Preparation And Properties Of Double Response LDH Composite Films

In this paper,the fluorescence biomolecules flavin mononucleotide(FMN)were combined with hydrotalcite(LDH)to obtain FMN-PSS/LDH UTFs,fluorescent dyes calcein and nuclear fast red(NFR)with LDH to obtain Calcein@NFR/LDH UTFs.We analyzed the surface morphology and microstructure of the two UTFs,and studied its practical application in temperature sensing and detection of melamine and cysteine.The concrete research content is as follows:1.The optical response to a variety of stimuli is one of the important ways for fluorescent chemosensors to expand its application.In this study,the FMN-PSS/LDH UTFs was prepared by layer-by-layer(LBL)self-assembly technique,and realizing the response to temperature stimulation and the detection of melamine.The results of XRD and SEM show that the FMN-PSS/LDH composite films are(a b)plane parallel to the substrate,the interlayer spacing is?2.37 nm,and the interlayer is single-layer.The non-radiation transition of FMN-PSS/LDH complex can be effectively controlled by the two-dimensional confinement effect ofLDH after the introduction of LDH carrier,and the non-radiation transition of FMN-PSS/LDH films has a good fluorescence response to the temperature.Thus constructing a "turn-on" melamine fluorescent film sensor.In a certain temperature range(-60?-60?)meet the linear equation:F=-2.4186T+452.23(R2=0.9973).In addition,we also investigated the fluorescence response of FMN-PSS/LDH composite ultrafine film with melamine.Melamine inhibited the binding of hydrophilic moiety of FMN molecule and H20 to avoid the fluorescence quenching caused by solvent polarity off,the fluorescence intensity of the substantial increase.In a certain concentration of melamine(0-160 nM)meet the linear equation:F=80.8+8.067[Melamine](R2=0.997)with a detection limit of 7 nM.In summary,the FMN-PSS/LDH UTFs achieved multiple responses to multiple stimuli and have good results,and we have made a preliminary discussion on the UTFs.2.We used a simple,convenient and efficient method to prepare a Calcein@NFR/LDH composite ultra-thin film,and use its unique optical properties achieve a dual signal detection for cysteine.Based on the LBL assembly technique,the Calcein molecule and NFR molecule were introduced into the LDH layer to realize the construction of the host-guest supramolecular system.The surface morphology and optical properties of the composite films were analyzed by SEM,AFM,fluorescence spectra,UV-Vis,LSCM and fluorescence time-resolved decay curves,which confirmed the orderly stability and good periodic characteristics of the UTFs.At the single wavelength excitation,the composite film showed enhanced fluorescence response to cysteine at both wavelengths.A good linear relationship was exhibited when the cysteine concentration ranges from 1.0×10-7 M to 1.2×10-6 M,and it was confirmed that the composite film had good reproducibility and good selectivity.In addition,we also carried out quantitative determination of cysteine tablets and granules.The results were consistent with those of the standard solution,which further confirmed the possibility of the UTFs.Therefore,the UTFs have potential application value in the drug and biological small molecule detection,molecular recognition and intelligent sensing and other fields.