Detection of Bacteria and Viruses with Fluorescent Nanotubes
Published:15 Aug.2023 Source:Ruhr-University Bochum
An interdisciplinary research team from Bochum, Duisburg and Zurich has developed a new approach to construct modular optical sensors which are capable of detecting viruses and bacteria. For this purpose, the researchers used fluorescent carbon nanotubes with a novel type of DNA anchors that act as molecular handles. The anchor structures can be used to conjugate biological recognition units such as antibodies aptamers to the nanotubes. The recognition unit can subsequently interact with bacterial or viral molecules to the nanotubes. These interactions effect the fluorescence of the nanotubes and increase or decrease their brightness.
The team used tubular nanosensors that were made of carbon and had a diameter of less than one nanometre. When irradiated with visible light, carbon nanotubes emit light in the near-infrared range. Near-infrared light is not visible to the human eye. However, it is perfect for optical applications, because the level of other signals in this range is highly reduced. In earlier studies, Sebastian Kruss' team had already shown how the fluorescence of nanotubes can be manipulated in order to detect vital biomolecules. Now, the researchers searched for a way to customise the carbon sensors for use with different target molecules in a straightforward manner.
The key to success were DNA structures with so-called guanine quantum defects. This involved linking DNA bases to the nanotube to create a defect in the crystal structure of the nanotube. As a result, the fluorescence of the nanotubes changed at the quantum level. Additionally, the defect acted as a molecular handle that allowed to introduce a detection unit, which can be adapted to the respective target molecule for the purpose of identifying a specific viral or bacterial protein. "Through the attachment of the detection unit to the DNA anchors, the assembly of such a sensor resembles a system of building blocks -- except that the individual parts are 100,000 times smaller than a human hair," outlines Sebastian Kruss.