Human serum albumin-based supramolecular host-guest boronate probe for enhanced peroxynitrite sensing.

Peroxynitrite (ONOO) is an important oxygen/nitrogen reactive species implicated in a number of physiological and pathological processes. However, due to the complexity of the cellular micro-environment, the sensitive and accurate detection of ONOO remains a challenging task. Here, we developed a long-wavelength fluorescent probe based on the conjugation between a TCF scaffold and phenylboronate; the resulting conjugate is capable of supramolecular host-guest assembly with human serum albumin (HSA) for the fluorogenic sensing of ONOO. The probe exhibited an enhanced fluorescence over a low concentration range of ONOO (0-9.6 μM), whist the fluorescence was quenched when the concentration of ONOO exceeded 9.6 μM. In addition, when human serum albumin (HSA) was added, the initial fluorescence of the probe was significantly enhanced, which enabled the more sensitive detection of low-concentrations of ONOO in aqueous buffer solution and in cells. The molecular structure of the supramolecular host-guest ensemble was determined using small-angle X-ray scattering.