title: Microfluidic enzymatic biosensing systems: A review.
abstract: Microfluidic biosensing systems with enzyme-based detection have been extensively studied in the last years owing to features such as high specificity, a broad range of analytes and a high degree of automation. This review gives an overview of the most important factors associated with these systems. In the first part, frequently used immobilization protocols such as physisorption and covalent bonding and detection techniques such as amperometry and fluorescence measurements are discussed with respect to effort, lifetime and measurement range. The Michaelis-Menten model describing the kinetics of enzymatic reactions, the role of redox mediators and the limitations of the linear measurement range of enzymatic sensors are introduced. Several possibilities of extending the linear measurement range in microfluidic systems such as diffusion-limiting membranes and the flow injection setup are presented. Regarding the integration of enzymes into microfluidic systems during the fabrication process, the constraints imposed by the biomolecules due to the limited usage of high temperatures and solvents are addressed. In the second part, the most common forms of enzyme integration into microfluidic systems, i.e. in channels and on electrodes, on microparticles, on paper and thread and as injected enzyme solutions, are reviewed, focusing on fabrication, applications and performance.
authors.affiliation: Electronic Components and Circuits, Faculty of Engineering Sciences, University Duisburg-Essen, Bismarckstrasse 81, 47057 Duisburg, Germany; Fraunhofer Institute for Microelectronic Circuits and Systems IMS, Finkenstrasse 61, 47057 Duisburg, Germany. Electronic address: stefan.mross@ims.fraunhofer.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mross
authors.affiliation: Fraunhofer Institute for Microelectronic Circuits and Systems IMS, Finkenstrasse 61, 47057 Duisburg, Germany.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Pierrat
authors.affiliation: Fraunhofer Institute for Microelectronic Circuits and Systems IMS, Finkenstrasse 61, 47057 Duisburg, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Zimmermann
authors.affiliation: Electronic Components and Circuits, Faculty of Engineering Sciences, University Duisburg-Essen, Bismarckstrasse 81, 47057 Duisburg, Germany; Fraunhofer Institute for Microelectronic Circuits and Systems IMS, Finkenstrasse 61, 47057 Duisburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Kraft
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004796:Clinical Enzyme Tests / Q000295:instrumentation*; D004209:Disposable Equipment; D004798:Enzymes / Q000032:analysis* / Q000737:chemistry*; D004867:Equipment Design; D056656:Lab-On-A-Chip Devices; D010209:Paper; D019095:Point-of-Care Systems; D018511:Systems Integration
chemical_list: D004798:Enzymes
keywords: Enzymes; Immobilization; Integration; Microfluidic systems