Fabrication Of CRGD-modified Reduction-sensitive Nano-pickering Emulsion For Enhanced Tumor Targeted Delivery Of Doxorubicin

There are still major challenge to anticancer drug delivery including targeting ability,controlled release and stability in the cpmplex environment.Here,PNA nanogels were firstly synthesized by emulsifier-free polymerizationmethod,and then nanoscale Pickering emulsion was fabricated with the PNA nanogels assembling at O/W interfaces.In addition,cyclic pentapeptide RGD is adopted as the targeting ligand to modify the system to further increase the antitumor activity,reduction-cleavage of the disulfidebonds of the nanogels at nanoscale Pickering emulsion interfaces could control the release of drug.The results were obtained as follow:(1)PNA nanogels were synthesized by emulsifier-free polymerization.There,the size,morphology and other physico-chemical properties were choosed to determin the appropriate degree of crosslink.The results indicated that the nanogels with 4% degree of crosslink wereexhibited significant deformability of swelling-shrinkage responding to temperature and pH.(2)PNA nanogel stabilized nanoscale Pickering emulsion was fabricated by Pickering emulsion technology.In order to enhance targeted antitumor effects and controllable drug-release,the nanoscale Pickering emulsion were crosslinked with cystamine to achieve circulation stability and redox-sensitive intracellular drug release.A cyclic pentapeptide c(Arg-Gly-Asp-d-Phe-Lys)(cRGDfK,or cRGD)was linked to the surface of pickering emulsion using EDC/NHS chemistry as the coupling technique.PE,ss-PE,and cRGD-ss-PE had uniform particle size distributions in water,with PDI <0.20 and an average diameter of about 249.2 nm,153.4 nm,and 151.9 nm respectively;TEM images of the cRGD-ss-PE showed a capsule-like and inherently hollow morphology,which provided enough space for the drug entrapment.(3)DOX was choosed as a model anti-cancer drug to demonstrate the capability of the nano pickering emulsion as a drug carrier.The results showed that PE had a high encapsulation efficiency(EE)of 98 ± 1.7 %(w/w)similar to the report and drug loading capacity of 6.2 ± 0.2 %(w/w)for hydrophobic DOX.In vitro release behavior showed that the PE crosslinked with the disulfide bond could maintain the nanocarrier structure to prevent DOX leakage at a normal environment and trigger selective release at the tumor site under a reducing environment.(4)The biocompatibility of blank PE and the cytotoxicity of DOX-loaded PE formulations were performed by MTT assay using B16F10 cells and HeLa cells after 24 hours of incubation.The results showed cRGD-ss-PE as a drug delivery vehicle has excellent biocompatibility and low toxicity;The enhanced cytotoxicity of DOX-cRGD-ss-PE for αvβ3 overexpressing B16F10 cells was attributed to cRGD peptide-mediated endocytosis and cellular uptake.