Weighing and Imaging Molecules One at a Time

UNAM researcher Asst. Prof. Selim Hanay has published a new paper on advancing the capabilities of nanomechanical sensors in Nature Nanotechnology, widely considered the top journal in the field.

Building on their creation of the first-ever mechanical device that can measure the mass of individual molecules, one at a time, a team of scientists have created nanodevices that can also reveal their shape. Such information is crucial when trying to identify large protein molecules or complex assemblies of protein molecules.

The work has been developed in collaboration between Bilkent University, Caltech and the University of Melbourne. The lead author of the work is Asst. Prof. Selim Hanay of the Department of Mechanical Engineering and UNAM.

Nanomechanical sensors (NEMS) are engineered, extremely small mechanical structures. Due to their miniscule sizes, NEMS can operate as exquisite sensors of physical changes. Previous experiments at Caltech demonstrated the capability of these sensors to measure the mass of single molecules. This paradigm (NEMS-based mass sensing) offered new capabilities for rapid and low-cost characterization of large biomolecules, accomplished at the chip scale.

Now, with the research published in the new paper, the capabilities of NEMS sensors have been expanded further. It has been shown that molecules’ size and shape, as well as their mass, can be detected by NEMS sensors. The multidimensional information (mass and shape) obtained from the analyte will open up new venues for biomolecular characterization. For instance, the determination of the type of a virus will be accomplished by considering both the weight of the virus and its characteristic shape.

In order to resolve the shape of a molecule, researchers used the higher-order mechanical vibration modes of the sensor and combine the information obtained from all vibration modes. The technique has been verified in experiments using micron-sized cantilevers, as well as in finite-element simulations. Previously, the capability to measure the shape of analytes with inertial mechanical sensors was unknown in the field; this work introduces a paradigm shift in terms of the sensing modalities of mechanical sensors.

The paper is accessible online at the website of Nature Nanotechnology: http://rdcu.be/cEUy. In addition to Selim Hanay, other authors of the paper are Dr. Scott Kelber (co-primary author), Dr. Cathal O’Connell (co-primary author), Prof. Paul Mulvaney, Prof. John Sader (corresponding author) and Prof. Michael Roukes (corresponding author). More information about nanomechanical sensors can be obtained from the Hanay Research Group, http://nems.bilkent.edu.tr .

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