Nanobody-Based Immunosensors for Point-of-Care Testing

A recent advancement in immunosensor technology has been reported by researchers at the Institute of Science Tokyo, introducing a novel nanobody-based immunosensor designed for efficient and accurate point-of-care testing. Published on December 17, 2024, this development is anticipated to significantly enhance in situ detection capabilities for applications ranging from clinical diagnosis to food safety monitoring and environmental assessment.

Overview of Immunosensors

Immunosensors are pivotal in biochemistry and medical science, providing reliable techniques for the detection of specific biomolecules through antibody-antigen interactions. As the demand for effective and cost-efficient testing escalates, innovations in immunosensor technology have become paramount. This article explores a groundbreaking design that addresses previous limitations encountered in conventional immunosensing.

Challenges in Conventional Immunosensing

Many traditional sensors, particularly those known as Quenchbodies (Q-bodies), offer a homogeneous detection method that eliminates the need for labor-intensive washing steps. However, Q-bodies primarily face limitations in:

• Functionality in Undiluted Fluids: They perform poorly in undiluted biological fluids like blood or milk.
• Stability: Storage and application challenges arise when designing paper-based devices for point-of-care testing.

Innovative Design: BRET Nano Q-Bodies

In a significant advancement, the team led by Associate Professor Tetsuya Kitaguchi engineered a new variant known as the BRET Nano Q-body. This novel design utilizes bioluminescence resonance energy transfer (BRET) to establish a more robust immunosensor capable of functioning in diverse harsh conditions and undiluted biological fluids.

Key Features of BRET Nano Q-Bodies

The innovative immunosensor combines several potent components:

Quantification Mechanism

The BRET Nano Q-body operates through a distinct mechanism: when a target antigen binds with the nanobody, the resultant structural changes reposition the TAMRA dye closer to the NanoLuc enzyme. This proximity recovers the quenching of TAMRA, thus enabling energy transfer and producing a measurable change in emission color—from blue, associated with NanoLuc, to red, attributed to TAMRA. The intensity ratio of these emissions allows for precise quantification of the target antigen.

Practical Applications and Testing

The researchers conducted a series of tests demonstrating the functionality of the BRET nano Q-bodies in practical scenarios:

• The immunosensor exhibited superior thermostability and function in various organic solvents and biological fluids.
• Impressive performance was recorded in detecting a chemotherapeutic drug concentration using paper devices designed for point-of-care testing.
• Long-term storage without temperature control did not adversely affect device performance.

“The proposed immunosensor… offers superior thermostability and endurance… making them useful for detection at bedside, in the field, and at home,” stated Kitaguchi.

Conclusion and Future Prospects

This innovative immunosensor presents a remarkable evolution in analytical biochemistry and technology. By addressing past limitations, the BRET Nano Q-body holds promise in transforming clinical diagnostics, therapeutic monitoring, and environmental assessments, paving the way for enhanced healthcare solutions. As the field prepares for widespread adoption, ongoing research will likely focus on integrating such technologies into everyday medical practices and environmental monitoring.

References

Yinghui Yang et al, BRET Nano Q-Body: A Nanobody-Based Ratiometric Bioluminescent Immunosensor for Point-of-Care Testing, ACS Sensors (2024).

Institute of Science Tokyo. Lifespan.io