1 4 butanediol diacrylate b4 5 amino 1 pentanol s5

1,4-Butanediol diacrylate (B4), 5-amino-1-pentanol (S5), and 1-(3-aminopropyl)-4-methyl-piperazine (E7) were purchased from Alfa Aesar (Ward Hill, MA). PBAE polymer was synthesized by a two-step reaction. First, an acrylate-terminated base polymer was first synthesized by Michael addition reaction of 1,4-butanediol diacrylate (B4) with 5-amino-1-pentanol (S5) at 1.05:1 acrylate:amine monomer molar ratio in the dark under magnetic stirring for 24 hours at 90°C. In the second step, the acrylate-terminated base polymer was endcapped through another Michael addition reaction in the presence of excess of primary amine-containing small-molecule 1-(3-aminopropyl)-4-methyl-piperazine (E7). For example, 625 mg of polymer in 4 ml of tetrahydrofuran (THF) was mixed with 4 ml of 0.5 M end-capping amine solution in THF and stirred at 500 rpm overnight at 23°C. The final polymer (termed “PBAE 457”) was purified by precipitation into diethyl ether and stored in dimethyl sulfoxide (DMSO) at 100 mg/ml with desiccant at −20°C until use. Molecular weight was determined by dissolving PBAE 457 at 5 mg/ml in 94% THF, 5% DMSO, and 1% piperidine. The polymer solution was filtered through a 0.2-μm polytetrafluoroethylene (PTFE) syringe filter and then analyzed by gel permeation chromatography using polystyrene standards.

1,4-Butanediol diacrylate (B4), 5-amino-1-pentanol (S5), and 1-(3-aminopropyl)-4-methyl-piperazine (E7) were purchased from Alfa Aesar (Ward Hill, MA). PBAE polymer was synthesized by a two-step reaction. First, acrylate-terminated base polymer (B4S5) was synthesized by Michael addition reaction of B4 with S5 at 1.1:1 acrylate:amine monomer molar ratio in the dark under magnetic stirring for 24 hours at 90°C. In the second step, the acrylate-terminated base polymer was end-capped through another Michael addition reaction in the presence of excess of primary amine-containing small-molecule E7. Briefly, the polymer (200 mg/ml) was mixed with 0.5 M E7 in anhydrous tetrahydrofuran (THF) at room temperature for 2 hours. The final polymer (B4S5E7, or 457) was purified by precipitation into diethyl ether and stored in anhydrous dimethyl sulfoxide (DMSO) at 100 mg/ml with desiccant at −20°C until use. Polymer molecular weight was assessed via gel permeation chromatography (Agilent, Savage, MD) relative to polystyrene standards, and the number average and weight average molecular weight were 8610 and 43,500 g/mol, respectively.