Application And Development Of Electrochemical Biosensor In Biological Detection

1.An electrochemical biosensor for detection of methyltransferase by reduced graphene oxide catalysing silver deposition.Objective: Preparaed a new reduced graphene oxide nano-materials and construction a novel electrochemical r GO/silver biosensor for detection of the activity of methyltransferase(MTase)and select dam MTase inhibitors.Methods: We used oxide graphene(GO)as materials,hydrazine hydrate as reducing agent to prepare r GO,which was characterized by atomic force microscopy,UV spectroscopy,Fourier transform infrared spectoscopy,X-ray photoelectron spectroscopy,and Raman spectroscopy.Using the deposited silver,an electrochemical r GO/silver biosensor was constructed to detect methyltransferase activity.We used electrochemical impedance spectroscopy to investigate the faradaic impedance spectra of the electrode modification during the different stages.We also optimizated experimental conditions such as SAM concentration,incubation time of r GO and deposition time of Ag.Under the optimal conditions,the methylase activity was detected.Hha I MTase activity was choosed to detect the specificity of r GO/silver biosensor for dam MTase activity detection.Gentamycin and 5-fluorouracil(blue)was choosed to detect the efficiency of dam MTase inhibitors,as detected by the r GO/silver biosensor.Results: Materials characterization showed the sheet structure of r GO with thickness of around 1 nm.Compared to GO,the number of oxygenated functional groups in r GO was significantly decreased and the sp2 hybridized degree was increased.Electrochemical impedance spectroscopy showed a successful preparation of the working electrode.Under optimum conditions,MTase activity,as detected by the r GO/silver biosensor,was between 0.1 and80.0 U/ml.With the increasing concentration of 5-fluorouracil and gentamycin,decreasing activity of dam MTase was also detected by the novel biosensor.Conclusion: This method enabled the detection of methylation enzyme activity and could also be used for screening of methylation enzyme inhibitor.2.Hemin-graphene nanosheets with intrinsic peroxidase-like activity bydouble-assisted signal amplification for colorimetric detection of leukemia.Objective: We functionalized graphene/hemin nano hybrid materials,to construct a double signal amplification biosensor to detect leukemia cells.Methods: We used oxide graphene(GO)and hemin as materials,hydrazine hydrate as reducing agent to prepare r GO,which was characterized by atomic force microscopy,UV spectroscopy,Fourier transform infrared spectoscopy,X-ray photoelectron spectroscopy,and Raman spectroscopy.We loaded Sgc8 aptamer on the surface of HGNs to prepare functional nanocomposite,meanwhile,the aptamers were biotinylated and combined with avidin magnetic beads to prepare functionalized nanoparticles.After magnetic enrichment,the CEM cells were detected.Finally,this method examineed the clinical lymphocytic leukemia patient’s blood sample.Results: We successfully prepared HGNs with thickness of around 4 nm.The UV spectral characterization show Sgc8 aptamers were successfully loaded on the surface of HGNs.The modified efficiency of Sgc8 aptamer on beads was64.7%.The best quality ratio of graphene and hemein was 1:5,the optimal concentration of magnetic capture probes are 240 n M,under optimal conditions,10 to 100000 CEM cells could be detected.When we detected the blood samples of clinical leukemia patient,it found that with the increasing of the treatment time,the detected signal reduced with the number of leukocytes.Conclusion: We synthesized the graphene/heme peroxidase successfully,based on it a double signal amplification method for detecting of leukemia cells was built.This method was also used to monitor the condition of patients with leukemia.