1
|
Sturm F, Zieger V, Koltay P, Frejek D, Kartmann S. Particle Detection in Free-Falling Nanoliter Droplets. MICROMACHINES 2024; 15:735. [PMID: 38930704 PMCID: PMC11205310 DOI: 10.3390/mi15060735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/27/2024] [Accepted: 05/28/2024] [Indexed: 06/28/2024]
Abstract
Sorting and dispensing distinct numbers of cellular aggregates enables the creation of three-dimensional (3D) in vitro models that replicate in vivo tissues, such as tumor tissue, with realistic metabolic properties. One method for creating these models involves utilizing Drop-on-Demand (DoD) dispensing of individual Multicellular Spheroids (MCSs) according to material jetting processes. In the DoD approach, a droplet dispenser ejects droplets containing these MCSs. For the reliable printing of tissue models, the exact number of dispensed MCSs must be determined. Current systems are designed to detect MCSs in the nozzle region prior to the dispensing process. However, due to surface effects, in some cases the spheroids that are detected adhere to the nozzle and are not dispensed with the droplet as expected. In contrast, detection that is carried out only after the droplet has been ejected is not affected by this issue. This work presents a system that can detect micrometer-sized synthetic or biological particles within free-falling droplets with a volume of about 30 nanoliters. Different illumination modalities and detection algorithms were tested. For a glare point projection-based approach, detection accuracies of an average of 95% were achieved for polymer particles and MCF-7 spheroids with diameters above 75 μm. For smaller particles the detection accuracy was still in the range of 70%. An approach with diffuse white light illumination demonstrated an improvement for the detection of small opaque particles. Accuracies up to 96% were achieved using this concept. This makes the two demonstrated methods suitable for improving the accuracy and quality control of particle detection in droplets for Drop-on-Demand techniques and for bioprinting.
Collapse
Affiliation(s)
- Fabian Sturm
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany
| | - Viktoria Zieger
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany
| | - Peter Koltay
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany
| | | | - Sabrina Kartmann
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems Engineering, University of Freiburg, 79110 Freiburg, Germany
- Hahn-Schickard, 79110 Freiburg, Germany
| |
Collapse
|
2
|
Zieger V, Woehr E, Zimmermann S, Frejek D, Koltay P, Zengerle R, Kartmann S. Automated Nanodroplet Dispensing for Large-Scale Spheroid Generation via Hanging Drop and Parallelized Lossless Spheroid Harvesting. MICROMACHINES 2024; 15:231. [PMID: 38398960 PMCID: PMC10893090 DOI: 10.3390/mi15020231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 01/14/2024] [Accepted: 01/19/2024] [Indexed: 02/25/2024]
Abstract
Creating model systems that replicate in vivo tissues is crucial for understanding complex biological pathways like drug response and disease progression. Three-dimensional (3D) in vitro models, especially multicellular spheroids (MCSs), offer valuable insights into physiological processes. However, generating MCSs at scale with consistent properties and efficiently recovering them pose challenges. We introduce a workflow that automates large-scale spheroid production and enables parallel harvesting into individual wells of a microtiter plate. Our method, based on the hanging-drop technique, utilizes a non-contact dispenser for dispensing nanoliter droplets of a uniformly mixed-cell suspension. The setup allows for extended processing times of up to 45 min without compromising spheroid quality. As a proof of concept, we achieved a 99.3% spheroid generation efficiency and maintained highly consistent spheroid sizes, with a coefficient of variance below 8% for MCF7 spheroids. Our centrifugation-based drop transfer for spheroid harvesting achieved a sample recovery of 100%. We successfully transferred HT29 spheroids from hanging drops to individual wells preloaded with collagen matrices, where they continued to proliferate. This high-throughput workflow opens new possibilities for prolonged spheroid cultivation, advanced downstream assays, and increased hands-off time in complex 3D cell culture protocols.
Collapse
Affiliation(s)
- Viktoria Zieger
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (S.Z.); (P.K.); (R.Z.); (S.K.)
| | - Ellen Woehr
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (E.W.); (D.F.)
