Femtosecond laser-induced fluorescence spectroscopy for the rapid detection of pathogenic bacteria

The existence of pathogenic microorganisms is a significant contributor to high morbidity rates in both developed and developing countries. Numerous human diseases have been related to Escherichia coli and Enterococcus faecalis. Fast diagnosis of these bacteria is crucial for limiting the progress of the associated diseases. The current study investigated the potential application of femtosecond laser-induced fluorescence spectroscopy (LIF) in monitoring bacteria. The INSPIRE HF100 laser system, which was pumped by a mode-locked femtosecond Ti: sapphire MAI TAI HP laser, delivered 100 femtosecond laser pulses to the samples. E. coli and E. faecalis were exposed to femtosecond laser pulses, and a spectrometer was used to monitor the fluorescence emission spectra. The measured LIF spectra of the two bacteria showed that E. coli and E. faecalis had fluorescence peaks at 502 and 512.5 nm, respectively. When the excitation wavelength varied from 350 to 400 nm, E. coli and E. faecalis fluorescence peak intensities linearly decreased. Furthermore, the LIF peaks revealed that the full width at half maximum of E. coli is 91.9 nm and that of E. faecalis is 101.3 nm. The current study findings suggest that femtosecond laser-induced fluorescence spectroscopy is a reliable, accurate, and sensitive approach for rapidly and directly identifying pathogenic bacteria.