Biomedical subjects

J Schotter

Publications and source records attributed to J Schotter.

5 recordsLinked to original sources

PubMed2005

Magnetic particles as markers and carriers of biomolecules.

The detection and manipulation of biomolecules on a common platform is of considerable interest not only for application in devices such as diagnostic tools but also for basic research in biological and medical systems. A promising approach is the utilisation of magnetic particles as markers and carriers for biomolecules. The principle functionality of this approach is demonstrated by the authors. Magnetic particles used as markers can be detected by highly sensitive magnetoresistive sensors resulting in a purely electronic signal. A direct comparison with the standard fluorescence method reveals the advantages of using the magnetic particles. In addition, magnetic particles used as carriers can be manipulated on-chip via currents running through especially designed line patterns. Some current drawbacks and future aspects are discussed. The combination of sensing and manipulating magnetic particles is a promising choice for future integrated lab-on-a-chip systems.

Biomarkers↗

PubMed2004

Detection and manipulation of biomolecules by magnetic carriers.

The detection and manipulation of single molecules on a common platform would be of great interest for basic research of biological or chemical systems. A promising approach is the application of magnetic carriers. The principles are demonstrated in this contribution. It is shown that paramagnetic beads can be detected by highly sensitive magnetoresistive sensors yielding a purely electronic signal. Different configurations are discussed. The capability of the sensors to detect even single markers is demonstrated by a model experiment. In addition, the paramagnetic beads can be used as carriers for biomolecules. They can be manipulated on-chip via currents running through specially designed line patterns. Thus, magnetic markers in combination with magnetoresistive sensors are a promising choice for future integrated lab-on-a-chip systems.

Biopolymers↗

PubMed2004

Analysing a magnetic molecule detection system--computer simulation.

The detection of single molecules, e.g. in biology is possible by marking the interesting molecules with magnetic beads and detect the influence of the beads on giant magnetoresistance (GMR)/tunnel magnetoresistance (TMR)/spin valve (SV) sensors. The development of suitable multilayers has been studied experimentally as well as theoretically in order to optimize the sensor parameters. A finite difference (FD) method including the usually used contributions to the total energy [exchange, antiferromagnetically (af) coupling, anisotropy and magnetostatic] is used for the simulation with additional contributions to the local field according to the stray fields of the beads. In this work, we will show the results of micromagnetic calculations of the magnetization behavior of GMR/TMR sensors considering also the interaction between the domains in the magnetic layers of the sensor and the bead area. We can present first calculations where the bead particles (signal source) and the magnetic layers (sensor device) are considered as a whole magnetic ensemble.

Biopolymers↗

PubMed2004

Comparison of a prototype magnetoresistive biosensor to standard fluorescent DNA detection.

We present a comparative analysis of a magnetoresistive biosensor to standard fluorescent DNA detection. The biosensor consists of giant magnetoresistive (GMR) type Cu/Ni(80)Fe(20) multilayers in the second antiferromagnetic coupling maximum. Each of the 206 elements of the magnetoresistive biosensor is patterned into a spiral-shaped line that can cover the area of a typical DNA spot (70 microm diameter). The probe DNA is assembled on top of the sensor elements in different concentrations ranging from 16 pg/microl to 10 ng/microl. Complementary biotin-labeled analyte DNA is hybridized to the probe DNA at a concentration of 10 ng/microl. A number of different commercially available magnetic microspheres are investigated to determine the most appropriate markers. The experimental comparison shows that the relative sensitivity of the magnetoresistive biosensor is superior to the fluorescent detection at low probe DNA concentrations.

Biosensing Techniques↗

PubMed2000

Ultrahigh-density nanowire arrays grown in self-assembled diblock copolymer templates.

We show a simple, robust, chemical route to the fabrication of ultrahigh-density arrays of nanopores with high aspect ratios using the equilibrium self-assembled morphology of asymmetric diblock copolymers. The dimensions and lateral density of the array are determined by segmental interactions and the copolymer molecular weight. Through direct current electrodeposition, we fabricated vertical arrays of nanowires with densities in excess of 1.9 x 10(11) wires per square centimeter. We found markedly enhanced coercivities with ferromagnetic cobalt nanowires that point toward a route to ultrahigh-density storage media. The copolymer approach described is practical, parallel, compatible with current lithographic processes, and amenable to multilayered device fabrication.

Journal Article↗