- Study Program Molecular and Technical Medicine, Faculty Medical and Life Science, University of Furtwangen, D-78054 Villingen-Schwenningen, Germany
| | - Stefan Zimmermann
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (S.Z.); (P.K.); (R.Z.); (S.K.)
| | - Daniel Frejek
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (E.W.); (D.F.)
| | - Peter Koltay
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (S.Z.); (P.K.); (R.Z.); (S.K.)
| | - Roland Zengerle
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (S.Z.); (P.K.); (R.Z.); (S.K.)
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (E.W.); (D.F.)
| | - Sabrina Kartmann
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (S.Z.); (P.K.); (R.Z.); (S.K.)
- Hahn-Schickard, Georges-Koehler-Allee 103, D-79110 Freiburg, Germany; (E.W.); (D.F.)
| |
Collapse
|
3
|
Yang X, Wang X, Li B, Chu J. A high-precision automated liquid pipetting device with an interchangeable tip. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:094102. [PMID: 37728420 DOI: 10.1063/5.0139565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 08/31/2023] [Indexed: 09/21/2023]
Abstract
Liquid handling is a necessary act to deal with liquid samples from scientific labs to industry. However, existing pipetting devices suffer from inaccuracy and low precision when dealing with submicroliter liquids, which significantly affect their applications in low-volume quantitation. In this article, we present an automated liquid pipetting device that can aspirate liquid from microplates and dispense nanoliter droplets with high precision. Liquid aspiration is realized by using a micropump and a solenoid valve, and on-demand nanoliter droplet printing is realized by using a low-cost and interchangeable pipette tip combined with a piezoelectric actuator. Based on the microfluidic printing technology, the volumetric coefficient of variation of the dispensed liquid is less than 2% below 1 µl. A demonstration of concentration dilution for quantitative analysis has been successfully performed using the automated liquid pipetting device, demonstrating its potential in low-volume liquid handling for a wide range of biomedical applications.
Collapse
Affiliation(s)
- Xin Yang
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230027, Anhui, China
| | - Xiaojie Wang
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230027, Anhui, China
| | - Baoqing Li
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230027, Anhui, China
| | - Jiaru Chu
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, Anhui, China
- Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230027, Anhui, China
| |
Collapse
|
4
|
A Drop-on-Demand Bioprinting Approach to Spatially Arrange Multiple Cell Types and Monitor Their Cell-Cell Interactions towards Vascularization Based on Endothelial Cells and Mesenchymal Stem Cells. Cells 2023; 12:cells12040646. [PMID: 36831313 PMCID: PMC9953911 DOI: 10.3390/cells12040646] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/09/2023] [Accepted: 02/12/2023] [Indexed: 02/22/2023] Open
Abstract
Spheroids, organoids, or cell-laden droplets are often used as building blocks for bioprinting, but so far little is known about the spatio-temporal cellular interactions subsequent to printing. We used a drop-on-demand bioprinting approach to study the biological interactions of such building blocks in dimensions of micrometers. Highly-density droplets (approximately 700 cells in 10 nL) of multiple cell types were patterned in a 3D hydrogel matrix with a precision of up to 70 μm. The patterns were used to investigate interactions of endothelial cells (HUVECs) and adipose-derived mesenchymal stem cells (ASCs), which are related to vascularization. We demonstrated that a gap of 200 μm between HUVEC and ASC aggregates led to decreased sprouting of HUVECs towards ASCs and increased growth from ASCs towards HUVECs. For mixed aggregates containing both cell types, cellular interconnections of ASCs with lengths of up to approximately 800 µm and inhibition of HUVEC sprouting were observed. When ASCs were differentiated into smooth muscle cells (dASCs), separate HUVEC aggregates displayed decreased sprouting towards dASCs, whereas no cellular interconnections nor inhibition of HUVEC sprouting were detected for mixed dASCs/HUVEC aggregates. These findings demonstrate that our approach could be applied to investigate cell-cell interactions of different cell types in 3D co-cultures.
