German researchers have developed a new method for detecting bacteria: They’ve used tiny optical sensors to visualize pathogens directly at the site of infection—a development that could eliminate the need to take tissue samples to be analyzed.1 The researchers’ method identifies pathogens faster and more easily than with established methods.

The sensors are based on modified carbon nanotubes with a diameter of less than one nanometer. When they are irradiated with visible light, they emit light in the near-infrared range (wavelength of 1,000 nanometres and more), which is not visible to humans. The fluorescence behavior changes when the nanotubes collide with certain molecules in their environment. Since bacteria secrete a characteristic mix of molecules, the light emitted by the sensors can thus indicate the presence of certain pathogens. In their current paper, the research team describes sensors that detect and differentiate harmful pathogens that are associated with, for example, implant infections.

“The fact that the sensors work in the near-infrared range is particularly relevant for optical imaging, because in this range there are far fewer background signals that can corrupt the results,” says Sebastian Kruß, PhD, formerly at Universität Göttingen, now at Ruhr-Universität Bochum. Since light of this wavelength penetrates deeper into human tissue than visible light, this could enable bacteria sensors read out even under wound dressings or on implants.

“In the future, this could constitute the foundation for optical detection of infections on intelligent implants, as sampling would no longer be required. It would thus allow the healing process or a possible infection to be detected quickly, resulting in improved patient care,” says Robert Nißler from the University of Göttingen, lead author of the study. “The possible areas of application are not limited to this. For example, improved rapid diagnosis of blood cultures in the context of sepsis is also conceivable in the future.”


1. Nißler R, Bader O, Dohmen M, et al. Remote near infrared identification of pathogens with multiplexed nanosensors. Nat Comm. Epub. November 25, 2020. doi: 10.1038/s41467-020-19718-5.

Featured image: Detecting pathogens without taking samples could be possible in the future with carbon nanotubes developed by a team led by Professor Sebastian Kruß (right) and Robert Nißler. Photo by Alexander Spreinat, courtesy Universität Göttingen.