Department of Bioengineering, University of Washington, 3720 15th Ave NE, Seattle, Washington, USA.
J Biomed Opt. 2012 Oct;17(10):101517. doi: 10.1117/1.JBO.17.10.101517.
Results on magnetically trapping and manipulating micro-scale beads circulating in a flow field mimicking metastatic cancer cells in human peripheral vessels are presented. Composite contrast agents combining magneto-sensitive nanospheres and highly optical absorptive gold nanorods were conjugated to micro-scale polystyrene beads. To efficiently trap the targeted objects in a fast stream, a dual magnet system consisting of two flat magnets to magnetize (polarize) the contrast agent and an array of cone magnets producing a sharp gradient field to trap the magnetized contrast agent was designed and constructed. A water-ink solution with an optical absorption coefficient of 10 cm⁻¹ was used to mimic the optical absorption of blood. Magnetomotive photoacoustic imaging helped visualize bead trapping, dynamic manipulation of trapped beads in a flow field, and the subtraction of stationary background signals insensitive to the magnetic field. The results show that trafficking micro-scale objects can be effectively trapped in a stream with a flow rate up to 12 ml/min and the background can be significantly (greater than 15 dB) suppressed. It makes the proposed method very promising for sensitive detection of rare circulating tumor cells within high flow vessels with a highly absorptive optical background.
本文展示了在模拟人类外周血管中转移性癌细胞的流场中捕获和操纵微尺度磁珠的结果。将结合磁敏纳米球和高光学吸收金纳米棒的复合造影剂与微尺度聚苯乙烯珠结合。为了在快速流中有效地捕获目标物体，设计并构建了一个由两个平面磁铁组成的双磁体系统，用于磁化（极化）造影剂，以及一组产生尖锐梯度场以捕获磁化造影剂的圆锥体磁铁。使用光学吸收率为 10 cm⁻¹ 的水基油墨溶液来模拟血液的光学吸收。磁动力光声成像是可视化珠粒捕获、流场中捕获珠粒的动态操纵以及对不敏感于磁场的静止背景信号的减除的有用工具。结果表明，在流速高达 12 ml/min 的流中可以有效地捕获微尺度物体，并且背景可以得到显著（大于 15 dB）抑制。这使得该方法非常有希望用于在具有高吸收光学背景的高流速血管中灵敏地检测罕见的循环肿瘤细胞。
