Construction of Multifunctional Coatings via Layer-by-Layer Assembly of Sulfonated Hyperbranched Polyether and Chitosan

Layer-by-layer assembly has shown a great deal of promise in biomedical coatings, as well as local drug delivery systems. The poor loading capacity of hydrophobic drugs within the multilayers is a drawback in their potential applications. Herein, sulfonated hyperbranched polyether (HBPO-SO3) with a hydrophobic core was incorporated into LBL films to provide nanoreservoirs for hydrophobic guest molecules. HBPO-SO3 was proven to form stable micelles in the sodium acetate and acetic acid buffer solution (HAc buffer) for LbL assembly. The QCM and ellipsometry experiments demonstrated that the LBL films can be fabricated via alternating deposition of HBPO-SO3 micelles and chitosan. The fluorescence emission spectra verified that the hydrophobic pyrene can be incorporated both by pre-encapsulation in HBPO-SO3 micelles and post-diffusion in preassembled multilayer Films. Compared with the pre-encapsulation approach, the post-diffusion process was more efficient in incorporating hydrophobic guest molecules into the LbL films and carried out a much more controllable release of the guest molecules. A multifunctional coating with potential anticoagulation, antibacterial, and local release of hydrophobic drug Probucal, which has powerful antioxidant properties and can prevent restenosis after coronary angioplasty, was then developed via post-diffusion of the anti-restenosis agents into the multilayer Films of HBPO-SO3 and chitosan.