Bubbles can be used to greatly improve the speed of magnetic separation (MS) and overcome the limitation of magnetic force on the capture distance, making low-field MS highly efficient and easily scalable. This novel method leads to the development of a medium-free continuous gas-assisted magnetic separator on small pilot scale using low-field permanent magnet. This separator is demonstrated highly efficient for recovery of proteins-loaded magnetic nanoparticles from large volume biosuspension. (C) 2014 American Institute of Chemical Engineers