Preparation and in vitro performance evaluation of doxorubicin loaded lipid calcium phosphate nanoparticles with shell-core structure / 药学学报

ABSTRACT

As an important drug carrier, liposome has the advantages of high biocompatibility and low immunogenicity. It has been widely used in the field of drug delivery, especially the targeted treatment of tumors. However, traditional liposomes are composed of flowing dynamic phospholipid membranes, which are easy to fuse together, resulting in aggregation and drug leakage. In addition, the lower degree of polyethylene glycol (PEG) modification also limits the targeted delivery performance of the vector in vivo. In view of the problems, a nanoparticle-targeted drug delivery system combining the inorganic carrier calcium phosphate with liposomes was designed, namely lipid calcium phosphate (LCP). Using doxorubicin (DOX) as a model drug, doxorubicin-loaded lipid calcium phosphate nanoparticles (DOX/LCP) were prepared by reverse microemulsion method, and the preparation conditions were investigated. The structure and morphology of calcium phosphate cores were observed by infrared spectroscopy, EDS spectroscopy, and transmission electron microscopy. The particle size, encapsulation efficiency, drug loading, stability and release behavior in vitro of DOX/LCP were investigated. Confocal microscopy and flow cytometry were used to qualitatively and quantitatively evaluate the uptake of DOX in drug-resistant tumor cell line MCF-7/DOX by LCP, respectively, and the thiazolium MTT colorimetric method was used to examine its cytotoxicity. LCP exhibited a typical core-shell structure with good size uniformity and dispersibility. The particle size was in (48.6 ±3.9) nm, the potential was in (−12.1 ±1.2) mV, and the encapsulation efficiency was above 80%. Moreover, it has a good stability in simulated plasma. In vitro release of LCP had a significant pH dependence. When the pH of the environment was 7.4, the cumulative release within 24 hours was less than 20%; as the pH of the release medium decreases, the release rate of DOX/LCP was accelerated gradually. Accumulated release over 24 hours exceeded 90% in the pH 4.5 medium. LCP significantly promoted the uptake and accumulation of DOX by drug-resistant cells, and the inhibition rate of drug-resistant tumors was significantly increased in vitro. The half maximal inhibitory concentrations (IC50) of LCP/DOX and free DOX were 4.6 and 11.8 μg·mL−1, respectively, and there was a significant difference between the two groups (P < 0.05). In summary, the LCP prepared in this study had a small particle size, high encapsulation efficiency and good stability. It had environmental responsiveness and potential inhibition of tumor drug resistance, which suggests a potential in the clinical application.