New targeted RGD peptides obtained by solid phase peptide synthesis (SPPS) were successfully screened by Molecular Operating Environment (MOE) and used for the building of the 6-O-carboxymethyl chitosan based carrier with an active target on the surface. CRGDYC-6-O-carboxymethyl chitosan based nanoparticles (NPs) loaded with doxorubicin hydrochloride (DOX) were successfully prepared by an ionic gelation method with the carrier synthesized before. Synthesis conditions and formulation parameters were optimized by determining the characteristics of nanoparticles including the particle size and drug encapsulation efficiency. 6-O-Carboxymethyl chitosan concentration, calcium chloride concentration and calcium chloride/6-O-carboxymethyl chitosan ratio all had effects on the particle size and drug encapsulation efficiency. Nanoparticles with an average diameter of 193.4 nm, an average drug loading efficiency of up to 69.5% and an average drug loading of up to 0.395% were prepared successfully with the optimal formulation. Flow cytometry and confocal microscopy analyses showed that the cellular uptake of DOX in human breast cancer cell lines (MCF-7) was higher in the CRGDYC-modified nanoparticles compared with the unmodified nanoparticles. In vivo imaging showed that the distribution of CRGDYC-modified nanoparticles in the tumor site was higher compared with the unmodified nanoparticles. These results suggest that CRGDYC-6-O-carboxymethyl chitosan may be a promising cancer targeting carrier which can enhance the intracellular uptake and cytotoxicity of the drug-loaded nanoparticles.

中文翻译：

---

筛选新型RGD肽以修饰用于靶向癌症治疗的纳米颗粒

通过分子操作环境（MOE）成功筛选了通过固相肽合成（SPPS）获得的新型靶向RGD肽，并将其用于构建表面具有活性靶标的6- O-羧甲基壳聚糖基载体。通过离子凝胶法成功合成了载有盐酸阿霉素（DOX）的CRGDYC-6- O-羧甲基壳聚糖纳米颗粒（NPs），并与载体进行了合成。通过确定纳米粒子的特性（包括粒径和药物包封效率）来优化合成条件和配方参数。6- O-羧甲基壳聚糖的浓度，氯化钙浓度和氯化钙/ 6- O-羧甲基壳聚糖的比例均对粒径和包囊效率有影响。使用最佳配方成功制备了平均直径为193.4 nm，平均载药率高达69.5％和平均载药率高达0.395％的纳米粒子。流式细胞仪和共聚焦显微镜分析表明，与未修饰的纳米粒子相比，CRGDYC修饰的纳米粒子在人乳腺癌细胞系（MCF-7）中对DOX的细胞摄取更高。体内成像显示，与未修饰的纳米颗粒相比，CRGDYC修饰的纳米颗粒在肿瘤部位的分布更高。这些结果表明CRGDYC-6- O-羧甲基壳聚糖可能是一种有前途的癌症靶向载体，它可以增强载药纳米颗粒的细胞内摄取和细胞毒性。