Hydroxy benzotriazole hobt

Type B gelatin (bloom 225) was purchased from Electron Microscopy Sciences. Carbic anhydride (CA), carbohydrazide (CH) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide HCl (EDC) were purchased from Acros Organics. Sodium hyaluronate (74 kDa) and dextran (20 kDa) were purchased from Lifecore Biomedical and Sigma-Aldrich respectively. Hydroxy benzotriazole (HOBt) was purchased from Oakwood Chemical. Poly(ethylene glycol)-tetra-propionaldehyde (PEG4pAld, 10 kDa) and PEG-tetra-thiol (PEG4SH, 10 kDa) were purchased from Layson Bio. α-chymotrpsin was purchased from Amresco. Hyaluronidase was purchased from Worthington Biochemical Corporation. Geltrex was purchased from Thermo Fisher Scientific. Anti-CD44 antibody and Alexa Fluor 488 donkey anti-mouse IgG was obtained from RayBiotech and Thermo Fisher Scientific, respectively. CAF marker antibody sampler kit was purchased from Cell Signaling. Live/dead viability kit was purchased from Biotium. High glucose DMEM was purchased from GE Healthcare. DPBS, fetal bovine serum (FBS), and antibiotic-antimycotic were purchased from Corning. All other chemicals were purchased from Sigma-Aldrich unless otherwise noted.

PEG-OH (8-arm, 20 kDa, JenKem), carbic anhydride (Sigma-Aldrich), 5-norbornene-2-carboxylic acid (Sigma-Aldrich), 4-dimethylaminopyridine (DMAP, Alfa Aesar), dopamine hydrochloride (Sigma-Aldrich), tyramine hydrochloride (Chem-Impex), isopropylamine (TCI chemicals), N,N’-Diisopropylcarbodiimide (DIC, Chem-Impex), N,N’-Dicyclohexylcarbodiimide (DCC, Sigma-Aldrich), hydroxybenzotriazole (HOBt, ≥20 wt% water, Oakwood Chemical), N,N’-diisopropylethylamine (DIPEA, TCI chemicals), cysteine (Sigma-Aldrich), and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP, ≥95%, Sigma-Aldrich), 4-arms thiolated PEG (PEG4SH, 10 kDa, Laysan Bio), 5,5’-dithiobis-(2-nitrobenzoic acid) (Ellman’s reagent, Life Technologies), pyridine (Fisher), anhydrous tetrahydrofuran (THF, Fisher), anhydrous dimethylformamide (DMF, amine-free, Fisher), anhydrous dichloromethane (DCM, Fisher), methanol (Sigma-Aldrich) and diethyl ether (Fisher) were used as received.