Research On The Construction Of Cross-responsive Fluorescence Sensor And Its Distinguishing And Recognition Performance

Fluorescent sensors have been widely used to detect and identify various analytes due to their high sensitivity,high selectivity,and rapid responses.Traditional fluorescent sensors use a "lock-and-key" recognition mode that allows for highly selective identification of specific analytes.However,selective sensors can not discriminate similar compounds or meet the demand in analyzing complex samples.Therefore,the development of cross reactive fluorescent sensors for discriminating multiple analytes has attracted increasing attention.At present,cross reactive fluorescent sensors are mainly classified into two types:multi-element based cross-reactive sensor arrays and single system-based fluorescent sensors with multi-wavelength cross-reactivity.In general,sensor arrays can generate distinguishable recognition patterns for a wide range of structurally similar analytes by combining the output signals from all the sensor elements.Differently,single system-based discriminative fluorescent sensors use the fluorescence variation at specific wavelengths as the data input to generate a recognition pattern for a given analyte.In this dissertation,two kinds of cross reactive fluorescent sensors were constructed,and their discrimination performances were studied.In the first work,using the strategy of surfactant assembly modulation effect,we developed a single system-based fluorescent sensor that can identify multiple metalloproteins in aqueous solution.Pyrene is used as the fluorescent reporter group because it has high quantum yield and can emit multiple emission bands.A novel cholic acid-modified pyrene derivative(compound 1)was synthesized and characterized.It was found that the change of the aggregation state of the anionic surfactant sodium dodecyl benzene sulfonate(SDBS)assembly can modulate the photophysical properties of the probe 1.The selected binary ensemble based on the 1/SDBS assembly with the monomer-excimer co-emission exhibited the typical multiple-wavelength cross-reactive responses to different metalloproteins.PCA studies revealed that the present ensemble sensor could discriminate 7 different metalloproteins in aqueous solution.Moreover,the binary ensemble also displayed great discrimination ability of identifying different metalloproteins in biofluids like serum and urine,which makes it has great potential in practical applications.In the second work,we aim to develop a three-element sensor array based on fluorescent mesoporous silica nanoparticles(MSNs)for discriminating biothiols.Three organic dyes containing pyronine(PYR),2-cyano-6-aminobenzothiazole(DBT)and 4-bromo-1,8-naphthalic anhydride(NAP)are designed to modify the surface of mesoporous silica nanoparticles via covalent chemical bonding.At present,we have successfully prepared spherical mesoporous silica nanoparticles with a size of 100-150 nm and a pore diameter of about 3.6 nm.The synthesized MSN-3-Isocyanatopropyltriethoxysilane(MSN-ICP)terminated monolayer-modified mesoporous nanoparticles were characterized by transmission electron microscopy(TEM),scanning electron microscope(SEM),infrared spectroscopy,thermogravimetric analysis(TGA),X-ray photoelectron spectroscopy(XPS)and X-Ray Powder Diffraction(XRD).The results demonstrated that the organic silanes were successfully immobilized on the surface of MSNs and had a little effect on the pore size.In addition,the compound pyronine(PYR)and the second sensing elements have been synthesized and characterized.The future plan is to synthesize the other two fluorescent dyes and chemically immobilize the three dyes on the surface of silica nanoparticles,and then study the discrimination behaviors of the three-element based sensor array for biothiols.