Qtracker™ 625 Cell Labeling Kit - FAQs

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8 product FAQs found

当我用Qtracker cell labeling reagents进行标记时，我得到一个点状标记图案。我如何让它更均匀？

Qtracker 细胞标记试剂经内吞作用被细胞摄取并被隔离于核内体。这使得标记呈点状或囊泡状。这个是正常的，没有办法使其在整个细胞质中均匀出现。

我该如何激发用于体内成像的量子点？

量子点可由410nm到低于发射光峰值波长40 nm内的光波长来激发。例如，Qtracker 655非靶向量子点可由410-615 nm激光激发。请谨记，产品名称上的波长指的是发射峰而不是激发峰。然而，由于量子点有吸光度的指数曲线，激发波长越低，它们的吸收效率越高，所以您最好采用最低的激光或激发波长。

我想用核酸染料来追踪我的细胞，比如DAPI或者Hoechst染料。您有什么建议吗？

这是不推荐的。这些染料与DNA和RNA的结合会影响核酸的正常功能，扰乱转录和增殖。诸如CellTracker染料或Qtracker试剂在不严重扰乱细胞正常活动的条件下对其进行追踪。如果您仍需要使用核酸染料进行标记且细胞是哺乳动物和非血液来源的话，CellLight 细胞核试剂可通过瞬时转染进入细胞，在核表达蛋白上表达GFP或RFP长达数天而不影响其功能。

我想追踪细胞，但贵司有很多产品可供选择，我该如何选择？

请浏览这里（https://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-tracing-tracking-and-morphology/cell-tracking.html）以帮助您选择适合您的应用的产品。首先确定追踪细胞的时间，然后考虑染料结合机制。钙黄绿素染料标记均匀且对短期细胞迁移示踪效果极佳，但也会被某些类型细胞迅速外排。亲脂性的花青素染料，如DiI，DIO，和类似的染料能标记细胞膜而不破坏其功能，并且能持续更长时间，但如果发生膜融合则可能会染上其他细胞。此外，它们还会在透化过程中丢失。CellTracker染料更有利于长期标记，其带有温和的氯甲基反应基团使之能够与细胞组分共价结合。CFDA SE也能共价地结合于细胞组分。在所有列出的试剂中，细胞内保留与否取决于细胞分裂的速率和细胞的固有特性（主动外排，膜和蛋白质的周转率等）。其中共价结合试剂比非共价结合的试剂展现出更长的保留时间。

Qtracker试剂是最持久并且荧光强度最高的细胞示踪染料，它通过内吞作用被细胞摄入。在许多样品中它们产生的信号可以持续检测长达数周，而且信号足够强，即使在固定和通透甚至加热和石蜡处理过程中，仍然能够维持较好的荧光信号。

When I label with Qtracker cell labeling reagents, I get a punctate label pattern. How do I make it more uniform?

Qtracker cell labeling reagents are taken up by the cell through endocytosis and sequestered in endosomes. This gives the label a punctate or vesicular appearance. This is normal. There is nothing that can be done to make it appear uniform throughout the cytoplasm.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

How do I excite quantum dots for in vivo imaging?

Quantum dots can be excited by wavelengths of light ranging from 250 nm to 40 nm below the emission peak wavelength. For example, Qtracker 655 non-targeted quantum dots can be excited from 250 -615 nm. The wavelength in the product name refers to the emission peak, not the excitation peak. Since quantum dots have an exponential curve to their absorbance, the lower the wavelength at which they are excited, the more efficiently they will absorb, so you will want to use your lowest available laser line or excitation wavelength.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I want to track my cells with a nucleic acid stain, like DAPI or Hoechst dye. Do you recommend this?

This is not recommended. When these stains bind to DNA and RNA, they may affect the normal function of the nucleic acids, disrupting transcription, as well as replication. Other reagents, such as CellTracker dyes or Qtracker reagents are more optimized for tracking without disrupting normal activity. If a nuclear label is still desired, though, and the cells are mammalian and non-hematopoietic, CellLight nuclear reagents can transiently transfect cells to express GFP or RFP on a nuclear-expressing protein for up to several days without affecting function.

Find additional tips, troubleshooting help, and resources within our Cell Tracing and Tracking Support Center.

I want to track my cells over time, and you have a lot of options to choose from. How do I pick the right one?

Please see this Web link (http://www.thermofisher.com/us/en/home/life-science/cell-analysis/cell-tracing-tracking-and-morphology/cell-tracking.html) to help you choose the right option for your application. Start by planning how long you want to track your cells, then consider the mechanism of binding. Calcein dyes are very uniform in label and are good for short-term cell migration, but may be rapidly effluxed from some cell types. Lipophilic cyanine dyes, such as DiI, DiO, and similar dyes label cell membranes, don’t disrupt function, and can last longer, but have the potential to cross to other cells if membranes fuse. They are also lost upon permeabilization. CellTracker dyes are better for longer-term labeling, as they possess a mildly reactive chloromethyl moiety that allows covalent binding to cellular components. CFDA SE also covalently binds to cellular components. With all the reagents, their retention within cells is dependent upon the rate of cell division and the inherent properties of the cell (active efflux, membrane and protein turnover rates, etc.) and reagents that allow for covalent attachment exhibit longer retention than those that do not.

The longest-lasting and brightest options are the Qtracker reagents, which are taken up through endocytosis. These are so bright individual quantum dots can be detected, and are also robust enough to survive not only fixation and permeabilization, but even the heat and solvents used in paraffin processing.

Find additional tips, troubleshooting help, and resources within our Cell Tracing and Tracking Support Center.