List of publications Dr. Ana Homann

• Journal Articles
• Talks
• Conference papers

Journal Articles

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2021

• A. Homann, L. Niebling, S. Zehnle, M. Beutler, L. Delamotte, M.C. Rothmund, D. Czurratis, K.-D. Beller, R. Zengerle, H. Hoffmann, N. Paust
  A microfluidic cartridge for fast and accurate diagnosis of Mycobacterium tuberculosis infections on standard laboratory equipment
  2021 Lab on a Chip, volume: 21, issue: 8, pages: 1540 - 1548
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  Abstract

  We present a novel centrifugal microfluidic approach for fast and accurate tuberculosis (TB) diagnosis based on the use of standard laboratory equipment. The herein presented workflow can directly be integrated into laboratories with standard equipment and automates complex sample preparation. The system consists of a microfluidic cartridge, a laboratory centrifuge and a standard PCR cycler. The cartridge includes all required reagents and automates collection of bacteria on filter membranes, bacterial lysis, nucleic acid extraction and aliquoting of the DNA extract for PCR analysis. We show that storage of the reagents in aluminium-coated pouches is stable during accelerated storage and transport tests. When the limit of detection was assessed, we found that the cartridge-automated workflow consistently detected 10 CFU ml−1 of mycobacteria in spiked sputum samples. First tests with clinical samples showed a 100% specificity for non-TB specimens. In addition, Mycobacterium tuberculosis (MTB) was re-found in pre-characterized smear microscopy and culture positive sputum samples suggesting a high diagnostic sensitvity. In summary, the novel cartridge-automated workflow enables a flexible and sensitive TB diagnosis without the need to invest in specialized instrumentation.
• M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. Homann, F. von Stetten, R. Zengerle, N. Paust
  High Dynamic Range Digital Assay Enabled by Dual-Volume Centrifugal Step Emulsification
  2021 Analytical Chemistry, volume: 93, issue: 5, pages: 2854 - 2860
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  Abstract

  We implement dual-volume centrifugal step emulsification on a single chip to extend the dynamic range of digital assays. Compared to published single-volume approaches, the range between the lower detection limit (LDL) and the upper limit of quantification (ULQ) increases by two orders of magnitude. In comparison to existing multivolume approaches, the dual-volume centrifugal step emulsification requires neither complex manufacturing nor specialized equipment. Sample metering into two subvolumes, droplet generation, and alignment of the droplets in two separate monolayers are performed automatically by microfluidic design. Digital quantification is demonstrated by exemplary droplet digital loop-mediated isothermal amplification (ddLAMP). Within 5 min, the reaction mix is split into subvolumes of 10.5 and 2.5 μL, and 2,5k and 176k droplets are generated with diameters of 31.6 ± 1.4 and 213.9 ± 7.5 μm, respectively. After 30 min of incubation, quantification over 5 log steps is demonstrated with a linearity of R2 ≥ 0.992.

2020

• M. Schulz, S. Probst, S. Calabrese, A. Homann, N. Borst, M. Weiss, F. von Stetten, R. Zengerle, N. Paust
  Versatile Tool for Droplet Generation in Standard Reaction Tubes by Centrifugal Step Emulsification
  2020 Molecules, volume: 25, issue: 8, page: 1914
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  Abstract

  We present a versatile tool for the generation of monodisperse water-in-fluorinated-oil droplets in standard reaction tubes by centrifugal step emulsification. The microfluidic cartridge is designed as an insert into a standard 2 mL reaction tube and can be processed in standard laboratory centrifuges. It allows for droplet generation and subsequent transfer for any downstream analysis or further use, does not need any specialized device, and manufacturing is simple because it consists of two parts only: A structured substrate and a sealing foil. The design of the structured substrate is compatible to injection molding to allow manufacturing at large scale. Droplets are generated in fluorinated oil and collected in the reaction tube for subsequent analysis. For sample sizes up to 100 µL with a viscosity range of 1 mPa·s–4 mPa·s, we demonstrate stable droplet generation and transfer of more than 6 × 105 monodisperse droplets (droplet diameter 66 µm ± 3 µm, CV ≤ 4%) in less than 10 min. With two application examples, a digital droplet polymerase chain reaction (ddPCR) and digital droplet loop mediated isothermal amplification (ddLAMP), we demonstrate the compatibility of the droplet production for two main amplification techniques. Both applications show a high degree of linearity (ddPCR: R2 ≥ 0.994; ddLAMP: R2 ≥ 0.998), which demonstrates that the cartridge and the droplet generation method do not compromise assay performance.

