for screening and diagnosis of cancer if a set of molecular markers can be quantified and statistically differentiated between cancerous cells and healthy cells. Markers of disease are often present at very low concentrations, so methods capable of low detection limits are required. Quantum dots (QDs) are nanoparticles that are emerging as promising probes for ultrasensitive detection of cancer biomarkers. QDs attached to antibodies, aptamers, oligonucleotides, or peptides can be used to target cancer markers. Their fluorescent properties have enabled QDs to be used as labels for in-vitro assays to quantify biomarkers, and they have been investigated as in-vivo imaging agents. QDs can be used as donors in assays involving fluorescence resonance energy transfer (FRET), or as acceptors in bioluminescence resonance energy transfer (BRET). The nanoparticles are also capable of electrochemical detection and are potentially useful for "lab-on-a-chip" applications. Recent developments in silicon QDs, non-blinking QDs, and QDs with reduced-size and controlled-valence further make these QDs bioanalytically attractive because of their low toxicity, biocompatibility, high quantum yields, and diverse surface modification flexibility. The potential of multiplexed sensing using QDs with different wavelengths of emission is promising for simultaneous detection of multiple biomarkers of disease.