Surface engineering and surface analysis of a biodegradable polymer with biotinylated end groups

In the design of advanced polymeric biomaterials there is a need to tailor the surface chemistry of the biomaterial to elicit beneficial interactions with cells and biomolecules. To facilitate the fabrication of complex biomaterial surfaces, we have previously described the synthesis and application of a poly(lactic acid)-poly(ethylene glycol) block copolymer (PLA-PEG) with the biotinylated PEG end groups (final polymer termed PLA-PEG-biotin). This polymer is biodegradable and resistant to nonspecific protein adsorption, and the biotin moiety allows surface chemical engineering to be achieved using avidin-biotin interactions. Here, we describe a detailed surface analysis of this polymer using X-ray photoelectron spectroscopy and surface plasmon resonance analysis. This analysis has revealed that the avidin-biotin surface engineering strategy is a rapid method of immobilizing biomolecules at biomaterial surfaces under aqueous conditions. The surface engineering generates a specific and high-density change in surface structure. The effect of PLA segment molecular weight and the influence of the surfactant on the nature of the surface engineering has been determined with the objective of proving that the extent of specific ligand immobilization is controllable and resilient to surface stabilization by surfactants.