Rotors of BOSCHIBAs as endoplasmic reticulum fluorescent probes in HeLa and human umbilical vein endothelial cells

Abstract

The fluorescence imaging technique is becoming a useful tool in the natural and life sciences. Commercial biomarkers are available; however, some disadvantages exist like high isolation cost, low-temperature storage, photodegradation, and low yields. Here two new fluorescent molecular rotors (SB-B 2 and SB-B2 3) derived from Boron Schiff bases (BOSCHIBAs) were synthesized and characterized by NMR (¹H and ¹³C), UV/Vis, and fluorescence spectroscopy. The crystal structure of SB-B2 3 by X-ray diffraction showed a binuclear complex and C₂ symmetry. Both compounds showed viscochromic and thermochromic properties. The binuclear rotor 3 showed a greater luminescence intensity increase than the mononuclear one at the highest level of viscosity (90%). From the remarkable findings and to our best knowledge this is the first time low cytotoxicity BOSCHIBAs exhibit selective fluorescent staining of endoplasmic reticulum in HeLa cells and HUVECs.