Abstract
Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems.
Highlights
Oxidase enzymes are one of the most common biorecognition agents being utilized in electrochemical enzymatic biosensors
The detection of hydrogen peroxide is amperometrically done by the working electrode of sensor that is positively-biased with respect to its reference electrode
While many approaches have been focused on overcoming this problem [1,2,3,4,5,6,7,8], we worked on developing a method to take advantage of this oxygen dependency to obtain special functionalities of dissolved oxygen and oxidase-based sensors [9,10]
Summary
Oxidase enzymes are one of the most common biorecognition agents being utilized in electrochemical enzymatic biosensors. The hydrogen bubble depletes oxygen near the sensor to mimic the analyte-free sample since the reaction cannot be completed without oxygen, providing a possibility to conduct a one-point (zero-value baseline) calibration procedure. In our previous attempt with glucose and lactate sensors [10], the generated bubble made contact directly with the biosensor placed in a fluidic channel in such a way that the active sensing area (i.e., enzyme layer) was completely surrounded by the bubble. As a consequence this configuration isolated the enzyme layer from the bulk solution by the surrounding bubble. The creatinine sensor performance was investigated by the chronoamperometric method at the optimum fluidic conditions
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