A New Approach to Building Sensors to Detect Bacteria and Viruses
An interdisciplinary research group from Bochum, Duisburg, and Zurich has devised a new method for building modular optical sensors that have the potential to detect bacteria and viruses.
3D printed model of carbon nanotubes, a key building block for the new biosensor. Unlike these 3D printed models, the nanotubes are actually 100,000 times thinner than a human hair. Image Credit: © Ruhr Universitat Bochum, Marquard
The scientists harnessed fluorescent carbon nanotubes with a new type of DNA anchor that serves as a molecular grip. The anchor structure can be used to conjugate biological recognition units such as antibody aptamer to nanotubes.
The recognition unit interacts with viral or bacterial molecules in the nanotube. The interaction causes an impact on the fluorescence of the nanotubes and increases or decreases their brightness.
A research group included Professors Sebastian Kruss, Justus Metternich, and four colleagues from Bochum Ruhr University (Germany), Fraunhofer Institute for Microelectronic Circuits and Systems, and ETH Zurich report their results in Journal of the American Chemical Societypublished on June 27th2023.
Direct Customization of Carbon Nanotube Biosensors
The researchers used a tubular nanosensor made of carbon and less than 1 nm in diameter. When exposed to visible light, the carbon nanotubes release light in the near-infrared range. It is impossible to see near-infrared light to the human eye, but it is ideal for optical applications because the signal levels of other things in this range have been significantly reduced.
Sebastian Kruss’ team has demonstrated how nanotube fluorescence can be manipulated to detect vital biomolecules in their previous research. Currently, scientists are exploring ways to adapt carbon sensors for use with various target molecules directly.
The key to success was a DNA structure with a suspected guanine quantum defect. This involves linking DNA bases to nanotubes to create defects in the crystal structure of that nanotube.
As a result, the fluorescence of the nanotubes changes at the quantum level. In addition, defects serve as molecular handles that allow the initiation of detection units, which can be adapted to individual target molecules for specific bacterial or viral protein determination causes.
By attaching detection units to DNA anchors, the assembly of such sensors resembles a system of building blocks – except that the individual pieces are 100,000 times smaller than a human hair..
Sebastian Kruss, Professor, Ruhr Bochum University
Sensors Identify Different Targets of Bacteria and Viruses
The research group showcased a new sensor concept that utilizes the SARS CoV-2 spike protein as an example. Therefore, scientists used aptamers that bind to the spike protein of SARS CoV-2.
Aptamers are folded strands of DNA or RNA. Due to their structure, they can bind to proteins selectively. In a later step, one can transfer the concept to an antibody or other unit of detection.
Justus Metternich, Professor, Ruhr Bochum University
With a high level of reliability, the availability of fluorescent sensors indicates the presence of the SARS-CoV-2 protein. The selectivity of sensors with guanine quantum defects is greater than the selectivity of sensors without the defect. Also, sensors with a guanine quantum defect are very stable in solution.
This is an advantage if you are thinking about measurements beyond simple aqueous solutions. For diagnostic applications, we have to measure in complex environments e.g. with cells, in blood, or within the organism itself.
Sebastian Kruss, Professor, Ruhr Bochum University
Sebastian Kruss heads the Functional Interfaces and Biosystems Group at Ruhr University Bochum and is also a member of the Ruhr Explores Solvation Cluster of Excellence (RESOLV) and the International Graduate School of Neuroscience.
This study was supported financially by the German Research Foundation as part of the RESOLV Cluster of Excellence (EXC 2033–390677874), the Volkswagen Foundation, and the Fraunhofer Attract Program (038–610097).
Journal Reference
Metternich, JT, et al. (2023) Near Infrared Neon Biosensor Based on Covalent DNA Anchors. Journal of the American Chemical Society. doi.org/10.1021/jacs.3c03336.
