Fluorescent nanocrystal quantum dots as medical diagnostic tools

Semiconductor fluorescent or metallic nanocrystal quantum dots (QDs) engineered with the bottom-top approaches provide several unique properties that make them superior imaging probes or contrast agents. Targeted fluorescent QDs make possible previously unachievable sensitivity of detection by tagging them with biomarkers. Recent advances in the QDs' surface treatment and/or encapsulation have made them stable in crude biological fluids, tissues and in vivo applications.

To try to determine the main trends of fluorescent QD development in the next 5 years and identify the areas of medical diagnostics where their use will provide breakthrough results in the near future.

A brief overview is provided of techniques for preparing fluorescent QD conjugates to make them stable in biological environments, and their applications to detection of viruses, bacteria and in vitro and in situ molecular diagnostics are described. Emerging areas of fluorescent QDs in vivo applications and related cytotoxicity issues are reviewed in the last part of the paper.

The last generation of fluorescent QDs has far-reaching potential for high-resolution cellular imaging, long-term in vivo observation of cell and molecular trafficking, drug delivery and diagnostics. The most important findings and challenges of the next few years will include optimized 'anatomy' of QDs ensuring their optimal size and stability, solving of short-term and long-term toxicity issues in QD in vivo applications and development of QD-adapted imaging systems able to explore in full QD advantages over organic dyes.