| Malignant tumor is now one of the most important diseases affecting human health. The appearance of tumor markers brings more hope to the early diagnosis of malignant tumor. Fluorescent probes are frequently used tools in optical bio-imaging technology, and they are meaningful in the aspect of tumor assistant diagnosis, the evaluation of tumor diagnosis, tumor prognosis and drug efficacy. However, traditional fluorescent probes are facing the phenomenon of aggregation fluorescence quenching(ACQ), which limits the range of concentration needed to achieve sensitivity, greatly reducing the efficiency of fluorescence labeling. Thus fluorescence probes functionalized with aggregation induced emission(AIE) features timely remedy the shortages faced by the traditional fluorescent molecules, which show new features in target identification and biological imaging, owning advantages of lower background, high signal to noise ratio and excellent resistance to photo bleaching performance. Lysosomal organelles of cancer cells and common cancer tumor marker MicroRNA-21 are chosen as our research objects. Fluorescent probes based on tetraphenylethylene(TPE) are designed and optical performance and capability in cell imaging are also been studied. The results showed they can not only overcome the ACQ phenomenon but also successfully detect our research objects, providing a new research platform to the development of biological sensors. The main research contents are as follows:1. A tetra-phenylethylene(TPE) based lysosome-targetable fluorescence probe TPE-CA was synthesized, which could selectively monitor pH change and exhibited a strong blue emission under acidic condition. Using crystallographic, analyses, mechanism about pH-sensitive fluorescent performance of TPE-CA have been illustrated at molecular level. Besides, experiment results show that TPE-CA is cell-permeable and biocompatible to HeLa, MCF-7 and HLF cells. The punctate fluorescent spots in co-staining experiment of TPE-CA with LTG and LTR proves that TPE-CA are indeed localized in the most acidic lysosomes organelles. In particular, TPE-CA also inherits the aggregation-induced emission(AIE) feature of TPE, showing better photo stability under continuous UV illumination compared with the commercial dyes(LTG and LTR). These results show that TPE-CA would be benefit to understand the acid environment of lysosomes in related cells and organs with potential biological significance.2. We utilize a facile probe based yellow emission AIEgens with super photo-stable property but without quencher, which are applied to monitoring miRNAs not only from urine sample extracts(in vitro) but also in live cells(in vivo). The assay could distinguish the cancer patients‘ urine samples and the normal persons‘ due to the good specificity. Moreover, the probe showed much higher fluorescence intensity in breast cancer cells(MCF-7, MicroRNA-21 in high expression) than that in cervical cancer cells(HeLa) and human lung fibroblast cells(HLF, MicroRNA-21 in low expression) in more than 60 minutes, which showed the good performance and super photo-stability for the probe in vivo. As controls, base mismatch and other RNA sequences are used to verify the good specificity. Another two probes with FAM/ Cy3 and corresponding quenchers respectively, could perform miRNAs detections in vitro, and parts of in vivo tests but not suitable for the long-term cell tracking due to the photo-bleach phenomena, which also demonstrates that the probe with AIEgens is the potential candidate for the accurate identification of cancer biomarkers. |
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