Monitoring copper ions in C. elegans using porphyrin phosphonic acids

Abstract

Herein we report a charge-assisted hydrogen bonded organic framework (HOF) built with an extended tethered phosphonic acid namely 5,10,15,20-Tetra-(4’-yl-[1’,1”-biphenyl]−4”phosphonic acid) porphyrin (p-H8-TBPPA) and phenyl phosphonic acid (PPA). Metal responsive fluorescent properties of the linker p-H8-TBPPA with biologically significant transition metal ions (Zn2+, Cu2+, Ni2+, Co2+, Fe2+, Mn2+) and heavy metal ions (Hg2+, Pb2+, Cd2+) is further characterized. p-H8-TBPPA shows distinct fluorescence responses for each metal ion with very specific decreases in intensity for the different analytes, and the strong turn off fluorescence of p-H8-TBPPA in presence of copper is used to monitor copper ion homeostasis in C. elegans. p-H8-TBPPA is also found to be non-toxic for Caco-2 cells and C. elegans at concentrations required for fluorescence measurements. These findings establish p-H8-TBPPA as a promising platform for the development of in vivo metal ion sensors, with potential applications in diagnostic imaging, and environmental monitoring.