One-step photostructuring of multiple hydrogel arrays for compartmentalized enzyme reactions in microfluidic devices

Obst, Franziska; Simon, Dávid; Mehner, Philipp J.; Neubauer, Jens W.; Beck, Anthony; Stroyuk, A. L.; Richter, Andreas; Voit, Brigitte; Appelhans, Dietmar

doi:10.1039/c9re00349e

Cited by 22 publications

(44 citation statements)

References 82 publications

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“…The catalytic activities were calculated from the slopes of the time-dependent absorption using Lambert-Beers law. The extinction coefficient ε 405 of (ABTS*) + was determined experimentally by a calibration (ε 405 = 27.5 L/(mmol cm) [15]. The following results were obtained at pH 7: HRP: 76.2 U/mg, GOx: 14.3 U/mg, Myo: 0.33 U/mg.…”

Section: Measurement Of Enzyme Activitiesmentioning

confidence: 97%

“…Poly(oxymethylene) (POM) and poly(methyl methacrylate) (PMMA) were purchased from PCH Technischer Handel GmbH (Dresden, Germany). Water-soluble core/shell quantum dots (QD) from AgInS/ZnS were synthesized as previously reported [15,47] and kindly provided by Oleksandr Stroyuk (TU Dresden, Institute for Physical Chemistry, Dresden, Germany).…”

Section: Chemicals and Materialsmentioning

confidence: 99%

“…The catalytic activities of GOx and HRP were determined in an ABTS assay in PBS buffer (100 mmol/L, pH 7.4) at 25 • C according to a previously described procedure [15]. The catalytic activity of Myo was determined with 5 mmol/L ABTS and 5 mmol/L H 2 O 2 .…”

Section: Measurement Of Enzyme Activitiesmentioning

confidence: 99%

“…Moreover, miniaturized flow-through devices offer high potential for the (bio) catalytic investigations as they are predestinated for the rapid screening of several reaction parameters and/or the realization of complex cascade reactions with a low material consumption and continuous product supply. Consequently, several biocatalytic conversions were integrated into microfluidic devices e.g., to screen enzymatic activities [3,8,9] or to perform continuous catalytic reactions [10][11][12][13][14][15][16][17]. Thereby, enzymes were either dissolved in an appropriate fluid and flushed through the device or immobilized therein.…”

Section: Introductionmentioning

confidence: 99%

“…Thereby, enzymes were either dissolved in an appropriate fluid and flushed through the device or immobilized therein. Especially for establishing multi-step cascade reactions with incompatible reaction steps, the immobilization of biocatalysts in compartmentalized flow-through devices is an elegant method and the construction of such devices was demonstrated by several research groups [11,18], including ours [15]. Within this approach, the substrate solution is pumped through the device and stepwise converted upon contact with the respective immobilized enzymes, thereby avoiding cross-inhibitions and enabling optimization of the reaction conditions for the individual steps.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogel Microvalves as Control Elements for Parallelized Enzymatic Cascade Reactions in Microfluidics

et al. 2020

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Compartmentalized microfluidic devices with immobilized catalysts are a valuable tool for overcoming the incompatibility challenge in (bio) catalytic cascade reactions and high-throughput screening of multiple reaction parameters. To achieve flow control in microfluidics, stimuli-responsive hydrogel microvalves were previously introduced. However, an application of this valve concept for the control of multistep reactions was not yet shown. To fill this gap, we show the integration of thermoresponsive poly(N-isopropylacrylamide) (PNiPAAm) microvalves (diameter: 500 and 600 µm) into PDMS-on-glass microfluidic devices for the control of parallelized enzyme-catalyzed cascade reactions. As a proof-of-principle, the biocatalysts glucose oxidase (GOx), horseradish peroxidase (HRP) and myoglobin (Myo) were immobilized in photopatterned hydrogel dot arrays (diameter of the dots: 350 µm, amount of enzymes: 0.13–2.3 µg) within three compartments of the device. Switching of the microvalves was achieved within 4 to 6 s and thereby the fluid pathway of the enzyme substrate solution (5 mmol/L) in the device was determined. Consequently, either the enzyme cascade reaction GOx-HRP or GOx-Myo was performed and continuously quantified by ultraviolet-visible (UV-Vis) spectroscopy. The functionality of the microvalves was shown in four hourly switching cycles and visualized by the path-dependent substrate conversion.

