Star-Shaped Block Copolymers by Copper-Catalyzed Azide-Alkyne Cycloaddition for Potential Drug Delivery Applications

Star‐shaped poly(ϵ‐caprolactone) is synthesized by ring‐opening polymerization and subsequently functionalized with alkyne groups. These are utilized for the attachment of linear poly(ethylene glycol) monomethyl ether azide (mPEG‐N3) and poly(2‐ethyl‐2‐oxazoline) azide (PEtOx‐N3) by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The resulting amphiphilic star‐shaped block copolymers are characterized by SEC, MALDI‐TOF mass spectrometry, NMR spectroscopy, and DLS. In order to elucidate the potential of both systems as drug carriers their loading capacity is studied with a model system, the hydrophobic dye fat brown RR. Furthermore, erythrocyte aggregation tests provide first indications that the two different star‐shaped block copolymers are compatible for potential applications in a biological context. Star‐shaped poly(ϵ‐caprolactone)‐block‐ poly(ethylene glycol) and poly(ϵ‐caprolactone)‐block‐poly(2‐ethyl‐2‐oxazoine) are synthesized by linking linear poly(ethylene glycol) and poly(2‐ethyl‐2‐oxazoline) to a 4‐arm star‐shaped poly(ϵ‐caprolactone) core. Their ability to uptake hydrophobic molecules is tested using a hydrophobic dye as a drug model. Erythrocyte aggregation is applied as a first biological compatibility test.