New technology eliminates finger-sticks for blood samples

Millions of people living with diabetes endure the daily burden of managing their condition, relying on devices that require frequent blood samples. Current glucose monitoring systems, although essential, often involve invasive methods like finger-pricking, which can be painful and inconvenient. Yet, advancements in bioengineering are set to transform this routine by offering an innovative alternative: a wearable sweat sensor.

Diabetes is a chronic condition that leads to elevated blood sugar levels, potentially causing serious complications such as heart disease, kidney failure, and nerve damage. While Type 1 diabetes, an autoimmune disease, necessitates strict glucose monitoring and insulin therapy, over 90% of diabetes cases are Type 2, a condition often managed through lifestyle changes and medication.

Effective monitoring is critical for both types to prevent complications, with projections suggesting that diabetes prevalence will soar to 1.3 billion by 2050, underscoring the urgent need for accessible and reliable monitoring solutions.

Continuous glucose monitoring (CGM) systems have emerged as a game-changer. Unlike traditional devices requiring multiple daily finger pricks, CGMs provide real-time feedback on glucose levels, helping individuals understand the impact of diet, exercise, and medication. These systems use interstitial fluid rather than blood, making them less invasive.

They also allow for a comprehensive view of glucose trends over time, empowering users to make informed decisions about their health. As promising as CGMs are, their reliance on enzymatic electrochemical mechanisms limits their longevity and stability.

Most CGMs today use enzymes to detect glucose, but these enzymes degrade over time, necessitating frequent sensor replacement and proper storage conditions. Attempts to extend enzyme stability through advanced protein engineering and chemical modifications have made progress but have not fully addressed the issue.

Non-enzymatic glucose sensors, which use electrocatalytic materials instead of enzymes, have shown promise for improved stability. However, their limited selectivity has hindered widespread adoption.

Researchers at Binghamton University, State University of New York, are exploring a revolutionary solution—a microbial whole-cell sensing system. Published in the journal, Microsystems & Nanoengineering, this innovative approach utilizes Bacillus subtilis bacterial spores to detect glucose in sweat.

The spores, engineered to germinate in response to glucose in potassium-rich environments, generate electricity as a byproduct of their metabolic activity. This electricity serves as a transducing signal for glucose detection, offering a stable, cost-effective, and sustainable alternative to conventional CGMs.

The system operates within a microengineered, paper-based microbial fuel cell (MFC). When glucose is present in sweat, it triggers the spores to germinate and become metabolically active. These cells then release electrons, which are captured by electrodes and converted into readable signals.

The process is self-powered and does not require external energy sources, making it highly suitable for wearable applications. Additionally, the dormant spores have a long shelf life and can withstand harsh environmental conditions, overcoming one of the significant limitations of current glucose monitoring systems.

Professor Seokheun “Sean” Choi, who leads the Bioelectronics and Microsystems Lab at Binghamton, emphasized the advantages of this approach: “The problem with using enzymes is that they denature and deactivate. Our spore-based system can endure very harsh environments and activates only when the right conditions are met.”

The MFC demonstrated remarkable sensitivity, accurately detecting glucose concentrations as low as 0.07 mM. Its selectivity was also impressive, maintaining accuracy even in the presence of interfering substances.

Unlike enzymatic biosensors, which degrade over time, the spore-based system retains its functionality and can be reactivated when needed. This durability makes it an attractive option for diabetes management and other biosensing applications.

Yang “Lexi” Gao, a Ph.D. student in Choi’s lab, played a pivotal role in this research. With a background in marine chemistry, Gao adapted her expertise to develop paper-based biosensors for glucose monitoring. She highlighted the sustainability and affordability of the system: “It’s clean and sustainable, and because it’s paper-based and disposable, it’s very easy and very cheap.”

Gao’s prior experience with “papertronics” included projects on biobatteries and moisture-harvesting devices, which laid the groundwork for this innovation.

The collaborative effort also involved Assistant Professor Anwar Elhadad, who guided Gao in understanding circuit design. Together, they developed the device’s indicator circuit, which converts the electrical signals into a visual format. When glucose levels exceed a predefined threshold, an LED lights up, providing users with real-time alerts.

While the prototype shows great potential, further research is needed to optimize the system’s performance. Choi noted, “Everyone has a different potassium concentration in their sweat, and I don’t know how this concentration affects the glucose. The sensitivity also is lower than conventional enzymatic biosensors. But from this work, we created a new sensing mechanism to detect glucose. No one has done that yet.”

The implications of this research extend beyond diabetes management. The spore-forming microbial whole-cell sensing platform could be adapted for various biosensing applications, including environmental monitoring and point-of-care diagnostics. Its stability, low cost, and sustainability make it a promising candidate for addressing global health challenges.

The potential to eliminate the pain and inconvenience of current glucose monitoring methods is a significant step forward in improving the quality of life for those with diabetes.

The innovative use of Bacillus subtilis spores not only paves the way for wearable, non-invasive sensors but also redefines the possibilities for biosensing technology as a whole. By leveraging the natural properties of these microbes, researchers have demonstrated how biology and engineering can converge to address persistent challenges in healthcare.

The research team’s accomplishments also underscore the importance of interdisciplinary collaboration. Gao’s expertise in chemistry, combined with Choi’s experience in bioelectronics and Elhadad’s knowledge of circuit design, exemplifies how diverse skill sets can lead to groundbreaking innovations.

The team’s work is supported by grants from the National Science Foundation, reflecting the broader commitment to advancing scientific discovery for societal benefit.

The road ahead involves addressing the variability in potassium concentrations among individuals and refining the sensor’s sensitivity. These challenges are not insurmountable, and the foundational work already achieved sets a strong precedent for future developments. As the research progresses, the potential applications of this technology will likely expand, influencing fields beyond healthcare.

The spore-based microbial fuel cell system represents more than just a technical innovation; it is a testament to the ingenuity and determination of researchers working to solve real-world problems.

By providing a stable, cost-effective, and user-friendly solution for glucose monitoring, this technology has the potential to transform diabetes management and improve outcomes for millions of people worldwide.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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