SpyDirect: A Novel Biofunctionalization Method for High Stability and Longevity of Electronic Biosensors

Area of Science:

• Bioelectronics
• Biosensor Technology
• Protein Engineering

Background:

• Electronic immunosensors are vital for rapid diagnostics, but protein immobilization on electrodes is challenging.
• Conventional methods using self-assembled monolayers (SAMs) for antibody coupling can limit protein sensor longevity, especially in organic electrochemical transistors.
• Protein adsorption and unfolding on electrode surfaces hinder sensor performance and stability.

Purpose of the Study:

• To develop a novel biofunctionalization method for electronic biosensors that enhances protein sensor longevity and stability.
• To overcome the limitations of SAM-based approaches in immobilizing bioreceptors for biosensing applications.
• To create a cost-effective, sustainable, and scalable method for producing high-performance electronic immunosensors.

Main Methods:

• Introduction of the SpyDirect method for direct, stable, and oriented coupling of nanobody receptors to gold electrodes.
• Utilizing cysteine-terminated spyTag peptides and autocatalytic attachment of nanobody-spyCatcher fusion proteins.
• Structure-guided design to optimize nanobody conformation and packing within the biorecognition layer.

Main Results:

• SpyDirect generates an ultrahigh-density array of oriented nanobody receptors without SAMs, improving sensor shelf-life.
• The method reduces background noise in complex media and enhances sensor stability.
• SpyDirect functionalization is faster, easier, solvent-free, and more eco-friendly than traditional SAM-based methods.

Conclusions:

• SpyDirect is a broadly applicable biofunctionalization strategy for electronic biosensors.
• This method enhances cost-effectiveness, sustainability, and longevity without compromising sensor sensitivity.
• SpyDirect offers a significant advancement in the development of robust and scalable biosensing platforms.