Immobilization of a boronic receptor for fructose recognition: influence on the photoinduced electron transfer process

The work presented here describes the synthesis on different solid supports of a luminescent probe, dansylphenylboronic acid (DPBA) for use in fructose recognition. While in aqueous solution DPBA changes its fluorescence in response to added fructose via a photoinduced electron transfer (PET) mechanism, we have found that once immobilized the fructose binding event could not be monitored by a change in fluorescence. It was observed, however, that the immobilized DPBA displayed enhanced acidity upon binding of fructose. The system was indeed selective for fructose in competitive binding experiments, preferring fructose over glucose. It is demonstrated that design of immobilized fluorescent sensors for fructose, based on a PET mechanism, is not an easy task due to the chemical and spectral changes experienced by the fluorescent probe upon immobilization.