Thermoresponsive Self-Immolative Polyglyoxylamides

Thermoresponsive polymers with lower critical solution temperatures (LCSTs) are of significant interest for a wide range of applications from sensors to drug delivery vehicles. However, the most widely investigated LCST polymers have nondegradable backbones, limiting their applications in vivo or in the environment. Described here are thermoresponsive polymers based on a self-immolative polyglyoxylamide (PGAM) backbone. Poly(ethyl glyoxylate) was amidated with six different alkoxyalkyl amines to afford the corresponding PGAMs, and their cloud point temperatures (T_cps) were studied in water and buffer. Selected examples with promising thermoresponsive behavior were also studied in cell culture media, and their aggregation behavior was investigated using dynamic light scattering (DLS). The T_cps were effectively tuned by varying the pendent functional groups. These polymers depolymerized end-to-end following the cleavage of end-caps from their termini. The structures and aggregation behavior of the polymers influenced their rates of depolymerization, and, in turn, the depolymerization influenced their T_cp. Cell culture experiments indicated that the polymers exhibited low toxicity to C2C12 mouse myoblast cells. This interplay between LCST and depolymerization behavior, combined with low toxicity, makes this new class of polymers of particular interest for biomedical applications.