Centrifugal gas-phase transition magnetophoresis (GTM) – a generic method for automation of magnetic bead based assays on the centrifugal microfluidic platform and application to DNA purification

Abstract

Transportation of magnetic beads between different reagents plays a crucial role in many biological assays e.g. for purification of biomolecules or cells where the beads act as a mobile solid support. Therefore, usually a complex set-up either for fluidic processing or for manipulation of magnetic beads is required. To circumvent these drawbacks, we present a facile and automated method for the transportation of magnetic beads between multiple microfluidic chambers on a centrifugal microfluidic cartridge "LabDisk". The method excels by requiring only one stack of stationary permanent magnets, a specific microfluidic layout without actively controlled valves and a predefined frequency protocol for rotation of the LabDisk. Magnetic beads were transported through three fluidically separated chambers with a yield of 82.6% ± 3.6%. Bead based DNA purification from a dilution series of a Listeria innocua lysate and from a lambda phage DNA standard was demonstrated where the three chambers were used for binding, washing and elution of DNA. Recovery of L. innocua DNA was up to 68% ± 24% and for lambda phage DNA 43% ± 10% compared to manual reference purification in test tubes. Complete purification was conducted automatically within 12.5 min. Since all reagents can be preloaded onto the LabDisk prior to purification, no further hands-on steps are required during processing. Due to its modular and generic character, the presented method could also be adapted to other magnetic bead based assays e.g. to immunoassays or protein affinity purification, solely requiring the adjustment of number and volumes of the fluidic chambers.

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

“…This is done by transporting the target-MB cluster through an immiscible phase, such as oil [4][5][6], wax [4,7,8], or air [8], often using an external permanent magnet. Such systems have been demonstrated for a number of applications including enzyme linked immunosorbent assays [6,9,10], nucleic acid extraction [4,7,8,[11][12][13][14], protein extraction [8], and cell extraction [15,16].…”

Rotary-based platform with disposable fluidic modules for automated isolation of nucleic acids

“…A versatile approach combining magnetic beads handling and a single layered microfluidic BLabDisk^for efficient DNA purification was described by (Strohmeier et al 2013). Due to the modular concept of microfluidic chambers and automated transportation of magnetic particles, the method can also be adapted to other magnetic bead based assays, e.g., to immunoassays or protein affinity purification.…”

An enzyme-linked immunosorbent assay on a centrifugal platform using magnetic beads

“…Strohmeier et al presented their work to transport magnetic beads between three fluidically separated chambers through one stack of stationary permanent magnets and disk spinning control. 14 In this work, we present a simple and effective mechanism to control the mobility of magnetic beads in both incubation and washing stages in the ELISA protocol. Our mechanism does not require any active control from external devices.…”

“…1,2,4 Magnetic beads emerged as an effective tool for bioassays. 12,[14][15][16] For a fixed amount of sample volume, magnetic beads can greatly increase the surface-to-volume ratio of the reaction sites. In addition, the ability to control the mobility of the magnetic beads under magnetic field results in a better mass transport between the reactants.…”

“…Assay sensitivity can be greatly improved through the application of magnetic beads. 14,17 Although magnetic beads were widely used in many microfluidic applications, handling magnetic beads was implemented mostly by manual operations. 12,18,19 Only a few approaches were reported with regard to the handling of the magnetic beads on the centrifugal platform.…”