New study led by Yanzi Zhou (Vendrell lab) develops fluorescent dyes that bacteria take up, producing species-specific light signatures. Instead of brightness, they measured how long these dyes glowed, improving reliability. Combined with antimicrobial peptides, this new method accurately assigns bacterial species in complex samples, offering a faster approach for diagnostics and targeted antibiotic use. Current ways to identify bacteriaAntimicrobial resistance (AMR) is an increasing global health challenge. To treat infections effectively and reduce unnecessary use of antibiotics, it is important to quickly and accurately identify the bacteria responsible. However, many existing diagnostic techniques rely on detecting specific molecular features, which means they need prior knowledge of the bacteria. This can make them slower and less effective, especially when dealing with new or changing strains.One new way to identify bacteria is using a system called a cross-reactive sensor array. Instead of searching for a single defining feature, this method uses a group of fluorescent sensors that work together. Each sensor responds slightly differently to different bacterium, and the combined responses create a unique pattern or ‘fingerprint’ that can be used to identify the species. To date, most existing arrays relied on signal intensity, which can vary depending on experimental conditions and sample composition.Creating fluorescent triangulenium dyes to measure glow timeIn this study, PhD student Yanzi Zhou, in collaboration with Matthieu Vermeren (IRR Imaging facility) and IRR Group Leaders David Dockrell and Beth Mills, aimed to improve this array system. They first created a collection of 20 new fluorescent ‘triangulenium’ dyes. These dyes are designed to work well in biological environments and can be linked to other molecules that help them interact with bacteria. A key advantage of these dyes is that they emit light for longer than natural background signals from cells. This makes it easier to separate their signals from the background noise.The researchers used a small number of these special dyes to create a sensor array and tested how they behaved inside bacterial cells. Rather than measuring how bright the dyes were, they measured how long the dyes continued to glow after being excited by light, a property called fluorescence lifetime.Combining dyes with antimicrobial molecules for more information and successful identificationThe first version of the system was able to correctly identify five out of seven bacterial species. The researchers enhanced the system by attaching some of the fluorescent triangulenium dyes to antimicrobial peptides. These molecules naturally target different parts of bacterial cells, such as the outer membrane, helping the dyes gather more detailed information about the bacterial cells.With these improvements, the team developed a refined system using just four probes - two dyes and two dye–peptide combinations. This version correctly assigned all seven bacterial species tested. It also worked in more complex samples, including blood and urine, and was able to correctly identify unknown samples and different strains. Greater detail of bacterial species (S. aureus and P.aeruginosa) with triangulenium dye + antimicrobial peptide (below, inside and around the bacteria) than with triangulenium dye alone (above, only inside the bacteria) Unique light-based signature given from different bacterial speciesEach type of bacterium produced its own distinct light-based signature. The researchers found that measuring fluorescence lifetime was more consistent and reliable than traditional methods based on brightness, because it was less affected by factors like concentration or sample conditions. Different fluorescently labelled triangulenium dyes (columns) with distinct light-based signature depending on the bacteria (e.g. E.Coli and A. baumannii). This approach offers a fast, flexible, and target-independent way to identify bacteria. Because it does not rely on predefined biomarkers, it can potentially detect and distinguish bacteria even when their molecular features are not fully known. Charles Lochenie IRR Translational Chemistry Manager and co-corresponding author of the study Lifetimes cross-reactive arrays are robust tools for imaging because the fingerprints they generate are very reproducible. By slightly adapting the dyes and the peptides, this technology could be used in the future to distinguish very similar cells like cancer cells at different stages of disease, which could not be detected otherwise. Marc Vendrell IRR Group Leader and Head of IRR Chemistry Hub Future work will focus on looking at testing the method in clinical settings; streamlining the workflow for faster and more automated analysis and applying the same concept to other biological systems beyond bacteria.This work was funded by EPSRC, ERC, UKRI and Marie Skłodowska-Curie Actions.Read the full paper in Nature CommunicationsCharles LochenieVendrell research groupIRR Chemistry HubDynafluors Tags CIR Publication date 13 May, 2026
