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View additional product information for Qdot™ 655 ITK™ Carboxyl Quantum Dots - FAQs (Q21321MP)
47 product FAQs found
在3,000 rpm下离心ITK Qdot纳米晶3-5分钟，可以从上清中去除白色沉淀，之后就可以直接使用上清了。
有机ITK Qdot纳米晶中有一定几率会析出白色沉淀。ITK Qdot纳米晶有时候会含有呈白色沉淀状的杂质。
闪烁是量子点固有的性质；实际上，所有的单一发冷光的分子都会闪烁，包括有机染料。由于其亮度和光稳定性，Qdot纳米晶的闪烁显得更加明显。激发能量越高，Qdot纳米晶闪烁甚至更快。使用Beta-巯基乙醇可以减少闪烁。
选择合适的封固液对保持Qdot纳米晶荧光性能至关重要。根据我们的研究，Qdot纳米晶适合用下列封固液：
•HistoMount封固液（货号00-8030），非常适合长期保存
•Cytoseal 60封固液
•Clarion封固液
•大多数基于聚乙烯醇的封固液（有限储存时间，<数周）
•基于水的封固液（有限储存时间，<1周）
•至多50%的甘油 （有限储存时间，<1周）
注：我们不推荐ProLong封固液与Qdot 纳米晶一同使用，因其会导致Qdot发生荧光淬灭。
冷冻会导致产品聚集。一旦聚集后就不能重新分散到溶液内。
一旦产品形成聚集，就无法重新分散到溶液内。我们建议重新购买。
在正常的储存过程中可能偶然会观察到少量Qdot纳米晶聚集。为了在使用前去除这些聚合物，我们建议在2,000 x g下离心1分钟。仅吸取上层清液并避免吸到沉淀。根据我们的经验，沉淀聚集物通常仅会导致10%以下的产品损耗。
我们没有系统地研究纳米晶的能量转移性质，尽管纳米晶可能作为能量转移的供体和受体。我们已经研究了通过双生物素交联剂相互偶联的Qdot 605链霉亲和素偶联物的荧光性，且发现任何浓度的生物素交联剂都不会影响交联后的纳米晶的发射强度。这些结果表明Qdot偶联物粒子间的淬灭可以忽略。
Qdot产品含有无机晶体形式的镉和硒（大颗粒中含有碲）。对于处理这些材料，我们只能建议您按照所有合适的当地的、州的和联邦条例来处理这些材料。关于这些材料成分的更多信息，查询材料安全数据登记表（Material Safety Data Sheet）。
我们没有研究过Qdot纳米晶的毒性。这种材料是以2 mM总Cd浓度的溶液提供的。我们已经在多种活细胞的体外标记实验中证明这些材料的用途，但是还没有研究这些材料对人类、动物、或培养细胞毒性的系统数据。
偶联到一个Qdot纳米晶上的分子的数量取决于偶联过程中使用的纳米晶与偶联分子的比率，Qdot纳米晶上可用的结合位点数量，以及Qdot纳米晶和目标分子的大小。总的来说，每个Qdot纳米晶上含有2-3个抗体，4-5个生物素分子，6-8个链霉亲和素分子。
ITK Qdot纳米晶使用第一代Qdot产品中外层聚合物的经典组成；除了氨基-PEG产品，外层聚合物不含有PEG。标准Qdot纳米晶的外层聚合物含有PEG。
每个Qdot ITK纳米晶大约有80–100官能团。我们使用一种免疫吸附测定方法来测定每种偶联物的EC50。
可以，您可以使用标准滤光片来观察Qdot纳米晶；可以使用低于发射波长的任何波长激发它们。切记，激发光波长越短，Qdot纳米晶发出的荧光越亮。
Qdot纳米晶不会像化学染料那样光漂白或褪色，不需要使用抗淬灭剂。根据我们的研究，Qdot纳米晶适合用下列封固液：
•HistoMount封固液（货号：00-8030），非常适合长期保存
•Cytoseal 60封固液
•Clarion封固液
•大多数基于聚乙烯醇的封固液（有限储存时间，<数周）
•基于水的封固液（有限储存时间，<1周）
•至多50%的甘油（有限储存时间，<1周）
提示：我们不推荐ProLong封固液与Qdot纳米晶一同使用。
