Application Research On Three Types Of Sensors Based On Functionalized Metal-Organic Framework Materials

As a new and unique crystalline porous material,metal-organic frameworks(MOFs)possess features such as tunable chemical structure,ultra-high porosity,ultra-large specific surface area,adjustable pore size/shape and surface,etc.have great potential in gas adsorption,catalysis,photoelectronics,bioimaging,energy storage and conversion applications.In addition,chemical sensing based on MOFs has become a particularly promising application.At present,many reports have employed MOFs materials to construct various types of sensors for the detection of metal ions,inorganic ions,explosives,volatile organic compounds(VOCs)and even cancer markers.However,for some sensors currently used for the detection of VOCs and biomarkers,usually because the weak physical interaction(such as adsorption,electrostatic interaction,etc.)between the targets and the sensing interface,or due to the complex composition of the targets,the sensor cannot effectively distinguish and detect the targets,and the sensing performance of the constructed sensors have some shortcomings,such as low sensitivity or poor selectivity.Based on functionalized MOFs,this work is devoted to the development and construction of sensors with high selectivity and sensitivity,and applied the sensors to the detection and identification of VOCs in the environment,VOCs in human exhalation and potential biomarkers.The main research contents of this thesis are as follows:1.Functionalized fluorescent probe of ethylene diamine(EDA)-Eu³⁺@UiO-66 was prepared by post-synthesis modification and doping method,and a ratiometric fluorescent sensor was constructed to detect aldehyde VOCs in the environment.Based on the condensation reaction between-NH₂and-CHO,EDA-Eu³⁺@UiO-66 can bond the aldehyde VOCs molecules to the surface of fluorescent probe.Since the aldehyde molecules can absorb the excitation light energy of EDA-Eu³⁺@UiO-66,which hinders the energy transfer from the ligand to Eu³⁺ions,which causes quenched fluorescence,resulting in selectively detection of aldehyde VOCs molecules in the water or gaseous aldehydes.2.Two functionalized UiO-66s were prepared by using functional ligands and post-processing methods,and then doped with the fluorescent molecule Rhodamine 6G(R6G)to obtain fluorescent probes of R6G@UiO-66-NH₂and R6G@UiO-66-NH-CO-COOH,then two ratiometric fluorescent sensors were constructed for detecting aldehyde and amine VOCs,respectively.Based on the aldehyde-amine condensation reaction between-NH₂and-CHO and the specific condensation reaction between-COOH and-NH₂,aldehyde VOCs molecules and amine VOCs molecules can react with these two probes,respectively,due to the electron transfer from-NH₂in the ligand to positively charged aldehydes and the binding of amines as electron donors,causing an enhancement in the relative fluorescence intensity of functionalized fluorescent probes,which leads to the selective detection of aldehyde VOCs and amine VOCs,respectively.3.H-ZIF-8 particles with hollow structure were mixed with different kinds of chemical-active dyes to construct a dyes/H-ZIF-8 colorimetric array sensor for the detection of flowing VOCs gases.Through digital subtraction of the images of the array sensor before and after exposure to VOCs,the distinguishable color difference maps towards different VOCs were obtained.Then hierarchical cluster analysis(HCA)and principal component analysis(PCA)based on the color difference vector were performed to evaluate the sensing performance of the array sensor.The porous hollow structure of H-ZIF-8 can effectively increase the contact time and contact probability between VOCs and reaction interface.This colorimetric array sensor can easily identify different concentrations and types of VOCs gases.4.The dyes/H-ZIF-8 array sensor was fixed in the medical mask as a sensor chip to identify and distinguish the exhaled breath of healthy people and lung cancer patients,which established a non-invasive lung cancer screening method.The results showed that the dyes/H-ZIF-8 array sensor had a good ability to distinguish mixed VOCs.When the sensor was applied to the mask breath test,with the help of PCA analysis method,the exhaled breath of healthy people and lung cancer patients can be clearly and accurately distinguished,and the recognition accuracy rate reached 94.7%.This work provides a potential new method for early screening of lung cancer.5.The Ru@MOFs/CNTs composites functionalized with the electrochemiluminescent(ECL)substance of Ru(bpy)₃²⁺were prepared and used as a light-emitting substrate to fabricated an ECL sensor for the detection of methylated RNA.The functionalized material can not only load a large amount of ECL luminescent material,but also act as a nanoreactor for ECL reaction,which overcomes the shortcomings of Ru(bpy)₃²⁺easy to release in aqueous phase detection,improving the ECL efficiency.Taking the methylated micro RNA-21 sequence as a model,the m⁶A antibody can specifically recognize and bind to the m⁶A site in the methylated RNA sequence,triggering the ECL quenching effect between Ru@MOFs/CNTs modified on the electrode surface and ferrocene(Fc).A"Signal-off"type of ECL sensing platform was established,which realized the simple,specific and sensitive analysis and detection of m⁶A RNA sequence.