Table 1.
Comparison for the outline of JIS Z 2801:2000 / ISO 22196 [5] and the protocols used in the different studies.
Table 2.
General information on test conditions according to ISO 22196:2011/ JIS Z 2801:2012 and deviations from the standard protocol.
Table 3.
Description of alternative test methods used in the study.
Table 4.
Summary of the results for antibacterial testing of the compounds in different laboratories.
Fig 1.
Testing of the effect of compound 1 and 3 on E. coli subject to incubation time (a) and calculation of the resulting R values according to ISO 22196 / JIS Z 2801 (b). Data is given as mean ± standard deviation. Note that the R values were calculated to the growth controls at the respective time points to avoid bias.
Fig 2.
Determination of the antibacterial effect of compound 1 and 3 on E. coli after twenty-four hours as a function of the inoculum density by measurement of the bacterial count (a) and calculation of the resulting R values according to ISO 22196 / JIS Z 2801 (b). Data is given as mean ± standard deviation.
Fig 3.
Assessment of the physiological state of the microorganisms on the outcome of antibacterial testing of compound 1 and 3.
Therefore, E. coli in the stationary phase and the exponential growth phase were compared as well as E. coli grown in shaking cultures over night or colonies used directly from agar plates. E. coli was monitored over twenty-four hours (a) and resulting R values were calculated after twenty-four hours according to ISO 22196 / JIS Z 2801 (b). Data is given as mean ± standard deviation.
Fig 4.
Evaluation of the influence of compound 1 and 3 on E. coli after twenty-four hours as a function of nutrient supply.
Experiments were performed in nutrient broth diluted 1:500, 1:50, and 1:5 compared to undiluted and resulting amounts of E. coli were measured (a) and R values calculated according to ISO 22196 (b). Data is given as mean ± standard deviation.
Fig 5.
AFM measurements of the PA6 control (a), compound 1 (b) and compound 3 (c). Surface roughness is depicted in a range from 0 to 400 nm. The scale bar determines a length of 2 μm.
Table 5.
Summary of material surface characterization for the compounds.