Publikationsliste Martin Trotter

• Originalarbeiten in wissenschaftlichen Fachzeitschriften
• Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften
• Konferenzbeiträge

Originalarbeiten in wissenschaftlichen Fachzeitschriften

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2020

• M. Trotter, D. Juric, Z. Bagherian, N. Borst, K. Gläser, T. Meissner, F. von Stetten, A. Zimmermann
  Inkjet-Printing of Nanoparticle Gold and Silver Ink on Cyclic Olefin Copolymer for DNA-Sensing Applications
  2020 Sensors, Band: 20, Nummer: 5, Seite: 1333
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  Kurzfassung

  Inkjet technology as a maskless, direct-writing technology offers the potential for structured deposition of functional materials for the realization of electrodes for, e.g., sensing applications. In this work, electrodes were realized by inkjet-printing of commercial nanoparticle gold ink on planar substrates and, for the first time, onto the 2.5D surfaces of a 0.5 mm-deep microfluidic chamber produced in cyclic olefin copolymer (COC). The challenges of a poor wetting behavior and a low process temperature of the COC used were solved by a pretreatment with oxygen plasma and the combination of thermal (130 °C for 1 h) and photonic (955 mJ/cm²) steps for sintering. By performing the photonic curing, the resistance could be reduced by about 50% to 22.7 μΩ cm. The printed gold structures were mechanically stable (optimal cross-cut value) and porous (roughness factors between 8.6 and 24.4 for 3 and 9 inkjet-printed layers, respectively). Thiolated DNA probes were immobilized throughout the porous structure without the necessity of a surface activation step. Hybridization of labeled DNA probes resulted in specific signals comparable to signals on commercial screen-printed electrodes and could be reproduced after regeneration. The process described may facilitate the integration of electrodes in 2.5D lab-on-a-chip systems.

2017

• N. Borst, F. Schuler, S. Wadle, M. Schulz, M. Specht, J. Li, L. Becherer, M. Trotter, A. B. Rodríguez-Martínez, N. Paust, R. Zengerle, F. von Stetten
  A technology platform for digital nucleic acid diagnostics at the point of care
  2017 Laboratoriumsmedizin, Band: 41, Nummer: 5
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  Kurzfassung

  The combination of digital amplification and centrifugal microfluidics can enable quantitative and fast diagnostics at the point of care (PoC). The new unit operation of centrifugal step emulsification allows high throughput droplet generation. Different methods for digital nucleic acid analysis, including PCR, recombinase polymerase amplification (RPA) and loop mediated isothermal amplification (LAMP), have already been demonstrated. Our novel approach of integrated sample-to-answer analysis is introduced, and examples for the detection of HIV and single cell analysis of antibiotic resistant bacteria are presented. Next to these LabDisk based systems, a microfluidic cartridge termed DropChip allows for digital amplification using only commercially available laboratory devices.

2016

• F. Schuler, M. Trotter, M. Geltman, F. Schwemmer, S. Wadle, E. Domínguez-Garrido, M. López, C. Cervera-Acedo, P. Santibáñez, F. von Stetten, R. Zengerle, N. Paust
  Digital Droplet PCR on Disk
  2016 Lab Chip, Band: 16, Seiten: 208 - 216
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  Kurzfassung

  Existing systems for digital droplet PCR (ddPCR) either suffer from low integration or are difficult to introduce to mass fabrication. Here we present an integrated system that is compatible to mass fabrication and combines emulsification, PCR, and fluorescence readout in a single chamber within a disposable cartridge (disk). Droplets are generated by injecting the sample into fluorinated oil via centrifugal step emulsification. The resulting emulsion is aligned in the PCR and readout zone by capillary action. During thermocycling, gas bubbles generated by degassing are removed by capillary driven transport through tapered regions in the PCR chamber. Thereby, the positioning of the emulsion within the readout zone of the PCR chamber is ensured at any time and no bubbles are present during readout. Manual handling of the disk solely requires pipetting of oil and PCR mix into the inlet structures, placing the disk into the thermocycler and subsequently into a microarray scanner. The functionality of the ddPCR process chain is demonstrated by quantitative detection of the cystic fibrosis causing mutation p.Phe508del, which is of interest for non-invasive prenatal testing (NIPT). The mutation was detected in a concentration range spanning four orders of magnitude. We envision that this work will lay the base for the development of highly integrated sample-to-digital-answer PCR systems that can be employed in routine clinical diagnosis.
• F. Schuler, M. Trotter, R. Zengerle, F. von Stetten
  Monochrome Multiplexing in Polymerase Chain Reaction by Photobleaching of Fluorogenic Hydrolysis Probes
  2016 Anal Chem, Band: 88, Nummer: 5, Seiten: 2590 - 2595
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  Kurzfassung

