Porphyrin Dyes for Nonlinear Optical Imaging of Live Cells

• Published in: iScience Vol. 4; pp. 153 - 163
• Main Authors: Khadria, Anjul, Fleischhauer, Jan, Boczarow, Igor, Wilkinson, James D., Kohl, Michael M., Anderson, Harry L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 29.06.2018; Elsevier
• Subjects: Chemistry; Imaging Methods in Chemistry; Nonlinear Optics; Organic Synthesis; Imaging Methods in Chemistry; Chemistry; Nonlinear Optics; Organic Synthesis
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2018.05.015

Second harmonic generation (SHG)-based probes are useful for nonlinear optical imaging of biological structures, such as the plasma membrane. Several amphiphilic porphyrin-based dyes with high SHG coefficients have been synthesized with different hydrophilic head groups, and their cellular targeting has been studied. The probes with cationic head groups localize better at the plasma membrane than the neutral probes with zwitterionic or non-charged ethylene glycol-based head groups. Porphyrin dyes with only dications as hydrophilic head groups localize inside HEK293T cells to give SHG, whereas tricationic dyes localize robustly at the plasma membrane of cells, including neurons, in vitro and ex vivo. The copper(II) complex of the tricationic dye with negligible fluorescence quantum yield works as an SHG-only dye. The free-base tricationic dye has been demonstrated for two-photon fluorescence and SHG-based multimodal imaging. This study demonstrates the importance of a balance between the hydrophobicity and hydrophilicity of amphiphilic dyes for effective plasma membrane localization. [Display omitted] •Amphiphilic porphyrin dyes with different hydrophilic head groups are synthesized•Necessity of balance between hydrophobicity and hydrophilicity for membrane dyes•Far-red to NIR absorbing dyes for multimodal and SHG-only imaging are presented•SHG from a dye labeling the intracellular organelles of live cells is shown Chemistry; Organic Synthesis; Imaging Methods in Chemistry; Nonlinear Optics