Using Some Nanoparticles as Contrast Agents for Optical Bioimaging

The introduction of nanometric contrast agents to optical imaging is helpful for the understanding of some biological processes at the molecular level, as well as the development of diagnostic tools and therapies. Optical imaging agents such as gold nanorods (GNRs), quantum dots (QDs), and organically modified silica (ORMOSIL) nanoparticles can overcome many drawbacks of conventional agents, such as poor contrast, photobleaching, and low chemical and optical stability in biological environment. These nanoparticles can also be developed for absorbance, emission, and scattering in the near-IR region, which allows optical approaches for deep-tissue real-time imaging. The synthesis methods and optical properties of GNRs, QDs, and ORMOSIL nanoparticles are briefly introduced, and some of their applications in optical bioimaging are demonstrated. Specific targeting, “green” synthesis methods, and optical signal demodulation are also introduced.