Development And Application Of Electrochemical Biosensor Based On Functional Nano-materials As Signal Amplification Elements

The rise of nanotechnology has led to the rapid development of biosensors.With the higher analytical requirements in research and practical applications,electrochemical biosensors face many challenges in terms of sensitivity,selectivity,and response speed.Objective:This study attempts to incorporate new functionalized nanomaterials and electrochemical sensing technologies and methods into the construction of biosensors.For one thing,appropriate signal amplification mechanisms were introduced into the sensor,for another,a variety of molecular recognition components e.g.biological enzymes and nucleic acid aptamers were adopted to further improve sensing performance.It is expected to promote the development of high sensitive and selective and miniaturized electrochemical biosensors and its application in clinical monitoring.Methods:The electrochemical characterization of the sensor was carried out by classical electrochemical methods such as cyclic voltammetry?CV?,electrochemical impedance spectroscopy?EIS?,square wave voltammetry?SWV?and differential pulse voltammetry?DPV?.Scanning electron microscopy?SEM?,Raman analysis and X-ray photoelectron spectroscopy?XPS?were used to characterize the morphology and elements of the electrode.Results:1.A platform is described for voltammetric sensing of hydrogen peroxide?H₂O₂?.It is based on the use of nitrogen-doped graphite foam modified with Prussian blue particles?PB/NGF?.Graphite foam was synthesized by chemical vapor deposition,and N doping was realized via dielectric barrier plasma discharge.PB particles were grown on the NGF through electrodeposition.SEM images of NGF verified the porous and interconnected structure of graphite foam,and XPS and Raman spectroscopy verified the successful doping with N.The performance of the PB/NGF electrode was characterized by CV and EIS which showed it to possess outstanding properties in terms of sensing H₂O₂.H₂O₂ was quantified in a range of 0.004 to 1.6 mM with a detection limit of 2.4?M.The PB/NGF electrode also is shown to be a viable substrate for loading glucose oxidase?GOx?.The Gox-functionalized PB/NGF electrode responds to glucose over the 0.2 to 20 mM concentration range at a potential of-50 mV?vs.Ag/AgCl?,with a sensitivity of 27.48 mA M^-1 cm^-22 and a 0.1 M detection limit?at an S/N ratio of 3?.The biosensor was successfully applied to the determination of glucose in spiked human serum samples,and this confirmed it practicability.2.A facile and sensitive sensor based on MXene modified screen-printed electrode?MXene/SPE?has been developed for detection of acetaminophen?ACOP?and isoniazid?INZ?,which are two commonly used drugs but might induce liver damage in certain circumstances.MXene showed excellent electrocatalytic activity toward the oxidation of ACOP and INZ compared with bare SPE in 0.1 M H₂SO₄,and the separated oxidation peak potentials ensured simultaneous detection of the targets with wide linear ranges from 0.25 to 2000?M for ACOP and 0.1 to 4.6 mM for INZ.The detection limits of ACOP and INZ were 0.048?M and 0.064 mM,respectively.?S/N=3?.MXene/SPE has been successfully applied for detection of ACOP and INZ in their pharmaceutical and biological samples with satisfactory recovery.3.A simple,label-free electrochemical biosensor was developed for the sensitive quantification of C-reactive protein?CRP?,an acute-phase proteins,which is produced in the liver,and is a marker of the body's inflammatory response.Sensor was developed by a CRP aptamer immobilized on the gold electrode by an Au-S bond as a recognition element,and methylene blue?MB?is used as an electroactive beacon to achieve sensitive and selective detection of CRP.The developed electrochemical aptamer sensor showed a good linear response to CRP in the concentration range of 0.01 to 200 nM with a detection limit of 37 pM?S/N=3?.In addition,the biosensor has good repeatability and stability,exhibiting high selectivity against coexisting protein interference.Above all,the aptasensor can be successfully used to detect CRP in human serum samples.The method is simple and sensitive,and provides a new strategy for label-free CRP determination.Conclusion:Studies have shown that nanomaterials with large specific surface area and good conductivity exhibit amplifying effect on the response signal of the sensor,and can exhibit good electrocatalytic activity under certain conditions.The immobilization of biomacromolecules ensures the selectivity of the analysis.The three kinds of sensors prepared have good analytical performance for the detection of the target,and can meet the analysis requirements in practical applications under the optimal experimental conditions.