An Enzyme-Activable Noncovalent Fluorescent Probe Based on Water Soluble Azobenzene Containing Polymer and AIEgen

Abstract

Covalent connected fluorescent probe is often effective, but sometimes it is inevitable to adopt complex molecular design and tedious synthesis process. With the advantages of relatively simple operability and widespread generality, noncovalent strategy is gradually considered an ideal choice to solve this dilemma. In this work, an enzyme-activatable noncovalent fluorescent probe based on water soluble positively charged azobenzene containing poly(ethylene oxide)-b-poly[2-(methacryloyloxy)-N,N,N-trimethylethan-1-aminium iodide-co-(4-(4-dimethylamino)phenylazophenyl methacrylate)] (PEG-b-PQDMA-co-PAZOMA) and negatively charged 3,3′-(((2-(4-(2,2-dicyano-1-phenylvinyl)phenyl)-2-phenylethene-1,1-diyl)bis(4,1-phenylene))bis(oxy))bis(propane-1-sulfonate) (TPE-2SO3−) is reported. Due to the fluorescence resonance energy transfer process from aggregates induced emission donor to azobenzene acceptor, this probe is nearly non-emissive. After the reduction of azo bond by azoreductase under hypoxic condition, the probe emits strong fluorescence with long emission wavelength, realizing efficient off–on property. In addition, the cleavage of the azobenzene do not show influence on the morphology of the nano sized self-assemblies.