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Section: Measurement Of Enzyme Activitiesmentioning

confidence: 97%

Section: Chemicals and Materialsmentioning

confidence: 99%

Section: Measurement Of Enzyme Activitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrogel Microvalves as Control Elements for Parallelized Enzymatic Cascade Reactions in Microfluidics

et al. 2020

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Logic Circuits Based on Chemical Volume Phase Transition Transistors for Planar Microfluidics and Lab‐on‐a‐Chip Automation

Beck

Mehner

Voigt

et al. 2022

Adv Materials Technologies

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Despite great progress of lab‐on‐a‐chip (LoC) technology platforms in the last 30 years, there is a lack of standardized microfluidic components, real on‐chip automation and progressive functional scalability of the fluidic circuits. Hydrogel‐based microfluidic circuits have a high scaling potential and provide on‐chip automation, but are complex in system design. An advanced circuit concept for planar microfluidic chip architectures, originating from the early era of the semiconductor‐based resistor‐transistor‐logic (RTL) is presented and the hydrogel‐based chemical volume phase transition transistor (CVPT) for logic gate operations is implemented. The circuit concept (CVPT‐RTL) is robust and simple in design, feasible with common materials and manufacturing techniques of the LoC technology. Thereby, three major challenges are solved: contamination issues, maintaining the signal compliance for cascadability, and chemical signal inversion. As a central element, a CVPT cascode is introduced. The functionality of the concept is verified by a 24 h test of the NAND gate operation and a self‐automated chemofluidic analog‐to‐digital converter, utilized as interface between bioreactors and extended microfluidic logic circuits. Moreover, the CVPT‐RTL cascode demonstrates the expected self‐stabilizing performance of the NAND gate. Accompanying simulations of the component behavior based on a network description implemented in Matlab Simscape match with the experimental results.

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Fundamentals of Hydrogel‐Based Valves and Chemofluidic Transistors for Lab‐on‐a‐Chip Technology: A Tutorial Review

Beck

Obst

Gruner

et al. 2022

Adv Materials Technologies

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By the integration of smart materials, hydrogel-based LoCs even differ from other LoC approaches, as they bring more diverse functionality on the chip and reduce external equipment for fluid transport and decision-making. [52,53] Regarding the level of external control, two fundamental platforms exist: microelectromechanical and chemofluidic hydrogel-based LoCs. The first includes electronically controlled microvalves, [54,55] micropumps, [56] switchable storages, [57] filters, adjustable membranes, [58] and bioreactors [59][60][61] all based on hydrogel components. Chemofluidic integrated circuits introduce direct feedback control to chemical and physical parameters by combining both actuator and sensor properties on hydrogel material level for the LoC technology. There is a comprehensive choice of self-regulating components including chemomechanical valves, [62][63][64][65] chemostats, [66,67] thermostats, [68] pumps, [69][70][71][72][73] and adjustable filters. [74] The recent development of a universal circuit element, the chemofluidic transistor, [75,76] allows exclusive chemical control and via a set of logic operations the realization of a complete self-powered and selfcontrolling information-processing system on one integrated circuit chip. [76][77][78][79][80] However, stimuli-responsive hydrogels are materials with complex physics and behavior. The fabrication of gel-based LoC needs sophisticated technology. Moreover, the correct design of hydrogel-based components must respect parameters reaching from multidomain thermodynamics, swelling kinetics, mechanical properties of the soft materials over fabrication to functional design. To emphasize the versatility of hydrogels, numerous reviews have been published, highlighting to a different extent the material classification, [81][82][83][84][85][86][87] hydrogel behavior, [88][89][90] fabrication methods, [91][92][93][94][95][96][97] and the application range. [52,[98][99][100][101][102][103][104] The unique characteristic of this tutorial review is not only that it provides an up-to-date overview of the research field of hydrogel-based components in microfluidics, it also gives best practice suggestions to take action into the area of material selection, patterning methods, and device design. These aspects are compiled into the formulation of five design rules. Furthermore, the most important scaling laws and supporting simulation methods are presented to the future designers of hydrogelbased components for microfluidics. Therefore, this tutorial review is addressed to those who want to learn more about Stimuli-sensitive hydrogels have an outstanding potential for miniaturized, integrated sensor, and actuator systems and especially for lab-on-chip technology, but the application is still in its infancy. One major reason may be that design and realization of hydrogel-based systems are exceptionally complex and demanding. Here, the design parameters of a key component, the hydrogel-based valve, are discussed in their entirety. Key developments in the fields...

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One-step photostructuring of multiple hydrogel arrays for compartmentalized enzyme reactions in microfluidic devices

Abstract: A moulding technique is presented for the simultaneous photostructuring on the μm scale of hydrogels with nanomaterials on one substrate, usable for the fabrication of microfluidic double-chamber reactors.

Cited by 22 publications

References 82 publications

Hydrogel Microvalves as Control Elements for Parallelized Enzymatic Cascade Reactions in Microfluidics

Hydrogel Microvalves as Control Elements for Parallelized Enzymatic Cascade Reactions in Microfluidics

Logic Circuits Based on Chemical Volume Phase Transition Transistors for Planar Microfluidics and Lab‐on‐a‐Chip Automation

Fundamentals of Hydrogel‐Based Valves and Chemofluidic Transistors for Lab‐on‐a‐Chip Technology: A Tutorial Review

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