LUCAS technology revolutionizes rapid viral diagnostics

Mass General Brigham researchers are shining a powerful new light into the viral darkness with the development of Luminescence CAscade-based Sensor (LUCAS), a rapid, portable, highly-sensitive diagnostic tool for processing complex biological samples. Compared to its diagnostic predecessors, LUCAS creates 500-fold stronger and 8-fold longer-lasting bioluminescence signals, overcoming longstanding challenges faced by point-of-care diagnostics. Their study published today in Nature Biomedical Engineering.

Developing effective diagnostics is incredibly challenging, especially when you think about the size of infectious disease particles and the complicated biological fluids we're attempting to identify them in. Finding an HIV particle in a human blood sample is like finding an ice cube in a jelly-filled Olympic swimming pool while blindfolded. With its novel enzyme cascade approach, LUCAS marks a substantial leap forward for sensing viruses in these complex biological samples."

Hadi Shafiee, PhD, senior author, faculty member, Division of Engineering in Medicine and Renal Division of Medicine at Brigham and Women's Hospital

Point-of-care diagnostics have become essential tools in many households, as people measure their blood sugar, take pregnancy tests, and even conduct their own COVID-19 assays. These diagnostics, which allow people to forgo tedious, expensive laboratory testing, are important for disease detection, treatment, and monitoring. Yet current diagnostics can fall short, with faults like inaccuracy and poor sensitivity. Bioluminescence has the potential to alleviate common shortcomings experienced by other methods, like background noise, false positives, photobleaching and phototoxicity.

Bioluminescence utilizes the same natural enzyme that makes fireflies glow to light up biological samples for imaging. The enzyme, luciferase, is added to a sample to find and flag viral particles. Then, luciferin molecules are introduced to that sample, prompting a luciferase reaction that creates a burst of light. But this reaction produces a light signal that is both weak and short-lived.

Shafiee and team developed a unique enzyme signal cascade to strengthen and prolong bioluminescence signals. They introduce another enzyme to the equation, called beta-galactosidase, that sticks to luciferin and releases it continuously, rather than allowing luciferin to float freely in the sample for one-and-done reactions. This extra step means more luciferin, more luciferase reactions, and more bioluminescence. In fact, this step enabled LUCAS to be 515 times more bioluminescent than non-LUCAS systems, and LUCAS signals maintained 96% strength after an hour.

To evaluate LUCAS' efficacy, the team used 177 viral-spiked patient samples and 130 viral-spiked serum samples infected with either SARS-CoV-2, HIV, HBV, or HCV. SARS-CoV-2 patient samples were collected via nasopharyngeal swab, while HIV, HBV, and HCV samples were collected via blood draw. LUCAS provided diagnostic answers within 23 minutes and with an average accuracy across all pathogens of over 94%.

The researchers designed LUCAS to be both portable and easy to use so that it can be an option for high- and low-resource point-of-care environments. As a next step, the team will be testing LUCAS' efficacy in other biological fluids and whether the method can identify more than one pathogen at once. Shafiee also notes that biomarker identification for many diseases, including Alzheimer's, is a rapidly evolving space-so having a tool like LUCAS ready to go as new biomarkers emerge could prove impactful in years to come.

"We always want to detect infection and disease as early as possible, as that can make all the difference when it comes to care and long-term outcomes," said first author Sungwan Kim, PhD, a postdoctoral researcher in Shafiee's lab at the Brigham. "With our focus on developing diagnostic tools that are sensitive, accurate, and accessible, we want to make early detection easier than it has ever been and push personalized care into a new era."