Modification of polylactide surfaces with lactide-ethylene oxide functional block copolymers: accessibility of functional groups.

Feasibility of using amphiphilic block copolymers composed of polylactide (PLA) and poly(ethylene oxide) (PEO) blocks for biomimetic surface modification of polylactide-based biomaterials for tissue engineering was investigated. PEO-b-PLA copolymers were deposited on the PLA surface from a solution in PEO-selective solvent. Copolymers with a neutral omega-methoxy end group of the PEO block (mPEO-b-PLA) were used to provide hydrophilic surface of PLLA, which exhibited suppressed nonspecific protein adsorption. Their analogues, containing biotin group at the end of PEO block (bPEO-b-PLA), were used as a model of functional copolymers, carrying a biomimetic group, for example, a cell-adhesion fibronectine-derived peptide sequence. The surface topography of functional groups on the modified surface and their accessibility for interaction with a protein receptor was investigated, taking advantage of specific biotin-avidin interaction, on surfaces modified with a combination of mPEO-b-PLA and bPEO-b-PLA copolymers. The accessibility of model biotin groups for interaction with their protein counterpart was proven through visualization of avidin or avidin-labeled nanospheres with atomic force microscopy.