DNA Immobilization and Hybridization Detection by the Intrinsic Molecular Charge Using Capacitive Field-Effect Sensors Modified with a Charged Weak Polyelectrolyte Layer.
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.
Institute of Nano- and Biotechnologies, FH Aachen , Campus Jülich, 52428 Jülich, Germany.
Thomas S
TS
Bronder
Institute of Nano- and Biotechnologies, FH Aachen , Campus Jülich, 52428 Jülich, Germany.|Peter Grünberg Institute (PGI-8), Research Centre Jülich GmbH , 52425 Jülich, Germany.
Arshak
A
Poghossian
Institute of Nano- and Biotechnologies, FH Aachen , Campus Jülich, 52428 Jülich, Germany.
Sabrina
S
Scheja
Institute of Nano- and Biotechnologies, FH Aachen , Campus Jülich, 52428 Jülich, Germany.|Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University , Hangzhou 310027, China.
Chunsheng
C
Wu
Institute of Pharmaceutical Chemistry, Philipps University Marburg , 35032 Marburg, Germany.
Michael
M
Keusgen
Institute of Measurement and Automatic Control, Leibniz University Hannover , 30167 Hannover, Germany.
Dieter
D
Mewes
Institute of Nano- and Biotechnologies, FH Aachen , Campus Jülich, 52428 Jülich, Germany.|Peter Grünberg Institute (PGI-8), Research Centre Jülich GmbH , 52425 Jülich, Germany.
Michael J
MJ
Schöning
D018076:DNA, Complementary / Q000032:analysis* / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D025802:Electric Capacitance; D055664:Electrochemical Techniques; D004573:Electrolytes / Q000737:chemistry*; D005452:Fluoresceins / Q000737:chemistry; D061925:Immobilized Nucleic Acids / Q000737:chemistry / Q000378:metabolism; D018625:Microscopy, Atomic Force; D008904:Miniaturization; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D011073:Polyamines / Q000737:chemistry; D012666:Semiconductors
D018076:DNA, Complementary; D004277:DNA, Single-Stranded; D004573:Electrolytes; D005452:Fluoresceins; D061925:Immobilized Nucleic Acids; D011073:Polyamines; C063994:polyallylamine; C024098:6-carboxyfluorescein
DNA; field-effect capacitive sensor; hybridization; intrinsic molecular charge; label-free detection; layer-by-layer technique; polyelectrolyte