TY  - JOUR
A1  - Achtsnicht, Stefan
A1  - Tödter, Julia
A1  - Niehues, Julia
A1  - Telöken, Matthias
A1  - Offenhäusser, Andreas
A1  - Krause, Hans-Joachim
A1  - Schröper, Florian
T1  - 3D printed modular immunofiltration columns for frequency mixing-based multiplex magnetic immunodetection
JF  - Sensors
N2  - For performing point-of-care molecular diagnostics, magnetic immunoassays constitute a promising alternative to established enzyme-linked immunosorbent assays (ELISA) because they are fast, robust and sensitive. Simultaneous detection of multiple biomolecular targets from one body fluid sample is desired. The aim of this work is to show that multiplex magnetic immunodetection based on magnetic frequency mixing by means of modular immunofiltration columns prepared for different targets is feasible. By calculations of the magnetic response signal, the required spacing between the modules was determined. Immunofiltration columns were manufactured by 3D printing and antibody immobilization was performed in a batch approach. It was shown experimentally that two different target molecules in a sample solution could be individually detected in a single assaying step with magnetic measurements of the corresponding immobilization filters. The arrangement order of the filters and of a negative control did not influence the results. Thus, a simple and reliable approach to multi-target magnetic immunodetection was demonstrated.
Y1  - 2019
U6  - http://dx.doi.org/10.3390/s19010148
SN  - 1424-8220
VL  - 19
IS  - 1
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Achtsnicht, Stefan
A1  - Schönenborn, Kristina
A1  - Offenhäusser, Andreas
A1  - Krause, Hans-Joachim
T1  - Measurement of the magnetophoretic velocity of different superparamagnetic beads
JF  - Journal of Magnetism and Magnetic Materials
N2  - The movement of magnetic beads due to a magnetic field gradient is of great interest in different application fields. In this report we present a technique based on a magnetic tweezers setup to measure the velocity factor of magnetically actuated individual superparamagnetic beads in a fluidic environment. Several beads can be tracked simultaneously in order to gain and improve statistics. Furthermore we show our results for different beads with hydrodynamic diameters between 200 and 1000 nm from diverse manufacturers. These measurement data can, for example, be used to determine design parameters for a magnetic separation system, like maximum flow rate and minimum separation time, or to select suitable beads for fixed experimental requirements.
KW  - magnetophoretic velocity
KW  - superparamagnetic bead
KW  - magnetic tweezers
KW  - magnetic separation
KW  - magnetic actuation
Y1  - 2019
U6  - http://dx.doi.org/10.1016/j.jmmm.2018.10.066
SN  - 0304-8853
VL  - 477
IS  - 1
SP  - 244
EP  - 248
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Achtsnicht, Stefan
A1  - Neuendorf, Christian
A1  - Faßbender, Tobias
A1  - Nölke, Greta
A1  - Offenhäusser, Andreas
A1  - Krause, Hans-Joachim
A1  - Schröper, Florian
T1  - Sensitive and rapid detection of cholera toxin subunit B using magnetic frequency mixing detection
JF  - Plos One
N2  - Cholera is a life-threatening disease caused by the cholera toxin (CT) as produced by some Vibrio cholerae serogroups. In this research we present a method which directly detects the toxin’s B subunit (CTB) in drinking water. For this purpose we performed a magnetic sandwich immunoassay inside a 3D immunofiltration column. We used two different commercially available antibodies to capture CTB and for binding to superparamagnetic beads. ELISA experiments were performed to select the antibody combination. The beads act as labels for the magnetic frequency mixing detection technique. We show that the limit of detection depends on the type of magnetic beads. A nonlinear Hill curve was fitted to the calibration measurements by means of a custom-written python software. We achieved a sensitive and rapid detection of CTB within a broad concentration range from 0.2 ng/ml to more
than 700 ng/ml.
Y1  - 2019
U6  - http://dx.doi.org/10.1371/journal.pone.0219356
SN  - 1932-6203
VL  - 14
IS  - 7
PB  - Plos
CY  - San Francisco
ER  -