Ocean NanoTech, LLC, Springdale, Arkansas 72764, USA.
ACS Appl Mater Interfaces. 2013 Apr 24;5(8):2901-7. doi: 10.1021/am303267g. Epub 2013 Apr 3.
The excellent optical properties of quantum dots (QDs), such as high brightness, high photostability, continuous absorption, and narrow emission bandwidth, make them ideal as optical labels to develop QD-based immunohistofluorescence (IHF) imaging for multiplexing cancer biomarker detection on formalin-fixed and paraffin-embedded (FFPE) tissues. IHF is very important for the prediction of a patient's response to cancer chemotherapy or radiotherapy. QD-based IHF faces several challenges that differ from those encountered by organic dye based IHF for clinical assays. The current work addresses some of these issues. Initially, the chemical stability of QDs and organic dyes were compared. The results showed that QDs were stable for at least 5 months on FFPE tissue, whereas organic dyes were photobleached shortly after exposure to light. Various staining methods were also studied. QD fluorescence intensity on the tissue stained with primary antibody (Ab, p16, survivin, EF1α) conjugated QDs from our company was comparable to the signal from a commercially available method in which the tissue was stained with a primary p16 Ab and a QD-labeled secondary goat anti mouse Ab respectively. Finally, the effect of the amount of Ab conjugated to QD on tissue imaging was also studied. There was no significant increase in the QD fluorescence signal on tissues when the Ab:QD ratio increased from 5 to 30. In addition, protein G was tested as an adaptor protein to link Ab to QDs for IHF staining. However, the proper blocking of the protein G on QDs was necessary to reduce crosstalk. The biomarker quantification in QD-based IHF was validated by conventional Western blot and immunohistochemistry. The results contained herein demonstrate a promising application of QDs in multiplex detection and quantification of biomarkers.
量子点(QD)具有出色的光学性能,如高亮度、高光稳定性、连续吸收和窄发射带宽,使其成为理想的光学标记物,可用于开发基于 QD 的免疫荧光(IHF)成像,以对福尔马林固定和石蜡包埋(FFPE)组织上的多种癌症生物标志物进行检测。IHF 对于预测患者对癌症化疗或放疗的反应非常重要。基于 QD 的 IHF 面临着与基于有机染料的 IHF 在临床检测中所遇到的不同挑战。目前的工作解决了其中的一些问题。首先,比较了 QD 和有机染料的化学稳定性。结果表明,QD 在 FFPE 组织上至少稳定 5 个月,而有机染料在暴露于光后很快就会发生光漂白。还研究了各种染色方法。用我们公司生产的与 p16、survivin、EF1α 等抗体(Ab)偶联的 QD 对组织进行染色后,QD 的荧光强度与商业方法相当,该商业方法分别用针对 p16 的一抗和 QD 标记的二抗山羊抗小鼠 Ab 对组织进行染色。最后,还研究了与 QD 偶联的 Ab 量对组织成像的影响。当 Ab:QD 比值从 5 增加到 30 时,组织上的 QD 荧光信号没有明显增加。此外,还测试了蛋白 G 作为衔接蛋白,将 Ab 连接到 QD 上进行 IHF 染色。然而,有必要对 QD 上的蛋白 G 进行适当的封闭,以减少串扰。通过传统的 Western blot 和免疫组化验证了基于 QD 的 IHF 中的生物标志物定量。本文的结果证明了 QD 在生物标志物的多重检测和定量中的应用具有广阔的前景。