Spectrally-selective mid-IR laser-induced inactivation of pathogenic bacteria

Micrometer-thick layers of Pseudomonas aeruginosa bacteria were prepared on fluorite substrates and scanned by focused mid-IR femtosecond laser radiation that was spectrally tuned to achieve the selective excitation of either the stretching C-H vibrations (3 mu m), or stretching C = O, C-N vibrations (6 mu m) of the amide groups in the bacteria. The enhanced biocidal efficiency of the latter selective excitation, compared to the more uniform 3-mu m laser excitation, was demonstrated by performing viability assays of laser-treated bacterial layers. The bacterial inactivation by the 6-mu m ultrashort laser pulses is attributed to dissociative denaturation of lipids and proteins in the cell membranes and intra-cell nucleic acids. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Research has demonstrated the enhanced biocidal efficiency of selective excitation using focused mid-IR femtosecond laser radiation on bacteria compared to uniform excitation. The bacterial inactivation by 6-mu m ultrashort laser pulses is attributed to the dissociative denaturation of lipids and proteins in the cell membranes and intra-cell nucleic acids.