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Automated Mixing of Isothermal assays using Magnetic Mixing Beads
- Emily Sutterby
- Mar 2
- 2 min read
Updated: May 2
Axxin instruments offer an alternative to the manual mixing step often required by isothermal assays by moving magnetic beads inside the sample-containing consumable using magnets.
Isothermal technologies for the amplification of DNA and RNA are well-established and offer a streamline, cost-effective alternative to PCR-based nucleic acid amplification testing (NAAT).
Recombinase-based isothermal amplification such as RPA and RAA is among the fastest commercially available amplification chemistries. Formulations are available which include reverse transcriptase for seamless one-step amplification and detection of DNA and RNA signatures in as little as 3 minutes. However, to unlock the full performance of recombinase-based assays, a second manual reagent mixing step is required a few minutes after the initial start of the detection reaction. Usually, this requires the user to open the detection instrument after the run has been started to remove the amplification tubes, vortex and spin them, and place them back into the instrument.
This cumbersome and error-prone procedure can be automated using Axxin instruments featuring a mechanism that allows for seamless mixing of reagents within the amplification tubes. The continuous mixing is facilitated through a magnet moving along the amplification tubes thereby actuating a stainless-steel ball placed inside each amplification tube.
Fluorescence is read in 200μL tubes or custom cartridges using a side view method. The optical arrangement is designed to provide an optical view through a cut-out in the heater block to the consumable. Magnets located inside the instrument are used to move the mixing bead out of the optical path during reading.
The arrangement used is designed to minimise the influences of the tube, including wall material, thickness and optical characteristics that may affect reading reliability.
Axxin recommends Simply Bearings 2mm stainless steel balls (M42G1000_2) available at:
Download the tech note below to discover how Xpedite Diagnostics used the unique automated mixing option of the T8-ISO instrument and by employing high-grade stainless-steel balls, to demonstrate probe-based detection of WNV RNA. Assays can be run in as little as 3 minutes with enhanced usability and without negative impact on the RAA assay performance compared to the traditional mixing mode.
