Functional Chitosan Nanoparticles Modified By Folic Acid For Hela Cells Targeted Therapy And Imaging

Cancer is one of the most devastating diseases in the world andits incidence continues to increase. Existing chemotherapeutic drugs are far from perfect withlimitations such as lack of tumor selectivityand intrinsic oracquired drug resistance. Despite a significant progressin early diagnosis and treatment, resistance to conventional chemotherapeutics continuously poses a tremendous challenge toeffective cancer therapy. Efficient and site-specific delivery of therapeutic drugs is a critical challenge in the clinical treatment of cancer. To minimize side effects, variousdrug delivery and targeting systems have been investigated.In addition, Biotherapy(for instance, gene therapy) is a new method to treat tumors. Over the past few decades, RNA interference(RNAi) has emerged as a promising strategy for the treatment of a wide range of diseases by silencing a gene and therefore by hindering the corresponding protein expression.This mechanism constitutes a highly precise tool due to sequence specificity of the shRNA and the use of this nucleic acid in cancer therapy has promising potential as several oncologic targets have already been identified. Since the instability and the lack of efficiency of naked shRNA have been demonstrated, many types of nanovectors have been investigated and some of them showed very good activity in vitro. But an ideal vector should gather the following characteristics:(i) its size mustbe below 200 nm,(ii) all the components have to be biocompatible,(iii) it must be stable enough in blood to protect the nucleic acid,(iv) opsonization and uptake by macrophages have to be avoided, and(v) after reaching the target site, endocytosis should occur in the cell but the nucleic acid must be able to further escape the endosome and be released in the cell cytoplasm. All of these barriersneed to be taken into account to develop powerful shRNA delivery systems.Nanotechnology provides a unique opportunity to generate more effective and less invasive diagnostic and treatment strategies through synthesis of multifunctional nanoparticles that provide molecularly targeted therapy. Furthermore, the nanoscale imparts unique physical properties on materials must have ahigh affinity to cancer cell receptors to maximizeuptake in target cells while minimizing nonspecific uptakein off-target cells.In this paper, we fistly constructeda multifunctional chitosan nanoparticles(denoted as FA-CS-FITC(DOX/C-Dots)) modified by folic acid(FA) and fluoresceinisothiocyanate(FITC), which encapsulated the doxorubicin(DOX) andcarbon dots(C-Dots). Then VEGF shRNA was electrostatically absorbed on the FA-CS-FITC(DOX/C-Dots) nanoparticles to form a durg/gene co-delivery system(FA-CS-FITC(DOX/C-Dots)/VEGF shRNA nanocomplex.Themean particle sizeand zeta potentialof the resultant nanocomplexwere 153 nm and +23.3mV,respectively. DOX encapsulating efficiencies was 58.59%(in weight).The release behavior of DOX from FA-CS-FITC(DOX/C-Dots) nanoparticles exhibited a biphasic patterncharacterized by an initial burst release followed by a slower and continuous release.The nanoparticles also presented a pH-triggered releasing profile,which suggested the nanocomples could as a controlled and sustained delivery system in cancer therapy.The results of confocal laser scanning microscopyfurther revealed that FA-CS-FITC(DOX/C-Dots)/VEGF shRNA nanocomplex could be selectively internalized into HeLa cells by FA mediated endocytosis.Cell proliferation experiments demonstrated that there is a synergistic effect for chemotherapy and gene therapy in anticancer. Moreover, the fluorescence images of FITC and C-Dots showedthat the FA-CS-FITC(DOX/C-Dots)/VEGF shRNA nanocomplex could also act as a contrast agent for dual-optical imaging. Thisproperty provides a benefit for monitoring gene delivery and drug delivery as a tracer.These data highlight multifunctionalFA-CS-FITC(DOX/C-Dots)/VEGF shRNA nanocomplexas an attractive platform of tarheted co-delivery of DOX and VEGF shRNA for cancer treatment, and also making it a potential candidate of nanoprobes for cellularfluorescent imaging.