TY  - JOUR
A1  - Molinnus, Denise
A1  - Bäcker, Matthias
A1  - Iken, Heiko
A1  - Poghossian, Arshak
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Concept for a biomolecular logic chip with an integrated sensor and actuator function
JF  - Physica status solidi (a)
N2  - A concept for a new generation of an integrated multi-functional biosensor/actuator system is developed, which is based on biomolecular logic principles. Such a system is expected to be able to detect multiple biochemical input signals simultaneously and in real-time and convert them into electrical output signals with logical operations such as OR, AND, etc. The system can be designed as a closed-loop drug release device triggered by an enzyme logic gate, while the release of the drug induced by the actuator at the required dosage and timing will be controlled by an additional drug sensor. Thus, the system could help to make an accurate and specific diagnosis. The presented concept is exemplarily demonstrated by using an enzyme logic gate based on a glucose/glucose oxidase system, a temperature-responsive hydrogel mimicking the actuator function and an insulin (drug) sensor. In this work, the results of functional testing of individual amperometric glucose and insulin sensors as well as an impedimetric sensor for the detection of the hydrogel swelling/shrinking are presented.
Y1  - 2015
U6  - http://dx.doi.org/10.1002/pssa.201431913
SN  - 1862-6319
VL  - 212
IS  - 6
SP  - 1382
EP  - 1388
PB  - Wiley
CY  - Weinheim
ER  - 
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  -