Binding kinetics enhancement of a microfluidic biosensor into a micro-channel through the application of a supplementary mechanism has received tremendous attention because of the obtained significant enhancement fact...Binding kinetics enhancement of a microfluidic biosensor into a micro-channel through the application of a supplementary mechanism has received tremendous attention because of the obtained significant enhancement factor. However, biosensor’s performance enhancement using only simple channel engineering is still rarely realized. Herein, we present a novel design of a complex reactive protein (CRP) biosensor into a U-shaped channel with a sensitive membrane located in the middle of the bent zone. Various critical factors affecting the equilibrium binding time are numerically investigated. The turn geometry is then optimized when the arc length along the inner and outer radii is almost the same, which leads to locally minimizing the channel height overhead the reaction surface and improves the analyte transport towards the sensing area. The numerical studies reveal that applying a local narrowing above the reaction surface can notably enhance the trapping and the surface formation of complex antibody-antigen, thus upgrading the biosensor performance. This work puts a significant advance towards microfluidic channel engineering and the exploration of micro-flow injection experimental studies.展开更多
Recent advances in large area graphene growth have led to many applications in different areas. In the present study, chemical vapor deposited （CVD） monolayer graphene supported on glass substrate electrochemical bi...Recent advances in large area graphene growth have led to many applications in different areas. In the present study, chemical vapor deposited （CVD） monolayer graphene supported on glass substrate electrochemical biosensing applications was examined as electrode material for We report a facile strategy for covalent functionalization of CVD monolayer graphene by electrochemical reduction of carboxyphenyl diazonium salt prepared in situ in acidic aqueous solution. The carboxyphenyl-modified graphene is characterized using Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, and atomic force microscopy （AFM）, as well as electrochemical impedance spectroscopy （hIS）. We also show that the number of grafted carboxyphenyl groups on the graphene surface can be controlled by the number of cyclic voltammetry （CV） scans used for electrografting. We further present the fabrication and characterization of an immunosensor based on immobilization of ovalbumin antibody on the graphene surface after the activation of the grafted carboxylic groups via EDC/NHS chemistry. The binding between the surface-immobilized antibodies and ovalbumin was then monitored using Faradaic EIS in [Fe（CN）6]^3-/4- solution. The percentage change of charge transfer resistance （Rct） after binding exhibited a linear dependence for ovalbumin concentrations ranging from 1.0 pg·mL^-1 to 100 ng·mL^-1, with a detection limit of 0.9 pg·mL^-1. Our results indicate good sensitivity of the developed functionalized CVD graphene platform, paving the way for using CVD monolayer graphene in a variety of electrochemical biosensing devices.展开更多
文摘Binding kinetics enhancement of a microfluidic biosensor into a micro-channel through the application of a supplementary mechanism has received tremendous attention because of the obtained significant enhancement factor. However, biosensor’s performance enhancement using only simple channel engineering is still rarely realized. Herein, we present a novel design of a complex reactive protein (CRP) biosensor into a U-shaped channel with a sensitive membrane located in the middle of the bent zone. Various critical factors affecting the equilibrium binding time are numerically investigated. The turn geometry is then optimized when the arc length along the inner and outer radii is almost the same, which leads to locally minimizing the channel height overhead the reaction surface and improves the analyte transport towards the sensing area. The numerical studies reveal that applying a local narrowing above the reaction surface can notably enhance the trapping and the surface formation of complex antibody-antigen, thus upgrading the biosensor performance. This work puts a significant advance towards microfluidic channel engineering and the exploration of micro-flow injection experimental studies.
文摘Recent advances in large area graphene growth have led to many applications in different areas. In the present study, chemical vapor deposited （CVD） monolayer graphene supported on glass substrate electrochemical biosensing applications was examined as electrode material for We report a facile strategy for covalent functionalization of CVD monolayer graphene by electrochemical reduction of carboxyphenyl diazonium salt prepared in situ in acidic aqueous solution. The carboxyphenyl-modified graphene is characterized using Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, and atomic force microscopy （AFM）, as well as electrochemical impedance spectroscopy （hIS）. We also show that the number of grafted carboxyphenyl groups on the graphene surface can be controlled by the number of cyclic voltammetry （CV） scans used for electrografting. We further present the fabrication and characterization of an immunosensor based on immobilization of ovalbumin antibody on the graphene surface after the activation of the grafted carboxylic groups via EDC/NHS chemistry. The binding between the surface-immobilized antibodies and ovalbumin was then monitored using Faradaic EIS in [Fe（CN）6]^3-/4- solution. The percentage change of charge transfer resistance （Rct） after binding exhibited a linear dependence for ovalbumin concentrations ranging from 1.0 pg·mL^-1 to 100 ng·mL^-1, with a detection limit of 0.9 pg·mL^-1. Our results indicate good sensitivity of the developed functionalized CVD graphene platform, paving the way for using CVD monolayer graphene in a variety of electrochemical biosensing devices.
