@incollection{PoghossianSchoening2017, author = {Poghossian, Arshak and Sch{\"o}ning, Michael Josef}, title = {Nanomaterial-Modified Capacitive Field-Effect Biosensors}, series = {Springer Series on Chemical Sensors and Biosensors (Methods and Applications)}, booktitle = {Springer Series on Chemical Sensors and Biosensors (Methods and Applications)}, publisher = {Springer}, address = {Berlin, Heidelberg}, doi = {10.1007/5346_2017_2}, pages = {1 -- 25}, year = {2017}, abstract = {The coupling of charged molecules, nanoparticles, and more generally, inorganic/organic nanohybrids with semiconductor field-effect devices based on an electrolyte-insulator-semiconductor (EIS) system represents a very promising strategy for the active tuning of electrochemical properties of these devices and, thus, opening new opportunities for label-free biosensing by the intrinsic charge of molecules. The simplest field-effect sensor is a capacitive EIS sensor, which represents a (bio-)chemically sensitive capacitor. In this chapter, selected examples of recent developments in the field of label-free biosensing using nanomaterial-modified capacitive EIS sensors are summarized. In the first part, we present applications of EIS sensors modified with negatively charged gold nanoparticles for the label-free electrostatic detection of positively charged small proteins and macromolecules, for monitoring the layer-by-layer formation of oppositely charged polyelectrolyte (PE) multilayers as well as for the development of an enzyme-based biomolecular logic gate. In the second part, examples of a label-free detection by means of EIS sensors modified with a positively charged weak PE layer are demonstrated. These include electrical detection of on-chip and in-solution hybridized DNA (deoxyribonucleic acid) as well as an EIS sensor with pH-responsive weak PE/enzyme multilayers for enhanced field-effect biosensing.}, language = {en} } @article{SchusserBaeckerKrischeretal.2014, author = {Schusser, Sebastian and B{\"a}cker, Matthias and Krischer, M. and Wenzel, L. and Leinhos, Marcel and Poghossian, Arshak and Biselli, Manfred and Wagner, P. and Sch{\"o}ning, Michael Josef}, title = {Enzymatically catalyzed degradation of biodegradable polymers investigated by means of a semiconductor-based field-effect sensor}, series = {Procedia Engineering}, volume = {87}, journal = {Procedia Engineering}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2014.11.689}, pages = {1314 -- 1317}, year = {2014}, abstract = {A semiconductor field-effect device has been used for an enzymatically catalyzed degradation of biopolymers for the first time. This novel technique is capable to monitor the degradation process of multiple samples in situ and in real-time. As model system, the degradation of the biopolymer poly(D, L-lactic acid) has been monitored in the degradation medium containing the enzyme lipase from Rhizomucor miehei. The obtained results demonstrate the potential of capacitive field-effect sensors for degradation studies of biodegradable polymers.}, language = {en} } @article{SchusserPoghossianBaeckeretal.2012, author = {Schusser, Sebastian and Poghossian, Arshak and B{\"a}cker, Matthias and Leinhos, Marcel and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Characterization of biodegradable polymers with capacitive field-effect sensors}, series = {Sensors and actuators B: Chemical}, volume = {187}, journal = {Sensors and actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2012.07.099}, pages = {2 -- 7}, year = {2012}, abstract = {In vitro studies of the degradation kinetic of biopolymers are essential for the design and optimization of implantable biomedical devices. In the presented work, a field-effect capacitive sensor has been applied for the real-time and in situ monitoring of degradation processes of biopolymers for the first time. The polymer-covered field-effect sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. The feasibility of this approach has been experimentally proven by using the commercially available biomedical polymer poly(D,L-lactic acid) (PDLLA) as a model system. PDLLA films of different thicknesses were deposited on the Ta₂O₅-gate surface of the field-effect structure from a polymer solution by means of spin-coating method. The polymer-modified field-effect sensors have been characterized by means of capacitance-voltage and impedance-spectroscopy method. The degradation of the PDLLA was accelerated by changing the degradation medium from neutral (pH 7.2) to alkaline (pH 9) condition, resulting in drastic changes in the capacitance and impedance spectra of the polymer-modified field-effect sensor.}, language = {en} }