Accessible and rapid COVID-19 testing has played a pivotal role in our battle against the pandemic, but it has not been without its challenges. Polymerase chain reaction (PCR) tests, long considered the gold standard for diagnostic accuracy, come with significant drawbacks. They demand precious time, sometimes taking a day or more to produce results, and rely on specialized equipment and skilled labor, increasing costs for healthcare systems and individuals alike.
Moreover, the sophistication of PCR tests makes them less nimble in responding to the emergence of new viral variants. Additionally, these tests have environmental consequences. Many of the biosensor tests developed to date use printed circuit boards (PCBs), which are notoriously difficult to recycle and slow to biodegrade. PCB production involves significant quantities of non-eco-friendly materials, including metals and plastics.
A disconcerting outcome of PCR testing is that a substantial portion ends up in landfills, contributing to material waste and secondary contamination. A sobering analysis by the World Health Organization (WHO) estimated that, as of February 2022, over 140 million test kits had been shipped, with the potential to generate 2,600 tons of non-infectious waste, primarily plastic, and 731,000 liters of chemical waste, equivalent to one-third of an Olympic-size swimming pool.
In response to this conundrum, César de la Fuente and his team have been tirelessly working on innovative ways to balance the need for swift, affordable, and accurate testing with the pressing environmental concerns. De la Fuente, a Presidential Assistant Professor in Bioengineering and Chemical and Biomolecular Engineering, with additional primary appointments in Psychiatry and Microbiology, recognized the urgency for “green” testing materials.
Their efforts resulted in the creation of RAPID, aptly named for its ability to generate results within minutes, maintaining a high level of accuracy. A more cost-effective version, called LEAD, was developed using electrodes crafted from graphite. The team also introduced COLOR, a low-cost optodiagnostic test printed on cotton swabs.
Their most recent breakthrough combines the speed and affordability of previous tests with eco-friendly materials. In a paper published in Cell Reports Physical Science, the team presents a new test constructed from bacterial cellulose (BC), an organic compound synthesized from various bacterial strains, serving as an alternative to PCBs.
Bacterial cellulose, produced naturally by bacteria, serves as the foundation for biosensors. It is highly adaptable and has found applications in wound care, regenerative medicine, and point-of-care diagnostics, which are crucial for pandemic prevention. These tests enable rapid and accurate diagnosis at the testing site without the need for costly, specialized equipment or transporting samples to a distant lab.
The new BC test is a game-changer on several fronts. It is non-toxic, biodegradable, cost-effective (costing less than $4.00 per test to produce), and scalable for mass production. Moreover, its cellulose fibers are produced without the chemicals used in traditional paper manufacturing, making the test almost entirely biodegradable, with only a small amount of silver, which can be easily removed and recycled by healthcare professionals.
Beyond its environmental merits, the BC test proved exceptionally accurate in clinical trials, correctly identifying multiple variants in under ten minutes. This means that the tests won't require constant adjustments to accurately detect new variants.
For de la Fuente, this new COVID test represents a step toward “responsible innovation,” recognizing the delicate balance between technological progress and environmental conservation.
“There's a tension between these two worlds of innovation and conservation,” he acknowledges. “When we create new technology, we have a responsibility to think through the consequences for the planet and to find ways to mitigate the environmental impact.”
De la Fuente's broader ambition extends beyond COVID-19. He envisions green alternatives for diagnostic testing that can have a positive impact across the board.
“There is a need for biodegradable diagnostic testing,” he asserts. “We will continue to refine this technology, with the hope that it can benefit many people in the future, while also expanding its applications to other emerging pathogens in anticipation of future pandemics.”
This groundbreaking study represents an international collaboration between the de la Fuente lab and William Reis De Araujo, a professor in analytical chemistry at the University of Campinas (UNICAMP) in São Paulo, Brazil, who leads the Portable Chemical Sensors Lab. These two teams have been collaborating for years, with De Araujo's expertise in electrochemistry complementing the diverse and interdisciplinary interests of the de la Fuente lab.
As we continue to navigate the ongoing effects of COVID-19 and look ahead to preventing future pandemics, accessible, accurate, and environmentally friendly testing is crucial to safeguarding both the health of our planet and its people. The findings of this study suggest that these goals need not be mutually exclusive.
Source: University of Pennsylvania