目的 为了提高三氧化二砷（arsenic trioxide，ATO）在体内的稳定性，使其具备pH响应及缓释特性，制备了pH响应的载三氧化二砷聚乳酸-羟基乙酸共聚物［poly （lactic-co-glycolic acid），PLGA］纳米粒（pH-ATO-PLGA@NPs），并对其进行了理化性质考察和细胞学评价。方法 以NaHCO₃为pH响应因子，采用复乳溶剂蒸发法制备pH-ATO-PLGA@NPs并进行单因素考察优化。随后，利用马尔文粒径仪考察pH-ATO-PLGA@NPs的粒径、多分散系数（polydispersity index，PDI）、Zeta电位、稳定性；透射电子显微镜（TEM）观察形态；电感耦合等离子体发射光谱仪测定包封率、载药量；透析袋法考察其在不同pH值的体外释药特性；MTT法考察载体及pH-ATO-PLGA@NPs对人源性肝癌HepG2细胞及人正常肝L02细胞的细胞毒性。结果 pH-ATO-PLGA@NPs外观圆整均一，其粒径、PDI、Zeta电位分别为（214.35±1.86）nm、0.24±0.02、（-35.49±1.88）mV；包封率及载药量分别为（62.32±2.61）%、（1.59±0.34）%。体外释放实验表明，pH-ATO-PLGA@NPs不仅可以达到缓释效果，还具有pH响应特性。细胞实验结果表明，PLGA及pH-PLGA纳米粒载体毒性低，生物相容性良好。pH-ATO-PLGA@NPs在pH 7.4培养基中半数抑制浓度（IC₅₀）值为（23.71±0.70）μmol/L，而在pH 6.5的培养基中IC₅₀值显著降低（P<0.01），为（16.40±0.62）μmol/L，具备pH响应特性。而在L02细胞中，pH-ATO-PLGA@NPs的细胞毒性［IC₅₀为（39.72±1.84）μmol/L］显著小于ATO溶液［IC₅₀为（28.25±1.33）μmol/L］（P<0.01），降低了在正常细胞中的毒性。结论 pH-ATO-PLGA@NPs具备缓释以及pH响应释药的特性，在肿瘤治疗方面具有较好的应用前景。

Objective To improve the stability of arsenic trioxide (ATO) in vivo with characteristics of pH response and sustained release, a pH responsive poly(lactic-co-glycolic acid) (PLGA) (pH-PLGA) nanoparticles was designed to load ATO. Then, the properties and cytological evaluation of pH responsive arsenic trioxide-loaded PLGA (pH-ATO-PLGA) nanoparticles (pH-ATO-PLGA@NPs) was been tested. Methods Using NaHCO₃ as the pH response factor, this study prepared pH-ATO-PLGA@NPs using the double emulsion solvent evaporation method. The particle size, PDI, and Zeta potential of pH-ATO-PLGA@NPs were measured by Malvern particle size analyzer; The morphology of pH-ATO-PLGA@NPs was investigated by transmission electron microscopy; The drug loading and entrapment efficiency of pH-ATO-PLGA@NPs detected by inductively coupled plasma emission spectrum. In vitro release characteristics of pH-ATO-PLGA@NPs under different pH conditions were investigated by dialysis bag method. MTT assay was used to investigate the toxicity of carrier and pH-ATO-PLGA@NPs to HepG2 and L02. Results The shape of the pH-ATO-PLGA@NPs was round and uniform, while the particle size, polydispersity coefficient (PDI), and Zeta potential were (214.35 ±1.86) nm, 0.24 ±0.02, (-35.49 ±1.88) mV, respectively. The encapsulation efficiency and the drug loading rate of pH-ATO-PLGA @NPs were (62.32 ±2.61)% and (1.59 ±0.34)%, respectively. In vitro release studies showed that pH-ATO-PLGA@NPs had the characteristics of sustained release and pH responsive drug release, which can achieve specific drug release in the tumor environment. The carrier displayed remarkable biocompatibility in HepG2 cells. MTT assay showed that the median lethal concentrations (IC₅₀ values) of (23.71 ±0.70) μmol/L at pH 7.4 while (16.40 ±0.62) μmol/L at pH 6.5 (P < 0.01), which showed pH responsive and strong inhibiting effect on tumor cells. In L02 cells, the cytotoxicity of pH-ATO-PLGA@NPs [IC₅₀ (39.72 ±1.84) μmol/L) was significantly lower than that of ATO solution [IC₅₀ (28.25 ±1.33) μmol/L) (P < 0.01), which reduced toxicity in normal cells. Conclusion The pH-ATO-PLGA@NPs reveals significantly sustained and pH responsive release characteristics. The pH-ATO-PLGA@NPs is a potential drug delivery system against tumor with tumor micro-environment responsive.

R283.6

浙江省自然科学青年基金项目（LQ19H280004）；浙江省药学会医院药学专项科研资助项目（石药专项）（2019ZYY22）；浙江省药学会医院药学专项科研资助项目（石药专项）（2019ZYY23）；浙江省药学会医院药学专项科研资助项目（石药专项）（2020ZYY04）