TY  - JOUR
A1  - Bronder, Thomas
A1  - Poghossian, Arshak
A1  - Scheja, Sabrina
A1  - Wu, Chunsheng
A1  - Keusgen, Michael
A1  - Mewes, Dieter
A1  - Schöning, Michael Josef
T1  - DNA Immobilization and Hybridization Detection by the Intrinsic Molecular Charge Using Capacitive Field-Effect Sensors Modified with a Charged Weak Polyelectrolyte Layer
JF  - Applied Materials & Interfaces
N2  - 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.
Y1  - 2015
U6  - http://dx.doi.org/10.1021/acsami.5b05146
VL  - 36
IS  - 7
SP  - 20068
EP  - 20075
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Schöning, Michael Josef
A1  - Bronder, Thomas
A1  - Wu, Chunsheng
A1  - Scheja, Sabrina
A1  - Jessing, Max
A1  - Metzger-Boddien, Christoph
A1  - Keusgen, Michael
A1  - Poghossian, Arshak
T1  - Label-Free DNA Detection with Capacitive Field-Effect Devices—Challenges and Opportunities
JF  - Proceedings
N2  - Field-effect EIS (electrolyte-insulator-semiconductor) sensors modified with a positively charged weak polyelectrolyte layer have been applied for the electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge. The EIS sensors are able to detect the existence of target DNA amplicons in PCR (polymerase chain reaction) samples and thus, can be used as tool for a quick verification of DNA amplification and the successful PCR process. Due to their miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge, those sensors can serve as possible platform for the development of label-free DNA chips. Possible application fields as well as challenges and limitations will be discussed.
Y1  - 2017
U6  - http://dx.doi.org/10.3390/proceedings1080719
SN  - 2504-3900
N1  - This article belongs to the Proceedings of "Proceedings of the 5th International Symposium on Sensor Science (I3S 2017)"
VL  - 1
IS  - 8
SP  - Artikel 719
PB  - MDPI
CY  - Basel
ER  -