Scientists took a common, albeit labor-intensive, laboratory test and redesigned it to perform on small 3D-printed pipette tips used to measure and transfer fluids in the laboratory.
An ELISA is a myenzyme-linked YommunoYesorbiting TOsay. It has been used for decades to test blood and other biological fluids for numerous substances and diseases, including various cancers, pathogens such as HIV and other infectious agents, and to measure levels of biological substances such as proteins.
The standard test is performed in laboratory plates with 96 small wells in each plate. Once liquid, such as blood, has been placed in the test wells, there is a long process of adding various antibodies to the samples that bind to the pathogen or protein being tested and rinsing out those that do not bind. Additional reagents, such as blocking buffers and detection chemicals, are added, and rinsing is required between each step. The end result is a visible color change to indicate whether the pathogen or other agent is present and at what levels.
Although ELISA is reliable, the tests are labor intensive and the antibodies and color indicators used can be expensive. Additionally, sophisticated devices are used to read the color intensities in each well and convert those readings into meaningful data about the amount of the agent of interest contained in the sample. Those devices cost thousands of dollars.
Interestingly, the process of adding, removing and rinsing is done using portable laboratory devices called pipettes. Like a miniature, old-fashioned turkey baster, pipettes use small, disposable plastic tips that are dipped into a liquid and drawn up by the pipette’s plunger. By depressing the plunger, the researcher can dispense the liquids into the small wells of the 96-well plates in amounts similar to a few drops of water.
“This latest invention is an example of how a relatively simple idea can result in a novel technology that could have a significant impact on public health,” says Seila Selimovic, Ph.D., director of the Biosensors and Physiological Detectors program at the National Institute of Biomedical Imaging and Bioengineering, which funded the work.
Selimovic is referring to the fact that researchers realized that the pipettes used for the laborious addition, extraction and rinsing of fluids could just as easily hold all the elements in the 96-well plates, allowing the entire test to be performed quickly within the tip of the plastic pipette.
“In the midst of all the pipetting and rinsing of an ELISA test, one of my colleagues said, ‘I wish making an ELISA was as easy as pipetting,'” explained Mohamed Sharafeldin, senior author of the work done in the lab of James Rusling, Ph.D., professor in the Department of Chemistry and the Neag Cancer Center at the University of Connecticut.
That comment led to the idea of 3D printing pipette tips capable of binding all the ELISA components contained in the 96-well plates, but inside the pipette tip. The result allowed the research team to add, remove, rinse, and view the final result inside the clear pipette tip, eliminating 96-well plates entirely. Additionally, expensive machines used to read color intensity can be replaced by a mobile phone application that takes a photograph of the color change on pipette tips and provides a readout of the test results.
The invention represents a great advance in terms of improvements over the typical ELISA. Testing showed that it gave comparable results; the cost is a fraction of that of a traditional ELISA; and the ease of the system requires much less training for users. The cell phone app allows you to take a photo of the color change on the pipette tips, which can be sent to a technician who reads the results remotely to help make a diagnosis. Finally, the standard ELISA can take up to eight hours. The new test lasts 90 minutes.
While some additional testing is still underway, the research team is optimistic not only about less pipetting, but also the potential use of their system in rural communities and developing countries, where the diagnostic accuracy of an ELISA in a simpler and more affordable form could have a very significant impact on the health care of these underserved populations.
The study was published in the June issue of ACS Analytical Chemistry.1. The work was funded by grant EB016707 from the National Institute of Biomedical Imaging and Bioengineering, and a grant from the University of Connecticut Academic Plan.
