The accuracy and sensitivity of some of the most common medical and laboratory tests, such as ELISA, microarrays and immunohistochemistry imaging, is markedly enhanced by the addition of polydopamine. Originally isolated from mussels, the substance boosts the resolution of these tests for biomarkers of HIV, Zika virus and proteins on cancerous tumors.

Microscopy images of Zika-infected primate placenta samples stained to detect Zika using immunohistochemistry. Left, a sample treated with the EASE protocol, with red/orange colored signals of Zika infection clearly visible (white arrows). The right image shows a sample treated with a standard protocol, and Zika virus — though present — is not detected. (Image credit: Junwei Li/Kristina Adams Waldorf/Michael Gale/Lakshmi Rajagopal/Xiaohu Gao)

University of Washington researchers applied an enzyme-accelerated signal enhancement (EASE) method to diagnostics, which adds dopamine and horseradish peroxidase (HRP) at a key step. HRP speeds up the rate of reactions in biomedical research and connects dopamine molecules together to form the polymer chain polydopamine. The latter accumulates on the surfaces of reaction vessels, such as small Petri dishes, and with its presence scientists can continue the traditional steps of their protocols but with substantially increased test sensitivity.

The researchers used EASE to detect the presence of Zika virus in the placental tissues of primates. The approach made the assay so sensitive that they were able to see which types of cells within the placenta were infected with Zika.

It is not fully understood why adding polydopamine boosts the sensitivity of these bioassays, but the team hopes that this simple modification will mean that scientists and medical professionals can easily incorporate EASE into their common practices and procedures.