Figure 1. Technological improvement in forward scatter (FS) for microparticle (MP) measurement: (A) Beads resolution improvement: FS distribution of a blend of fluorescent latex beads (0.1/0.14, 0.3, 0.5 and 0.9 μm) with a threshold on fluorescence. (B) Background noise reduction: Scatters dot plot showing blue (0.9 μm beads), red (0.5 μm beads), green (0.3 μm beads) and violet (0.1/0.14 μm beads) beads with a FS threshold. Grey dots are background noise.
*FSRI, forward scatter relative intensity measured on the Apogee A40. **Diameter of a lipid or cellular microparticle with the same forward scatter relative intensity as the particle that was measured. Equivalent microparticle diameter (mm) = 3.2911(PD) - 0.2768, where PD = polystyrene microsphere diameter (mm).
为了解决这一问题，Apogee的工程师们研发了专利的折射率校正功能，无论是单参数的柱状图（Histogram）还是双参数的散点图（Cytogram），只要单击右键选择“Choose Calibration Scale”就会出现一条校正大小的标尺，并且可以根据检测样本的折射率来选择相应折射率的标尺（图2），那么我们就可以根据样本的直径大小和折射率这两个参数来设门和选择我们感兴趣的区域（region of interest, ROI），得到真实可靠的结果。
（3）不依赖于抗体微珠的外泌体检测能力
由于外泌体（exosomes）的直径特别小（40 - 100nm），超出了传统流式细胞仪的检测范围，为此，很多公司提供了特异抗体标记的微珠用于外泌体的富集和流式分析，但这种方法的局限是操作复杂，对抗体特异性要求很高，而且无法知道外泌体的绝对数量。而Apogee A50-Micro超高的灵敏度和分辨率使其可以直接对样本中的外泌体进行分析和计数，操作简单，结果准确，美国个性化医疗的领军生物技术公司Caris Life Sciences正是利用A50-Micro来检测和分析复杂病人样本中的微囊泡和外泌体[3]。一流企业的选择，值得您的信赖！
[1] Lacroix R, Robert S, Poncelet P, Dignat-George F. Overcoming limitations of microparticle measurement by flow cytometry. Semin Thromb Hemost. 2010 Nov;36(8):807-18.
[2] Chandler WL, Yeung W, Tait JF. A new microparticle size calibration standard for use in measuring smaller microparticles using a new flow cytometer. J Thromb Haemost. 2011 Jun;9(6):1216-24.
[3] Abstracts from the Third International Meeting of ISEV 2014. Rotterdam, The Netherlands, April 30th – May 3rd, 2014. J Extracell Vesicles. 2014; 3:24214.
