Highly Selective Analysis Based On Aggregation-induced Emission

Molecular recognition regulates almost all life processes. To sense, probe and make use of such microscopic molecular events, analytical chemistry plays vital roles. Discovery of new molecular recognition system, and development of novel analytical methods and detection techniques are becoming the hot spots in the field of modern analytical chemistry. Aggregation-Induced Emission(AIE) effectively overcomes the disadvantages of conventional fluorophores in low signal-to-noise ratio and limited sensitivity, therefore provides a new insight to the analysis of bioactive species in complex biosystems. In this dissertation, by taking advantage of the unique AIE effect and molecular recognition, highly selective and sensitive methods were developed based on novel fluorescence turn-on probes.The deleterious effect of Al3+ toward biospheres and human health calls urgently for effective Al3+-specific fluorescence sensors, which however is still challenging arising from relative weak coordination and strong hydration abilities of Al3+. To this end, a new fluorescence turn-on chemosensor 2-(4-(1,2,2-triphenylvinyl)phenoxy) acetic acid(TPE-COOH) specific for Al3+ was presented by combining the aggregationinducede mission(AIE) effect of tertaphenylethylene and the complexation capability of carboxyl. The introduction of carboxylic group provides the probe with good watersolubility which is important for analyzing biological samples. The recognition toward Al3+ induced the molecular aggregation and activated the blue fluorescence of the TPE core. The high selectivity of the probe was demonstrated by discriminating Al3+ over a variety of metal ions in a complex mixture. A detection limit down to 21.6 n M was determined for Al3+ quantitation, which below the detection limit of most reported Al3+ probe. The recognition mechanism was further investigated by competitive binding assays, transmission electron microscope(TEM), Fourier transform infrared spectrometer(FT-IR), and nuclear magnetic resonance(NMR) characterization. The feasibility of the probe for the quantitative determination of Al3+ in aqueous samples was also verified. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al3+ in living He La cells were successfully achieved. The AIE effect of the probe enables high signal-tonoise ratio for bioimaging even without multiple washing steps. These superiorities make this probe a great potential for the functional study and analysis of Al3+ in complex biosystems.The recognition between biological macromolecules plays crucial roles in living biosystems. By the combination of AIE phenomenon and molecular recognition between sense-antisense peptides, a novel approach for the efficient screening of tumortargeting peptides was investigated. A tumor-related protein LAPTM4 B was chosen as the target. Antisense peptides based on the degeneration of genetic codon were synthesized by using solid phase peptide synthesis strategy, purified by RP-HPLC and characterized by MALDI TOF MS. The interaction between the AIE fluorophore-label target peptide and antisense peptides were studied by recording the variations in the fluorescence spectra. The effects of ionic strength and p H on the binding affinity were also examined. Two antisense peptides with higher affinity towards the target were screened. Binding constants characterization and the bioimaging of cancer cells were subsequently carried out.