亲水性的Qdot纳米晶在pH 8.3–9.0的硼酸盐缓冲液中储存和运输，而有机Qdot纳米晶则在癸烷中储存和运输。我们研究过Qdot纳米晶在多种不同溶剂中的稳定性，更多信息详见溶剂稳定性（https://www.thermofisher.com/us/en/home/brands/molecular-probes/key-molecular-probes-products/qdot/qdot-reg--nanocrystal0.html）。
当在4℃下存储时，Qdot纳米晶可稳定6个月。由于可能发生聚集，Qdot纳米晶绝对不能冷冻。关于最高360°C暴露温度的信息见温度稳定性（https://www.thermofisher.com/us/en/home/brands/molecular-probes/key-molecular-probes-products/qdot/qdot-reg--nanocrystal0.html）。
Qdot纳米晶在pH6–9的范围内最稳定，最低至pH 5。由于可能存在自聚集，Qdot纳米晶不能在pH > 9的条件下使用，并且不能在pH < 4的条件下使用，否则聚合物和暴露的核/壳就会开始分离。关于更多详情和pH推荐范围，详见Qdot 纳米晶的pH范围（https://www.thermofisher.com/us/en/home/brands/molecular-probes/key-molecular-probes-products/qdot/qdot-reg--nanocrystal0.html）。
你可以在两种FRET情况下使用Qdot纳米晶：
•Qdot纳米晶作为供体而荧光染料作为受体
•镧系元素（铽、铕等）作为供体而Qdot纳米晶作为受体
注意：不得在FRET实验中同时将Qdot纳米晶作为供体和受体。
我们提供氨基（PEG）、羧基和链霉亲和素官能化的Qdot Innovator’s Tool Kit ITK 纳米晶用于偶联自己感兴趣的蛋白或其它生物分子。其中氨基（PEG）衍生形式的纳米晶可以与异硫氰酸盐和琥珀酰亚胺酯偶联，或使用水溶的碳化二亚胺结合羧酸。羧基衍生形式的纳米晶能够结合到蛋白质和修饰的寡核苷酸的氨基基团上。链霉亲和素衍生形式的纳米晶则能够结合生物素化的偶联物来形成稳定的标记复合物。
Qdot纳米晶及其生物偶联物非常适合需要长时间光稳定性、单一激发、多色分析的实验。部分应用示例包括：
•流式细胞术
•细胞和组织染色
•细胞示踪
•WesternDot蛋白免疫印记
•活体成像
相比于传统的荧光染料，Qdot纳米晶有很多优势：
•Qdot纳米晶激发范围宽，可被任何低于其发射峰的波长所激发。激发波长越低，消光系数和纳米晶亮度就越高。
•可以使用单一的激发波长进行Qdot纳米晶多色检测。
•Qdot纳米晶呈现出较大的斯托克斯位移。
•Qdot纳米晶发射光谱带较窄
•相比传统的荧光染料，Qdot纳米晶光稳定性好。
Qdot纳米晶由四个基本层组成，从内核到外壳依次为：
1.晶核（CdSe或CdSeTe）：决定了Qdot纳米晶的颜色
2.无机层（ZnS）：用于提高Qdot纳米晶的亮度和稳定性
3.有机/聚合物涂层：提供水溶性和/或用于偶联的官能团
4.生物分子：共价结合到聚合物层，包括免疫球蛋白、链霉亲和素、受体配体或寡核苷酸。
The core/shells are only a few nanometers in diameter (some are elliptical), but with the outer polymer coatings, a fully-functionalized Qdot nanocrystal can range from 15 to 21 nm in hydrodynamic diameter, similar in size to some proteins.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Spinning your ITK Qdot nanocrystals at approximately 3,000 rpm for 3-5 minutes should remove the white precipitate from the supernatant. Use the supernatant immediately.