  Multiplexing in polymerase chain reaction (PCR) is a technique widely used to save cost and sample material and to increase sensitivity compared to distributing a sample to several singleplex reactions. One of the most common methods to detect the different amplification products is the use of fluorogenic probes that emit at different wavelengths (colors). To reduce the number of detection channels, several methods for monochrome multiplexing have been suggested. However, they pose restrictions to the amplifiable target length, the sequence, or the melting temperature. To circumvent these limitations, we suggest a novel approach that uses different fluorophores with the same emission maximum. Discrimination is achieved by their different fluorescence stability during photobleaching. Atto488 (emitting at the same wavelength as 6-carboxyfluorescein, FAM) and Atto467N (emitting at the same wavelength as cyanine 5, Cy5) were found to bleach significantly less than FAM and Cy5; i.e., the final fluorescence of Atto dyes was more than tripled compared to FAM and Cy5. We successfully applied this method by performing a 4-plex PCR targeting antibiotic resistance genes in S. aureus using only 2 color channels. Confidence of discrimination between the targets was >99.9% at high copy initial copy numbers of 100 000 copies. Cases where both targets were present could be discriminated with equal confidence for Cy5 channel and reduced levels of confidence (>68%) for FAM channel. Moreover, a 2- plex digital PCR reaction in 1 color channel was shown. In the future, the degree of multiplexing may be increased by adding fluorogenic probe pairs with other emission wavelengths. The method may also be applied to other probe and assay formats, such as Förster resonance energy transfer (FRET) probes and immunoassays.

2015

• F. Schuler, F. Schwemmer, M. Trotter, S. Wadle, R. Zengerle, F. von Stetten, N. Paust
  Centrifugal step emulsification applied for absolute quantification of nucleic acids by digital droplet RPA
  2015 Lab Chip, Band: 15, Seiten: 2759 - 2766
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  Kurzfassung

  Aqueous microdroplets provide miniaturized reaction compartments for numerous chemical, biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for the fast and easy production of monodispers droplets. Homogenous droplets with preselectable diameters in a range from 120 μm to 170 μm were generated with coefficients of variation of 2-4% and zero run-in time or dead volume. The droplet diameter depends on the nozzle geometry (depth, width, and step size) and interfacial tensions, only. Droplet size is demonstrated to be independent of the dispersed phase flow rate between 0.01-1 μl/s, proving the robustness of the centrifugal approach. Centrifugal step emulsification can easily be combined with existing centrifugal microfluidic unit operations, is compatible to scalable manufacturing technologies such as thermoforming or injection moulding and enables fast emulsification (> 500 droplets per second and nozzle) with minimal handling effort (2-3 pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute quantification of Listerias monocytogenes DNA concentration standards with a total analysis time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with processing times of about 2 hours, the overall processing time of digital analysis was reduced by more than a factor of 4.

2012

• Jochen Hoffmann, Martin Trotter, Felix von Stetten, Roland Zengerle, Günter Roth
  Solid-phase PCR in a picowell array for immobilizing and arraying 100,000 PCR products to a microscope slide
  2012 Lab Chip, Band: 12, Nummer: 17, Seiten: 3049 - 3054
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  Kurzfassung

  We present a method for performing highly parallel PCR reactions in a picowell array (PWA) simultaneously immobilizing generated PCR products covalent and spatially-resolved onto a microscope slide via solid-phase PCR (SP-PCR). This so called PWA-SP-PCR is performed in picowell arrays featuring 100,000 wells∙cm^-2 of 19 pL reaction volumes with a surface-to-volume-ratio of 0.2 µm-1. Positive signals are obtained in 97.2 % of the 110,000 wells on an area of 110 mm^2. Immobilized DNA is either detected sequence-unspecific via streptavidin-Cy5 or sequence-specific by Cy3 labeled hybridization probes. Amplification and immobilization is demonstrated for template DNA ranging from 100 bp up to 1513 bp length. Compared to widely established emulsion based PCR (emPCR) approaches, leading to PCR products immobilized onto bead surfaces in highly parallel manner, the novel technique results in direct spatial registration of immobilized PCR products in a microarray format. This enables the subsequent use for massively parallel analysis similar to standard microarrays.

Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften

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2020

• M. Trotter, N. Borst, R. Thewes, F. von Stetten
  Electrochemical DNA sensing – Principles, commercial systems, and applications
  2020 Biosens Bioelectron, Band: 154, Seite: 112069
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  Kurzfassung

  Driven by the vision of robust and portable, yet sensitive DNA detection systems for point-of-need applications, the development of electrochemical DNA sensing principles has been of high interest. Many different principles have been developed and these are regularly reviewed. However, the maturity of electrochemical principles and their ability to produce competitive real-world applications is rarely assessed. In this review, general electrochemical DNA sensing principles are briefly introduced and categorized into heterogeneous vs. homogeneous approaches, and then the subcategories label-free vs. labeled and reagent-less vs. reagent-dependent principles. We then focus on reviewing the electrochemical sensing principles implemented in DNA detection systems, which are commercially available or close to market entry, considering the complete analysis process, automation and the field of application. This allows us to outline and discuss which principles have proved suitable for which kinds of applications, as well as the stage of integration and automation. Examples from all the identified categories of electrochemical DNA sensing principles have found application in commercial detection systems or advanced prototypes. Various applications have already been demonstrated, ranging from on-site skin care testing, to food safety to the most frequent in vitro diagnostic tests, partially conducted in automated sample-to-answer devices. Our review is intended to enable researchers in areas related to electrochemistry, biochemistry or microfluidics to assess the commercial state of the art of electrochemical nucleic acid testing, and the interdisciplinary challenges for further improvements.
  
