A team of researchers has embedded synthetic biology reactions into fabrics, creating wearable biosensors that can be customized to detect pathogens and toxins. The team at the Wyss Institute for Biologically Inspired Engineering has integrated this technology into standard face masks to detect the presence of the SARS-CoV-2 virus in a patient’s breath. The button-activated mask gives results within 90 minutes at levels of accuracy comparable to standard nucleic acid-based diagnostic tests like polymerase chain reactions (PCR).

The research is published in Nature Biotechnology in the paper titled, “Wearable materials with embedded synthetic biology sensors for biomolecule detection.

“We have essentially shrunk an entire diagnostic laboratory down into a small, synthetic biology-based sensor that works with any face mask, and combines the high accuracy of PCR tests with the speed and low cost of antigen tests,” said co-first author Peter Nguyen PhD, research scientist at the Wyss Institute. “In addition to face masks, our programmable biosensors can be integrated into other garments to provide on-the-go detection of dangerous substances including viruses, bacteria, toxins, and chemical agents.”

The SARS-CoV-2 biosensor is based on technology previously developed by Jim Collins, PhD, professor at MIT and founding member of the Wyss Institute, and called wearable freeze-dried cell-free (wFDCF) technology. First applied to diagnostics during the Zika virus outbreak in 2015, the team created biosensors that can detect pathogen-derived RNA molecules, coupled them to a fluorescent indicator protein, and embedded the genetic circuit into paper to create a cheap, accurate, portable diagnostic. Following their success embedding the biosensors into paper, they set their sights on making them wearable.

“We wanted to contribute to the global effort to fight the virus, and we came up with the idea of integrating wFDCF into face masks to detect SARS-CoV-2. The entire project was done under quarantine or strict social distancing starting in May 2020. We worked hard, sometimes bringing non-biological equipment home and assembling devices manually. It was definitely different from the usual lab infrastructure we’re used to working under, but everything we did has helped us ensure that the sensors would work in real-world pandemic conditions,” said co-first author Luis Soenksen, PhD, a postdoctoral fellow at the Wyss Institute.

The final product consists of three different freeze-dried biological reactions that are sequentially activated. The first reaction cuts open the SARS-CoV-2 virus’ membrane to expose its RNA. The second reaction is an amplification step that makes double-stranded copies of the Spike-coding gene from the viral RNA. The final reaction uses CRISPR-based SHERLOCK technology to detect any Spike gene fragments, and in response cut a probe molecule into two smaller pieces that are then reported via a lateral flow assay strip. Whether or not there are any Spike fragments available to cut depends on whether the patient has SARS-CoV-2 in their breath. This difference is reflected in changes in a simple pattern of lines that appears on the readout portion of the device, similar to an at-home pregnancy test.

When SARS-CoV-2 particles are present, the wFDCF system cuts a molecular bond that changes the pattern of lines that form in the readout strip, similar to an at-home pregnancy test. [Wyss Institute at Harvard University]

The wFDCF face mask is the first SARS-CoV-2 nucleic acid test that achieves high accuracy rates comparable to current gold standard RT-PCR tests while operating fully at room temperature, eliminating the need for heating or cooling instruments and allowing the rapid screening of patient samples outside of labs.

“This work shows that our freeze-dried, cell-free synthetic biology technology can be extended to wearables and harnessed for novel diagnostic applications, including the development of a face mask diagnostic. I am particularly proud of how our team came together during the pandemic to create deployable solutions for addressing some of the world’s testing challenges,” said Collins.

In their paper, the researchers demonstrate that a network of fiber optic cables can be integrated into their wFCDF technology to detect fluorescent light generated by the biological reactions, indicating detection of the target molecule with a high level of accuracy. This digital signal can be sent to a smartphone app that allows the wearer to monitor their exposure to a vast array of substances.

“This technology could be incorporated into lab coats for scientists working with hazardous materials or pathogens, scrubs for doctors and nurses, or the uniforms of first responders and military personnel who could be exposed to dangerous pathogens or toxins, such as nerve gas,” said co-author Nina Donghia, staff scientist at the Wyss Institute.

The team is actively searching for manufacturing partners who are interested in helping to enable the mass production of the face mask diagnostic for use during the COVID-19 pandemic, as well as for detecting other biological and environmental hazards.

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