Synthesis Of Novel AIE Probe/Photosensitizer And Its Application In Intracellular Imaging Assay Of Zinc Ions

Aggregation-induced emission?AIE?is a distinct photophysical phenomenon associated with chromophore aggregation.AIE chromophores may successfully overcome the drawback,aggregation-caused quenching?ACQ?,which conventional fluorophores consistently bear,resulting in strong fluorescenc e once molecules aggregate but no-emission as individual molecule.This concept was proposed in 2001and suffered a fierce development up to now,investigation of AIE mechanism and application of novel AIEgens for diverse fields have been great research focus at present.On account of the AIE mechanism,researchers have designed plentiful“turn-on”AIE probes possessing more reliable signal with lower background at the detection process.Meanwhile,irresponsive AIEgens perform no background signal and wash-free causing decrease of operation time and less loss of sample.And the aggregations constructed during detection always possess excellent photostability and resistance to photobleaching so that is available for long-time trace and monitor.Unfortunately,most reported AIEgens bear short excitation and emission wavelength strongly limiting the application of bioimaging.Accordingly,a novel two-photon excitation/red emission AIE chemsensor was designed and synthesized for successful detection of intracellular fluorescent imaging of exogenetic Zn²⁺.Furthermore,three new photosensitizers were prepared and their PDT function was also investigated,anticipating to provide a new route for diagnosis and therapy of internal tumors.Two specific studies were carried out:1.A new two-photon excitation/red-emission AIE chemsensor for zinc ion bioimaging in living cellsIn chapter 2,a new AIE chemsensor TPE-QB was designed and constructed based on the classical AIE molecule of tetraphenylethylene for succesful fluorescence bioimaging of exogenous zinc ion in HeLa cells via two-photon microscopy.In aqueous solution,dispersive TPE-QB molecule performed weak fluorescence emission,whereas recovered strongly red emission signal when Zn²⁺was added.The response mechanism is that Schiff base group of TPE-QB could form stable cHeLate with Zn²⁺and trigger the AIE activity to emit red fluorescence.And TPE-QB had high selectivity and sensitivity to Zn²⁺.2.Synthesis of novel AIE photosensitizers and investigation of the PDT performanceAccording to the design principle of AIE photosensitizer,a series of photosensitizers with high photosensitization rate were synthesized via extension of the conjugated structure and enhancement of the pushing-drawing effect in chapter 3.The generation of ¹O₂ in living cells and ablation of cancer cells were respectively studied.Otherwise,considering that conventional PDT consistently bothered by inferior penetration depth,a novel chemiluminescence-driven photosensitizer?CPS?was prepared by coupled reaction between a chemiluminescent group and a photosensitizer group to search a new route for PDT of tumors.