Are you a medical researcher, clinical diagnostician, or scientist in the biopharmaceutical industry? If so, you know that ELISA kits are essential for your work. But with so many different brands and types of ELISA kits on the market, how can you be sure to get the best for your needs? Here are eight significant criteria for choosing one to meet your specific requirement.
1. Your Analyte
What type of protein or species are you studying? Whether you want to identify, quantify, or purify a protein, you need ELISA test kits designed for your analyte of interest. For example, if looking for an ELISA kit to measure mouse cytokines, find one validated for use with those samples. You will choose between competitive and sandwich ELISA. Your option depends on the protein quantity and the epitope you wish to target. Competitive ELISA is ideal for low protein levels or if you want to target a conformational epitope.
2. The Species
Various species have distinct biological compositions and structures. Proteins from humans cannot resemble those from other mammals. ELISA kits target specific species like humans, mice, rats, or other animals. The required kit depends on the animal you want to collect the samples. Some ELISA kits can cross-react. To study human proteins, buy one that shows no cross-reactivity with the proteins of other mammals.
3. Kit Sensitivity and Specificity
Do you want to distinguish proteins from the same species but with varying functions? If yes, you need an ELISA kit with high specificity. The kit should discriminate between proteins that differ by a few amino acids. To accurately detect low protein levels, it should also have high sensitivity. For instance, cytokine ELISA kits can measure picogram quantities of proteins.
Sensitivity and specificity are inversely related. A highly sensitive kit may have low specificity and vice versa. To study a unique protein, choose a kit with high specificity. However, if looking for all the proteins in a sample, go for a kit with high sensitivity. You may have to sacrifice one attribute for the sake of the other.
4. Type of Antibodies
The antibodies used in ELISA manufacture determine the kit’s quality. Most of them come with a primary antibody. It detects the presence of a target antigen in serum, plasma, or cell lysates. The secondary antibody binds to the primary antibody. The enzyme HRP or AP produces a colored end-product upon reaction with the substrate. Using only primary antibodies saves time and reduces cross-sensitivity.
5. The Protocols Applied
Each ELISA kit comes with a set of instructions and protocols. They guide you on how to use the kit to get accurate results. Some have multiplexing capabilities. They allow you to measure more than one protein at a time. But if you are trying various samples, use a standardized kit to ensure consistency. Also, kits with step-by-step procedures are convenient to use. They help you avoid mistakes that can lead to inaccurate results.
6. The ELISA Assay Range
The dynamic range is the difference between the highest and lowest concentrations of an analyte an ELISA test can measure. It is the range over which an ELISA assay gives a linear response to the analyte concentration. The broader the dynamic range, the better. It means you have guaranteed results over a wide range of analyte concentrations.You can also consider the linear range or working range. It is the interval over which an ELISA assay gives a straight line when plotted against analyte concentration. It is narrower than the dynamic range. The linear range helps to calculate the amount of analyte in a sample. It is essential for accurate ELISA measurements.
7. Sample Size
Some samples are in limited supply. They are from hard-to-get or rare sources. If you have such, choose an ELISA kit that requires minimal sample amounts. The best ones use as little as ten microliters of serum or plasma. Others may require up to 500 microliters, depending on the antigen. The sample size you need also depends on the number of ELISA plates you want to use. If you intend to do many experiments, buy a kit with many plates to use fewer samples.
8. Your Budget
The price of an ELISA kit varies depending on the type of proteins you want to measure. For instance, cytokine ELISA kits are more expensive than kits for measuring enzymes. Also, multiplex kits that measure more than one protein at a time are pricier than standard ones (those for a single protein). Prices can also depend on the features of a given kit. Some have extra accessories or come in bulk. The bottom line is to buy what you need and can afford without compromising results.
ELISA kits can help you save time and money while ensuring accurate results. But ensure you buy the best for your specific needs. Go for kits with high specificity and sensitivity. They should also have a wide dynamic range and come with simple protocols. Additionally, check the sample size required, the number of plates, and the price. With these eight factors in mind, you can get the best ELISA kit for your research.