A Survey Of Self-Assembled Monolayers For The Surface Properties And Performance Of Electrochemical Aptamer-Based Sensors

Highly selective and specific biosensors have been widely used in many applications including clinical medicine,food detection and environmental monitoring.Electrochemical aptamer-based(E-AB)sensor,as an important branch of biosensor,not only inherits the advantages of strong specificity and high sensitivity of biosensor,but also has excellent characteristics such as simple operation,fast detection speed,high accuracy and wide spectrum detection range.Therefore,this promising sensor is expected to be used in many fields in the future,especially clinical treatment and in vivo detection.Real-time monitoring of the metabolism of specific substances in human body will greatly improve the diagnosis and treatment ability of modern medicine.However,before implementing this technology into practical application,E-AB sensor still need to improve its practical detection systems,including baseline stability,anti-fouling property,stability,sensitivity and other detection performance.This work introduces the development,classification and application of biosensors,summarizes the research status of E-AB sensors,discusses the challenges and solutions of E-AB sensors in complex systems,and discusses the influence of self-assembled monolayers(SAMs)in E-AB sensors on the sensing performance.In view of the difficulties and challenges in these applications,this work focuses on the surface of E-AB sensor,namely the self-assembled monolayers,which is an important part of the sensor.By designing and synthesizing a series of self-assembled monolayers and then assembly it onto the surface of the E-AB sensor,the strategy of effectively adjusting the surface interface hydrophilicity and anti-fouling performance and finally improving the detection performance of the sensor is achieved.Based on this strategy,two studies on self-assembled monolayers with different structures have been carried out.1.Surface properties of electrochemical sensors constructed with hydrophobic terminal group sulfhydryl monolayer and exploration of sensor propertiesIn this work,a series of sulfhydryl molecules with hydrophobic groups were selected and used as antifouling layers in the construction of E-AB sensors.The results show that the chain length of the self-assembled monolayers and the hydrophobic groups greatly affect the surface wettability and anti-fouling properties of the E-AB sensor.When these monolayers are assembled into the E-AB sensor,the sensitivity,stability and specificity of the test signal can be well regulated.This work also reveals the mechanism of the resistance of hydrophobic monolayers to nonspecific adsorption:These hydrophobic SAMs rapidly adsorb non-target materials to the surface of the complex system within a short time,thus preventing further adsorption of other substances.In addition,the work produced a series of radar maps to assess the overall performance of these hydrophobic sulfhydryl monolayers.2.Surface properties of electrochemical sensors constructed with monolayer containing an alkynyl group and exploration of sensor propertiesBase on the first work,this work selected a series of alkynyl molecules with different hydrophilic and hydrophobic groups,also as anti-fouling layer applied in the construction of E-AB sensor,and explore its overall performance in the whole blood system.The results showed that these different groups would also affect the performance of the sensor by affecting the wettability and anti-fouling properties of the SAMs surface.Moreover,different groups lead to different wettability of these SAMs,so their anti-fouling mechanism correspond to hydrophilic and hydrophobic SAMs respectively.This study also produced radar maps to assess the overall performance of these alkynyl monolayers in the blood.In short,this work achieves the purpose of improving sensor detection performance by selecting and designing different self-assembled monolayers.It is of great significance to the practical application of E-AB sensor and the design and construction of other biosensors in the future.In addition,this work also shows that the influence of different structures and functional groups on the properties of SAMs is traceable,which provides an important reference and basis for the future modulation of surface properties from the molecular level.