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You are getting this Elisa Kit spam from China, too? The only way I see, would be to use a known reference standard so you can titrate both the specificity and the sensitivity of the kit. Ideally you would compare it with a known and proven kit. If you have the reference available in the lab and the cheap kit is not too expensive you can give it a try. I ...


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Not necessarily. Sensitivity and specificity are decision criterion-based measures. They are not actually separable from another, they are a consequence of choosing a threshold at which to say "the test reports positive" or "the test reports negative", a consequence of this binary result. As such they are weighed against each other. You ...


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This page from Cole-Parmer includes everything you could possibly want to know about the adsorption of biomolecules to polystyrene. To summarize: binding is neither covalent nor ionic, but it is generally mediated by non-specific intermolecular van der Waals interactions, which generally are about 100X weaker than ionic or covalent bonds the exception is ...


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I want to add something on top of Chris answer. The production of an antibody it is usually a quite slow (and expensive) process, an alternative that worth to consider is phage display (https://en.wikipedia.org/wiki/Phage_display). Once you find the phage that effectively bind your protein of interest, you can use it instead of an antibody in what is called ...


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You are correct, the selectivity advantage of an indirect or sandwich ELISA comes from the fact that two antibodies are employed - one to capture the analyte, the other to detect it. Here is the classic illustration of how this type of ELISA works. First ([1]), the capture antibody is coated onto the plate and bound via one of a number of different types of ...


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Just a few direct ways can figure out whether Elisa Kits are authentic or not. Proposing to visit their factory. Generally bait company does not agree with it. Complete range of kits. If a company has every and each ELISA Kit, it is usually fake. Unless they are very large and professional companies, such as abcam, cellsignal, sigma, sabbiotech and so on. ...


2

The method is based on the principle that the amount of antigen bound to the plastic will be proportional to the concentration in the sample being tested. And of course an ELISA will usually be run with a calibration in parallel so that the signal from your sample is compared to that from standards. The wells will be rinsed anyway in subsequent steps to ...


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It's often not necessarily an advantages vs disadvantages question, but one determined by available reagents and what question is being asked. For example, if you are developing a test for the antibody response to an antigen following immunization, you likely use a protocol like this: coat plates with antigen of interest (assume block / wash as appropriate ...


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I think the most promising routes use antibodies. You could either develop an ELISA or do western blot analysis of plant material - both need a good and specific antibody. To generate these, the protein of interest (or at least parts of it) are injected into animals (typically mice or rabbit) and then antibodies are pourified from the blood of these animals. ...


2

Is your detection or secondary antibody aggregating? I've done extensive clinical ELISA development in the past and when this problem inevitably crops up for these assays the most likely culprits in order were: Plate washer acting funny Antibody aggregates binding nonspecifically to the plate Inefficient blocking reagent/not enough time spent blocking ...


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In general, ECL is more sensitive than TMB for ELISA detection. The minimum detection limit of TMB is 60pg/mL and 20pg/mL for ultra TMB [1], whereas the detection limit of ECL can be as low as about 1.7pg/mL [2]. Resources: https://info.gbiosciences.com/blog/elisa-substrates-a-selection-guide https://www.thermofisher.cn/cn/zh/home/life-science/antibodies/...


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I found the question quite interesting and will to provide a concept and a speculation although I could not answer the question to my own satisfaction (edits to this regard are welcome) Currently (2020), the advanced form of ELISA tests for HIV are designed to simultaneously detect both the HIV P24 antigen (produced by the virus) and anti-HIV igG and igM ...


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The full oxidation of TMB ( 3,5,3’,5’-tetramethylbenzidine) is 2-electron process. The first step (one electron oxidation) gives the blue product, which is then further oxidized to a yellow product (2nd electron) that is stable in acid. At high concentrations this might appear brown. You might also not be fully quenching, leading to a mixture of blue and ...


1

can we use both methods depending on whether the marker enzyme on the antibody is given a fluorescent or chromogenic substrate? This is essentially correct. You can have the same ELISA work on different methods of detection. The most common ELISA is colorimetric, and works by binding a secondary antibody conjugated to some enzyme to your primary antibody. ...


1

As far as I am concerned the intra-assay CV is the average of individual CVs found in an assay. So let's assume you have a data set of 40 samples, and for each sample you have 2 replicates (results), like the one below. You would first calculate the mean for each sample, so in the sample above that would be: $$\frac{0.132 + 0.128}{2} = 0.130$$ Then you ...


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If you have the resources you should ideally titrate your cytokines. You'll find that cytokines from different vendors may exhibit varying stability or availability in vitro, but also that you obtain varying levels of activation. Standard NK-92 culture conditions are 100-300 IU/mL IL-2 in RPMI1640 medium, 10% serum and 2mM L-glutamine (or 1X GlutaMAX, life ...


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My answer: 4.79 µg/ml (All values below are µg/ml) Calibration data Determine the mean of the four absorbance values at each dilution. The calibration curve is then a plot of concentration (x-axis) against mean absorbance. Note that the actual concentration in the assay is (2123/2200)/dilution where dilution is 20, 40 or 80. If you chart this you will ...


1

I agree with the other answers and the biggest difference is indeed the specificity. An indirect ELISA is indeed more specific, but also for a reason which isn't described here yet: Using indirect ELISA means your plate is coated with the primary antibody. Since this primary AB is attached to the well surface with its heavy chain, the 2 light chains (= the ...


1

Using different wavelength for reference give some advantages. You can measure a baseline of each well. All well might not have the same baseline because each well might not be the exactly same as others. In addition, you could make scratches on it, you might touch the bottom, or you get some dirt from your bench. And this can be corrected by A540 in your ...


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This problem is rampant and has been plaguing the research community for a decade. I can explain how exactly do these companies make these fake kits, how to experimentally verify what I said is true, and how to spot them by just looking at their website. I can even point fingers and name a few known and notorious companies that do this malpractice. What I ...


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