Monitoring of bacteria
The ability to monitor bacterial presence and behaviour is of critical importance in biomedical research, as it underpins the development of effective diagnostic, therapeutic, and antimicrobial strategies. Antimicrobial resistance (AMR) refers to the ability of bacteria to survive antibiotic treatments. This resistance is largely driven by the overuse and misuse of antibiotics, which often makes them ineffective, especially in the presence of bacterial biofilms. As a result, there is a growing need for new diagnostic methods that can quickly detect and identify bacteria, confirm the presence of biofilms, and monitor treatment effectiveness in real time.
Our research group has developed different approaches for monitoring both individual bacterial strains [1] and bacterial biofilms [2]. For single-bacterium analysis, a chip-scale electro-photonic microsystem was designed, featuring an array of photonic crystal (PhC) nanocavities, each capable of trapping a single E. coli cell. This device provided detailed information on the metabolic state of individual bacteria by tracking the spectral response of the nanocavities, with a measured quality factor (Q) of 2.3 × 10³. For biofilm monitoring, our research group proposed an on-chip dual-array of micro and nano-scale interdigitated electrodes that integrates both optical and electrical sensing techniques. This platform enables real-time tracking of biofilm growth and assessment of antibiotic effectiveness. The optical method allows for the detection of small bacterial populations with high spatial resolution, as demonstrated by a resonance shift (Δλ) of approximately 0.9 nm and a reflectance change of about 0.02 in the presence of a bacterial layer. The electrical method complements this by continuously monitoring changes in impedance, providing insights into the different stages of biofilm development and evaluating how effectively antibiotics can disrupt the biofilm.
References
[1] D. Conteduca, G. Brunetti, F. Dell’Olio, M.N. Armenise, T.F Krauss and C. Ciminelli, “Monitoring of individual bacteria using electro-photonic traps,” Biomedical Optics Express, 10(7), 3463-3471, 2019. doi: https://doi.org/10.1364/BOE.10.003463.
[2] G. Brunetti, D. Conteduca, M. N. Armenise, and C. Ciminelli, “Novel micro-nano optoelectronic biosensor for label-free real-time biofilm monitoring,” Biosensors, 11(10), 361, 2021. doi: https://doi.org/10.3390/bios11100361