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Since the 1970s, the enzyme-linked immunosorbent assay (ELISA) has served as the mainstay for single-target protein quantitation, despite several cumbersome steps in its workflow. Specifically, assay steps associated with preparation, incubation, and washing can be vastly improved using innovative tools of the trade developed by Thermo Fisher Scientific. Here we describe three tools designed to simplify ELISA protocols.
Invitrogen Instant ELISA Kits are a family of immunoassays that have a condensed workflow format designed to alleviate the inconveniences of multiple preparation and incubation steps (Table 1). In conventional ELISA kits, the precoated plates provide only the capture antibody, to which the sample and detection reagents must be added sequentially. In contrast, Instant ELISA Kits come with ready-to-use plates that contain all necessary assay components—including capture antibody and lyophilized detection antibody, streptavidin-HRP, and sample diluent. These prepared plates greatly reduce pipetting time and enable a simple one-wash protocol (Table 1). Furthermore, serially diluted, lyophilized protein standards are provided in additional strip wells, eliminating the need for plate setup or serial dilutions to create a standard curve and leaving less room for error.
17 steps for conventional ELISA kits | 7 steps for Instant ELISA Kits |
---|---|
1. Washing of coated plates | |
2. Reconstitution of standard proteins | |
3. Addition of sample diluent to standard wells | |
4. Titration of standard curve | 1. Rehydration of plate |
5. Addition of sample diluent | |
6. Sample addition | 2. Sample addition |
7. Dilution of biotin conjugate | |
8. Addition of biotin conjugate | |
9. Incubation | 3. Incubation |
10. Preparation of streptavidin-HRP conjugate | |
11. Washing | |
12. Addition of streptavidin-HRP conjugate | |
13. Incubation | |
14. Washing | 4. Washing |
15. Addition of TMB substrate | 5. Addition of TMB substrate |
16. Addition of stop solution | 6. Addition of stop solution |
17. Calculation of results | 7. Calculation of results |
Rehydrating standards, introducing samples, and adding reagents can be simplified using a preprogrammed pipetting protocol that can be easily transferred to the Thermo Scientific E1-ClipTip Electronic Multichannel Pipette (Figure 1A), saving valuable time and minimizing potential errors. A preprogrammed pipetting protocol can be downloaded from the Thermo Scientific My Pipette Creator app (Figure 1B) to an E1-ClipTip pipette. Using the My Pipette Creator app, custom pipetting programs can be quickly created, edited, and then transferred to a E1-ClipTip pipette through a USB or, for some models, a wireless connection. Once programmed, the pipette will automatically step you through the protocol (Figure 1C) with concise and clear instructions, even prompting when it is time for the plate to be incubated.
Figure 1. Preprogrammed pipetting tools.(A) The programmable Thermo Scientific E1-ClipTip Multichannel Pipette. (B) The Thermo Scientific My Pipette Creator app, powered by our Connect cloud-based platform) makes it easy to access and create assay protocols. (C) An example of a protocol for an Invitrogen Instant ELISA Kit.
During an ELISA protocol, wash steps are extremely important for decreasing background levels, which can impact both the variability and sensitivity of the assay. Manual wash steps with either squirt bottles or multichannel pipettes can be awkward and unwieldy, introducing another potential source of variation. The Thermo Scientific Wellwash Versa Microplate Washer (Figure 2) makes wash steps easier, more efficient, and more consistent. With programmable volumes and soak times, the Wellwash Versa instrument is designed for high performance and versatility and can be configured with a 2 x 8 head to accommodate the 2 x 8-well standard curve strip format.
Figure 2. Automation of wash steps.Thermo Scientific Wellwash Versa Microplate Washer.
The ELISA workflow can be significantly streamlined when combining these three time-saving tools, generating data with low coefficients of variation (CVs) (Figure 3). The Instant ELISA Kit format simplifies both the preparation and incubation steps and reduces hands-on time. Instead of tending to your plate every hour to perform washes, you have a 3-hour window to focus on something else before wrapping up the assay run. The My Pipette Creator app and E1-ClipTip electronic pipette make the steps in the ELISA workflow more efficient by reducing pipetting time and minimizing errors. And the Wellwash Versa Microplate Washer automates the single Instant ELISA wash step, providing consistency to help prevent incomplete washing and associated adverse outcomes, as well as convenience.
Figure 3. Standard curve data with an average CV of 3.3% using the TNF alpha Human Instant ELISA Kit. The Invitrogen TNF alpha Instant ELISA Kit was used according to the manufacturer’s protocol using a programmable Thermo Scientific E1-ClipTip Multichannel Pipette and the Thermo Scientific Wellwash Versa Microplate Washer. Data were analyzed using the Thermo Scientific Multiskan Sky Microplate Spectrophotometer with Thermo Scientific SkanIt Software.
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