4 4 azobis 4 cyanopentanoic acid a cpa

Acrylic acid (AA, 99.5%) stabilized with 200 ppm 4-methoxyphenol, methanol (99.8%), and sodium borate buffer were obtained from VWR (Radnor, PA, USA). 4,4′-Azobis-(4-cyanopentanoic acid) (A-CPA) and 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPA-DB) (>97% HPLC) was obtained from Sigma-Aldrich (St. Louis, MO, USA). Methoxy-poly(ethylene glycol)-amine powder (PEG-NH₂) was obtained from Jenkem Technologies (Beijing, China) and 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) was obtained from TCI America (Portland, OR, USA). All chemicals were used as received unless otherwise specified.

5-(2-hydroxyethyl)-4-methylthiazole (98%, Sigma Aldrich, Darmstadt, Germany), 4-dimethylaminopyridine (DMAP) (99%, Sigma Aldrich), 2-methylpropenoic acid (99%, Sigma Aldrich), N,N′-dicyclohexyl carbodiimide (DDC) (99%, Sigma Aldrich), 4-(2-(methacryloyloxy)-ethoxy)-4-oxobutanoic acid (99%, Sigma Aldrich), anhydrous acetonitrile (CH₃CN) (99.8%, Alfa Aesar), 2-hydroxyethyl methacrylate (HEMA) (99.99%, Sigma-Aldrich), poly(ethylene glycol) diacrylate (M_n = 575 g/mol, PEGDA) (99.99%, Sigma-Aldrich), 4,4’-azobis (4-cyanopentanoic acid) (ACPA) (≥75%, Sigma-Aldrich), phosphate buffered saline powder (PBS, pH 7.4, Sigma Aldrich) and NaCl solution (0.9%, BioXtra, suitable for cell culture, Sigma Aldrich) were used as received.