A stable lanthanide-functionalized nanoscale metal-organic framework as a fluorescent probe for pH

A fluorescent pH sensor based on post-synthetically modified nanoscale UiO-67-bpydc by encapsulating Eu 3+ cations in the pores was fabricated. The Eu 3+ incorporated sample (Eu 3+ @UiO-67-bpydc) shows excellent luminescence due to the sensitization and protection provided by the parented framework. Subsequently, Eu 3+ @UiO-67-bpydc was developed as a pH sensor. Eu 3+ @UiO-67-bpydc shows good chemical resistance to both acidity and alkalinity solutions with pH ranging from 1.06 to 10.99, which makes it potentially useful for wide-range pH sensor. In addition, cycling experiments have demonstrated the utilizability of the sensor. The MTT analysis shows that Eu 3+ @UiO-67-bpydc possesses favourable biocompatibility. Furthermore, fluorescence imaging of Eu 3+ @UiO-67-bpydc in PC12 cells was also performed to test its feasibility in vivo. Given its exceptional stability and pH-dependent fluorescent intensity, the fluorescent probe should be a promising candidate for application in fluorescent pH sensing in vitro and in vivo.