Conjugated polymer nanoparticles for rapid visualization of microbial cells

Fluorescent detection is indispensable for microbial detection due to its unparalleled sensitivity and the ability to identify minute quantities of microorganisms. Luorescent dyes emit light upon interaction with specific biomolecules, enabling rapid visualization of microorganisms in complex samples. However, photobleaching, sensitivity to environmental conditions, and non-specific binding associated with conventional fluorescent dyes can limit their performance. Addressing these limitations is important for developing robust and reliable fluorescence-based microbial visualization systems. Conjugated polymer nanoparticles (CPNs) have emerged as promising fluorescent materials because of their enhanced photostability, brightness, and tunable optical properties, which may overcome some limitations of conventional fluorescent dyes. This study explores the application of MEH-PPV CPNs as fluorescent probes for the visualization of microorganisms. The experimental work involved the preparation and characterization of CPNs, optimization of the fluorescent probe concentration, and evaluation of their fluorescence-associated labeling of representative Gram-positive bacteria, Gram-negative bacteria, and yeast. In addition, the applicability of the CPNs for microbial visualization was evaluated using selected clinical samples, where fluorescence associated with microbial cells was observed with relatively low background interference. The findings demonstrate that MEH-PPV CPNs can facilitate rapid fluorescence-based visualization of diverse microbial cells and highlight their potential as an alternative fluorescent material for microbial imaging and staining applications.