*2.1. Materials*

PU (pellethane 2363-80AE) was provided by Lubrizol Corporation (Wickliffe, OH, USA). Methylenediphenyl 4,40 -Diisocyanate (MDI) was bought from Aladdin Chemical Co. Ltd. (Shanghai, China). N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), toluene, and triethylamine were purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China), and HA was obtained from Xianding Biotechnology Co. Ltd. (Shanghai, China). 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl), N-Hydroxysuccinimide (NHS), Lysozyme (LYS), bovine fibrinogen (BFG), human serum albumin (HSA), and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) were obtained from Yuanye Bio-Technology Co. Ltd. (Shanghai, China). Sodium dodecyl sulfate (SDS) and the Micro BCA Protein Assay Kit were obtained from Sangon Biotech (Shanghai, China) Co. Ltd. Fetal bovine serum (FBS) and Dulbecco's modified

Eagle medium (DMEM) medium were obtained from Gibco (Grand Island, NY, USA). *E. coli* (DH5 alpha), *S. aureus* (ATCC 6538), and *P. aeruginosa* (ATCC 2785) and lysogenic broth (LB) medium were provided by Professor Cui, East China University of Science and Technology (ECUST, Shanghai, China). PHMG was provided by Professor Guan, ECUST. (DMEM) medium were obtained from Gibco (Grand Island, NY, USA). *E. coli* (DH5 alpha), *S. aureus* (ATCC 6538), and *P. aeruginosa* (ATCC 2785) and lysogenic broth (LB) medium were provided by Professor Cui, East China University of Science and Technology (ECUST, Shanghai, China). PHMG was provided by Professor Guan, ECUST.

human serum albumin (HSA), and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) were obtained from Yuanye Bio-Technology Co. Ltd. (Shanghai, China). Sodium dodecyl sulfate (SDS) and the Micro BCA Protein Assay Kit were obtained from Sangon Biotech (Shanghai, China) Co. Ltd. Fetal bovine serum (FBS) and Dulbecco's modified Eagle medium

#### *2.2. The Fabrication of the PU-(PHMG/HA)<sup>n</sup> Films 2.2. The Fabrication of the PU-(PHMG/HA)n Films*

*Polymers* **2021**, *13*, x FOR PEER REVIEW 3 of 14

Ten grams of commercial PU was dissolved in 100 mL DMF by magnetic stirring. Then, the PU solution was vacuum dried at 60 ◦C for 72 h to obtain thin PU films, and the films were cut into discs (6 mm in diameter and 1 mm in thickness). Afterward, PU films were put into MDI solution for a 3 h reaction to obtain PU-NCO films. Finally, the PU-PHMG film was prepared by the reaction of amino groups of PHMG with PU-NCO. Ten grams of commercial PU was dissolved in 100 mL DMF by magnetic stirring. Then, the PU solution was vacuum dried at 60 °C for 72 h to obtain thin PU films, and the films were cut into discs (6 mm in diameter and 1 mm in thickness). Afterward, PU films were put into MDI solution for a 3 h reaction to obtain PU-NCO films. Finally, the PU-PHMG film was prepared by the reaction of amino groups of PHMG with PU-NCO.

Carboxyl activated HA intermediate was prepared according to the literature [31]. A total of 0.24 g EDC·HCl and 0.15 g NHS were slowly added to 50 mL HA solution (1%, m/v) in turn under the condition of pH 4.75 with stirring for a 2.5 h reaction. After that, the reaction was terminated by increasing the pH value to 7.5. The reaction product was further dialyzed to remove EDC and NHS at room temperature for two days. Finally, carboxyl-activated HA was obtained and freeze-dried by a vacuum freeze dryer. Carboxyl activated HA intermediate was prepared according to the literature [31]. A total of 0.24 g EDC∙HCl and 0.15 g NHS were slowly added to 50 mL HA solution (1%, m/v) in turn under the condition of pH 4.75 with stirring for a 2.5 h reaction. After that, the reaction was terminated by increasing the pH value to 7.5. The reaction product was further dialyzed to remove EDC and NHS at room temperature for two days. Finally, carboxyl-activated HA was obtained and freeze-dried by a vacuum freeze dryer.

PU-(PHMG/HA)<sup>n</sup> films were prepared by sequential assembling HA and PHMG onto the PU-PHMG film layer by layer. Figure 1 illustrates the fabrication process of the PU-(PHMG/HA) films. The assembling time per polymer layer was 20 min [32]. In between the PHMG and HA assembling steps, the assembled films were put into deionized (DI) water to remove the unassembled molecules and dried at 60 ◦C. Different samples were obtained by adjusting the polyelectrolyte concentration and the number of bilayers self-assembled, and Table 1 lists the formulations for various samples. PU-(PHMG/HA)n films were prepared by sequential assembling HA and PHMG onto the PU-PHMG film layer by layer. Figure 1 illustrates the fabrication process of the PU-(PHMG/HA) films. The assembling time per polymer layer was 20 min [32]. In between the PHMG and HA assembling steps, the assembled films were put into deionized (DI) water to remove the unassembled molecules and dried at 60 °C. Different samples were obtained by adjusting the polyelectrolyte concentration and the number of bilayers self-assembled, and Table 1 lists the formulations for various samples.

**Figure 1.** Synthesis procedure for the PU-(PHMG/HA) films. **Figure 1.** Synthesis procedure for the PU-(PHMG/HA) films.


**Table 1.** The formulations of the PU-(PHMG/HA)n films synthesized.
