Lanthanide coordination polymer probe for time-gated luminescence sensing of pH in undiluted human serum

Lanthanide coordination polymers (LCPs) have emerged as fascinating materials because of their specific structure and properties. In this work, utilizing hydrosoluble biomolecule of guanosine-5'-monophosphate (GMP) as bridging linker, lanthanide terbium ions (Tb³⁺) as metal nodes, and silver ions (Ag⁺) as sensitizers, we synthesized a pH responsive luminescent lanthanide CP probe of Tb/GMP/Ag. The probe possesses high luminescence due to the sensitization of Ag⁺; While in alkaline solutions, Ag⁺ in Tb/GMP/Ag immediately binds to OH^-, forming Ag₂O precipitation and resulting in a distinct fluorescence quenching of Tb/GMP/Ag. This probe displays high selectivity for OH^- and a broader pH detection range of 7.5-13.0. In addition, based on the high anti-interference ability in serum, we applied Tb/GMP/Ag to measure pH in undiluted human serum samples, yielding satisfactory results.