ortho-Substituted fluorescent aryl monoboronic acid displays physiological binding of d-glucose

An ortho-fluorinated phenylboronic acid incorporated into the BODIPY-fluorophore, sensor 1, exhibits a significant response in emission intensity upon binding of d-glucose and d-fructose. This sensor displays a desired binding strength toward d-glucose at the physiological level, that is Kd values between 10 and 20 mM. This binding strength of sensor 1 has been shown to be independent of the employed buffer, that is, saline buffer, 50 mM phosphate buffer, and 50 mM phosphate buffer in 52.3 w/w% MeOH. The d-glucose binding strength and the fluorescence response of a BODIPY-based ortho-methylated phenylboronic acid, sensor 2, show a significantly decreased d-fructose binding affinity. This sensor also exhibits buffer-dependent binding strength and fluorescence response upon binding of d-glucose and d-fructose.