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Welden R, Das A, Krause S, Schöning MJ, Wagner PH, Wagner T. Actively Driven Light-Addressable Sensor/Actuator System for Automated pH Control for the Integration in Lab-On-A-Chip (LoC) Platforms. ACS Sens 2024; 9:1533-1544. [PMID: 38445576 DOI: 10.1021/acssensors.3c02712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
The miniaturization of microfluidic systems usually comes at the cost of more difficult integration of sensors and actuators inside the channel. As an alternative, this work demonstrates the embedding of semiconductor-based sensor and actuator technologies that can be spatially and temporally controlled from outside the channel using light. The first element is a light-addressable potentiometric sensor, consisting of an Al/Si/SiO2/Si3N4 structure, that can measure pH changes at the Si3N4/electrolyte interface. The pH value is a crucial factor in biological and chemical systems, and besides measuring, it is often important to bring the system out of equilibrium or to adjust and control precisely the surrounding medium. This can be done photoelectrocatalytically by utilizing light-addressable electrodes. These consist of a glass/SnO2:F/TiO2 structure, whereby direct charge transfer between the TiO2 and the electrolyte leads to a pH change upon irradiation. To complement the advantages of both, we integrated a light-addressable sensor with a pH sensitivity of 41.5 mV·pH-1 and a light-addressable electrode into a microfluidic setup. Here, we demonstrated a simultaneous operation with the ability to generate and record pH gradients inside a channel under static and dynamic flow conditions. The results show that dependent on the light-addressable electrode (LAE)-illumination conditions, pH changes up to ΔpH of 2.75 and of 3.52 under static and dynamic conditions, respectively, were spatially monitored by the light-addressable potentiometric sensor. After flushing with fresh buffer solution, the pH returned to its initial value. Depending on the LAE illumination, pH gradients with a maximum pH change of ΔpH of 1.42 were tailored perpendicular to the flow direction. In a final experiment, synchronous LAE illumination led to a stepwise increase in the pH inside the channel.
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Affiliation(s)
- Rene Welden
- Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Heinrich-Mußmann-Str. 1, Jülich 52428, Germany
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven 3001, Belgium
| | - Anirban Das
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Steffi Krause
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Michael J Schöning
- Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Heinrich-Mußmann-Str. 1, Jülich 52428, Germany
- Institute of Biological Information Processing (IBI-3), Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Patrick H Wagner
- Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Heinrich-Mußmann-Str. 1, Jülich 52428, Germany
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven 3001, Belgium
| | - Torsten Wagner
- Institute of Nano- and Biotechnologies (INB), Aachen University of Applied Sciences, Heinrich-Mußmann-Str. 1, Jülich 52428, Germany
- Institute of Biological Information Processing (IBI-3), Forschungszentrum Jülich GmbH, Jülich 52428, Germany
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Cristóbal-Lecina E, El-Maiss J, Figueras E, Singh AC, Krishnamoorthy S, Østerbye T, Pascual García C, Andreu D. Acid-Modulated Peptide Synthesis for Application on Oxide Biosensor Interfaces. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:3092. [PMID: 38132988 PMCID: PMC10746054 DOI: 10.3390/nano13243092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
In this paper we report an acid-modulated strategy for novel peptide microarray production on biosensor interfaces. We initially selected a controlled pore glass (CPG) as a support for solid-phase peptide synthesis (SPPS) to implement a chemistry that can be performed at the interface of multiple field effect transistor (FET) sensors, eventually to generate label-free peptide microarrays for protein screening. Our chemistry uses a temporary protection of the N-terminal amino function of each amino acid building block with a tert-butyloxycarbonyl (Boc) group that can be removed after each SPPS cycle, in combination with semi-permanent protection of the side chains of trifunctional amino acid residues. Such a protection scheme with a well-proven record of application in conventional, batchwise SPPS has been fine-tuned for optimal performance on CPG and, from there, translated to SPR chips that allow layer-by-layer monitoring of amino acid coupling. Our results validate this acid-modulated synthesis as a feasible approach for producing peptides in high yields and purity on flat glass surfaces, such as those in bio-FETs.
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Affiliation(s)
- Edgar Cristóbal-Lecina
- Proteomics and Protein Chemistry Unit, Department of Medicine and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain;
| | - Janwa El-Maiss
- MRT Department, Luxembourg Institute of Science and Technology, L-4420 Belvaux, Luxembourg; (J.E.-M.); (A.C.S.); (S.K.)
| | - Eduard Figueras
- Proteomics and Protein Chemistry Unit, Department of Medicine and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain;
| | - Aruna Chandra Singh
- MRT Department, Luxembourg Institute of Science and Technology, L-4420 Belvaux, Luxembourg; (J.E.-M.); (A.C.S.); (S.K.)
| | - Sivashankar Krishnamoorthy
- MRT Department, Luxembourg Institute of Science and Technology, L-4420 Belvaux, Luxembourg; (J.E.-M.); (A.C.S.); (S.K.)
| | - Thomas Østerbye
- Department of Immunology and Microbiology, University of Copenhagen, 2200 København, Denmark;
| | - César Pascual García
- MRT Department, Luxembourg Institute of Science and Technology, L-4420 Belvaux, Luxembourg; (J.E.-M.); (A.C.S.); (S.K.)
| | - David Andreu
- Proteomics and Protein Chemistry Unit, Department of Medicine and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain;
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Abstract
Electrochemistry represents an important analytical technique used to acquire and assess chemical information in detail, which can aid fundamental investigations in various fields, such as biological studies. For example, electrochemistry can be used as simple and cost-effective means for bio-marker tracing in applications, such as health monitoring and food security screening. In combination with light, powerful spatially-resolved applications in both the investigation and manipulation of biochemical reactions begin to unfold. In this article, we focus primarily on light-addressable electrochemistry based on semiconductor materials and light-readable electrochemistry enabled by electrochemiluminescence (ECL). In addition, the emergence of multiplexed and imaging applications will also be introduced.
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Light-Addressable Actuator-Sensor Platform for Monitoring and Manipulation of pH Gradients in Microfluidics: A Case Study with the Enzyme Penicillinase. BIOSENSORS-BASEL 2021; 11:bios11060171. [PMID: 34072213 PMCID: PMC8230332 DOI: 10.3390/bios11060171] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 11/17/2022]
Abstract
The feasibility of light-addressed detection and manipulation of pH gradients inside an electrochemical microfluidic cell was studied. Local pH changes, induced by a light-addressable electrode (LAE), were detected using a light-addressable potentiometric sensor (LAPS) with different measurement modes representing an actuator-sensor system. Biosensor functionality was examined depending on locally induced pH gradients with the help of the model enzyme penicillinase, which had been immobilized in the microfluidic channel. The surface morphology of the LAE and enzyme-functionalized LAPS was studied by scanning electron microscopy. Furthermore, the penicillin sensitivity of the LAPS inside the microfluidic channel was determined with regard to the analyte’s pH influence on the enzymatic reaction rate. In a final experiment, the LAE-controlled pH inhibition of the enzyme activity was monitored by the LAPS.
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