Facile synthesis,optical properties,and live cells imaging of two novel hydrophilic two-photon fluorophores with long-wavelength emission

Two novel organic compounds, TPIM1 and TPIM2, with hydroxyl terminal hydrophilicity groups, have been designed and synthesized. Their one- and two-photon photophysical properties have been experimentally investigated, and emission wavelengths are 591 and 595 nm in phosphate buffered saline (PBS), respectively. The two-photon action cross-sections of two compounds were estimated by two-photon excited fluorescence technique using 200 fs, 76 MHz, Ti-sapphire laser, which are 95 and 70 GM for TPIM1 and TPIM2 in PBS, respectively. The photostability and cytotoxicity were evaluated to demonstrate the potential utility of TPIM1 as a suitable standalone fluorophore for live cells two-photon fluorescence biological imaging. TPFM imaging results demonstrate that HepG2 treated with 10 μM TPIM1 provides bright images with negligible toxicity.