Fig 1.
Effect of Hydrofluoric (HF) acid etching on glass substrates.
Optical microscopic image of glass substrates etched by HF for (a) 0 s, (b) 45 s, (c) 60 s and (d) 90 s. The sample having 0 s etching duration is the control sample.
Fig 2.
Variation in etched area fraction with etching time.
Etched area fractions (A) corresponding to the ratio of etched area to the total observed area of glass substrates shown in Fig 1 with additional samples (etching durations of 30 s, 75 s, 105 s, and 120 s), is plotted against etching time (t). Area fractions were calculated from at least 5 areas (each of dimension 182 μm × 99 μm) of a given sample. Average values and error bars are shown in the graph. Average value points are connected by a spline curve for visual aid only.
Fig 3.
Variation of surface roughness with etching time.
Roughness was measured by profilometry, scanning at least 5 areas of the samples shown in Fig 1 with additional samples (etching durations of 30 s, 75 s, 105 s, and 120 s), averaging over 40 profiles in each case. Data points are connected by spline curve for visual guide only.
Fig 4.
Effect of substrate surface etching on biofilm growth.
Scanning Electron Microscopic (SEM) image of Pseudomonas aeruginosa biofilm on glass surfaces etched for (a) 0 s (b) 45 s (c) 60 s and (d) 90 s. The sample at 0 s is the control sample.
Fig 5.
Pseudomonas biofilm growth with etching time.
Colony Forming Unit (CFU) of P. aeruginosa (five isolates) from the samples shown in Fig 4 with additional samples (etching durations of 30 s, 75 s, 105 s, and 120 s). The data at 0 s is the control data. Averages taken over 5 isolates of the bacteria for each etching time point are shown. The spline joining the averages is for visual aid only.
Fig 6.
Effect of substrate surface etching on biofilm growth.
SEM image of Staphylococcus aureus biofilm grown on glass surfaces etched for (a) 0 s (b) 45 s (c) 60 s and (d) 90 s. The sample at 0 s is the control sample.
Fig 7.
Staphylococcus biofilm growth with etching time.
Colony Forming Unit (CFU) of S. aureus (five isolates) from the samples shown in Fig 6 with additional samples (etching durations of 30 s, 75 s, 105 s, and 120 s). The data at 0 s is the control data. Averages taken over 5 isolates of the bacteria for each etching time point are shown. The spline joining the averages is for visual aid only.
Fig 8.
Cartoon showing a schematic representation of the growth of biofilms on glass surfaces etched for different times from a cross-sectional view.
The black line represents the glass surface, the red line shows bacterial biofilm. The nominal length scale is indicated.