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The precipitate in the organic ITK Qdot nanocrystals occurs with some frequency. The ITK Qdot nanocrystals sometimes include impurities that show as a white precipitate.
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Blinking is an inherent property of quantum dots; in fact, all single-luminescent molecules blink, including organic dyes. The brightness and photostability of Qdot nanocrystals makes the blinking more visibly apparent. Under higher energy excitation, Qdot nanocrystals blink even faster.
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Appropriate mounting media selection is very important to retain the fluorescence of Qdot nanocrystals. In our studies, Qdot nanocrystals work best with the following mountants:
HistoMount medium (Cat No. 00-8030); best for long term archiving
Cytoseal 60 Mountant
Clarion Mountant
Most polyvinyl alcohol-based mountants (limited storage time, less than weeks)
Water-based mountants (limited storage time, less than week)
Up to 50% glycerol (limited storage time, less than week)
Note: We do not recommend using ProLong mounting media with Qdot nanocrystals as it will quench their fluorescence.
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Freezing will cause the product to aggregate. The Qdot nanocrystals cannot be dispersed into solution after aggregation.
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Once your product undergoes aggregation, it cannot be dispersed back into solution. We recommend purchasing a new product.
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You may occasionally observe a small amount of aggregation of the Qdot nanocrystals during proper storage. To remove any aggregates that may have formed prior to use, we recommend centrifuging the vial at 2,000 x g for 1 min. Pipette only the supernatant and avoid the pellet. In our experience, pelleting any aggregates that may have formed typically results in a loss of less than 10% of the product.
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We have not systematically investigated the energy transfer properties of the quantum dots, though the quantum dots may have useful properties as both energy transfer donors and acceptors. We have investigated the fluorescence of Qdot 605 Streptavidin conjugates that are coupled to each other through a bis-biotin linker, and found that the emission intensity of the materials was unperturbed at any concentration of biotin cross-linker. These results suggest that the interparticle quenching of these Qdot conjugates is negligible.
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The Qdot products contain cadmium and selenium (and tellurium, in the larger particles) in an inorganic crystalline form. We can only advise that you dispose of the material in compliance with all applicable local, state, and federal regulations for disposal of these classes of material. For more information on the composition of these materials, consult the Material Safety Data Sheet.
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We have not investigated the toxicity of the Qdot nanocrystals. The materials are provided in a solution which is approximately 2 mM total Cd concentration. We have demonstrated the utility of these materials in a variety of live-cell in vitro labeling experiments, but do not have systematic data investigating the toxicity of the materials to humans, to animals, or to cells in culture.
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The number of molecules conjugated to one Qdot nanocrystal is based on the ratio of quantum dot:molecule used in the conjugation, the number of available binding sites on the Qdot nanocrystal, and the size of both the Qdot nanocrystal and the molecule of interest. In general, there are 2-3 antibodies, 4-5 biotin molecules, and 6-8 streptavidin molecules per Qdot nanocrystal.
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ITK Qdot nanocrystals use the original formulation of outer polymer provided in the first generation of the Qdot products; except for the Amine-PEG products, the outer polymer does not include PEG. The outer polymer of the standard Qdot nanocrystals includes PEG.
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There are approximately 80-100 functional groups of each Qdot ITK nanocrystal. We use a type of immunosorbent assay to determine the EC50 of each conjugate.
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Yes, you can visualize Qdot nanocrystals using a standard filter; they will excite at any wavelength below their emission. Keep in mind that the lower the excitation value the brighter the Qdot nanocrystal fluorescence output.
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Qdot nanocrystals do not require the use of antifades as they do not photobleach or fade in the same manner as a chemical dye. In our studies, Qdot nanocrystals work best with the following mountants:
- HistoMount medium (Cat No. 00-8030); best for long-term archiving
- Cytoseal 60 Mountant
- Clarion Mountant
- Most polyvinyl alcohol-based mountants (limited storage time, less than a week)
- Water-based mountants (limited storage time, less than a week)
- Up to 50% glycerol (limited storage time, less than a week)
Note: We do not recommend using ProLong or SlowFade mounting media with Qdot nanocrystals.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Hydrophilic Qdot nanocrystals are stored and shipped in borate buffer pH 8.3-9.0, and organic Qdot nanocrystals are stored and shipped in decane.
