Study On The Rapid And Facile Detection Of Small Biomolecule Based On MnO₂ Nanosheets

Small biomolecules such as glucose,amino acid and glutathione are the component of large biomolecules,which plays a vital role in maintaining the metabolism and the process of biological function.The content and activity of those small biomolecules relate closely to the health of organism,thus it is of crucial significance to study deeply toward expounding the secrets of life,disease therapy,developing new functionalized medicine.In additionally,establishing novel,fast,simple,sensitive method for biomolecules detection become the research highlights in the biochemistry analytical field recently.Aiming the research goals mentioned above,this work integrated nanomaterials and biochemistry detection strategy,proposed simple,fast,sensitive detection method for glucose and glutathione.The main points of this thesis focused on following aspect:1.Glucose provides essential function towards metabolism process in biological systems and has close relationships with diabetes or hypoglycemia.In this work,a simple and one-step colorimetric method for highly sensitive glucose detection was proposed.Glucose could be catalyzed by glucose oxidase(GOx)to generate gluconic acid and hydrogen peroxide(H2O2).Consequently,the obtained H2O2 triggered the rapid decomposition of MnO2 nanosheets colloidal suspension and generated an obvious absorbency changing at 376 nm.By simply monitoring the absorbency variation,a low detection limit of 0.17 ?M for glucose could be obtained with a good linear range from 0.5 μM to 50 μM.Besides absorbency measuring,the visual detection of glucose by bared eyes could also be realized very easily through the observable color changing from yellowish-brown to colorless.In addition,the proposed method could be successfully applied to the determination of glucose in real samples with satisfactory recoveries.This proposed nanosensor is very fast,convenient,environmental friendly and requires no sophisticated instruments as well as complicated functional nanomaterials,which reveals that this method has potential for diabetes mellitus study and can be easily expanded to the analysis of other H2O2-involved analytes.2.A very simple,fast and label-free colorimetric method for highly sensitive glutathione quantification is proposed.Without glutathione,MnO2 nanosheets exhibit a strong ultraviolet–visible(UV–vis)absorption peak at 376 nm with the color showing as yellowish-brown.Once glutathione is introduced,MnO2 nanosheets are reduced to Mn2+ ions rapidly,which leads to a yellowish-brown color fading and a remarkable decrease of the absorbance at 376 nm.Based on the distinct color change,a method for highly sensitive and selective detection of glutathione was realized with bare eyes and UV–vis spectroscopy,respectively.This method has a wide dynamic range from 0.5 ?M to 100 ?M and shows a good linear relationship from 0.5 ?M to 10 ?M with a detection limit of 0.1 ?M.Additionally,this developed assay has also been successfully applied to the detection of glutathione in biological fluids with satisfactory results.3.A novel lateral flow test strip for glutathione detection strategy is established basing on the fluorescence recovery of quantum dots.Firstly,the prepared Biotin-QDs were loaded on the MnO2 nanosheets to formation of QDs-MnO2 nanocomposites.As a target fluorescence probe for GSH,the nanocomposites were spiked onto the conjugated pad.Next,streptavidin was spiked onto the nitrocellulose membrane(NC)as the test line,and each part of the strip was assembled together to formation of test strip.When glutathione was present on the sample pad,the solution moved forward to conjugated pad,MnO2 nanosheets would be reduced to Mn2+ ions,then the Biotin-QDs were released and the fluorescence was recovered subsequently captured by streptavidin on the test line.The more MnO2 nanosheets were reduced to Mn2+ with the increasing concentration of glutathione,the more Biotin-QDs were captured on the test line.By simply monitoring the fluorescence intensity on the test line,a low detection limit of 0.03 mM for glucose could be obtained with a good linear range from 0.05 mM to 1.5 mM.This single-on test strip for glutathione detection exhibits good sensitivity and selectivity.This detection platform may be used to detect other biomolecules by design different probes.