By Will Soutter
Scientists at the Institute for Bioengineering of Catalonia and the University of Barcelona have partnered with the Centro National de Biotecnologia in Madrid and developed a novel technique for identifying nanoscale objects and viruses using an electrostatic force microscope (EFM).
The technique helps overcome the difficulties faced in measuring various properties, such as thermal, electrical, chemical and mechanical properties, that provide the uniqueness to an object. EFM is a form of atomic force microscope that helps identify nano-objects without the use of labels.
In order to detect the physical distribution and presence of objects, scientists have been using chemical labeling. This labeling which utilizes fluorescent dyes or other visible substances can lead to misinformation. This has led to the necessity of identifying nano-objects without labeling.
Atomic force microscopy involves dragging of a nano-sized tip located on a micro-lever across a nanoscale object. It senses the shape, and the lever’s movement is monitored for reconstructing the image. Certain constraints exist in this method as it may not help differentiate between objects with similar shapes.
Materials react to applied electric fields in a unique manner due to their permittivity or ‘dielectric constant.’ The researchers applied an electric field through the nano-tip, which sensed the dielectric responses. These responses were sensed through the micro-lever.
The dielectric constants were quantified accurately and used as a ‘fingerprint’ for differentiating objects with similar shapes.
The novel non-invasive method holds potential in medical applications for label-free detection of viruses. The researchers were able to differentiate between DNA-containing viruses and empty viruses. The technique can be used to ascertain the performance of nano-electronic devices.