L929 fibroblast cell line

The L929 fibroblast cell line was purchased from Bioresource Collection and Research Center (BCRC, Hsinchu City, Taiwan). Cells were maintained in Dulbecco's modified Eagle medium (DMEM, Corning, NY, USA) supplemented with 10% fetal bovine serum (FBS, Corning, NY, USA) and 1% antibiotic of penicillin–streptomycin solution (Corning, NY, USA) at 37 °C in a 5% CO₂ incubator (BB15, Thermo Fisher Scientific, MA, USA).

The L929 fibroblast cell line was purchased from Bioresource Collection and Research Center (BCRC, Hsinchu City, Taiwan). Cells were maintained in Dulbecco‘s Modified Eagle Medium (DMEM, Corning, NY, USA) supplemented with 10% fetal bovine serum (FBS, Corning, NY, USA) and 1% antibiotic of penicillin‐streptomycin solution (Corning, NY, USA) at 37°C in a 5% CO₂ incubator (BB15, Thermo Fisher Scientific, MA, USA). To investigate the cytotoxicity of MDABCO‐NH₄I₃, 1 × 10⁴ cells of L929 fibroblasts were seeded in a 96‐well cell culture plate (Cat. No. 310109008, Thermo Fisher Scientific, MA, USA) and incubated at 37 ℃ in the 5% CO₂ incubator overnight. Then, the media were replaced with various concentrations of MDABCO‐NH₄I₃ and further incubated for 24 h. Cell viability was determined by the Cell Counting Kit‐8 (CCK‐8, Dojindo Laboratories, Kumamoto, Japan). The absorbance at the wavelength of 450 nm was measured by a microplate spectrophotometer (Multiskan GO, Thermo Fisher Scientific, MA, USA). Images of the cell morphologies were obtained by using an inverted optical microscope (Olympus CK30, Olympus, Tokyo, Japan).

Chitosan (CTS) with 85% deacetylation (molecular weight < 5 kDa), type B gelatin (GEL), methacrylic anhydride (MA), fluorescamine (98%), dimethyl sulfoxide (DMSO), and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP; 95%) were purchased from Sigma-Aldrich (Aldrich, St. Louis, MO, USA). Gallic acid (GA; 3,4,5-trihydroxybenzoic acid monohydrate, 98%), pyrogallol (PG; 1,2,3-trihydroxybenzene, 99%), and tannic acid (TA, 95%) were obtained from Alfa Aesar (Heysham, UK), and their chemical structures are shown in Figure 1a.
Escherichia coli (E. coli; ATCC 8739), Staphylococcus aureus (S. aureus; ATCC 25923), Porphyromonas gingivalis (P. gingivalis; A7436), Streptococcus mutans (S. mutans; ATCC 700610) strains, and L929 fibroblast cell line (RM60091) were obtained from the Bioresource Collection and Research Center (Hsinchu, Taiwan). Dulbecco’s modified Eagle medium (DMEM), fetal bovine serum (FBS), and penicillin/streptomycin solution were purchased from Gibco (Langley, OK, USA). The alamarBlue reagent was from Invitrogen (Grand Island, NY, USA). Bacto tryptic soy broth and Wilkins-Chalgren anaerobe broth were purchased from Becton Dickinson (Sparks, MD, USA) and Oxoid (Hampshire, UK), respectively. All reagents were of analytical grade and used as received without further purification.