We have demonstrated a postprocessed complementary metal oxide semiconductor (CMOS) integrated circuit (IC) capable of on-chip magnetic separation, i.e., removing via magnetic forces the nonspecifically bound magnetic beads from the detection area on the surface of the chip. Initially, 4.5 μm wide superparamagnetic beads sedimenting out of solution due to gravity were attracted to the detection area by a magnetic concentration force generated by flowing current through a conductor embedded in the IC. After sedimentation, the magnetic beads that did not bind strongly to the functionalized surface of the IC through a specific biochemical complex were removed by a magnetic separation force generated by flowing current through another conductor placed laterally to the detection area. As the spherical bead pivoted on the surface of the chip, the lateral magnetic force was further amplified by mechanical leveraging, and 50 mA of current flowing through the separation conductor placed 18 μm away from the bead resulted in 7.5 pN of tensile force on the biomolecular tether immobilizing the bead. This force proved high enough to break nonspecific interactions while leaving specific antibody-antigen bonds intact. A sandwich capture immunoassay on purified human immunoglobulin G showed strong correlation with a control enzyme linked immunosorbent assay and a detection limit of 10 ng∕ml or 70 pM. The beads bound to the detection area after on-chip magnetic separation were detected optically. To implement a fully integrated molecular diagnostics platform, the on-chip magnetic separation functionality presented in this work can be readily combine with state-of-the art CMOS-based magnetic bead detection technology.
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机译:我们已经证明了后处理的互补金属氧化物半导体(CMOS)集成电路(IC)能够在芯片上进行磁分离,即通过磁力从芯片表面的检测区域去除非特异性结合的磁珠。最初,由于重力使从溶液中沉淀出来的4.5μm宽的超顺磁珠被磁集中力吸引到检测区域,该磁集中力是使电流流过嵌入IC中的导体而产生的。沉淀后,通过电流流过另一条横向放置在检测区域的导体所产生的磁分离力,可以去除未通过特定生化复合物牢固结合至IC功能化表面的磁珠。当球形珠在芯片表面上枢转时,通过机械杠杆作用进一步放大了横向磁力,流过距珠子18μm的分离导体的50 mA电流在生物分子上产生7.5 pN的拉力系绳固定珠子。证明该力足够高,可以破坏非特异性相互作用,同时保持特异性抗体-抗原键完整。纯化的人免疫球蛋白G的三明治捕获免疫分析显示与对照酶联免疫吸附分析有很强的相关性,检出限为10 ng / ml或70 pM。芯片上磁分离后,结合到检测区域的磁珠被光学检测。为了实现一个完全集成的分子诊断平台,可以轻松地将这项工作中介绍的片上磁分离功能与基于CMOS的最新磁珠检测技术结合起来。
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