Sensitive Detection of Sulfur Dioxide by Constructing a Protein Supramolecular Complex: a New Fluorescence Sensing Strategy

In this work, a new dye (DAC-CPO) with typical donor-π-acceptor (D-π-A) structure was designed, which could enter the IB subdomain of human serum albumin (HSA) and form the host–guest supramolecular system. Formation of the HSA/DAC-CPO complex was confirmed by the competitive displacement experiments and the molecular-docking study. DAC-CPO alone had no response to sulfur dioxide (SO 2 ), while the HSA/DAC-CPO complex displayed an obvious increased fluorescence response and remarkable blue-shifted emission to SO 2 . The sensitive detection method of SO 2 in aqueous solution was developed with the linear range of 0.5 ~ 4.0 μM. Spectrum data of polarity and viscosity showed that formation of the complex hindered the internal charge-transfer (ICT) process and restricted the rotation of the dye, resulting in the speed increase of reaction between the dye and SO 2 . In addition, the HSA/DAC-CPO complex had also been successfully used for rapid detection of SO 2 in actual samples.