[Show abstract][Hide abstract] ABSTRACT: Hydrogen sulfide (H2S) is accepted as a third “gasotransmitter’’ of human physiology and pathology but remains difficult to study, in large part because of the lack of methods for selective monitoring of this small signaling molecule in live biological specimens. We now report a new reaction-based polymeric fluorescent sensor for selective imaging of H2S in living cells. A novel functional monomer, 2-allyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinoline-6-sulfonyl azide (AISA) was firstly synthesized and copolymerized with styrene to obtain a polymeric fluorescent sensor material. AISA and poly(styrene-co-AISA) (PSAISA) showed fast turn-on fluorescence signal enhancement and high selectivity for hydrogen sulfide (H2S) over other biologically relevant species including HSO3-, SO42-, S2O32- and cysteine. Furthermore, upon reaction with H2S, PSAISA gave a strong spectral response changing from colorless to bright yellow. The data of FT-IR and 1H NMR confirmed that the fluorescence enhancement of PSAISA was caused by the reduction of sulfonyl azide to sulfonamide groups in the presence of H2S. This property was successfully used to image H2S in living cells, thus demonstrating the potential of this material in biosensor applications.
[Show abstract][Hide abstract] ABSTRACT: Well-controlled polymerization of N-vinylpyrrolidone (NVP) on Au surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP) was carried out at room temperature by a silanization method. Initial attempts to graft poly(N-vinylpyrrolidone) (PVP) layers from initiators attached to alkanethiol monolayers yielded PVP films with thicknesses less than 5 nm. The combined factors of the difficulty in the controllable polymerization of NVP and the instability of alkanethiol monolayers led to the difficulty in the controlled polymerization of NVP on Au surfaces. Therefore, the silanization method was employed to form an adhesion layer for initiator attachment. This method allowed well-defined ATRP polymerization to occur on Au surfaces. Water contact angle, X-ray photoelectron spectroscopy (XPS), and reflectance Fourier transform infrared (reflectance FTIR) spectroscopy were used to characterize the modified surfaces. The PVP-modified gold surface remained stable at 130 °C for 3 h, showing excellent thermal stability. Thus, postfunctionalization of polymer brushes at elevated temperatures is made possible. The silanization method was also applied to modify SPR chips and showed potential applications in biosensors and biochips.