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When stored at 4 degrees C, Qdot nanocrystals are stable for approximately 6 months. Qdot nanocrystals should never be frozen due to the possibility of aggregation. The temperature stability of Qdot nanocrystals is summarized below. Please note that fluorescence is not temperature dependent.
<0 degrees C: NEVER freeze Qdot nanocrystals - polymer induces aggregation at freezing temperatures.
>4 degrees C: Core/Shell/Polymer stable at 4 degrees C for ~ 6 months. May be filter sterilized using uncharged filters.
<60 degrees C: Core/Shell/Polymer stable at 60 degrees C (as in in situ hybridization).
<65 degrees C: Core/Shell/Polymer stable at 65 degrees C for only ~1 hour, beyond 1 hour, emission drops off.
<100 degrees C: Core/Shell/Polymer stable up to 100 degrees C brief exposure. OK for 5 minutes at 100 degrees C.
<360 degrees C: Only Core/Shell stable up to 360 degrees C.
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Qdot nanocrystals are most stable at pH 6-9, and marginal stability of Qdot nanocrystals is shown down to a pH 5. Qdot nanocrystals should not be used at pH > 9 due to the possibility of self-aggregation and clumping, and Qdot nanocrystals should not be used pH less than 4 as the polymer and exposed core/shell will begin to dissociate. For more information on Qdot nanocrystals and recommended pH ranges, see pH Ranges for Qdot Nanocrystals (https://www.thermofisher.com/us/en/home/brands/molecular-probes/key-molecular-probes-products/qdot/qdot-reg--nanocrystal0.html)
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You can use Qdot nanocrystals with FRET applications in two scenarios:
- Qdot nanocrystals as donors with fluorescent dyes as acceptors
- Lanthanide (terbium, europium, etc.) as donors with Qdot nanocrystals as acceptors
Note: You cannot perform FRET experiments using Qdot nanocrystals as both donor and acceptor.
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We offer amino (PEG), carboxyl, and streptavidin-functionalized Qdot Innovator's Tool Kit ITK Nanocrystals for the preparation of custom conjugates of proteins or other biomolecules. Amino (PEG)-derivitized forms can be coupled to isothiocyanates and succinimidyl esters or with native carboxylic acids using water-soluble carbodiimides. Carboxyl-derivitized forms can be coupled to amine groups of proteins and modified oligonucleotides. Streptavidin-derivitized forms can be bound with biotinylated conjugates to form stable labeled complexes.
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Qdot nanocrystals and bioconjugates are ideal for experiments requiring long-term photostability or single-excitation, multicolor analysis. Some example applications include:
- Flow cytometry
- Cell and tissue staining
- Cell tracking
- WesternDot western blotting
- In vivo imaging
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Qdot nanocrystals offer many advantages over traditional fluorescent dyes:
- Qdot nanocrystals have a broad excitation range, and they can be excited by any wavelength below their emission peak. The lower the excitation wavelength, the higher the extinction coefficient and Qdot nanocrystal brightness.
- Multicolor detection using Qdot nanocrystals can be done using a single excitation wavelength.
- Qdot nanocrystals exhibit a large Stokes shift.
- Qdot nanocrystals have a narrow emission band.
- Qdot nanocrystals have excellent photostability compared to traditional fluorescent dyes.
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A Qdot nanocrystal is comprises four basic layers. Listed from inner core to outer shell, these are:
1) Core nanocrystal (CdSe or CdSeTe): Determines the color of the Qdot nanocrystal
2) Inorganic shell (ZnS): Improves brightness and stability of the Qdot nanocrystal
3) Organic/polymer coating: Provides water solubility and/or functional groups for conjugation
4) Biomolecule: Covalently attached to the polymer shell and can include antibodies, streptavidin, receptor ligands, or oligonucleotides.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.