Calix[4]arene Based Redox Sensitive Molecular Probe for SERS Guided Recognition of Labile Iron Pool in Tumor Cells.

Targeting the intracellular "labile" iron pool is turned as a key modulator for cancer progression since the former is responsible for several pathological processes in tumor cells. Herein, we report a nonfluorescent calix[4]arene based triazole appended molecular probe (PTBC) for redox-specific detection of Fe3+ under physiological condition by UV-vis, FT-IR, 1H NMR, HR-MS spectroscopies, ITC, and the binding strategy between Calix[4]arene and Fe3+ was modeled by DFT calculations. As a new insight PTBC probe showed significant Raman fingerprint through surface enhanced Raman scattering (SERS) modality revealing the ultrasensitive detection of Fe3+ with a LOD of 2 nM. Interestingly, intracellular "iron pool" has been recognized in human lung adenocarcinoma cells (A549) by the PTBC illustrating the distinct Raman mapping. Finally, PTBC imparted cytotoxicity via reactive oxygen species (ROS) generation in cellular milieu signifies its capability as a theranostic molecular probe.