Synthesis Of9,10-Distyrylanthracene Deirvatives With Aggregation-Induced Emission Characteristics And Their Application In Fluorescent Probes

Development of highly efficient fluorescent materials to be used inelectroluminescent devices, optical sensors, and bioimaging has caused significantscientific interests. Fluorescence (FL) chemo-/biosensors have received greatattention due to their potential applications in chemistry, materials science, biology,and medicine. Upon binding with ions or neutral organic or inorganic molecules, FLof the sensors can be enhanced/quenched and/or hypsochromic/bathochromic-shifted,thus enabling visual observation of the analytes. However, FL dyes tend to aggregatewhen dispersed in aqueous media or bound to the analytes in large quantities. Theaggregation often quenches FL, which results in drastic reductions in their FL signals.This aggregation-caused quenching (ACQ) has been a thorny problem in thedevelopment of efficient FL sensory systems, especially in bioassays of traceamounts of biomolecules. Thus, there is a high demand for the development of simpleand stable FL sensors without ACQ.Recently, materials with aggregation-induced emission (AIE) properties haveattracted more and more attention, because they offer an efficient path to the solutionof this spiny problem of ACQ. Since the first AIE-active material1-methyl-1,2,3,4,5-pentaphenylsilole was reported by Tang' s group, manyAIE-active dyes have been developed by various research groups, such as TPE, CN-MBE,cis-DPDSB,PPB derivatives, conjugated polymers and others. The AIEdyes are highly emissive in the solid state and hence are mainly used for theconstruction of organic light-emitting diodes. In the past few years, application ofAIE molecules in building new chemo-/biosensors has attracted significant scientificinterests. In biological research fields, AIE fluorophores have been widely exploredas sensors for DNA, heparin, ATP, pH, CO2, and glucose. However, until now, thestudies of utilizing AIE dyes as FL sensors mainly concentrate on TPE derivativesand silole derivatives, so that developing new AIE-active sensory materials would bevery rewarding work. And fewer studies were reported about the applications of theAIE fluorophores as bioimaging probes than those about light emitting diodes andbiosensors. Therefore, we synthesized some new AIE-active DSA derivatives, andexplored their utilities as pH sensor and bioimaging probes based on AIEcharacteristics.1. Novel Fluorescent pH Sensors and Biological Probe Based on AnthraceneDerivatives with Aggregation-induced Emission CharacteristicsIn this study, three functionalized9,10-distyrylanthracene (DSA) derivatives,namely,9,10-bis(4-hydroxystyryl)anthracene (4),9,10-bis{4-[2-(diethylamino)-ethoxy]styryl}anthracene (6), and9,10-bis{4-[2-(N,N,N-triethylammonium)eth-oxy]styryl}anthracene dibromide (7), were synthesized and their fluorescence propertieswere investigated. The three DSA derivatives possess a typical AIE property. Dye4isa phenol moiety-containing compound, which shows aggregations at pH values ofsmaller than10to result in its high fluorescence intensity.6is amine containingcompound, which starts to aggregate at slightly basic conditions resulting a pKa of6.90. Dye7is ammonium salt containing compound, it can interact strongly withprotein or DNA to amplify its emission, thus7is a fluorescent turn "on" biologicalprobe for protein and DNA detection. And it is also selective, which works for nativeBSA and ct DNA but not their denatured forms. Therefore we not only developed afew new compounds showing the AIE phenomena, but also controlled the AIEthrough an environmental stimulation and demonstrated the new AIE molecules aresuitable for pH and biomacromolecules sensing.2. A series of poly[N-(2-hydroxypropyl)methacrylamide] copolymers with anthracene-derived fluorophores showing aggregation-induced emission propertiesfor bioimagingIn this work, a series of new poly[N-(2-hydroxypropyl)methacr-ylamide]-basedamphiphilic copolymers were synthesized through a radical copolymerization of amonomeric/hydrophobic fluorophore possessing AIE property withN-(2-hydroxypropyl)meth-acrylamide. Influences of the polymer structures withdifferent molar ratios of the AIE fluorophores on their photophysical properties werestudied. Results show that the AIE fluorophores aggregate in the cores of the micellesformed from the amphiphilic random copolymers and polymers with morehydrophobic AIE fluorophores facilitate stronger aggregations of the AIE segments toobtain higher quantum efficiencies. The polymers were endocytosed by twoexperimental cell lines, human brain glioblastoma U87MG cells and humanesophagus premalignant CP-A, with a distribution into the cytoplasm. The polymersare non-cytotoxic to the two cell lines at a polymer concentration of1mg/mL.3. Using fluorine-containing amphiphilic random copolymers to manipulate thequantum yields of aggregation-induced emission fluorophores in aqueous solutionsand the use of these polymers for fluorescent bioimagingIn this work, two new series of AIE fluorophore-containing amphiphiliccopolymers possessing the segments of a monomeric AIE fluorophore,N-(2-hydroxypropyl)methacrylamide (HPMA),[2-(methacryloyloxy)ethyl]trim-ethylammonium chloride (MATMA), and/or2,2,2-trifluoroethyl methacrylate(TFEMA) were synthesized. The increases of molar fractions of the hydrophobic AIEfluorophores and/or the trifluoroethyl moieties result in the higher quantum yields ofthe AIE fluorophores in the polymers. Using1-mol%of AIE fluorophores with thetuning of molar fractions of TFEMA,40%quantum yield was achieved. The quantumyield difference indicates the importance of the fluorine segments for getting highquantum yields of the AIE fluorophores. These polymers were explored forfluorescent bioimaging using human brain glioblastoma U87MG and humanesophagus premalignant CP-A cell lines. All the polymers are cell permeable andlocated in the cellular cytoplasma area. The polymers are non-cytotoxic to the twocell lines. Because the polymers contain19F segments, we studied the spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) of these polymers. These newmultifunctional materials are the first series of fluorinated polymers with AIEfluorophores for bioapplications.