2014

• A. Kloke, A. R. Fiebach, S. Zhang, L. Drechsel, S. Niekrawietz, M. Hoehl, R. Kneusel, K. Panthel, J. Steigert, F. von Stetten, R. Zengerle, N. Paust
  The LabTube – A novel microfluidic platform for assay automation in laboratory centrifuges
  2014 Lab Chip, volume: 14, pages: 1527 - 1537
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  Abstract

  Assay automation is the key for successful transformation of modern biotechnology into routine workflows. Yet, it requires considerable investment in processing devices and auxiliary infrastructure, which is not cost-efficient for laboratories with low or medium sample throughput or point-of-care testing. To close this gap, we present the LabTube platform, which is based on assay specific disposable cartridges for processing in laboratory centrifuges. LabTube cartridges comprise interfaces for sample loading and downstream applications and fluidic unit operations for release of prestored reagents, mixing, and solid phase extraction. Process control is achieved by a centrifugally-actuated ballpen mechanism. To demonstrate the workflow and functionality of the LabTube platform, we show two LabTube automated sample preparation assays from laboratory routine: DNA extractions from whole blood and purification of His-tagged proteins. Equal DNA and protein yield were observed compared to manual reference runs, while LabTube automation could significantly reduce the hands-ontime to one minute per extraction.

Talks

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2013

• F. von Stetten, A. Kloke, A. Fiebach, L. Drechsel, S. Zhang, N. Paust, J. Steigert, R. Zengerle
  LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
  2013 Gordon Research Conference on ”Physics and Chemistry of Microfluidics: Challenges, Advances and New Technologies for Diagnostics” in Lucca, Tuscany, Italy , 09. – 14.06.2013

Conference papers

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2021

• L. Niebling, S. Burger, N. Paust, A. R. Homann
  Fast and on-site animal species identification in processed meat
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. R. Homann, F. von Stetten, R. Zengerle, N.Paust
  High dynamic range digital assay enabled by dual volume centrifugal step emulsification
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021

2019

• S. Burger, L. Drechsel, A. Homann, F. von Stetten, R. Zengerle, N. Paust
  LabSlice XL – A centrifugal microfluidic cartridge for the automated bio-chemical processing of industrial process water
  2019 Transducers, Berlin, 23. - 27. 06. 2019

2014

• N. Paust, A. R. Fiebach, L. Drechsel, S. Zhang, R. Zengerle, F. von Stetten
  LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
  2014 IFCC WorldLab Istanbul, 22.-26-06-2014, Istanbul, Türkei
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  Abstract

  The “LabTube” is a novel centrifugal lab-on-a-chip platform that uses a standard laboratory centrifuge as processing device. It automates multistep protocols such as nucleic acid extraction or protein purification, decreasing the hands-on-time from > 6 to 1 minute per extraction. Future applications will include point-ofcare sample-to-answer nucleic acid analysis. The LabTube approach lowers the market entry barrier for microfluidics as the user only requires to purchase disposable parts without the need to invest in specialized processing devices.
• F. von Stetten, A. Kloke, A.R. Fiebach, J. Steigert, M. Hoehl, R. Zengerle, N. Paust
  LabTube - a novel centrifugal microfluidic lab-on-a-chip platform for operation in standard laboratory centrifuges
  2014 Biosensors 2014, Melbourne, Australia, 27.05.2014 – 30.05.2014

2013

• A. Kloke, S. Niekrawietz, A.R. Fiebach, J. Bernhardt, R. Kneusel, K. Schemel, J. Ritzel, F. von Stetten, R. Zengerle, N. Paust
  Disposable LabTube cartridges for automated protein purification in standard lab centrifuges
  2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , pages: 1628 - 1630
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  Abstract

