@article{DantismRoehlenWagneretal.2018,
  author    = {Dantism, Shahriar and R{\"o}hlen, Desiree and Wagner, Torsten and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Optimization of Cell-Based Multi-Chamber LAPS Measurements Utilizing FPGA-Controlled Laser-Diode Modules},
  series = {physica status solidi a : applications and materials sciences},
  volume    = {215},
  journal   = {physica status solidi a : applications and materials sciences},
  number    = {15},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-6319},
  doi       = {10.1002/pssa.201800058},
  pages     = {Article number 1800058},
  year      = {2018},
  abstract  = {A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric device, which detects concentration changes of an analyte solution on the sensor surface in a spatially resolved way. It uses a light source to generate electron-hole pairs inside the semiconductor, which are separated in the depletion region due to an applied bias voltage across the sensor structure and hence, a surface-potential-dependent photocurrent can be read out. However, depending on the beam angle of the light source, scattering effects can occur, which influence the recorded signal in LAPS-based differential measurements. To solve this problem, a novel illumination unit based on a field programmable gate array (FPGA) consisting of 16 small-sized tunable infrared laser-diode modules (LDMs) is developed. Due to the improved focus of the LDMs with a beam angle of only 2 mrad, undesirable scattering effects are minimized. Escherichia coli (E. coli) K12 bacteria are used as a test microorganism to study the extracellular acidification on the sensor surface. Furthermore, a salt bridge chamber is built up and integrated with the LAPS system enabling multi-chamber differential measurements with a single Ag/AgCl reference electrode.},
  language  = {en}
}
@article{BronderJessingPoghossianetal.2018,
  author    = {Bronder, Thomas and Jessing, Max P. and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Detection of PCR-Amplified Tuberculosis DNA Fragments with Polyelectrolyte-Modified Field-Effect Sensors},
  series = {Analytical Chemistry},
  volume    = {90},
  journal   = {Analytical Chemistry},
  number    = {12},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {0003-2700},
  doi       = {10.1021/acs.analchem.8b01807},
  pages     = {7747 -- 7753},
  year      = {2018},
  abstract  = {Field-effect-based electrolyte-insulator-semiconductor (EIS) sensors were modified with a bilayer of positively charged weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) and probe single-stranded DNA (ssDNA) and are used for the detection of complementary single-stranded target DNA (cDNA) in different test solutions. The sensing mechanism is based on the detection of the intrinsic molecular charge of target cDNA molecules after the hybridization event between cDNA and immobilized probe ssDNA. The test solutions contain synthetic cDNA oligonucleotides (with a sequence of tuberculosis mycobacteria genome) or PCR-amplified DNA (which origins from a template DNA strand that has been extracted from Mycobacterium avium paratuberculosis-spiked human sputum samples), respectively. Sensor responses up to 41 mV have been measured for the test solutions with DNA, while only small signals of ∼5 mV were detected for solutions without DNA. The lower detection limit of the EIS sensors was ∼0.3 nM, and the sensitivity was ∼7.2 mV/decade. Fluorescence experiments using SybrGreen I fluorescence dye support the electrochemical results.},
  language  = {en}
}