Sodium bicarbonate

Methacrylation of GelMA was quantified by measuring the available primary amine groups with 2,4,6-trinitrobenzene sulfonic acid (TNBSA) (Millipore Sigma) after synthesis. GelMA, gelatin, and Bovine Serum Albumin (Millipore Sigma) were dissolved in 0.1 M sodium bicarbonate (VWR) at pH 8.5 at 400 μg·mL⁻¹ and diluted to 200, 150, 100, 50, and 20 μg·mL⁻¹ with 0.1 M sodium bicarbonate (NaHCO₃). Glycine (Millipore Sigma) was dissolved at 20 μg·mL⁻¹ and diluted to 15, 10, 5, 2, and 0 μg·mL⁻¹ with 0.1 M NaHCO₃. BSA and Glycine were used as standard compounds for calculating the primary amine concentration. Each solution was tested in triplicate with 100 μL per well in a 96 well plate. TNBSA was diluted to 0.01% with 0.1 M NaHCO₃ and 50 μL was introduced to each well. Reaction continued for 2 hours at 37°C. Reaction was stopped by adding 50 μL of 10% sodium dodecyl sulfate in deionized H₂O and 25 μL 1 N HCl to each well. Absorbance was measured at 420 nm and 335 nm using a Biotek Synergy H1 microplate reader to determine available primary amines. Each tested condition was replicated (n = 9). Statistical analysis included t-test comparisons with a p-value of 0.05. Error bars are plotted as the standard deviation.

CamSA, 7-deoxy-CamSA, and 12-deoxy-CamSA were synthesized by the Abel-Santos laboratory^{30 (link)}. Sodium cholate, chenodeoxycholate (CDCA), taurocholate, metanilic acid (mSA), cholestyramine, cefoperazone, HistoDenz, PMA, and HPLC-grade solvents were obtained from Sigma-Aldrich Corporation (St. Louis, MO, USA). Artificial gastric juice was obtained from Ricca Chemical Company (Arlington, TX, USA). The Vivid™ CYP3A4 Green Screening Kit (Cat #P2857) was obtained from Thermo Fisher Scientific (Waltham, MA, USA). Clindamycin phosphate and ketoconazole was obtained from TCI (Portland, OR, USA). Metronidazole was obtained from Spectrum Chemical (Gardena, CA, USA). Microbiological media, colistin, vancomycin, gentamicin, sodium thioglycolate, ammonium acetate, HCl, sodium bicarbonate, and kanamycin were obtained from VWR (Radnor, PA, USA). C. difficile strain 630 was obtained from the American Type Culture Collection (ATCC).