@article{BronderPoghossianSchejaetal.2015,
  author    = {Bronder, Thomas and Poghossian, Arshak and Scheja, Sabrina and Wu, Chunsheng and Keusgen, Michael and Mewes, Dieter and Sch{\"o}ning, Michael Josef},
  title     = {DNA Immobilization and Hybridization Detection by the Intrinsic Molecular Charge Using Capacitive Field-Effect Sensors Modified with a Charged Weak Polyelectrolyte Layer},
  series = {Applied Materials \& Interfaces},
  volume    = {36},
  journal   = {Applied Materials \& Interfaces},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington, DC},
  doi       = {10.1021/acsami.5b05146},
  pages     = {20068 -- 20075},
  year      = {2015},
  abstract  = {Miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge favor the semiconductor field-effect platform as one of the most attractive approaches for the development of label-free DNA chips. In this work, a capacitive field-effect EIS (electrolyte-insulator-semiconductor) sensor covered with a layer-by-layer prepared, positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was used for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization. The negatively charged probe single-stranded DNA (ssDNA) molecules were electrostatically adsorbed onto the positively charged PAH layer, resulting in a preferentially flat orientation of the ssDNA molecules within the Debye length, thus yielding a reduced charge-screening effect and a higher sensor signal. Each sensor-surface modification step (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), reducing an unspecific adsorption by a blocking agent, incubation with noncomplementary DNA (ncDNA) solution) was monitored by means of capacitance-voltage and constant-capacitance measurements. In addition, the surface morphology of the PAH layer was studied by atomic force microscopy and contact-angle measurements. High hybridization signals of 34 and 43 mV were recorded in low-ionic strength solutions of 10 and 1 mM, respectively. In contrast, a small signal of 4 mV was recorded in the case of unspecific adsorption of fully mismatched ncDNA. The density of probe ssDNA and dsDNA molecules as well as the hybridization efficiency was estimated using the experimentally measured DNA immobilization and hybridization signals and a simplified double-layer capacitor model. The results of field-effect experiments were supported by fluorescence measurements, verifying the DNA-immobilization and hybridization event.},
  language  = {en}
}
@article{SchusserKrischerBaeckeretal.2015,
  author    = {Schusser, Sebastian and Krischer, Maximillian and B{\"a}cker, Matthias and Poghossian, Arshak and Wagner, Patrick and Sch{\"o}ning, Michael Josef},
  title     = {Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors},
  series = {Analytical Chemistry},
  volume    = {87},
  journal   = {Analytical Chemistry},
  number    = {13},
  publisher = {ACS Publications},
  address   = {Washington, DC},
  issn      = {1520-6882},
  doi       = {10.1021/acs.analchem.5b00617},
  pages     = {6607 -- 6613},
  year      = {2015},
  abstract  = {Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.},
  language  = {en}
}
@incollection{PoghossianSchusserBaeckeretal.2015,
  author    = {Poghossian, Arshak and Schusser, Sebastian and B{\"a}cker, M. and Leinhos, Marcel and Sch{\"o}ning, Michael Josef},
  title     = {Real-time in-situ electrical monitoring of the degradation of biopolymers using semiconductor field-effect devices},
  series = {Biodegradable biopolymers. Vol. 1},
  booktitle = {Biodegradable biopolymers. Vol. 1},
  publisher = {Nova Science Publ.},
  address   = {Hauppauge},
  isbn      = {978-1-63483-632-6},
  pages     = {135 -- 153},
  year      = {2015},
  language  = {en}
}
@inproceedings{PoghossianBronderWuetal.2015,
  author    = {Poghossian, Arshak and Bronder, Thomas and Wu, Chunsheng and Sch{\"o}ning, Michael Josef},
  title     = {Label-free sensing of biomolecules by their intrinsic molecular charge using field-effect devices},
  series = {Semiconductor Micro- and Nanoelectonics : Proceedings of the tenth international conference, Yerevan, Armenia, September 11-13},
  booktitle = {Semiconductor Micro- and Nanoelectonics : Proceedings of the tenth international conference, Yerevan, Armenia, September 11-13},
  isbn      = {978-5-8084-1991-9},
  pages     = {61 -- 63},
  year      = {2015},
  language  = {en}
}