Study On Glutathione And Related Enzymes Activity Based On Electrochemical Biosensor

In recent years,with the progress of science and technology of electrochemical sensors has wide application prospect areas related to disease prevention,in fermentation industry,medicine and food processing due to its good selectivity,detection of short time,no pollution.Because of their excellent specific surface area and unique electrical properties,many nanomaterials have been applied to design of highly sensitive biosensing methods,such as graphene,quantum dots,gold nanoparticles and mesoporous silica nanoparticles.In this thesis,a series of novel electrochemical biosensors with low cost,fast detection and wider detection range are studied:(1)This work used MSNs and DNA biogate to design a homogeneous electrochemical assay for direct and rapid detection of GSH based on n-dodecanethiol modified SPE.The DNA biogate were used for electrochemical assay by using the specific reaction to displace the GSH and open the molecular gate for release of MB.Then,the immobilized n-dodecanethiol could not only avoid nonspecific protein adsorption but also enhance the currents response due to accumulation of MB molecules that penetrated into the alkanethiol layer.It employed SPE to detection the GSH and the detection ranging from 1.0 nmol·L-1 to 1.0 ?mol·L-1 with a detection limit of 0.6 nMol-L'1.In this way,the target-responsive controlled release system-based electrochemical assay thus offered a promising scheme for the development of advanced homogeneous assay without the sample separation and washing procedure.(2)We envision that a highly sensitive,simple and universal strategy for electrochemical detection of GSH based on HCR signal amplification.By detecting the change of GSH in the enzyme reaction solution,we can indirectly obtain the activity of GR.The presence of the GSH leads to the formation of dsDNA polymers on the sensing surface through in situ HCR.Numerous indicators can be efficiently intercalated into the grooves of the dsDNA polymers to achieve universal detection of target.The proposed assay showed a wide detection ranging from 1.0 nmol-L'1 to 500 nmol·L-1 with a detection limit of 0.6 nmol·L-1.As a result,this demonstration could offer a totally new approach to fabrication of stable biosensors with high sensitivity.(3)It was observed that the impedance of electrode increased obviously after the electrode being modified by glutathione,and the value of impedance was closely related to the GSH concentration.The proposed assay of GSH showed a wide detection ranging from 250 ?mol·L-1 to 16 mmol·L-1 and the GR detection ranging from 0.005-0.5U(1 U means reduction of 1.0?mol GSSG per min at pH 7.2 at 25?).The enzymatic activity of GR obtained by this method was compared with those obtained by colorimetric detection,and the results showed that the new method was reliable.Therefore,this new method is highly sensitive with convenience consuming time within 20 minutes to complete a test,thus showing a promising potential of being applied in medicine.