  
   
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Konferenzbeiträge

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2022

• M. Trotter, A. Schreiber, D. Kleinknecht, N. Borst, M. Kuderer, K. Gläser, F. von Stetten
  Mobile elektrochemische Plattform zur molekularen Diagnostik in der häuslichen Pflege
  2022 5. Müchner Poit-of-Care Testing Symposium, Munich, September,27-29, 2022

2021

• M. Trotter, D. Juric, Z. Bagherian, N. Borst, K. Gläser, F. von Stetten, A. Zimmermann
  Integration of nanoporous gold electrodes in microfluidic chambers by inkjet-printing for biosensing applications
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021

2018

• Z. Bagheryan, M. Trotter, L. Becherer, N. Borst, F. von Stetten
  A universal approach for electrochemically DNA detection based on mediator displacement LAMP
  2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland
• M. Trotter, N. Borst, F. von Stetten
  Mediator probes for electrochemical DNA detection: Universal electrode functionalization for specific detection of different targets
  2018 9th Euro Biosensors & Bioelectronics Congress November 29-30, 2018 Dublin, Ireland

2015

• F. Schuler, M. Trotter, S. Wadle, F. Schwemmer, R. Zengerle, F. von Stetten, N. Paust
  Centrifugal microfluidic step emulsification for digital droplet recombinase polymerase amplification
  2015 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences October 25-29, 2015, Gyeongju, KOREA
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  Kurzfassung

  For the first time we show centrifugal step emulsification. It enables the fast and easy production of monodispers w/o droplets with minimal handling effort (3 pipetting steps). In contrast to previously presented centrifugal emulsification systems [1], homogenous droplets with pre-selectable diameters were generated with zero run-in time and zero dead volume. The centrifugal microfluidic step emulsification was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). Compared to digital droplet PCR, the amplification time was reduced by a factor of 4 from 2 hours to 30 minutes.

2014

• M. Trotter, F. Stumpf, F. von Stetten, J. Hoffmann, R. Zengerle, G. Roth
  One-step single cell solid-phase PCR
  2014 5th annual conference for advances in qPCR & dPCR , Barcelona, Spain, 14. - 15. 05.2014

2012

• M. Trotter, F. von Stetten, G. Roth, R. Zengerle, J. Hoffmann
  Massively-parallel digital solid-phase PCR for the in-situ generation of a sequencing-ready picowell array circumventing emPCR
  2012 Digital PCR Conference, San Diego, USA, 15.10. – 16.10.2012

2011

• J. Hoffmann, M. Trotter, F. von Stetten, R. Zengerle, G. Roth
  Single-Molecule PCR in a Picowell Array Simultaneously Immobilizing PCR Products to a PDMS Coverslide
  2011 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS), October 2-6, 2011, Seattle, Washington, USA , Seiten: 900 - 902
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  Kurzfassung

  For the first time, we amplified single DNA-molecules (“Digital PCR”) randomly distributed in a picowell array and simultaneously immobilized the generated PCR-products to the surface of a PDMS coverslide (“solid-phase PCR”) which was used as sealing of the picowells during PCR. First, by this unprecedented technique PCR-products can be recovered for both, further reactions/analysis and counting the number of initial DNA-molecules from digital signals with a good signal to noise ratio of 10. Second, our experiments demonstrate the currently smallest low-volume on-chip PCR in an array of 18.5 pL wells. This may enable single-cell PCR experiments by filling PCR microreactors with truly single-cells due to geometrical constriction. KEYWORDS: Digital PCR, solid-phase PCR, parallelization

2009

• Henning Hoefemann, Hans-Martin Trotter, Roland Gronmaier, Felix von Stetten, Roland Zengerle, Stefan Haeberle
  Rheoplug – Segmented flow based viscometer
  2009 Proc. of the Thirteenth International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS), Jeju, Korea, November 1-5 , Seiten: 76 - 78
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  Kurzfassung

  We present a novel method to measure the viscosity of liquid mixtures in μLvolume plugs based on a segmented flow platform [1]. Therefore, up to three different liquids of different viscosities are injected into a common plug which is afterwards transported through an air filled channel by a 15-20 mbar vacuum below ambient pressure at the chip outlet. Rapid mixing within the plugs is enabled by internal advection and the plug velocity directly depends on the viscosity of the plug. Following this approach, the viscosities of water/PEG mixtures in the range of 1-68 mPa s could be successfully measured on-chip.