Optical nano agents in the second near infrared window for biomedical applications.
The optical technology presents non invasive, non destructive, and non ionizing features and has the ability to display various chemical components in tissues to provide useful information for various biomedical applications. Regarding selection of light wavelengths, second near infrared (NIR II, 900 1700 nm) light is a much better choice compared to both visible (380 780 nm) and traditional near infrared (780 900 nm) light, because of its advantages including deeper penetration into biological tissues, less tissue scattering or absorption, and decreased interference by fluorescent proteins. Thus, using optical nano agents that absorb or emit light in the NIR II window can achieve deeper tissue optical imaging with higher signal to background ratios and better spatial resolution for diagnosis. What's more, some of these nano agents can be further applied for imaging guided surgical removal, real time monitoring of drug delivery, labeling lymphatic metastasis, biosensing, and imaging guided phototherapy. In this review, we attempt to summarize the recent advances of various NIR II nano agents (including single walled carbon nanotubes, quantum dots, rare earth doped nanoparticles, other inorganic nanomaterials, small organic molecule based nanoparticles, and semiconducting polymer nanoparticles) in both bioimaging and therapeutic applications, and discuss the challenges and perspectives of these nano agents for clinical practice in the near future.
Chemical Society reviews