Scientists at Moscow University and colleagues have developed a new class of hybrid optical sensors capable of real-time detection of bacteria in solutions and rapid analysis of their resistance to antibiotics. The study was supported by the Russian Science Foundation (project No. 22-72-10062) and published in the leading international journals ACS Applicationmaterials&Interfaces and ResultsinSurfacesandInterfaces.
The sensors created are based on porous silicon nanowires modified with bimetallic gold and silver nanoparticles. This architecture combines two complementary optical approaches: interference (based on the Fabry–Perot effect) and spectroscopic, based on the effect of giant raman scattering (GCR, eng. SERS). The first one provides registration of bacteria by changing the effective optical thickness of the sensor layer, and the second one provides highly sensitive detection of spectral profiles reflecting the molecular composition of the microbial cell wall without the use of labels.
The non-pathogenic Listeriainnocua bacterium, widely used in microbiological research, was chosen as a model organism. Due to the morphological similarity and similar structure of the cell wall, L. innocua can be considered as a model for testing sensors designed to diagnose Gram-positive pathogens, including Mycobacterium Tuberculosis. The sensors demonstrated sensitivity to bacterial concentrations from 3.2 million CFU/ml in the SERS mode and from 6.4 million CFU/ml in the interferometric mode.
Antibiotic resistance remains one of the most acute threats to global health: according to WHO, the number of resistant bacterial strains is steadily increasing, reducing the effectiveness of standard therapy. In these conditions, technologies that make it possible to quickly and reliably determine the sensitivity of microorganisms to antibiotics are of particular importance.
One of the key results of this study was the confirmation of the possibility of using the developed sensor substrates for rapid analysis of bacterial antibiotic resistance. During incubation of Listeriainnocua with various antibiotics, reproducible changes in the GCR spectra were recorded directly on the surface of the sensors, reflecting the molecular response of cells to antimicrobial effects. The dynamics of changes in the intensity of diagnostic peaks, in particular in the region of 736 and 1320 cm⁻1, made it possible to differentiate the sensitivity of bacteria to various drugs in real time. The proposed approach does not require long-term cultivation and provides an informative spectroscopic response within the first hours of observation, significantly exceeding the speed of traditional phenotypic methods used in clinical microbiology.
"We have created a platform that combines high molecular sensitivity, reproducibility of the signal and the speed of obtaining the result. Such systems have the potential to become the basis of compact diagnostic devices for rapid identification of bacterial infections and selection of effective antimicrobial therapy directly at the place of medical care," emphasizes Lyubov Osminkina, initiator of the development, Head of the laboratory of the Department of Medical Physics at the Faculty of Physics of Moscow State University.
The study was carried out by a team of the Faculty of Physics and the Faculty of Materials Sciences of Lomonosov Moscow State University and the N.F. Gamaleya Research Center for Epidemiology and Microbiology.
Due to the scalability of the technology and the use of biocompatible materials, the development can be adapted for a wide range of tasks in medicine, sanitary microbiology, food industry and environmental monitoring.
Please note that this press release is based on materials provided by the company. AK&M Information Agency shall not be held liable for its contents, nor for the legal and other consequences of its publication.
