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Knowledge of electromagnetic properties of biomolecules is essential for a fundamental understanding of electric field interaction with biosystems and for development of novel biomedical diagnostic and therapeutic methods. To enable systematic analysis of the dielectric properties of biomolecule solutions we presented here a method for a rational design of radiofrequency and microwave chip for quantitative dielectric sensing. At first, we estimated the primary frequency band of interest using a relaxation time of targeted molecule via the Stokes–Einstein–Debye equation. Then we proposed a microwave sensing chip for the estimated frequency band and evaluated its performance using both analytical modeling and numerical electromagnetic simulations. We fabricated the chip and experimentally demonstrated that we can extract the complex permittivity (0.5–40 GHz) of the water solution of alanine – one of the most common proteinogenic amino acids – without any calibration liquid and with about 20-fold smaller volume than with commercial methods. The observed dependence of extracted complex permittivity on the alanine concentration was interpreted using molecular dynamics simulations. The procedure we described here can be applied for the development of dielectric sensing method of any polar biomolecule solution.

Self-assembly is at the heart of many promising nanoscience technologies as well as at the core of life processes. Tubulin proteins self-assemble into microtubules, tube-like structures that are essential in cellular functions such as cell division and intracellular transport and also a major target in cancer therapies. Therefore, it is crucial to develop efficient methods for monitoring tubulin self-assembly at the molecular level. To mitigate the limitations of current methods, we propose a new approach based on a microwave lab-on-a-chip method to monitor tubulin self-assembly states. To that end, we designed a dedicated microwave platform with integrated microfluidics with a sensing volume of 30 nL. In parallel, we used a standard bulk light-scattering-based method to assess the tubulin self-assembly and to validate the microwave chip results. Using our chip, for the first time, we demonstrate that the self-assembly state of tubulin into microtubules can be monitored using microwave microfluidics technology. Our results introduce a novel label-free electromagnetic monitoring and analytical method for bionanotechnology and biomedicine applications that can potentially be integrated into advanced microscopy systems.