Collapse
|
5
|
Troendle K, Rizzo L, Pichler R, Koch F, Itani A, Zengerle R, Lienkamp SS, Koltay P, Zimmermann S. Scalable fabrication of renal spheroids and nephron-like tubules by bioprinting and controlled self-assembly of epithelial cells. Biofabrication 2021; 13. [PMID: 33513594 DOI: 10.1088/1758-5090/abe185] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 01/29/2021] [Indexed: 12/11/2022]
Abstract
Scalable fabrication concepts of 3D kidney tissue models are required to enable their application in pharmaceutical high-throughput screenings. Yet the reconstruction of complex tissue structures remains technologically challenging. We present a novel concept reducing the fabrication demands, by using controlled cellular self-assembly to achieve higher tissue complexities from significantly simplified construct designs. We used drop-on-demand bioprinting to fabricate locally confined patterns of renal epithelial cells embedded in a hydrogel matrix. These patterns provide defined local cell densities (cell count variance < 11 %) with high viability (92 ± 2 %). Based on these patterns, controlled self-assembly leads to the formation of renal spheroids and nephron-like tubules with a predefined size and spatial localization. With this, we fabricated scalable arrays of hollow epithelial spheroids. The spheroid sizes correlated with the initial cell count per unit and could be stepwise adjusted, ranging from Ø = 84, 104, 120 to 131 µm in diameter (size variance < 9 %). Furthermore, we fabricated scalable line-shaped patterns, which self-assembled to hollow cellular tubules (Ø = 105 ± 22 µm). These showed a continuous lumen with prescribed orientation, lined by an epithelial monolayer with tight junctions. Additionally, upregulated expression of kidney-specific functional genes compared to 2D cell monolayers indicated increased tissue functionality, as revealed by mRNA sequencing. Furthermore, our concept enabled the fabrication of hybrid tubules, which consisted of arranged subsections of different cell types, combining murine and human epithelial cells. Finally, we integrated the self-assembled fabrication into a microfluidic chip and achieved fluidic access to the lumen at the terminal sites of the tubules. With this, we realized flow conditions with a wall shear stress of 0.05 ± 0.02 dyne/cm² driven by hydrostatic pressure for scalable dynamic culture towards a nephron-on-chip model.
Collapse
Affiliation(s)
- Kevin Troendle
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| | - Ludovica Rizzo
- Institute of Anatomy and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Rämistrasse 71, Zurich, ZH, 8006, SWITZERLAND
| | - Roman Pichler
- Department of Nephrology, Universitätsklinikum Freiburg, Hugstetter Str. 55, Freiburg, 79106, GERMANY
| | - Fritz Koch
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| | - Ahmad Itani
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| | - Roland Zengerle
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| | - Soeren S Lienkamp
- Institute of Anatomy and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Rämistrasse 71, Zurich, ZH, 8006, SWITZERLAND
| | - Peter Koltay
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| | - Stefan Zimmermann
- Department of Microsystems Engineering, Albert-Ludwigs-Universitat Freiburg, Fahnenbergplatz, Freiburg im Breisgau, 79085, GERMANY
| |
Collapse
|
6
|
Tröndle K, Koch F, Finkenzeller G, Stark GB, Zengerle R, Koltay P, Zimmermann S. Bioprinting of high cell‐density constructs leads to controlled lumen formation with self‐assembly of endothelial cells. J Tissue Eng Regen Med 2019; 13:1883-1895. [DOI: 10.1002/term.2939] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 06/03/2019] [Accepted: 07/01/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Kevin Tröndle
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems EngineeringUniversity of Freiburg Freiburg Germany
| | - Fritz Koch
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems EngineeringUniversity of Freiburg Freiburg Germany
| | - Günter Finkenzeller
- Department of Plastic and Hand Surgery, Faculty of MedicineMedical Center—University of Freiburg Freiburg Germany
| | - G. Björn Stark
- Department of Plastic and Hand Surgery, Faculty of MedicineMedical Center—University of Freiburg Freiburg Germany
| | - Roland Zengerle
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems EngineeringUniversity of Freiburg Freiburg Germany
- Hahn‐Schickard, Freiburg Freiburg Germany
| | - Peter Koltay
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems EngineeringUniversity of Freiburg Freiburg Germany
- Hahn‐Schickard, Freiburg Freiburg Germany
- Freiburg Center for Interactive Materials and Bioinspired Technologies (FIT) Freiburg Germany
| | - Stefan Zimmermann
- Laboratory for MEMS Applications, IMTEK—Department of Microsystems EngineeringUniversity of Freiburg Freiburg Germany
| |
Collapse
|
7
|
Kulju S, Riegger L, Koltay P, Mattila K, Hyväluoma J. Fluid flow simulations meet high-speed video: Computer vision comparison of droplet dynamics. J Colloid Interface Sci 2018; 522:48-56. [PMID: 29574268 DOI: 10.1016/j.jcis.2018.03.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS While multiphase flows, particularly droplet dynamics, are ordinary in nature as well as in industrial processes, their mathematical and computational modelling continue to pose challenging research tasks - patent approaches for tackling them are yet to be found. The lack of analytical flow field solutions for non-trivial droplet dynamics hinders validation of computer simulations and, hence, their application in research problems. High-speed videos and computer vision algorithms can provide a viable approach to validate simulations directly against experiments. EXPERIMENTS Droplets of water (or glycerol-water mixtures) impacting on both hydrophobic and superhydrophobic surfaces were imaged with a high-speed camera. The corresponding configurations were simulated using a lattice-Boltzmann multiphase scheme. Video frames from experiments and simulations were compared, by means of computer vision, over entire droplet impact events. FINDINGS The proposed experimental validation procedure provides a detailed, dynamic one-on-one comparison of a droplet impact. The procedure relies on high-speed video recording of the experiments, computer vision, and on a software package for the analyzation routines. The procedure is able to quantitatively validate computer simulations against experiments and it is widely applicable to multiphase flow systems in general.
