On-chip Sorting Of Multiple Targets By The Difference In Aggregation During The Lateral Magnetophoresis

Magnetic separation is widely used in biochemical analysis.Multi-targets sorting by magnetic force has always been an interesting and valuable subject.With the development of microfluidic device,the magnetic sorting of multiple types of cells has been achieved.However,the separations of multiple small targets by magnetic force still remain a challenge.To solve the problem,different types of magnetic probes coupled with small targets have to be sorted.Here,we propose a strategy to separate magnetic nano-beads(MNs)with either a strong or weak magnetic responsiveness on a chip system.The sorting principle is utilizing the lateral magnetophoresis of MNs.A theoretical model is proposed to analyze the lateral displacement of MNs including aggregation and deflection.The difference in the properties of lateral magnetophoresis was investigated with the help of fluorescent signals.On this basis,chips were designed to separate MNs.By adjusting the flow rates,MNs with different magnetic responsiveness were sequentially separated.The sorting efficiency is acceptable and the procedure is easy to perform.MNs with strong magnetic responsiveness can be completely separated,which is valuable for rare targets sorting.The system was applied to sort DNA from hepatitis B virus(HBV)and complementary DNA from hepatitis C virus(HCV)simultaneously.This system has the potential for wide application in biochemical analysis.