The encapsulation rate and pH sensitivity of arsenic were improved in liposome nanoparticles by the calcium acetate gradient method.

The study proposed improving the arsenic encapsulation efficiency (EE) in liposomes and make it pH responsive. Liposomes were prepared using the ethanol injection method (EIM), thin film dispersion method (TFM) and CAGM with sodium arsenite (NaAsO₂). The orthogonal experimental was used to optimize the preparation conditions of the CAGM. The arsenic-carrying liposomes were characterized by polydispersity index (PDI), transmission electron microscopy (TEM), in vitro release experiments and inductively coupled plasma emission spectrum (ICP). The toxicity was investigated by rat glioma cells (C6) and human brain micro vascular endothelial cells (HBMEC). The results indicated that the CAGM can effectively improve the EE of NaAsO2 and has a pH response compared with EIM and TFM. The size of nanoparticles prepared by CAGM was 118.8 ±56.67 nm, the arsenic EE was 54.3 ±9.82%, the drug loading rate was 7.13 ±0.72% (P <0.01), pH sensitivity was shown at pH 5.5. The optimal parameters of the CAGM were 3 mg NaAsO2, 5:1 egg phosphatidylcholine (EPC) to cholesterol (CHOL) and 240 mmol/L calcium acetate (CaAC2). The results showed that the CAGM has good biocompatibility and is one of the effective ways to improve the NaAsO2 encapsulation rate and pH response in liposome nanoparticles.