Collapse
Affiliation(s)
- S Kulju
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland
| | - L Riegger
- BiofluidiX GmbH, Engesserstrasse 4a, 79108 Freiburg, Germany
| | - P Koltay
- BiofluidiX GmbH, Engesserstrasse 4a, 79108 Freiburg, Germany
| | - K Mattila
- Faculty of Information Technology, University of Jyväskylä, P.O. Box 35 (Agora), FI-40014 University of Jyväskylä, Finland; Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
| | - J Hyväluoma
- Natural Resources Institute Finland (Luke), Humppilantie 14, 31600 Jokioinen, Finland.
| |
Collapse
|
8
|
Fan J, Men Y, Hao Tseng K, Ding Y, Ding Y, Villarreal F, Tan C, Li B, Pan T. Dotette: Programmable, high-precision, plug-and-play droplet pipetting. BIOMICROFLUIDICS 2018; 12:034107. [PMID: 29861810 PMCID: PMC5962442 DOI: 10.1063/1.5030629] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 05/09/2018] [Indexed: 05/19/2023]
Abstract
Manual micropipettes are the most heavily used liquid handling devices in biological and chemical laboratories; however, they suffer from low precision for volumes under 1 μl and inevitable human errors. For a manual device, the human errors introduced pose potential risks of failed experiments, inaccurate results, and financial costs. Meanwhile, low precision under 1 μl can cause severe quantification errors and high heterogeneity of outcomes, becoming a bottleneck of reaction miniaturization for quantitative research in biochemical labs. Here, we report Dotette, a programmable, plug-and-play microfluidic pipetting device based on nanoliter liquid printing. With automated control, protocols designed on computers can be directly downloaded into Dotette, enabling programmable operation processes. Utilizing continuous nanoliter droplet dispensing, the precision of the volume control has been successfully improved from traditional 20%-50% to less than 5% in the range of 100 nl to 1000 nl. Such a highly automated, plug-and-play add-on to existing pipetting devices not only improves precise quantification in low-volume liquid handling and reduces chemical consumptions but also facilitates and automates a variety of biochemical and biological operations.
