A new type of arm patch may enable blood-free detection and measurement of antibodies to provide insights into COVID-19 and other medical conditions, according to researchers at the University of Tokyo.
In a study published Friday in Scientific Reports, the researchers described the development of a novel device that uses porous microneedles to obtain dermal interstitial fluid instead of a finger stick to collect blood samples for point-of-care testing.
"The proposed device has great potential for rapid screening of various infectious diseases in addition to COVID-19 as an effective complementary method with other diagnostic tests," the University of Tokyo researchers wrote in the study, adding, "The developed device integrating porous [microneedles] and immunochromatographic biosensors is expected to enable minimally invasive, simple, and rapid anti-SARS-CoV-2 IgM/IgG antibody testing."
Thus far during the COVID-19 pandemic, antibody tests that detect an infection that has already passed have had limited uptake. RT-PCR and antigen testing remain the go-to modalities, largely because they detect an active infection.
Although the U.S. Food and Drug Administration (FDA) continues to warn against the use of antibody tests to detect an active SARS-CoV-2 infection, the agency is reviewing certain antibody-based laboratory or point‐of‐care based assays for potential emergency use authorizations. Those tests must be high-volume and able to determine whether the antibodies are neutralizing, according to the FDA.
With the view that SARS-CoV-2 antibody tests may eventually find better traction, researchers and companies continue to develop them.
The University of Tokyo researchers noted that the detection of IgM and IgG can provide useful information about the approximate course of the COVID-19 infection. They believe the microneedle patch and its associated test has the potential to broaden use of antibody testing overall, especially at the point of care.
Currently, when people are self-testing using COVID-19 lateral flow assays, they use a lance to draw blood and then pipette the sample into a well in a cassette, prior to adding drops of buffer for sample dilution.
"Bleeding caused by finger prick may cause pain and increase the risk of infection or even cross-contamination," the University of Tokyo researchers noted. "Moreover, patients have to dispose of the test kit components, which are a potential biohazardous waste. Thus, minimally invasive and easy-to-use methods are urgently needed to achieve rapid detection of SARS-CoV-2-specific antibodies."
In the study, the researchers integrated the patch with a paper-based immunochromatographic assay for the detection of anti-SARS-CoV-2 antibodies in dermal interstitial fluid in about three minutes.
The patch consists of biodegradable porous microneedles made of polylactic acid and extracts the sample using capillary action.
"The compact size of the integrated diagnostic device is advantageous to both clinicians and patients," the researchers wrote.