## 2 Materials and Methods
### BC/PHB Blends Preparation  
PHB powder, PCL pellets, and PLA pellets were, respectively, dissolved in chloroform to make solutions containing 40 g/L of each polymer. BC production was achieved using _Komagateibacter medientiess_ ID13488 as described in [PERSON] et al. (2022) [53].  
Stripes of 1 \(\times\) 10 cm of BC were cut and each sample was immersed in 30 mL of polymer solution inside 50 mL. Falcon tubes. Tubes containing the samples were incubated overnight at 30 \({}^{\circ}\)C and 120 rpm in a horizontal position. After incubation, the films were removed from the solution and left inside the waste fume hood for at least 4 h to allow complete evaporation of the chloroform. The films were immersed in 20 mL of distilled water and autoclaved (121 \({}^{\circ}\)C, 15 min) prior to the test of antimicrobial activity.  
The obtained BC blends were cut in 1 \(\times\) 2 cm pieces and each piece was fully immersed into 5 mL of TSNP solution with the highest concentration obtained after the water evaporation method (42.64 \(\upmu\)L/mL) and incubated overnight at 30 \({}^{\circ}\)C with agitation on a horizontal platform (100 rpm). Afterwards, films were removed from the solution and dried overnight at 60 \({}^{\circ}\)C. To estimate the amount of TSNP absorbed from the solution into the BC materials, the UV-VIS spectrum reading of the solution was measured before and after the immersion and incubation, and the difference in the absorbance at the peak of the spectrum, between the initial and final solution, was observed. A calibration curve with dilutions of the TSNP solution was used to obtain an estimation of the resulting concentration based on absorbance.  
Scanning electron microscopy (SEM) images were obtained using Mira XMU SEM (Tescan(tm), Brno, Czech Republic) in back scattered electron mode for surface analysis. The accelerating voltage used was 9 kV. Prior to analysis, tested samples were placed on an aluminum stub and sputtered with a thin layer of gold using the Baltec SCD 005 for 110 at 0.1 mbar vacuum.  
Figure 1: Seed solution (**left**) and TSNP solution (**right**).  
Evaluation of Antimicrobial Activity  
The antimicrobial activity of all derived materials was evaluated against _E. coli_ ATCC 95922 and _S. aureus_ ATCC 25923 in Luria-Bertani (LB) broth (10 g/L tryptone, 10 g/L NaCl, and 5 g/L yeast extract, pH 7.2). Overnight cultures of the bacteria were diluted to a concentration of 10\({}^{8}\) CFU/mL to be used as pre-culture. dried BC films (10 mg of each specimen) were immersed in fresh LB broth and inoculated with 1% (\(v/v\)) from pre-culture, for a final concentration of 10\({}^{6}\) CFU/mL of bacteria. Untreated materials were used as negative control. After incubation for 24 h at 37 \({}^{\circ}\)C and 100 rpm, BC films were removed from the cultures and optical density (OD) of the cultivated broth was measured at 630 nm using a Biotek Synergy HT microplate reader (Biotek Instruments GmbH, Bad Friedrichshall, Germany). Growth percentage was calculated using the following equation (Equation (1)).  
\[\text{Growth Percentage}=\left(\frac{\text{Absorbance of tested sample}}{\text{Absorbance of positive control}}\right)\times 100 \tag{1}\]