| 초록 |
In recent years, interest in stimuli-responsive materials is rapidly growing due to many potential applications in biotechnology such as target drug-delivery and molecular sensors. In particular, molecular sensors capable of detecting changes in environmental pH have been extensively sought for probing biological phenomena in living cells. The primary objective of this study is to development a new pH sensor molecule which shows a robust on-and-off pH sensitive characteristic in the efficiency of fluorescence resonance energy transfer (FRET). Sulfadimethoxine (SD) is chosen for pH sensitive moiety and is conjugated with acryloyl chloride to synthesize SD monomer (SDM). 7-Acetoxy-4-bromomethyl coumarin (abC) and coumarin 343 (C343) are selected as FRET donor and acceptor, respectively. For both enhanced water stability and biocompatibility, modified abC is conjugated with carboxylated poly(ethylene glycol) (PEG) to synthesize PEGylated abC (PabC) macroinitiator. SDM is then polymerized via atom transfer radical polymerization using PabC macroinitiator, which results in the pH sensitive polymeric backbone with FRET donor at one end. By generating hydroxyl group in the other end of the polymeric backbone, FRET acceptor is then conjugated with the hydroxyl group using carbodiimide coupling method. The resulting polymeric backbone undergoes a reversible pH-induced coil-globule transition at a specific pH point due to the unique properties of SD group, which suggests that the distance between FRET donor and FRET acceptor is controllable by changing the end-to-end distance of the polymeric backbone. FRET from abC to C343 is studied as a function of pH.
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