Study On Amphiphilic Molecular Aggregate Fluorescence Sensors With Fingerprint Recognition Ability

Along with the extensive development of economy, people tend to pay great attention to issues such as food security, environmental pollution, and disease diagnosis. The abuse of food additive, excessive pesticide residues, and serious environmental pollution have made detection and analysis more difficult and chanllegable since samples are more complex, and multiple contaminants usually co-exist. The traditional selective sensors with the lock-and-key recognition mode can not meet the demand in analyzing complex samples. Therefore, developing new methods with high-throughput detection ability are in high demand so as to solve these problems.By mimicking the mammalian systems of taste and smell, sensor arrays comprising of several cross-reactive sensing units can generate a specific fingerprint recognition pattern for each analyte. Sensor arrays are not only able to discriminate chemically or structurally similar analytes, but also able to analyze mixture samples. However, the practical application of sensor array is restricted due to its high dependence on unit numbers and tedious collection and processing of data.Recently, various single system-based fluorescent sensors with multi-wavelength cross-reactivity and fingerprint recognition capabilities have been developed through different methods. Research on this kind of sensors is becoming a hotspot, since it can not only overcome the poor discrimination power of traditional selective sensors, but also avoid the issue of complex data acquisition accompanied with using sensor arrays. Compared to the methods developed by other groups, we introduce amphiphilic assemblies to modulate the photophysical properties of small fluorescent molecules to realize cross-reactive responses and pattern recognition. This method has several advantages such as simple composition, easy preparation, high sensitivity and detection in aqueous solution.On the basis of the development of fluorescent sensor arrays and single fluorescent sensors with fingerprint recognition ability in our lab, the objectives of this dissertation is to develop single system-based fluorescent sensors with discriminative powers by using surfactant assemblies and simple fluorophroes.Three simple amphiphilic fluorescent probes containing a pyrene unit, Py-Cl, Py-C2, and Py-C3, were specially designed and synthesized. The fluorescence emission spectra illustrates that the photophysical behaviors of these three pyrene-based fluorophores can be modulated by commercially available, anionic surfactant sodium dodecyl sulfate (SDS). The introduction of SDS enriches the emission signals of the three probes in aqueous solution and has realized monomer and excimer co-emission. It lays a solid foundation for cross-reactive responses to multiple analytes. The Py-C1/SDS system exhibits both turn-off responses and ratiometric responses to different metal ions. The combination of fluorescence variation at four different wavelengths can generate a recognition pattern to the quenching metal ions. Moreover, it is proved that the use of SDS assemblies is critical to the cross-reactive responses of Py-C1 to the metal ions. The Py-C2/SDS and Py-C3/SDS systems show cross-reactive responses to proteins. The former displays turn-off responses to metalloproteins and ratiometric responses to non-metalloproteins, whereas, the latter exhibits turn-off responses to metalloproteins and turn-on responses to non-metalproteins. Therefore, both of these sensor systems can discriminate non-metalloprotein from metalloproteins.