| Microparticle sorting is widely used in the fields of biomedicine,clinical detection,and chemical analysis.Microarray-based non-biological particle sorting has the characteristics of low sample consumption and high efficiency,and it is a research hotspot in the field of particle sorting.Force-driven deterministic lateral displacement(f-DLD)sorting is one of the methods of microarray sorting.It has the advantages of simple device,low design requirements,and no need for syringe pumps.It is widely used for sorting cells,antibodies,etc.Therefore,in this article,a magnetic force that does not damage biological substances was used as the driving force,and a method of sorting the magnetic beads with the deterministic lateral displacement using the magnetic force as the driving force is established,which was called magnetic-driven deterministic lateral displacement(m-DLD),and we used it for antibody detection.Firstly,this article used software COMSOL Multiphysics 5.5 to simulate the magnetic field generated by cuboids,cylinders,triangular prisms,and hexagonal prism magnets and the force of the magnetic field on the magnetic beads with diameters of 10μm,20 μm,30 μm,and 40 μm.We did not consider the influence of the chip structure on the force of the magnetic beads.Simulation results provide guidance for experimental design.When a rectangular magnet was used to construct a magnetic field,the change in magnetic force is small,which is beneficial to increase the stability of the magnetic bead movement.Therefore,this article chose a cuboid magnet to construct a magnetic field.The longer the chip,the larger the flux and the smaller the magnetic force.Considering the flux of the chip and the force of the magnetic beads,this article set the length of the chip to 1.2 cm.The characteristics of different microarray layouts were analyzed,and the microarray type of the chip was determined as a mirror micropillar array.The experiments of sorting magnetic beads with diameters of 10 μm and 30 μm were carried out on a microfluidic chip.The influence of the forcing angle and inlet width of the chip on the sorting efficiency was explored.The optimal forcing angle and inlet width were obtained.The separation of 10 μm and 30 μm magnetic beads was successfully achieved in this article,and the separation efficiency reached 87.58% and92.78%,respectively,which proved the feasibility of m-DLD sorting magnetic beads.In order to make m-DLD more widely used,this article expanded the stage of microarray of the chip from one stage to two stages.The structural parameters(microarray stage,micropillar diameter,micropillar gap,and the shape of inlet)of the two-stage chip and the one-stage chip are different.The magnetic beads with diameters of 10 μm,20 μm and 40 μm were selected as the experimental objects.The influence of the forcing angle on the sorting efficiency and the influence of the inlet width of the second-stage microarray on the sorting efficiency were investigated.The separation of three magnetic beads of 10 μm,20 μm and 40 μm was successfully achieved,and the separation efficiency reached 88.04%,90.10%,and 93.30%,respectively.Finally,the newly m-DLD method was used for the preliminary application research of immunosensor detection.The shortcomings of using immunofluorescence to detect multiple antibodies were analyzed,and the advantages of m-DLD optimized immunofluorescence to detect multiple antibodies were analyzed.The 10 μm,20 μm,and 40 μm magnetic beads were coupled with different antibodies to complete the preparation of immunomagnetic beads.The m-DLD was used to complete the sorting of immunomagnetic beads,the type of antibody was successfully recognized according to the outlet number,and the fluorescence intensity of the immunomagnetic beads at the outlet was measured.Qualitative and semi-quantitative analysis of mouse anti-human AFP,mouse anti-human PSA,and mouse anti-human HBs Ag were achieved.The detection method of antibodies based on m-DLD optimizes the immunofluorescence method.The method of recognizing the type of antibody by the outlet number is simple and intuitive,which avoids the problem of using immunofluorescence to detect the antibody affected by the fluorescent area of the magnetic bead. |
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