Poly(ethylene glycol) (PEG) is used as a coating material in the emerging field of polymer-based drug delivery to prolong the circulation time of nanoparticles in the bloodstream. Yet, after localizing in the pathological site, the coating is expected to shed so that nanoparticles can deliver their contents in an efficient manner. In present study, a novel 'smart' nano-sized composite micelle system (CMS) was designed and developed for tumor targeting delivery. CMS is chemically composed of an amphiphilic poly(L-lactic acid)- poly(ethylene glycol) conjugate with a cleavable acetal group as a linker between the hydrophobic PLLA chain and the hydrophilic PEG chain (PLLA-acetal-PEG), and an amphiphilic poly(L-lactic acid)-b-poly(L-lysine) diblock copolymer end-functionalized with a targeting ligand, eg. RGD peptide (PLLA-b-PLL-RGD). CMS was prepared from the mixed self-assembly of PLLA-acetal-PEG and PLLA-b-PLL-RGD in dioxane/water. The micelle morphology of CMS was verified by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Since the acetal group is acid-cleavable, the shell-forming PEG chains will fall off automatically from CMS after arriving in the acidic tumor environment, exposing the RGD targeting ligands and positively charged PLL chains, which promote the tumor cell binding of particles and subsequent drug release. Preliminary study has shown that this novel CMS has good drug-loading capacity and efficient tumor targeting and binding abilities in vitro. Further study including more physical and biological assessment of CMS is being conducted in our lab.

Novel "smart" nano-sized composite micelle system (CMS) for tumor targeting delivery

247th National Meeting (2014)

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