3D Printed Modular Immunofiltration Columns for Frequency Mixing-Based Multiplex Magnetic Immunodetection

Abstract

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.

Sensitive and rapid detection of cholera toxin subunit B using magnetic frequency mixing detection

“…This induced voltage is then amplified and filtered, and the amplitudes of the mixing terms can be determined. For example, in [36,38,43] this is done in a two-stage multiplication process, whereas in this work, we used direct digitalization of the signal trace and Fast Fourier Transform (FFT) analysis. This was chosen because we used different beads in this research, and different beads might create different phase shifts between the excitation and the detection signal traces, as shown in [44].…”

Multiplex Detection of Different Magnetic Beads Using Frequency Scanning in Magnetic Frequency Mixing Technique

“…The SignBit output of the driving frequency ( f 2 ) DDS, which changes its state when the most important bit of the internal DAC changes, is used for a triggered start of sample recording. In this research, we performed a direct digitization of the picked-up and preamplified signals, in contrast to prior work where a two-stage multiplication process was used [14,15,16,20]. This has the advantage that we can record many different harmonics at the same time and determine their phases without requiring a more complex hardware setup.…”

“…Different approaches have been performed both experimentally and in simulations to realize so-called multiparametric immunoassays [19]. Recently, we have shown a method where this is done by using the same MBs but with spatial separation of different capture zones [20]. When different types of MBs are used to label different targets, their different magnetic properties can be used to distinguish them without the need of spatial separation.…”

“…In this research, we analysed whether different MB types can be distinguished by using the magnetic frequency mixing technique and by scanning the frequency of the magnetic probing field. If this is possible, we can later use this to develop an immunoassay where different targets can be detected and quantified in the same sample at the same time without the need of any mechanical movement of the sample holder, as it was done in Reference [20]. In contrast to many of the above mentioned works from other groups, the magnetic beads used in this study are much bigger commercially available magnetic beads.…”

A Novel Method for Antibiotic Detection in Milk Based on Competitive Magnetic Immunodetection

“…In a recent study, a highly sensitive and quantitative detection of aflatoxin B1 has been demonstrated based on newly developed competitive magnetic immunodetection (cMID) [23]. Using frequency mixing magnetic detection (FMMD), a dose-depending measuring signal is obtained in a portable handheld measuring FMMD device [23,26,29,30]. A detailed explanation of FMMD is given in [23,29,31].…”