Development of a new pyridinium probe for the detection of zinc ions and monitoring autophagy

Development of molecular probes for imaging various analytes in biological tissues and cells has high importance in the modern disease diagnostics, therapy monitoring and patient management. Zinc is one of the most abundant transition metals present in human body and evidence suggest that it plays crucial role in autophagy process. Herein, we report a new, rigid pentacyclicpyridinium based probe, PYD-PA having a pendant N,N-di(pyridin-2-ylmethyl)amine(DPA) for Zn²⁺ ion detection in cellular environment. The pyridinium moiety itself serves as mitochondria targeting unit and DPA act as the coordination site for Zn²⁺.The probe exhibited highly selective response to Zn²⁺ over other biological metal ions, good water solubility, photostability, pH insensitivity, and low cytotoxicity. The demonstration of bioimaging in L6 cell lines of rat confirmed intracellular Zn sensing ability of the probe. Furthermore,the probe was successfully applied for sensitively monitoring the fluctuation of intracellular free zinc ions in real time during autophagy condition