(Color online) Optical delivery system. M is mirror, BS is beam splitter, L is lens, D is detector, H is half wave plate, P is polarizer, and He–Ne is helium-neon laser; paths of the guiding and the Ti-sapphire beams are shown by the sketch. The inset displays the image of a laser-ablated area on the surface of the biofilm taken by the CCD camera.
(Color online) LDPI-MS instrument schematic with inset showing an expanded view of (a) ionization/extraction region ion optics. (b) is reflectron time-of-flight mass analyzer, (c) is reflectron detector, (d) is vacuum compatible translation stage, (e) is load lock, (f) is 349 nm Nd:YLF desorption laser, (g) is 157 nm fluorine laser for VUV postionization, and (h) is camera for optical imaging of sample.
Ablation craters on the surface of a thin Staphylococcus epidermidis biofilm ( thick) grown on ITO-coated glass slide imaged by CCD camera. Laser spot diameter was set to be . Fluences in the range between (craters toward top left) and (craters toward bottom right) were applied.
(Left) SEM image of an area of ablated on the surface of thick biofilm ( thick). Laser was focused to a spot diameter of and ablation was done by rastering laser beam across the surface with spacing between shots. Magnification was 80×. (Right) Top right corner of the ablated region shown on the left image. Magnification was 3000×. The depth penetration was estimated by counting layers of cells from the top to the bottom, as the diameter of an individual S. epidermidis cell is .
(Left) SEM image of intact surface of biofilm. Magnification was 3000×. (Right) Bottom of laser-ablated region at the same magnification. Comparison between left and right image is indicating that integrity of individual cells on the bottom of ablated region is disrupted since cells are lysed by laser ablation.
LDPI-MS of sulfadiazine detected within intact biofilm and from the bottom of the laser-ablated region. Intensity in spectral region above m/z 50 was multiplied by 5 and for the ablated film, multiplied by 25 above m/z 250.
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