Preparation And Evaluation Of Borneol And Folic Acid Co-Modified Doxorubicin Loaded PAMAM Conjugates In Vitro And In Vivo

Objective Effective targeting drug delivery system for tumor treatment still remains great challenge because of the existence of BBB and aggressive growth of tumors.Herein,a multifunctional targeting strategy was presented,in which a novel targeting drug carrier(FA-BO-PAMAM)based on the PAMAM G,dendrimer modified with borneol(BO)and folic acid(FA)molecules on the periphery and doxorubicin(DOX)loaded in the interior was designed to achieve the purposes of enhancing the blood-brain barrier(BBB)transportation and improving the drug accumulation both in vitro and in vivo.Methods 1H-NMR and FT-IR were used to confirm the synthesis of FA-BO-PAMAM;its morphology and mean size were analyzed by dynamic light scattering(DLS)and transmission electron microscope(TEM);drug loading(DL%)and entrapment efficiency(EE%)were investigated by UV-Vis spectrophotometry;drug release behavior in vitro was studied by dialysis method.Based on the HBMEC and C6 cells,cytotoxicity assay,cellular uptake and anti-tumor activity in vitro were investigated to evaluate the properties of nanocarriers in vitro.An orthotopic model of C6 glioma was prepared,and then tissue biodistribution and in vivo antitumor activity of BO-PAMAM/DOX and FA-BO-PAMAM/DOX solution agent were evaluated on C6 tumor bearing rats after vein injection.Results The nanocarrier of FA-BO-PAMAM was successfully synthesized,which was spherical in morphology with the average size of(22.28±0.42)nm,Zeta potential of(7.6±0.89)mV;besides,the DL%and EE%of FA-BO-PAMAM/DOX were(6.64±0.09)%and(64.58±0.85)%,respectively.In vitro release studies showed that about 62.11%and 38.46%of DOX released from FA-BO-PAMAM/DOX in the media of pH 5.5 and pH 7.4,respectively,which was an obviously reduced compared with free DOX,indicating pronounced sustained-release characteristics and a comparatively fast drug release at weak acidic condition.Cytotoxicity assay showed that BO and FA-modified conjugates decreased the cytotoxicity of PAMAM against both HBMEC and C6 cells;Moreover,modification with FA increased the total uptake of DOX by C6 cells and enhanced the cytotoxicity of DOX-polymer against C6 cells.The results in vivo demonstrated that DOX displayed significant longer blood retention time,with prolonged AUC,T1/2,and MRT,and reduced Vc and CL after encapsulation into BO-PAMAM and FA-BO-PAMAM conjugates.Biodistribution profiles of DOX were also significantly changed.Brain tumor accumulation of conjugates was increased as compared with DOX solution.FA-BO-PAMAM/DOX exhibited longer survival times and higher tumor inhibition ratio compared with other groups.Besides,the anti-tumor effect of FA-BO-PAMAM/DOX was also demonstrated by the hematoxylin and eosin staining.The toxicity experiments in vivo suggested that the FA-BO-PAMAM/DOX reduced the toxicity of DOX to blood,heart and kidney.Conclusion FA-BO-PAMAM/DOX was prepared successfully and showed sustained release character in vitro.The pharmacokinetic behavior of DOX was markedly improved by FA-BO-PAMAM with longer retention time,lower clearance and bigger AUC values.Additionally,FA-BO-PAMAM/DOX increased the DOX accumulation in tumor tissue and decreased the toxicity of free DOX,indicating that FA-BO-PAMAM/DOX exhibited a potential in treatment of brain glioma.