06 Feb Revolutionizing biomarker detection: The power of microfluidic sensing
In the field of biomolecular analysis and diagnostics, the detection of proteins plays a critical role. Typically, conventional immunosensing assays rely on surface-capture of target molecules, which can limit specificity, sensitivity, and the ability to provide information beyond simple concentration measurements. In this week’s research highlight, we delve into a recent paper published in Nature Communications that introduces a new way of directly detecting proteins in solution using a surface-free, single-molecule microfluidic sensing platform known as the digital immunosensor assay (DigitISA). The DigitISA platform combines microchip electrophoretic separation with single-molecule detection to achieve absolute quantification of proteins in a single step, providing a new experimental paradigm for protein biomarker sensing.
“we demonstrate that the assay provides information beyond stoichiometric interactions, and enables characterization of immunochemistry, binding affinity, and protein biomarker abundance. Taken together, our results suggest a experimental paradigm for the sensing of protein biomarkers, which enables analyses of targets that are challenging to address using conventional immunosensing approaches.“, the authors explained.
DigitISA is a game-changing microfluidic device that brings a new approach to protein biomarker detection. Unlike traditional immunosensing assays, which rely on surface-capture of target molecules, the DigitISA platform is based on microchip electrophoretic separation and single-molecule detection, making it a surface-free solution for direct protein biomarker detection. This microfluidic chip provides absolute number and concentration quantification of proteins in a single step, delivering highly sensitive results in the picomolar range. The ability to perform immunochemistry analysis, determination of binding affinities, and characterization of protein biomarker abundance is what sets DigitISA apart from traditional surface-based assays. With potential for multicolor single-molecule spectroscopy and FRET techniques, as well as other microfluidic separation modalities, the DigitISA platform is poised for further development and optimization. While it currently requires expertise in advanced microfluidics and single-molecule optics, DigitISA holds promise as a commercial benchtop instrument.
The DigitISA approach releases fundamental constraints of conventional immunosensing, enabling quantitative protein biomarker sensing even at low concentrations and with low-affinity capture probes. In this work, aptamers were used as affinity probes for their higher electrophoretic mobility, recognition capabilities, and ease of production. The platform also provides direct quantitation of target concentration, characterization of immunochemistry/valency and stoichiometry, and the possibility for future development of antibody-based probes. Despite its limitations, such as the requirement for a probe and the lack of high throughput, DigitISA is a new experimental paradigm for protein biomarker sensing with broad applicability in biomolecular analysis and diagnostics. It opens the door for sensitive multimodal analysis in situations where traditional assays do not work well, paving the way for DigitISA to become an orthogonal tool in the field.
“Taken together, the microchip DigitISA platform presented herein constitutes a new experimental paradigm for protein biomarker sensing. We have demonstrated that the method is at least on par in terms of sensitivity with more traditional assay (i.e., in the picomolar range), yet with a number of qualitative advances.“, the authors explained.
Figures and the abstract are reproduced from Krainer, G., Saar, K.L., Arter, W.E. et al. Direct digital sensing of protein biomarkers in solution. Nat Commun 14, 653 (2023). https://doi.org/10.1038/s41467-023-35792-x
Read the original article: Direct digital sensing of protein biomarkers in solution