  The protein purification process is often the bottleneck for the efficient production of a large number of different proteins. Automation of these procedures is often the crux of the matter and is frequently a trade-off between efficiency and cost. Using our novel disposable LabTube cartridges we demonstrate how the process of His-tagged protein purification can be automated in standard laboratory centrifuges. LabTube cartridges include prestored reagents which are sequentially applied to a Ni-NTA purification matrix by an integrated ballpen mechanism actuated by acceleration changes of the centrifuge. Fully automated runs demonstrated similar yield and purity compared to manual purifications with sample addition as the only manual handling step. Thus, the user is available for parallel tasks during 95 % of the overall process time (33 min). In contrast manual processing requires the user to be present for 18 minutes out of the 33 minute overall process time. Since LabTube automation requires no investment in a special lab automation device, this platform lowers the market entry barrier for lab automation.
• A.R. Fiebach, S. Zhang, L. Drechsel, A. Kloke, N. Fritzemeier, D. Wulff, J. Steigert, R. Zengerle, F. von Stetten, N. Paust
  LabTube – an innovative platform for assay automation in laboratory centrifuges
  2013 Microsystemtechnik (MST) Kongress 2013, Aachen, 14. - 16.10.2013 , pages: 27 - 30
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  Abstract

  In this paper we present the innovative LabTube platform: A fully automated, easy to handle and cost-effective system that automatizes diverse assays on standard laboratory centrifuges and thus offers a reasonable alternative to existing lab-on-a-chip systems. The LabTube has the size of a 50 ml centrifuge tube and is composed of three stacked revolvers that are operated by a centrifuge-triggered ball-pen mechanism. The upper revolver provides the reagent pre-storage, the middle revolver comprises the assay-specific fluidic unit operations and the lower revolver functions as a unit for the collection and separation of the processed reagents. To demonstrate the functionality of the LabTube on the basis of a frequently used assay, a DNA extraction was performed. The fully automated DNA extraction from rapeseed lysate in the LabTube resulted in a DNA yield of 17,7 +/- 8,1 ng μl -1 in comparison to a manual reference with 14,8 +/- 1,5 ng μl -1. Thus, the hands-on time was reduced from 15 minutes to 1 minute by employing the LabTube, without the need for special training or special laboratory equipment. Currently, the LabTube is also under investigation for protein analysis and for point-of-care diagnostic.
• J. Liebeskind, A. Kloke, A. R. Fiebach, F. von Stetten, R. Zengerle, N. Paust
  Mixing by on-chip generated gas bubbles for assay automation in standard laboratory centrifuges
  2013 MicroTAS 2013, Freiburg, 27.-31.10.2013 , pages: 967 - 969
• A. Kloke, L. Drechsel, S. Zhang, A.R. Fiebach, N. Paust, R. Zengerle, F. von Stetten
  The LabTube Platform – Disposable Cartridges For Automated Processing Of Biochemical Assays In Standard Laboratory Centrifuges
  2013 21st annual international BIODETECTION TECHNOLOGIES, Washington, DC, USA, 18-19.6. 2013
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  Abstract

  A laboratory centrifuge can be applied to automate biochemical assays for point-of-care diagnostics or sample preparation such as DNA or protein extraction. Key innovation is integration of liquid handling into a 50 ml centrifuge tube. This "LabTube" harbors three revolvers which are stepwise rotated against each other by a g-force operated ball pen mechanics. The first revolver sequentially releases pre-stored reagents into the second revolver which is equipped with a mixing chamber and a solid phase column. Fractions of processed liquids are collected by the third revolver. Automated LabTube based DNA-extractions showed comparable yields to manual reference extractions.

2012

• R. Zengerle, J. Hoffmann, G. Roth, O. Strohmeier, A. R. Fiebach, L. Drechsel, S. Zhang, A. Kloke, N. Paust, D. Mark, F. von Stetten
  Microfluidic Apps on standard Lab-instruments
  2012 MicroTAS, Okinawa, Japan, 28. Okt. - 01. Nov. 2012 , pages: 239 - 241
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  Abstract

  Here we promote a new way of thinking: Designing microfluidic chips that can be processed on standard instruments which are already present in typical laboratory setups. Those instruments could be standard lab centrifuges, real-time PCR cyclers or even second generation sequencers. We call this approach the Microfluidic App approach