Article
Refine
Year of publication
Institute
- INB - Institut für Nano- und Biotechnologien (485) (remove)
Has Fulltext
- no (485) (remove)
Language
- English (485) (remove)
Document Type
- Article (485) (remove)
Keywords
- frequency mixing magnetic detection (4)
- LAPS (3)
- capacitive field-effect sensor (3)
- field-effect sensor (3)
- magnetic nanoparticles (3)
- tobacco mosaic virus (TMV) (3)
- Bacillus atrophaeus (2)
- Light-addressable potentiometric sensor (2)
- Raman spectroscopy (2)
- biosensors (2)
- gold nanoparticles (2)
- hydrogen peroxide (2)
- light-addressable potentiometric sensor (2)
- microfluidics (2)
- (Bio)degradation (1)
- Alginate beads (1)
- Bacillus atrophaeus spores (1)
- CNOT (1)
- CRISPR/Cas9 (1)
- Calorimetric gas sensor (1)
- Capacitive field-effect (1)
- Capacitive model (1)
- Chemical images (1)
- Chemical imaging sensor (1)
- Chemical sensor (1)
- C–V method (1)
- DNA biosensor (1)
- DPA (dipicolinic acid) (1)
- Dehydrogenase (1)
- Detergent protease (1)
- Diaphorase (1)
- EIS capacitive sensor (1)
- Electrolyte–insulator–semiconductor (1)
- Enzymatic biosensor (1)
- Enzyme coverage (1)
- Enzyme logic gate (1)
- Extracellular enzymes (1)
- Field effect (1)
- Field-effect biosensor (1)
- Field-effect sensor (1)
- Hydrogen peroxide (1)
- Hypersecretion (1)
- Impedance spectroscopy (1)
- Lab-on-Chip (1)
- Label-free detection (1)
- Layer-by-layer adsorption (1)
- LbL films (1)
- MOS (1)
- Marker-free mutagenesis (1)
- Multianalyte detection (1)
- Negative impedance convertor (1)
- O2 plasma (1)
- Organic light-emitting diode display (1)
- Penicillin (1)
- Poly(allylamine hydrochloride) (1)
- Poly(d,l-lacticacid) (1)
- Polyimide (1)
- Real-time monitoring (1)
- Resonance-mode measurement (1)
- Simultaneous determination (1)
- Sn₃O₄ (1)
- Stenotrophomonas maltophilia (1)
- Sterilisation process (1)
- TMV adsorption (1)
- Ta₂O₅ gate (1)
- Uracil-phosphoribosyltransferase (1)
- XOR (1)
- actuator-sensor system (1)
- aminooctanethiol (1)
- annealing (1)
- aquaculture (1)
- artificial olfactory image (1)
- aseptic parameters (1)
- aspergillus (1)
- bi-enzyme biosensor (1)
- biosensor (1)
- calorimetric gas sensor (1)
- calorimetric gas sensor;hydrogen peroxide;wireless sensor system (1)
- capacitive EIS sensor (1)
- capacitive model (1)
- catalytic metal (1)
- chemical sensor (1)
- chip-based sensor setup (1)
- colorization (1)
- control gate (1)
- coupled Néel–Brownian relaxation dynamics (1)
- detection of charged macromolecules (1)
- electrical conductivity of liquids (1)
- electrolyte-insulator semiconductor sensor (EIS) (1)
- electrolyte-insulator-semiconductor capacitors (1)
- electronic nose (1)
- endospores (1)
- enzyme cascade (1)
- enzyme kinetics (1)
- enzyme-logic gate (1)
- equivalent circuit (1)
- field-effect structure (1)
- filamentous fungi (1)
- frequency mixing (1)
- gas sensor (1)
- gaseous hydrogen peroxide (1)
- genome engineering (1)
- glucose oxidase (GOx) (1)
- heavy metals (1)
- horseradish peroxidase (HRP) (1)
- hydroxylation (1)
- immobilization (1)
- impedance spectroscopy (1)
- key performance indicators (1)
- light-addressable electrode (1)
- light-addressing technologies (1)
- magnetic actuation (1)
- magnetic beads (1)
- magnetic biosensing (1)
- magnetic relaxation (1)
- magnetic sandwich immunoassay (1)
- magnetic sensing (1)
- magnetic sensors (1)
- magnetic separation (1)
- magnetic tweezers (1)
- magnetophoretic velocity (1)
- metal-oxide-semiconductor structure (1)
- micromagnetic simulation (1)
- multi-sensing platform (1)
- multianalyte detection (1)
- multiparametric immunoassays (1)
- multiplex detection (1)
- nanobelts (1)
- nanoparticle coverage (1)
- on-chip integrated addressable EISCAP sensors (1)
- optical sensor setup (1)
- optical spore trapping (1)
- optical trapping (1)
- organosilanes (1)
- penicillinase (1)
- plant virus detection (1)
- plug-based microfluidic device (1)
- polystyrene sulfonate (1)
- scanned light pulse technique (1)
- silanization (1)
- spore kill rate (1)
- sterilisation (1)
- sterility (1)
- sterilization (1)
- sterilization conditions (1)
- superparamagnetic bead (1)
- superparamagnetic nanoparticles (1)
- surface functionalization (1)
- temperature (1)
- thermometry (1)
- turnip vein clearing virus (TVCV) (1)
- urease (1)
- visualization (1)
Planar and three-dimensional (3D) interdigitated electrodes (IDE) with electrode digits separated by an insulating barrier of different heights were electrochemically characterized and compared in terms of their sensing properties. Due to the impact of the surface resistance, both types of IDE structures display a non-linear behavior in low-ionic strength solutions. The experimental data were fitted to an electrical equivalent circuit and interpreted taking into account the surface-charge-governed properties. The effect of a charged polyelectrolyte layer electrostatically assembled onto the sensor surface on the surface resistance in solutions with different KCl concentration is studied. In case of the same electrode footprint, 3D-IDEs show a larger cell constant and a higher sensitivity to molecular adsorption than that of planar IDEs. The obtained results demonstrate the potential of 3D-IDEs as a new transducer structure for a direct label-free sensing of charged molecules.
