Preparation And Properties Of PLGA - Mediated Multifunctional Compound Medical Materials

Poly (lactic-co-glycolic acid) (PLGA) is a typical synthetic lipophilic polymer material with the advantage of non-toxic, well-biodegradable and good biocompatibility, which has been approved by the US Food and Drug Administration (FAD) as a high molecular material for human use. Nowadays, PLGA material has been widely used in preparation of microspheres, microcapsules, nanoparticles, micropills, implants and membranes. Furthermore, it also attracts more and more interest in molecular imaging and tissue engineering.In this paper, we focused on fabrication of PLGA hybridmaterials and investigated its application in molecular imaging. First, a simple method to prepare Au nanoparticle-coated, polydopamine-modified poly(lactic-co-glycolic acid) (AuNPs@PDA/PLGA) hybrid capsules for combined ultrasound imaging and high-intensity focused ultrasound (HIFU) therapy was presented. In this approach, PLGA nanocapsules are prepared firstly via a fecile and efficient water/oil/water (W/O/W) emulsion strategy, and are then modified with PDA through the self-polymerization of dopamine in a weakly alkaline aqueous environment. Subsequently, chloroauric acid (HAuCl4) solution is added, and AuCl4- ions are absorbed on the surfaces of the PDA/PLGA nanocapsules by the active catechol and amine groups of PDA coatings. Finally, these absorbed AuCl4- ions are reduced in situ to AuNPs to form AuNPs@PDA/PLGA hybrid capsules. The in vitro ultrasound imaging experiments shows that AuNPs@PDA/PLGA hybrid capsules are suitable for ultrasound contrast imaging. Moreover, the potential of the nanocapsules to enhance HIFU therapy is also demonstrated. These results show that ultrasound-guided HIFU therapy ex vivo with AuNPs@PDA/PLGA hybrid capsules is highly efficient on degassed bovine livers due to the high thermal energy accumulation of AuNPs. Thus, the successful integration of the AuNPs and PLGA nanocapsules provides an alternative strategy for highly efficient ultrasound-guided HIFU therapy.In the second part, a facile approach to embed nitrogen-doped mesoporous carbon nanospheres (N-MCNs) loaded with an anticancer drug (doxorubicin hydrochloride, Dox) into the poly (lactic-co-glycolic acid) (PLGA) nanofibers as a drug delivery vehicle was investigated. Initially, the uniform N-MCNs were synthesized and characterized to encapsulate Dox molecules, and then the Dox-loaded N-MCNs were incorporated into PLGA via electrospinning, resulting in a new hybrid drug-loaded nanofibrous scaffold (PLGA/N-MCNs/Dox). The physicochemical characteristics of the as-prepared hybird nanofibers were measured by a serious of techniques, meanwhile the in vitro Dox release profiles and cytocompatibility of these obtained nanofibers were also evaluated. The results showed that the N-MCNs possessed high Dox-loading capacity and pH-triggered Dox release was discovered due to the special supramolecular n-n stacking between the carbonaceous framework of N-MCNs and Dox molecules. More importantly, the hybrid PLGA/N-MCNs/Dox nanofibers also possessed high drug capacities and released Dox in a sustained and pH-responsive manner, and the PLGA/N-MCNs nanofibers displayed good cytocompatibility similar to pure PLGA nanofibers. So, we believed that this approach of forming organic/inorganic hybrid nano fiber-based drug delivery system could serve as a model technique in the fields of tissue engineering and pharmaceutical science.