The Establishment Of Titanium Carbide Quantum Dot As Fluorescent Probe And Its Application In Biomolecule Detection

MXenes are a new type of two-dimensional transition metal carbides,nitrides or carbonitrides.The surface of MXenes material is rich in functional groups such as hydroxyl,oxygen or fluorine.The surface of MXenes is rich in functional groups such as hydroxyl,oxygen or fluorine.The flexible surface group regulation and layered structure endowed these materials with good metal conductivity,surface hydrophilicity,good mechanical properties and chemical stability,and they are currently popular materials for research.Therefore,they have important application value in biomedicine,photocatalysis,energy storage,photoelectricity,sensing,and water purification.Quantum dots can be successfully prepared by decomposing or fragmenting two-dimensional materials.However,there are few reports on preparation of MXenes quantum dots（MQDs）and their optical properties and analytical applications.The research of fluorescent MXenes quantum dots is still an urgent problem for researchers.In this paper,the different surface functional agents of titanium carbide quantum dots（Ti₃C₂ MQDs）and the further exploration of the synthesis method are discussed.As a starting point,the fluorescence properties of Ti₃C₂ MQDs synthesized are studied.Fluorescence and colorimetric probes were constructed using the synthesized Ti₃C₂MQDs for the detection of various biomolecules.The main research contents of this paper are summarized as follows:1.ε-polylysine-functionalized titanium carbide quantum dots（PLL-Ti₃C₂ MQDs） were synthesized by hydrothermal method usingε-polylysine（PLL）as a protective agent.PLL-Ti₃C₂ MQDs have blue photoluminescence,and the emission wavelength and emission peak intensity have excitation wavelength dependence. Excitation and emission peaks at 330 nm and 415 nm,respectively,its quantum yield is 22%.After adding cytochrome c（cyt-c）,the fluorescence of PLL-Ti₃C₂MQDs can be quenched by internal filtration effect.In the concentration range of 0.2-40μM,the response to cyt-c has a good linear relationship,and the detection limit is 20.5 nM.In the presence of trypsin,cyt-c is hydrolyzed to peptides,and Fe³⁺ions in cyt-c may be reduced to Fe²⁺by the use of digestive enzymes,resulting in the restoration of blue fluorescence of PLL-Ti₃C₂ MQDs. The fluorescence intensity increased linearly in the range of 0.5-80μg m L^-1 trypsin concentration,and the detection limit was 0.1μg m L^-1.This method has been successfully applied to the determination of cyt-c and trypsin in serum samples, indicating this experimental method has a good application prospect in actual samples.2.We synthesized glutathione-functionalized titanium carbide quantum dots（GSH-Ti₃C₂ MQDs）by hydrothermal method,and constructed a uranic acid（UA）"naked eye"colorimetric and ratio fluorescent probe based on titanium carbide quantum dots.The method is the oxidation of uric acid to allantoin and hydrogen peroxide under the catalysis of uricase.O-phenylenediamine（OPD）is then oxidized to yellow 2,3-diaminophenazine（oxOPD）under conditions of horseradish peroxidase （HRP）and hydrogen peroxide.The fluorescence emission of GSH-Ti₃C₂ MQDs overlaps with the ultraviolet absorption of oxOPD to a large extent,which causes fluorescence resonance energy transfer between GSH-Ti₃C₂ MQDs and oxOPD.In addition,the detection process has obvious color changes,which proves the feasibility of"naked eye"detection.Therefore,we have developed a"naked eye" colorimetric and ratio fluorescence probe based on GSH-Ti₃C₂ MQDs combined with uricase/HRP enzyme for detection of UA.3.We improved the synthesis method based on the above two studies.Ti₃C₂ MQDs were synthesized by microwave method for the first time.Ti₃C₂ MQDs were characterized by FL,UV,FTIR and TEM.Based on the internal filtration effect between curcumin and Ti₃C₂ MQDs and the reaction between curcumin and hypochlorite,we have established a two-channel"naked eye"colorimetric and ratio fluorescent probe for the detection of curcumin and hypochlorite.The detection range of curcumin is 0.05-10μM,and the detection limit is 20 nM.The detection range of hypochlorite is 25-275μM,and the detection limit is 5μM.