Preparation And Application Of Silicon-based And Mangan-based Nano-sensors Based On H₂O₂ And GSH Detection

With the development and advancement of science and technology,human health issues have attracted people’s attention.The health of the diet and the stability of the metabolic levels of various indicators in the body have also attracted people’s attention.For example,the content of nutrients such as glucose and oil play an important role in dietary health.In the process of food processing,temperature,cooking time,as well as p H regulation and other factors will cause damage to nutrients,resulting in the loss of nutrients.Some people even add excessive food additives to cheat consumers with shoddy quality,which leads to hidden dangers in food safety.Therefore,there are more and more sensitive biosensors with high sensitivity and specificity at the biological level,which have become the research hotspots of many researchers.There are many kinds of biosensors,among which biosensors based on fluorescent signals,color signals and magnetic signals have such advantages as biomechanics due to their strong operability,simple experimental procedure,short time-consuming,high specificity and good visualization effect.It has an important position in the field of detection of biologically active molecules.In this paper,based on different biological small molecules,combined with the fluorescence and colorimetric sensing mechanism of nanomaterials,new sensors were designed for rapid detection of hydrogen peroxide and glutathione,providing new ideas for food diversity and safety.The main research contents of this paper are as follows:（1）Detection of hydrogen peroxide based on the construction of Silicon dioxide-hemoglobin（Si O₂-Hb）fluorescence sensing systemCarbon quantum dots were synthesized by hydrothermal method,and silica was coated on the surface to form core-shell nanoparticles.Then,mitochondria target groups were modified on the surface of silica particles by activating carboxyl and amino groups.For the core/shell materials（CDs@Si O₂-TPP）coated with silica modified by mitochondrial targeting,the transmission electron microscope showed that the structure and morphology were spherical,and the particle size was about 300 nm.Zeta potential and Fourier near-infrared spectroscopy respectively verified the successful modification of mitochondrial targeted groups on the particle surface from the perspective of electronegativity and functional groups,further proving the successful preparation of CDs@Si O₂-TPP.CDs@Si O₂-TPP was used as a fluorescent probe to quench the fluorescence of CDs@Si O₂-TPP with hemoglobin（Hb）residues to form a fluorescence closed state,while hydrogen peroxide（H₂O₂）has the oxidability to oxidize ferrous ions in heme into ferric ions,thereby releasing the fluorescence signal of CDs@Si O₂-TPP to form a fluorescence open state.The results show that this method is green,easy to operate and has obvious signal.The fluorescence emission intensity ratio is positively correlated with the concentration of H₂O₂.Therefore,the fluorescence"on-off-on"mode can be used for the quantitative detection of hydrogen peroxide（2）Construction of reaction system for oxidizing rhodamine B by manganese dioxide nanosheetsMnO₂nanosheets have good water solubility and enzymatic catalysis,it can be synthesized by potassium permanganate reduction method.The morphology of Mn O₂nanosheets was characterized by atomic force microscopy and transmission electron microscope.It was found that the size of Mn O₂nanosheets was small and its thickness was about 2 nm.X-ray photoelectron spectroscopy and Fourier infrared spectroscopy confirmed the existence of Mn⁴⁺,further proving the successful preparation of manganese dioxide nanosheets.Under strong acidic conditions,the enzymatic catalysis of Mn O₂ nanosheets can oxidize Rh B and destroy its structure.The occurrence of oxidation reaction was verified by UV-Vis and fluorescence spectra,and the oxidation process and mechanism of Rh B were explained by mass spectra.Therefore,a new sensing platform was designed by taking advantage of the oxidation characteristics of Mn O₂ nanosheets and the ultraviolet and fluorescence dual signal characteristics of Rh B.In addition,the oxidized products of Rh B had green fluorescence,and it was found that the product was not significantly toxic and had good biocompatibility through cytotoxicity experiment and cell imaging experiment,providing a new method for the preparation of fluorescent imaging probe.（3）Detection of glutathione by MnO₂-RhB sensorColorimetry,fluorescence and magnetic resonance imaging were established for glutathione（GSH）detection based on Mn O₂-Rh B sensor.In the strong acid environment,the system showed good ratio response to GSH detection by colorimetry and fluorescence.Due to the direct competitive reaction between GSH and Rh B,different concentrations of GSH were added to manganese dioxide solution,and then a certain amount of Rh B solution was added.The color of the solution was observed to change from light green to pink as the concentration increased.When the concentration of GSH is within the range of 0-4μmol·L^-1,there is a good linear relationship between the concentration and the absorbance intensity ratio(A₅₅₆/A₅₀₀),and R²=0.992.The fluorescence of the solution from green to orange can also be observed under the UV lamp,and when the concentration of GSH is within the range of 0.05-2 mol·L^-1,there is a good linear relationship between the concentration and the fluorescence intensity ratio(F₅₂₀/F₅₇₅),R²=0.992.The minimum detection limit of this system is 50 nmol·L^-1.Rh B could not be oxidized and cleaved by Mn O₂ under neutral conditions.If GSH is added to the system,Mn O₂ only reacts with GSH to generate Mn²⁺,which can be used as magnetic resonance imaging（MRI）contrast agent.In this system,GSH content is indirectly determined by MRI.In addition,the sensor system can be used to monitor serum glutathione concentrations in humans.Compared with traditional detection methods,this ratio type dual-signal sensor has the advantages of high accuracy,good reproducibility and low detection limit,and can also realize visual detection,providing a new idea for rapid detection of GSH in biological systems.