Liquid-Crystalline Block Copolymers Comprising Cholesterol-Based Dendritic Moieties and Poly(L,L-lactide) Chains

Liquid-crystalline (LC) biomaterials are garnering attention as promising materials due to their ordered nanostructures and dynamic properties. The introduction of biobased molecular moieties into LC materials may be useful to develop highly functional biomaterials. The integration of biodegradable polymers with naturally occurring molecules is favored for bioadaptive LC materials. Poly(L,L-lactide) (PLLA), has been extensively studied for biomedical applications, from drug delivery to tissue engineering due to its in vivo degradability and compatibility with tissues. However, there is a demand for PLLA-based materials to possess additional bioactive functionalities, such as improved interactions with cells. Here, we present the synthesis and self-assembled properties of A-B-A triblock copolymers incorporating PLLA segments (B) and mesogenic dendrons with cholesteryl moieties (A) at their peripheral parts. Mesogenic copolymers exhibit thermotropic LC properties attributed to their self-assembled lamellar nanostructures. The presence of peripheral mesogenic dendrons was observed to disrupt the crystallization of PLLA, thereby preserving the dynamic LC properties unhindered by PLLA crystals. Additionally, the surface wettability of mesogen-functionalized PLLA demonstrated greater hydrophobicity compared to pristine PLLA, owing to the incorporation of hydrophobic cholesterol moieties. Despite the common notion that hydrophobic surfaces are less bioactive, our results show significantly enhanced cell adhesion and proliferation on mesogen-functionalized PLLA surfaces in comparison to PLLA alone. The cholesterol trident dendrons conjugating the central PLLA segment appear to significantly promote the cellular surfaces. This bioactivity can be attributed to the soft and dynamic properties of mesogen-functionalized PLLA based on the LC nanostructure. Microstructural analysis in the hydrated state revealed a macroscopically smooth surface with nanometer-scale roughness for mesogen-functionalized PLLA, and the LC nanostructure demonstrated responsiveness to hydration. This research sheds light on the potential of LC biomaterials for enhanced biomedical applications.