Walter Harrington
University of Arkansas at Little Rock, USA
Title: Photoswitchable nonfluorescent nanoprobes for tracking individual tumor and bacterial cells
Biography
Biography: Walter Harrington
Abstract
The development of photoswitchable fluorescent proteins with controllable light–dark states and spectral shifts in emission in response to light led to breakthroughs in study of cell biology. Nevertheless, conventional photoswitching is not applicable for weakly fluorescent proteins and is limited by low penetration of UV and visible light used into tissue, strong autofluorescent background, and phototoxicity concerns. As an alternative, photoacoustic (PA) imaging has demonstrated a tremendous potential in biomedical study of nonfluorescent cells and proteins. However, little progress has been made in the development of photoswitchable PA contast agents. Here, we introduce a novel concept of photoswitchable PA probes consisting of capsulated thermochromic dyes and absorbing nanoparticles, which can control light–dark states and spectral shifts in absorption in response to laser light. In these hybrid probes, temperature-sensitive dye absorption is photoswitched through laser heating of doped nanoparticles. The proof-ofconcept was demonstrated using near-infrared laser and two thermochromic dyes with magnetic nanoparticles that are reversibly photoswitched either from a colored light state to colourless dark state or from one colour to another. PA imaging provided visualization of these probes in solution and cells. We also propose photoswitching of plasmonic resonances in gold nanoparticle clusters through interparticle distance changes. A potential application of new nonfluorescent photoswitchable multicolour probes are discussed with focus on cellular diagnostics, tracking circulating tumor cells, viruses and bacteria, and magnetic and NIR photothermal therapy of cancer and infections.
