Influence of binding-site density in wet bioadhesion

The influence of binding-site density in wet bioadhesion was investigated. Active ester polymers reacted quickly and quantitatively with amines to form the corresponding poly(acrylamides), opening the possibility of obtaining multifunctional polymeric materials. Active ester polymers were used based on pentafluorophenylacrylates for their higher solubility and reactivity when compared to the commonly used poly(N-hydroxysuccinimide-acrylates). The required amount of 3-hydroxytyramine hydrochloride in 1.5 mL DMF and 0.1 mL trimethylamine was added, and the clear mixture was stirred for 3 hours at 50°C. The solution was concentrated to about 5 mL in vacuum, and all polymers were precipitated by cold ethyl ether, with the exception of p(DMA), which was purified by precipitation using ethyl acetate. It was observed that the attractive forces are identical for all catechol-containing copolymers, irrespective of the catechol content.