Quorum q150t es system

One-centimetre catheter sections directly beneath eyeholes were cut longitudinally to expose the intraluminal crystalline biofilm, before being fixed in 2.5% w/v glutaraldehyde in 0.1 M cacodylate buffer at pH 7.2 overnight. The following day, samples were placed into fresh 0.1 M cacodylate buffer at pH 7.2, prior to dehydration in a series of ethanol solutions (25, 50, 75, 95, 95 and 100% w/v, 1-h incubations in each). Sections were then air-dried and mounted on aluminium stubs using carbon cement (Agar Scientific, Stansted, UK). Samples were viewed using a Zeiss-evo LS15 microscope (Carl Zeiss Ltd, UK), either uncoated in variable pressure (VP) mode, or were subsequently coated with platinum and viewed under high vacuum (HV). Parameters for VP imaging were 100-μm VP aperture, a chamber pressure of 50 pa with 0% humidity, an accelerating voltage of 20 kV EHT and using a VP secondary electron detector. For HV observations, samples were sputter-coated with platinum using a Quorum Q150T ES system (Quorum Technologies, UK), before being viewing at a chamber pressure of c. 3.5 × 10⁻³ pa (0% humidity) using an accelerating voltage of 5 kV EHT and a secondary electron detector.

Biofilms formed on catheters recovered from timed models were visualized directly by scanning electron microscopy (SEM) as previously described by Holling et al.^{20 (link)}. Catheter sections (1 cm) were mounted directly onto aluminum stubs using Leit adhesive carbon tabs (Agar Scientific, Stansted, United Kingdom), and stored overnight in a desiccator at room temperature. The following day, catheter sections were sputter coated with platinum using a Quorum Q150T ES system (Quorum Technologies, United Kingdom), and viewed using a Zeiss Evo LS15 microscope under high vacuum at an accelerating voltage of 5 kV and using a 5 quadrant backscatter detector (5Q-BSD).