ELISA and ECL Capabilities at VelaLabs

At VelaLabs, we use a variety of technologies, including ELISA and ECL, to deliver precise and reliable protein binding results in multiple biological matrices including serum or plasma.

Our ELISA and ECL services cover a wide range of applications, including:

• Binding potency: Quantitative evaluation of sample activity by comparison to a reference. The detected signal is directly proportional to the amount of bound sample analyte. Confirmation assay for Cell-based assays (see Protein Expression and neutralizing antibodies).
• Competition ELISA: Determination of the analyte (antigen) concentration present in the tested sample by measuring the amount of sample antigen able to compete with a labelled or plate-bound antigen for a limited amount of specific antibody. The detected signal is inverse proportional to the amount of bound sample analyte.
• Anti-Drug antibodies: Determining the amount of drug binding antibodies present after drug treatment. Confirmation assay for Cell-based assays (see Protein Expression and neutralizing antibodies).
• Pharmacokinetics: Determining the concentration of a drug or biologic in biological matrix over time, enabling calculation of pharmacokinetic parameters such as absorption, distribution, metabolism and elimination
• Toxicokinetic: Determining the concentration of a toxic substance in biological matrix over time, enabling calculation of pharmacokinetic parameters such as absorption, distribution, metabolism and elimination

Our experts at VelaLabs are ready to develop and establish ELISA- and ECL-based assays according to national and international guidelines tailored for your needs.

Find out more about:

C1q Binding ELISA

Enzyme-Linked Immunosorbent Assay (ELISA) is based on the specific binding between an antigen and an antibody, where one component is immobilized on a solid surface and the other is detected using an enzyme-linked antibody. Upon addition of a suitable substrate, the enzyme catalyses a reaction that produces a measurable signal (usually a colour change), the intensity of which is proportional to the amount of target analyte present.

Electrochemiluminescence (ECL) is based on the generation of light through electrochemically stimulated reactions, in which a labelled molecule containing a luminescent tag emits light upon excitation at an electrode surface. When a target analyte forms a complex with specific binding partners (e.g., antigen–antibody), the label is brought to the electrode, where an applied voltage triggers a chemical reaction that produces light; the emitted signal is measured and is proportional to the amount of analyte present.

The overall sensitivity of ELISA- and ECL-based immunoassays differ greatly due to fundamental differences in signal generation and detection mechanisms.

ELISA relies on enzyme-mediated conversion of a substrate into a measurable colorimetric, fluorescent or chemiluminescent signal. This allows ELISA to achieve limits of detection in the nanogram per milliliter range, with optimized chemiluminescent assays occasionally being able to detect even picogram of analyte. In contrast, ECL‑based assays utilize electrochemically stimulated luminescent labels, such as ruthenium complexes, which emit photons upon redox cycling at an electrode surface producing a measurable light signal. This mechanism enables development of methods with detection limits in the low picogram per milliliter range making ECL more suitable for the detection of low-abundance analytes.

This superior sensitivity of ECL assay is largely attributed to their enhanced signal‑to‑noise ratio. In general ELISA, background signal can arise from non-specific adsorption, incomplete washing between incubation steps and variability in enzyme kinetics, all which contribute to a reduction in analytical sensitivity. By comparison, ECL signal generation is mostly confined to the electrode surface of the assay plate and only occurs upon application of a defined electrochemical reaction, therefore minimizing background and improving signal quality. ECL assays also allow for measurements in a broader dynamic range, typically spanning four to six orders of magnitude, whereas ELISA is in general limited to a range of two to three orders of magnitude allowing for a more accurate quantification across a wider spectrum of analyte concentrations without the need for extensive sample dilutions. This superior sensitivity also allows for a reduction of the necessary amount of test sample. While ELISA usually requires a minimal volume of 50 – 100 µL per well, ECL can work with volumes as low as 10 µL per well.

ECL-based methods also offer improved reproducibility as environmental conditions such as temperature, pH or substrate stability only have minor influence on the generated signal, whereas ELISA shows increased sensitivity to such factors. Furthermore, ECL assays generally involve fewer steps, further reducing potential variability.

Additionally, while ELISA is generally restricted to measuring one analyte per well, ECL may be developed to detect multiple targets simultaneously in the same sample.

However, while ECL-based immunoassays provide substantially greater analytical sensitivity, lower background signal and a wider dynamic range compared to ELISA, development and optimization of ECL methods may result in higher costs due to the methodological simplicity and broad availability of standard reagents of ELISA.

Analysis details

• Instruments: Our laboratory is equipped with two qualified SpectraMax devices, allowing multiple analysis runs per day. In addition, we have a MESO QuickPlex SQ 120 from Meso Scale Discovery (MSD) for ECL analysis. We are listed on MSD's homepage as official CRO partner lab for their devices.
• Turnaround time: We aim to create methods that not only produce reliable and repeatable results, but also fulfil all needs of our customers while still maintaining highest quality standards. Once the assay is established, sample measurement will be performed according to the quality agreement or within two weeks after arrival at VelaLabs.

Assay development

When establishing a new assay, we verify the following aspects to ensure the stability of the method:

• Coating procedure: Testing different buffer compositions and coating procedures (e.g. different antibodies) to create the optimal surface for the measurement
• Assay range: Optimizing the applied concentrations of the reference to enable reliable measurement of even trace amounts of analyte (ng amount of analyte measurable)
• Accuracy and Precision: Testing 5 concentrations within the assay range to verify adherence to applicable guidelines
• Reproducibility: Testing whether modifications of assay conditions negatively impact the performance