Collapse
Affiliation(s)
- Jinzhen Fan
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | | | - Kuo Hao Tseng
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - Yi Ding
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - Yunfeng Ding
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - Fernando Villarreal
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - Cheemeng Tan
- Department of Biomedical Engineering, University of California, Davis, California 95616, USA
| | - Baoqing Li
- Authors to whom correspondence should be addressed: and
| | - Tingrui Pan
- Authors to whom correspondence should be addressed: and
| |
Collapse
|
9
|
Gutzweiler L, Kartmann S, Troendle K, Benning L, Finkenzeller G, Zengerle R, Koltay P, Stark GB, Zimmermann S. Large scale production and controlled deposition of single HUVEC spheroids for bioprinting applications. Biofabrication 2017; 9:025027. [DOI: 10.1088/1758-5090/aa7218] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
10
|
A Disposable Dispensing Valve for Non-Contact Microliter Applications in a 96-Well Plate Format. MICROMACHINES 2015. [DOI: 10.3390/mi6040423] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
11
|
Kirchner TB, Hatab NA, Lavrik NV, Sepaniak MJ. Highly ordered silicon pillar arrays as platforms for planar chromatography. Anal Chem 2013; 85:11802-8. [PMID: 24228860 DOI: 10.1021/ac402261p] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Unlike HPLC, there has been sparse advancement in the stationary phases used for planar chromatography. Nevertheless, modernization of planar chromatography platforms can further highlight the technique's ability to separate multiple samples simultaneously, utilize orthogonal separation formats, image (detect) separations without rigorous temporal demands, and its overall simplicity. This paper describes the fabrication and evaluation of ordered pillar arrays that are chemically modified for planar chromatography and inspected by fluorescence microscopy to detect solvent development and analyte bands (spots). Photolithography, in combination with anisotropic deep reactive ion etching, is used to produce uniform high aspect ratio silicon pillars. The pillar heights, diameters, and pitch variations are approximately 15-20 μm, 1-3 μm, and 2-6 μm, respectively, with the total pillar array size typically 1 cm × 3 cm. The arrays are imaged using scanning electron microscopy in order to measure the pillar diameter and pitch as well as analyze the pillar sidewalls after etching and stationary phase functionalization. These fluidic arrays will enable exploration of the impact on mass transport and chromatographic efficiency caused by altering the pillar array morphology. A C18 reverse stationary phase (RP), common RP solvents that are transported by traditional but uniquely rapid capillary flow, and Rhodamine 6G (R6G) as the preliminary analyte are used for this initial evaluation. The research presented in this article is aimed at understanding and overcoming the unique challenges in developing and utilizing ordered pillar arrays as a new platform for planar chromatography: focusing on fabrication of expansive arrays, studies of solvent transport, methods to create compatible sample spots, and an initial evaluation of band dispersion.
Collapse
Affiliation(s)
- Teresa B Kirchner
- Department of Chemistry, University of Tennessee , Knoxville, Tennessee 37996, United States
| | | | | | | |
Collapse
|
12
|
Bammesberger SB, Malki I, Ernst A, Zengerle R, Koltay P. A Calibration-Free, Noncontact, Disposable Liquid Dispensing Cartridge Featuring an Online Process Control. JOURNAL OF LABORATORY AUTOMATION 2013; 19:394-402. [PMID: 23981469 DOI: 10.1177/2211068213499757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Indexed: 11/16/2022]
Abstract
We present a noncontact liquid dispenser that uses a disposable cartridge for the calibration-free dosage of diverse biochemical reagents from the nanoliter to the microliter range. The dispensing system combines the advantages of a positive displacement syringe pump (responsible for defining the aliquot's volume with high accuracy) with a highly dynamic noncontact dispenser (providing kinetic energy to detach the liquid from the tip). The disposable, noncontact dispensing cartridge system renders elaborate washing procedures of tips obsolete. A noncontact sensor monitors the dispensing process to enable an online process control. To further increase confidence and reliability for particularly critical biomedical applications, an optional closed-loop control prevents malfunctions. The dispensing performance was characterized experimentally in the range of 0.25 to 10.0 µL using liquids of different rheological properties (viscosity 1.03-16.98 mPas, surface tension 30.49-70.83 mN/m) without adjusting or calibrating the actuation parameters. The precision ranged between a coefficient of variation of 0.5% and 5.3%, and the accuracy was below ±10%. The presented technology has the potential to contribute significantly to the improvement of biochemical liquid handling for laboratory automation in terms of usability, miniaturization, cost reduction, and safety.
