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Johannsen B, Baumgartner D, Karkossa L, Paust N, Karpíšek M, Bostanci N, Zengerle R, Mitsakakis K. ImmunoDisk—A Fully Automated Bead-Based Immunoassay Cartridge with All Reagents Pre-Stored. BIOSENSORS 2022; 12:bios12060413. [PMID: 35735560 PMCID: PMC9221266 DOI: 10.3390/bios12060413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 05/31/2022] [Accepted: 06/07/2022] [Indexed: 11/16/2022]
Abstract
In this paper, we present the ImmunoDisk, a fully automated sample-to-answer centrifugal microfluidic cartridge, integrating a heterogeneous, wash-free, magnetic- and fluorescent bead-based immunoassay (bound-free phase detection immunoassay/BFPD-IA). The BFPD-IA allows the implementation of a simple fluidic structure, where the assay incubation, bead separation and detection are performed in the same chamber. The system was characterized using a C-reactive protein (CRP) competitive immunoassay. A parametric investigation on air drying of protein-coupled beads for pre-storage at room temperature is presented. The key parameters were buffer composition, drying temperature and duration. A protocol for drying two different types of protein-coupled beads with the same temperature and duration using different drying buffers is presented. The sample-to-answer workflow was demonstrated measuring CRP in 5 µL of human serum, without prior dilution, utilizing only one incubation step, in 20 min turnaround time, in the clinically relevant concentration range of 15–115 mg/L. A reproducibility assessment over three disk batches revealed an average signal coefficient of variation (CV) of 5.8 ± 1.3%. A CRP certified reference material was used for method verification with a concentration CV of 8.6%. Our results encourage future testing of the CRP-ImmunoDisk in clinical studies and its point-of-care implementation in many diagnostic applications.
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Affiliation(s)
- Benita Johannsen
- Hahn-Schickard, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; (L.K.); (N.P.); (R.Z.)
- Correspondence: (B.J.); (K.M.); Tel.: +49-761-203-7252 (B.J.); +49-761-203-73252 (K.M.)
| | - Desirée Baumgartner
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;
| | - Lena Karkossa
- Hahn-Schickard, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; (L.K.); (N.P.); (R.Z.)
| | - Nils Paust
- Hahn-Schickard, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; (L.K.); (N.P.); (R.Z.)
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;
| | - Michal Karpíšek
- BioVendor-Laboratorní Medicína a.s., Research & Diagnostic Products Division, Karasek 1767/1, Reckovice, 62100 Brno, Czech Republic;
- Faculty of Pharmacy, Masaryk University, Palackeho trida 1946/1, 61242 Brno, Czech Republic
| | - Nagihan Bostanci
- Section of Oral Health and Periodontology, Division of Oral Diseases, Department of Dental Medicine, Karolinska Institutet, 14104 Huddinge, Sweden;
| | - Roland Zengerle
- Hahn-Schickard, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; (L.K.); (N.P.); (R.Z.)
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;
| | - Konstantinos Mitsakakis
- Hahn-Schickard, Georges-Koehler-Allee 103, 79110 Freiburg, Germany; (L.K.); (N.P.); (R.Z.)
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;
- Correspondence: (B.J.); (K.M.); Tel.: +49-761-203-7252 (B.J.); +49-761-203-73252 (K.M.)
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Shih CH, Chang CC, Liu CY, Wu HC. The centrifugal viscometer. BIOMICROFLUIDICS 2021; 15:054101. [PMID: 34504638 PMCID: PMC8412967 DOI: 10.1063/5.0060908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
In this study, a viscometer, which can measure the viscosity of low-volume liquids (25 μl) within 30 s, was developed on a centrifugal platform. The centrifugal viscometer consists of a disk platform and a motor. Under disk rotation, centrifugal, Coriolis, and viscosity-induced drag forces result in deflection of liquid flow. The viscosity of the liquid sample is determined by the deflection angle of the liquid, which can be examined through image analysis or visual inspection. The viscosities of a series of Newtonian model fluids were tested by the centrifugal viscometer and the results showed good agreement with the ones tested by a conventional rotational viscometer. Since the centrifugal viscometer only requires a motor to function, the microfluidic disk can be produced in large quantities at a low cost through injection molding, and the deflection angle can be detected through visual inspection, it provides an inexpensive, easy to operate, and portable approach to measure low-volume liquid viscosity.
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Chen Y, Shen M, Zhu Y, Xu Y. A novel electromagnet-triggered pillar valve and its application in immunoassay on a centrifugal platform. LAB ON A CHIP 2019; 19:1728-1735. [PMID: 31020298 DOI: 10.1039/c9lc00043g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The lab-on-a-disc is a powerful microfluidic platform that skillfully takes advantage of centrifugal force to controllably drive liquids with the assistance of passive or active valves. However, the passive valves are mainly triggered by the rotation speed and can be easily influenced by the surface chemistry of the channel, while the active valves usually require a complicated fabrication or actuation procedure. In this study, a novel active valve that can be easily triggered by an electromagnet was proposed and applied on the centrifugation platform. This valve, named the electromagnet-triggered pillar (ETP) valve, consisted of a metal pin and pressure sensitive adhesive (PSA) tape, and is closed until the pin is lifted up by an electromagnet to partially separate the PSA tape from the substrate. As a typical application, this valve is utilized to construct a centrifugal chip for mycotoxin detection. With four ETP valves in a unit, the sample and liquid reagents can be sequentially released into the reaction chamber that was spotted with mycotoxin conjugates to accomplish the whole immunoassay. Four mycotoxins (aflatoxin B1, ochratoxin A, T-2 toxin, and zearalenone) were simultaneously detected on this chip with limits of detection lower than the permissible limits set by the regulatory agencies of China, demonstrating the practicability of this easy-to-use active valve.
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Affiliation(s)
- Yiqi Chen
- Department of Biomedical Engineering, Tsinghua University School of Medicine, Beijing 100084, China.
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