Advances in Imaging Reactive Oxygen Species

Abstract

Reactive oxygen species (ROS) play a pivotal role in many cellular processes and can be either beneficial or harmful. The design of ROS-sensitive fluorophores has allowed for imaging of specific activity and has helped elucidate mechanisms of action for ROS. Understanding the oxidative role of ROS in the many roles it plays allows us to understand the human body. This review provides a concise overview of modern advances in the field of ROS imaging. Indeed, much has been learned about the role of ROS throughout the years; however, it has recently been shown that using nanoparticles, rather than individual small organic fluorophores, for ROS imaging can further our understanding of ROS.

Keywords: ROS; animal imaging; chromophores; imaging; molecular imaging; radicals.

FIGURE 1.

Modification of hydrocyanines for increased stability and in vivo sensitivity. (A) Structure of recently reported thiophene-bridged hydrocyanines (THBC). (B) Increase in stability of THBC toward autooxidation in phosphate-buffered saline. (C) Increase in stability of active thiophene-bridged cyanines (gray) toward ROS-dependent degradation, compared with Cy3 (orange). Graph represents percentage of probe intact after incubation with 250 μM of indicated ROS. (Reprinted from Maity et al. (6).)

FIGURE 2.

(i) Illustration of HCy5 (ROS) and Cy7 (RNS) on upconversion nanocrystal (UCN) surface. In presence of ROS, nonfluorescent HCy5 is converted into fluorescent Cy5, whereas in presence of RNS, fluorescent Cy7 decomposes, causing signal reduction at 800 nm. (ii) Schematic representation of UCN in live mice for bioimaging. MSQT = multispectral optoacoustic tomography; UCL = upconverted luminescence. (Reprinted from Ai et al. (32).)