Rational design of a negative photochromic spiropyran-containing fluorescent polymeric nanoprobe for sulfur dioxide derivative ratiometric detection and cell imaging

It is highly desirable to develop high-performance ratiometric fluorescent probes for SO 2 derivative detection and realize their application in biological imaging. In this study, we report the rational design of a novel negative photochromic spiropyran derivative, spiro[azahomoadamantane-pyran] (MAHD-SP), with notable orange fluorescence in its stable ring-opened state without UV regulation. The unsaturated double bond of MAHD-SP underwent the Michael addition reaction of the SO 2 derivative, making the fluorescence quenching of MAHD-SP obvious. Then, MAHD-SP, a fluorescent conjugated polymer PFO and a polymeric surfactant PEO 113 - b -PS 49 were used to construct a ratiometric fluorescent polymeric nanoprobe ( RFPN ) via a coprecipitation method. The probe exhibited high sensitivity and selectivity for the ratiometric detection of SO 2 derivatives in pure aqueous solutions. Moreover, the good biocompatibility of RFPN can be used to visualize exogenous and endogenous SO 2 derivative generation in living cells. Graphical abstract