Direct digital sensing of protein biomarkers in solution

Area of Science:

• Biomolecular analysis
• Proteomics
• Analytical chemistry

Background:

• Protein detection is crucial for diagnostics and research.
• Conventional immunosensing assays often rely on surface capture, limiting their capabilities.
• There is a need for advanced methods to quantify and characterize proteins in solution.

Purpose of the Study:

• To develop a surface-free, single-molecule microfluidic sensing platform for direct digital protein biomarker detection.
• To enable absolute quantification and characterization of proteins in solution.
• To overcome the limitations of conventional immunosensing approaches.

Main Methods:

• Development of a digital immunosensor assay (DigitISA).
• Integration of microchip electrophoretic separation with single-molecule detection.
• Application to diverse targets like amyloid aggregates, exosomes, and biomolecular condensates.

Main Results:

• DigitISA enables absolute number/concentration quantification of proteins in a single, solution-phase step.
• The assay provides information beyond simple concentration, including immunochemistry and binding affinity.
• Successful detection and characterization of various protein biomarkers were demonstrated.

Conclusions:

• DigitISA represents a new paradigm for protein biomarker sensing.
• This surface-free approach enhances specificity, sensitivity, and analytical depth.
• The platform is suitable for analyzing challenging targets not amenable to conventional methods.