A rapid and practical technique for real-time monitoring of biomolecular interactions using mechanical responses of macromolecules

Abstract

Monitoring biological reactions using the mechanical response of macromolecules is an alternative approach to immunoassays for providing real-time information about the underlying molecular mechanisms. Although force spectroscopy techniques, e.g. AFM and optical tweezers, perform precise molecular measurements at the single molecule level, sophisticated operation prevent their intensive use for systematic biosensing. Exploiting the biomechanical assay concept, we used micro-electro mechanical systems (MEMS) to develop a rapid platform for monitoring bio/chemical interactions of bio macromolecules, e.g. DNA, using their mechanical properties. The MEMS device provided real-time monitoring of reaction dynamics without any surface or molecular modifications. A microfluidic device with a side opening was fabricated for the optimal performance of the MEMS device to operate at the air-liquid interface for performing bioassays in liquid while actuating/sensing in air. The minimal immersion of the MEMS device in the channel provided long-term measurement stability (>10 h). Importantly, the method allowed monitoring effects of multiple solutions on the same macromolecule bundle (demonstrated with DNA bundles) without compromising the reproducibility. We monitored two different types of effects on the mechanical responses of DNA bundles (stiffness and viscous losses) exposed to pH changes (2.1 to 4.8) and different Ag+ concentrations (1 μM to 0.1 M).

Pick‐and‐Place Assembly of Single Microtubules

“…Although not demonstrated in this study, an integrated displacement sensor (based on parallel plate capacitors) allows measuring the stiffness and viscous losses of the captured filaments (Figure a). This property enables the detection of mechanical changes on microtubules allowing the picking process to be used for a wide range of applications.…”

Real-time mechanical characterization of DNA degradation under therapeutic X-rays and its theoretical modeling

“…DNA trapping protocol DNA trapping is based on a combination of dielectrophoresis (DEP) 21 and lateral combing as explained elsewhere 22 . A drop (3 μl) of double-stranded λ-DNA (48.5 kbp, 16 μm in length) solution diluted in deionized water is introduced into the 'DNA cavity' on the side of the main cavity (Figure 3).…”

Optimization of Surface Treatment on MEMS Probes for Single-cell Capture and Release

“…MEMS tweezers have been developed for the biomolecular characterization of cellular and subcellular samples with an object manipulation function. (8,9) The stiffness and viscoelastic properties of a trapped biosample can be extracted by resonance frequency measurement with high sensitivity (0.1 nm resolution in actuation with integrated value and 300 µN/m in stiffness measurements). The device is capable of high-throughput mechanical characterizing as well as transporting single-cells for subsequent detailed assays such as gene expression analyses.…”