Research On The Construction And Application Of Ratiometric Fluorescence Biosensing System Based On Nanomaterials

Biomolecules are an active substance in living organisms,which play an important role in regulating life,and they are essential for maintaining basic life activities.For example,the imbalance of the content of some biomolecules in the biological system will seriously affect the overall health,so in recent years,people have paid more and more attention to the detection of biomolecules.The level of small biological molecules such as uric acid has a great relationship with human health,abnormal levels of uric acid are closely related to many metabolic disorders;and the long-term lack of ascorbic acid not only reduces the function of the immune system,but also causes diseases such as scurvy.However,due to the diversity and complexity of living systems,the application of various detection methods has also encountered great challenges.However,in the large environment of living systems,designing methods for the specific detection of biomolecules has encountered great challenges because the living systems are too complex and diverse.Therefore,based on the above aspects,we constructed two ratio fluorescence biosensing systems to detect uric acid and ascorbic acid respectively.And through a series of measuring instruments to characterize the material morphology structure,system detection mechanism and so on.We have established a dual emission ratiometric fluorescence biosensor detection system for the analysis of hydrogen peroxide(H₂O₂)and uric acid(UA),The construction of the sensor system is based on iron-nitrogen-doped carbon dots(N,Fe-CDs)with peroxidase activity and silver nanoclusters(BSA-Ag NCs)modified with bovine serum albumin(BSA).By the catalysis of uriase,UA was oxidized by oxygen dissolved in the solution and H₂O₂is produced.The carbon site with peroxidase activity can catalyze H₂O₂to generate hydroxyl radicals,which etches to the BSA-Ag NCs.When the excitation wavelength is set to 390 nm,the N,Fe-CDs has a fluorescence peak at 450 nm,and as for BSA-Ag NCs,the fluorescence peak is at 650 nm.With increasing concentration of H₂O₂or UA,the red fluorescence at 650 nm for BSA-Ag NCs decreases due to the etching of BSA-Ag NCs by hydroxyl radicals,while the blue fluorescence of N,Fe-CDs is restored.Based on the relationship between the fluorescence intensity ratio(I₄₅₀/I₆₅₀)to detect H₂O₂and UA,the linear range of H₂O₂was 0.6-100?mol/L with a detection limit of 0.30?mol/L,while the linear range of UA was 0.8-133?mol/L with a detection limit of 0.49?mol/L.This method measures and analyzes the concentration of uric acid in human urine,and the accuracy and recovery rate are satisfactory.This ratiometric fluorescent approach can be used for analysis of UA and H₂O₂for biomedical applications.Ascorbic acid is detected based on a cobalt oxyhydroxide nanosheet biosensor with oxidation mimic enzyme function.The detection mechanism is that the oxidation of o-phenylenediamine(OPD)by cobalt oxyhydroxide nanosheets produces yellow fluorescence.After the introduction of ascorbic acid,the ascorbic acid and the cobalt oxyhydroxide nanosheets undergo a redox reaction,the cobalt oxyhydroxide nanosheets are reduced to Co²⁺,and the cobalt oxyhydroxide nanosheets oxidize the ascorbic acid to DHAA,thereby inhibiting the production of oxy-phenylenediamine(ox OPD).The produced DHAA can also combine with OPD to produce new blue fluorescence.Based on this,we combined DFQ with o-phenylenediamine oxide to establish a ratio fluorescence biosensor system for quantitative detection of ascorbic acid.The experimental results show that AA is in the concentration range of 0.1-15?mol/L,the ratio of the fluorescence intensity of the system to the concentration of AA increases linearly,and the detection limit is 0.08 ?mol/L.