| Chemotherapy is one of the primary means of cancer therapy. However, chemotherapeutics such as Doxorubicin usually has the characteristics of poor water solubility, low selectivity and strong side effects. Therefore, study on targeting drug delivery system(TDDS) based on nanoparticles has attracted more attention. Nano drug carrier could be accumulated in tumor sites via passive targeting and active targeting. Site-specific drug delivery can be achieved by introuduce ligands of cancer cell surface to the particles. In this study, K5 polysaccharide and hyaluronic acid(HA) were used as the hydrophilic chain, while boronate modified deoxycholic acid was used as the hydrophobic block. We designed and synthesized pH-responsive K5 AD and HAAD micelles and the micelles’ physical and chemical properties, surface characteristic, in vitro drug release, anti-tumor activity and cellular uptake efficiency were investigated.(1) The preparation and property research of DOX-loaded K5 AD micelleThree K5 ADs with different degrees of AD substitution were synthesized. The chemical structures of K5 AD conjugate was identified by 1H NMR, and the degree of substitution(DS) was determined the UV absorbance at 263 nm. The DS of K5 AD were calculated as 0.21, 0.19 and 0.06(K5AD-21, K5AD-19 and K5AD-6), respectively. The critical micelle concentration(CMC) and particle size of K5AD-21, K5AD-19 and K5AD-6 micelles were measured to be 123.73 mg/L, 65.56 mg/L, 23.5 mg/L and 290 nm, 227 nm, 197 nm, respectively. The DOX loading efficiency(DL) and encapsulation efficiency(EE) were calculated to be 2.14%, 6.58%, 10.63% and 10.72%, 32.92%, 53.15%. It is clear that the CMC and particle size of the micelles decreased, while DL and EE increased with the increasing of DS, suggesting K5 AD with higher DS is better nano drug carrier. In vitro drug release study of K5 AD revealed an acid-sensitive profile, i.e., the DOX-loaded K5 AD micelles showed relatively slow releasing behavior at pH 7.4, and accelerated releasing behavior at pH 5.0. In vitro cytotoxicity assay found that DOX-loaded micelles are significant more toxic against tumor cells than normal cells. The flow cytometry analysis demonstrated the K5 AD micelles could transport more DOX into cells at short time, showing improved efficacy.(2) The preparation and property research of DOX-loaded HAAD micelleThe boronate derived deoxycholic acid(AD) was first synthesized via amidation reaction. Afterwards, hyaluronic acid-boronate modified deoxycholic acid(HAAD) was prepared via boronate ester bond. HAAD could self assemble into micelles in water solution with the average size of 171 nm. The DL value of DOX was 9.15%. Moreover, the DOX-loaded HAAD micelles could show pH-responsive drug release behavior, the drug release rate was faster at acidic milieu. The flow cytometry analysis demonstrated the DOX-loaded HAAD micelles could be internalized by CD44-overexpressed MCF-7 cells more effectively. Additionally, the cytotoxicity assay showed DOX-loaded HAAD micelles had less toxicity against normal cells than that of tumor cells, showing selectivity.Above all, the results suggested that polysaccharide-based micelles showed good biocompatibility. After internalizing by cells, DOX would be accelerated released from micelles at tumor cells, showing selectivity and pH-responsive. The novel TDDS has great potential in clinical application. |
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