Problem: Enzyme-linked immunosorbent assays (ELISAs) are commonly used in diagnostic and quality-control laboratories. During an ELISA, an unknown amount of antigen is immobilized to the surface of a microplate well and an enzyme-linked antibody is subsequently bound. Between each step, the plate needs to be washed with a solution to remove any non-specific background, such as that caused by unbound proteins or antibodies. After the final wash step, the addition of an enzyme substrate produces a measurable change to indicate the quantity of antigen in the sample.

Reducing background noise and assay variation is the main challenge when interpreting ELISA data. To ensure reliable results with excellent accuracy and precision—while maximizing assay sensitivity—high-quality washing is essential. It is vital that all of the washing steps of any ELISA are performed as efficiently as possible. Any unbound material left in the wells increases levels of background noise, decreasing assay sensitivity and the quality of resulting data. As such, the well washing process needs to be as thorough as possible to remove any unbound material and provide optimized assay conditions.

Solution: In order to provide confidence in the accuracy, precision and sensitivity of obtained ELISA data, a standard and reliable washing protocol needs to be employed, where wash parameters are controllable and fully optimized. The Thermo Scientific Wellwash and Wellwash Versa microplate washers are excellent tools for effectively washing 96- and 384-well plates, ensuring that any unbound protein is eliminated from the reaction well.

Parameters for washing, such as volume, cycle number, speed, position, time, aspiration mode and shaking during soaking are easily adjustable to guarantee the best possible washing performance. As a result, unbound materials are efficiently removed at each washing step of the ELISA, maintaining background noise at a minimal level to increase assay sensitivity. If not removed, unbound protein can bind non-specifically to the enzyme active sites, reducing assay specificity. Through the incorporation of a sweep mode, the possibility of this occurring is significantly reduced, since these washers ensure extremely low residual volumes, efficiently removing any un-bound or non-specifically bound protein. Furthermore, by shaking the assay during soaking, experimental efficiency is increased, while saving on liquid consumption.

It is essential that during these washing steps, there is no cross-contamination of the wells within the ELISA plates, to ensure accurate data generation. Sensitive washing steps together with a special wash head design ensure that contamination is minimized while preserving the covalent bonds of the solid phase antigen. Potentially damaging mechanical actions are therefore eliminated, providing a gentle, yet thorough, wash. The accurate dispensing and aspiration of washing solutions via specially developed wash heads maximize efficiency. A reliable and accurate ELISA is obtained every time, through the automatic prime and rinse features that prevent clogging of the liquid channels. The addition of an aerosol cover also prevents aerosols of infectious diseases from spreading, therefore maintaining the integrity of resulting data for any downstream analysis.

With such importance on the effectiveness of the ELISA wash steps, microplate wash systems need to be easy to use. The Wellwash and Wellwash Versa incorporate language options and a context-specific help feature, which ensures that washing protocols are developed quickly and easily, with minimal user training. All users can therefore effectively use the equipment regardless of experience levels, resulting in increased throughput.

The more advanced Wellwash Versa can also be connected to robotic systems, making it a suitable tool for high-throughput laboratories. As such, multiple ELISAs can be performed with outstanding precision, accuracy, and repeatability.

For more information, please visit www.thermoscientific.com/wellwash