The conjunction of (bio-)chemical recognition elements with nanoscale biological building blocks such as virus particles is considered as a very promising strategy for the creation of biohybrids opening novel opportunities for label-free biosensing. This work presents a new approach for the development of biosensors using tobacco mosaic virus (TMV) nanotubes or coat proteins (CPs) as enzyme nanocarriers. Sensor chips combining an array of Pt electrodes loaded with glucose oxidase (GOD)-modified TMV nanotubes or CP aggregates were used for amperometric detection of glucose as a model system for the first time. The presence of TMV nanotubes or CPs on the sensor surface allows binding of a high amount of precisely positioned enzymes without substantial loss of their activity, and may also ensure accessibility of their active centers for analyte molecules. Specific and efficient immobilization of streptavidin-conjugated GOD ([SA]-GOD) complexes on biotinylated TMV nanotubes or CPs was achieved via bioaffinity binding. These layouts were tested in parallel with glucose sensors with adsorptively immobilized [SA]-GOD, as well as [SA]-GOD crosslinked with glutardialdehyde, and came out to exhibit superior sensor performance. The achieved results underline a great potential of an integration of virus/biomolecule hybrids with electronic transducers for future applications in biosensorics and biochips.
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.
Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO2 structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied.
In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA.
Field-effect-based electrolyte-insulator-semiconductor (EIS) sensors were modified with a bilayer of positively charged weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) and probe single-stranded DNA (ssDNA) and are used for the detection of complementary single-stranded target DNA (cDNA) in different test solutions. The sensing mechanism is based on the detection of the intrinsic molecular charge of target cDNA molecules after the hybridization event between cDNA and immobilized probe ssDNA. The test solutions contain synthetic cDNA oligonucleotides (with a sequence of tuberculosis mycobacteria genome) or PCR-amplified DNA (which origins from a template DNA strand that has been extracted from Mycobacterium avium paratuberculosis-spiked human sputum samples), respectively. Sensor responses up to 41 mV have been measured for the test solutions with DNA, while only small signals of ∼5 mV were detected for solutions without DNA. The lower detection limit of the EIS sensors was ∼0.3 nM, and the sensitivity was ∼7.2 mV/decade. Fluorescence experiments using SybrGreen I fluorescence dye support the electrochemical results.
Abstractauthoren Graphene oxide (GO) nanoparticles were incorporated in temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The nanoparticles increase the light absorption and convert light energy into heat efficiently. Thus, the hydrogels with GO can be stimulated spatially resolved by illumination as it was demonstrated by IR thermography. The temporal progression of the temperature maximum was detected for different concentrations of GO within the polymer network. Furthermore, the compatibility of PNIPAAm hydrogels with GO and cell cultures was investigated. For this purpose, culture medium was incubated with hydrogels containing GO and the viability and morphology of chinese hamster ovary (CHO) cells was examined after several days of culturing in presence of this medium.
Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel films with incorporated graphene oxide (GO) were developed and tested as light-stimulated actuators. GO dispersions were synthesized via Hummers method and characterized toward their optical properties and photothermal energy conversion. The hydrogels were prepared by means of photopolymerization. In addition, the influence of GO within the hydrogel network on the lower critical solution temperature (LCST) was investigated by differential scanning calorimetry (DSC). The optical absorbance and the response to illumination were determined as a function of GO concentration for thin hydrogel films. A proof of principle for the stimulation with light was performed.
Disruption experiments targeted at the Bacillus licheniformis degSU operon and GFP-reporter analysis provided evidence for promoter activity immediately upstream of degU. pMutin mediated concomitant introduction of the degU32 allele – known to cause hypersecretion in Bacillus subtilis – resulted in a marked increase in protease activity. Application of 5-fluorouracil based counterselection through establishment of a phosphoribosyltransferase deficient Δupp strain eventually facilitated the marker-free introduction of degU32 leading to further protease enhancement achieving levels as for hypersecreting wild strains in which degU was overexpressed. Surprisingly, deletion of rapG – known to interfere with DegU DNA-binding in B. subtilis – did not enhance protease production neither in the wild type nor in the degU32 strain. The combination of degU32 and Δupp counterselection in the type strain is not only equally effective as in hypersecreting wild strains with respect to protease production but furthermore facilitates genetic strain improvement aiming at biological containment and effectiveness of biotechnological processes.