Heterobifunctional poly(ε-caprolactone): Synthesis of α-cholesterol-ω-pyrene PCL via combination of ring-opening polymerization and “click” chemistry

A well-defined novel α-cholesterol and ω-pyrene heterobifunctional poly(ε-caprolactone) (Chol-PCL-Pyr) was synthesized by a combination of ring-opening polymerization (ROP) and “click” chemistry techniques. A cholesterol compound with hydroxyl functional group was used as the initiator in the ROP of ε-caprolactone (ε-CL) to prepare α-cholesterol-ω-hydroxy PCL polymer (Chol-PCL-OH). ω-Hydroxy functionality of Chol-PCL-OH was then successfully converted into bromide and azide. Further end-group modification of ω-azide poly(ε-caprolactone) (Chol-PCL-N3) was achieved quantitatively by copper (I)-catalyzed cycloaddition of azide functional group and 1-ethynyl pyrene, which led to the desired PCL with α-cholesterol and ω-pyrene groups (Chol-PCL-Pyr). The effect of molar ratio of ε-CL to the initiator on the molecular weight of the obtained Chol-PCL-Pyr was also investigated.

A well-defined novel α-cholesterol ω-pyrene heterobifunctional poly(ε-caprolactone) (Chol-PCL-Pyr) is prepared via a combination of ROP and “click” chemistry techniques, and its detailed characterization is provided. Chol-PCL-Pyr shows both liquid crystalline and fluorescent properties. It is believed that it can be used as biocompatible and biodegradable materials in drug delivery, drug loading, and controlled release systems, and in fluorescent studies for signaling the cell pathway and cell membrane.