Collapse
Affiliation(s)
- Stefan Borja Bammesberger
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - Imad Malki
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - Andreas Ernst
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany BioFluidix GmbH, Freiburg, Germany
| | - Roland Zengerle
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany HSG-IMIT-Institut für Mikro- und Informationstechnik, Freiburg, Germany
| | - Peter Koltay
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany HSG-IMIT-Institut für Mikro- und Informationstechnik, Freiburg, Germany
| |
Collapse
|
13
|
Tropmann A, Tanguy L, Koltay P, Zengerle R, Riegger L. Completely superhydrophobic PDMS surfaces for microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8292-5. [PMID: 22590992 DOI: 10.1021/la301283m] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This study presents a straightforward two-step fabrication process of durable, completely superhydrophobic microchannels in PDMS. First, a composite material of PDMS/PTFE particles is prepared and used to replicate a master microstructure. Superhydrophobic surfaces are formed by subsequent plasma treatment, in which the PDMS is isotropically etched and PTFE particles are excavated. We compare the advancing and receding contact angles of intrinsic PDMS samples and composite PTFE/PDMS samples (1 wt %, 8 wt %, and 15 wt % PTFE particle concentration) and demonstrate that both the horizontal and vertical surfaces are indeed superhydrophobic. The best superhydrophobicity is observed for samples with a PTFE particle concentration of 15 wt %, which have advancing and receding contact angles of 159° ± 4° and 158° ± 3°, respectively.
Collapse
Affiliation(s)
- Artur Tropmann
- Laboratory for MEMS Applications, IMTEK-Department of Microsystems Engineering, University of Freiburg, Georges-Koehler-Allee 103, Freiburg im Breisgau, Germany 79110.
| | | | | | | | | |
Collapse
|
14
|
Towards a "Sample-In, Answer-Out" Point-of-Care Platform for Nucleic Acid Extraction and Amplification: Using an HPV E6/E7 mRNA Model System. JOURNAL OF ONCOLOGY 2011; 2012:905024. [PMID: 22235204 PMCID: PMC3253481 DOI: 10.1155/2012/905024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/06/2011] [Indexed: 01/04/2023]
Abstract
The paper presents the development of a “proof-of-principle” hands-free and self-contained diagnostic platform for detection of human papillomavirus (HPV) E6/E7 mRNA in clinical specimens. The automated platform performs chip-based sample preconcentration, nucleic acid extraction, amplification, and real-time fluorescent detection with minimal user interfacing. It consists of two modular prototypes, one for sample preparation and one for amplification and detection; however, a common interface is available to facilitate later integration into one single module. Nucleic acid extracts (n = 28) from cervical cytology specimens extracted on the sample preparation chip were tested using the PreTect HPV-Proofer and achieved an overall detection rate for HPV across all dilutions of 50%–85.7%. A subset of 6 clinical samples extracted on the sample preparation chip module was chosen for complete validation on the NASBA chip module. For 4 of the samples, a 100% amplification for HPV 16 or 33 was obtained at the 1 : 10 dilution for microfluidic channels that filled correctly. The modules of a “sample-in, answer-out” diagnostic platform have been demonstrated from clinical sample input through sample preparation, amplification and final detection.
Collapse
|
15
|
Cellular-, Tissue-, Bioengineering (2). BIOMED ENG-BIOMED TE 2011. [DOI: 10.1515/bmt.2011.852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
16
|
Haeberle S, Naegele L, Burger R, von Stetten F, Zengerle R, Ducrée J. Alginate bead fabrication and encapsulation of living cells under centrifugally induced artificial gravity conditions. J Microencapsul 2008; 25:267-74. [PMID: 18465307 DOI: 10.1080/02652040801954333] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study presents a novel method for the direct, centrifugally induced fabrication of small, Ca2+-hardened alginate beads at polymer-tube micronozzles. The bead diameter can arbitrarily be adjusted between 180-800 microm by the nozzle geometry and spinning frequencies between 5-28 Hz. The size distribution of the main peak features a CV of 7-16%, only. Up to 600 beads per second and channel are issued from the micronozzle through an air gap towards the curing agent contained in a standard lab tube ('Eppi'). Several tubes can be mounted on a 'flying bucket' rotor where they align horizontally under rotation and return to a vertical position as soon as the rotor is at rest. The centrifugally induced, ultra-high artificial gravity conditions (up to 180 g) even allow the micro-encapsulation of alginate solutions displaying viscosities up to 50 Pa s, i.e. approximately 50,000 times the viscosity of water! With this low cost technology for microencapsulation, HN25 and PC12 cells have successfully been encapsulated while maintaining vitality.
Collapse
Affiliation(s)
- Stefan Haeberle
- HSG-IMIT-Institute for Micromachining and Information Technology, Villingen-Schwenningen, Germany.
| | | | | | | | | | | |
Collapse
|