The Fabrication Of Multilayers Of Poly(Lactic Acid) Nanoparticals By Layer-by-Layer Assembly

Layer-by-layer (LBL) is one of the most important techniques to fabricated ultrathin films because of its simplicity, universality, precise control on film composition and thickness and so on. To combine the LBL coating with the drug delivery system has loaded a variety of different types of drugs into LBL multilayer films, but there is a lack of an effective method to load different types of drugs into a multilayer film. For this problem, we introduced polylactic acid nanoparticles into the LBL film to develop a new preparation method of drug delivery coatings, and the method can introduce different types of drugs into one and the same multilayer film and it has many other advantages. This work will provide a new way to prepare drug-loaded multilayers based on LBL technology.Firstly, the poly(lactic acid) nanoparticles (PLA NPs), which encapsulated pyrene as a model drug, were prepared by nano-precipitation methods, and PLA NPs morphology, diameter and surface potential were monitored by SEM, TEM and DLS. Secondly, PLA NPs and cation polyelectrolyte poly(ethyleneimine)(PEI) were chosen as primitives to build multilayer thin films. The results of UV-vis spectroscopy verified that the growth of multilayers is stable and homogeneous. The composition of the PLA NPs/PEI LBL film was characterized by FT-IR. Meanwhile, the morphology of the PLA NPs/PEI LBL film was characterized by SEM. The load of pyrene into the multilayer films was also verified by fluorescence spectroscopy. Finally, the release profile of pyrene from the LBL films in PBS (pH=7.4) was further studied and the result indicated that the PLA NPs/PEI films were capable of sustainedly releasing pyrene as expected. Because of the PLA NPs are biocompatible and biodegradable, the kind of film will have bright prospects in biological materials, tissue engineering, gene engineering and other fields.