乳糖酸修饰的黄芩苷自组装胶束载药系统的制备及体外评价

目的制备乳糖酸(lactobionic acid,LA)修饰的O-羧甲基壳聚糖(O-carboxymethyl chitosan,OCMC)偶联黄芩苷(baicalein,BC)的自组装胶束,并考察其作为载体共同递送阿霉素(doxorubicin,DOX)和黄芩苷的可行性。方法以OCMC为水溶性骨架,通过酰胺化反应依次将黄芩苷、乳糖酸偶联到骨架上,分别获得O-羧甲基壳聚糖-黄芩苷偶联物(CMBC)和靶向的乳糖酸-O-羧甲基壳聚糖-黄芩苷偶联物(LA-CMBC)。利用核磁、红外确证偶联物的结构;透析-超声法制备自组装胶束并表征;芘荧光探针法测定临界聚集浓度(critical micelle concentration,CMC);制备载药胶束DOX/LACMBC,紫外测定阿霉素的包封率和载药量;透析法考察载药胶束在不同pH值条件下的释放行为;MTT法考察体外抗肿瘤活性。结果为考察取代度对粒径的影响,制备了3种取代度的CMBC胶束,粒径在164～215 nm,LA-CMBC和DOX/LACMBC胶束的粒径分别约为156 nm和180 nm。LA-CMBC胶束的CMC值为(0.081±0.019)mg/mL。载药胶束中阿霉素的包封率为(69.67±3.87)%,载药量为(16.08±0.25)%。体外释放表明DOX/LA-CMBC具有缓释性和pH敏感性。细胞毒性实验表明,DOX/LA-CMBC胶束对HepG2肝癌细胞生长具有显著的抑制作用。结论制备的载药胶束DOX/LA-CMBC粒径均匀、载药量较好,提高了黄芩苷的水溶性,且具有良好的pH敏感性和抗癌活性。

Preparation and in vitro evaluation of self-assembled micellar drug delivery system of baicalin modified with lactobionic acid

Objective To prepare a self-assembled micelle of lactobionic acid (LA) modified O-carboxymethyl chitosan (OCMC) coupled with baicalein (LA-CMBC), and investigate the feasibility of using it as a drug carrier for doxorubicin (DOX) and baicalein (BC) delivery. Methods Using OCMC as water-soluble skeleton, CMBC and LA-CMBC were obtained by coupling BC and LA to OCMC via amidation reaction. The structure of the conjugate was confirmed by ¹H-NMR and IR. The self-assembled micelles were prepared by dialysis-ultrasonic method. The critical micelle concentration (CMC) of conjugate was determined by pyrene fluorescence probe. The drug-loading micelles (DOX/LA-CMBC) were prepared using LA-CMBC as the carrier. The encapsulation rate and drug loading were measured by UV. The release behavior of DOX/LA-CMBC was investigated by dialysis method. MTT assay was used to evaluate the antitumor activity of drug-loaded micelles in vitro. Results In order to investigate the effect of substitution degree on particle size, CMBC micelles with three substitution degrees were prepared. The diameters of CMBC micelles ranged from 164 to 215 nm. The particle sizes of LA-CMBC and DOX/LA-CMBC micelles were about 156 nm and 180 nm, respectively. The CMC value of LA-CMBC micelles was (0.081 ±0.019) mg/mL. The encapsulation efficiency of DOX/LA-CMBC was (69.67 ±3.87)%, and drug loading was (16.08 ±0.25)%. In vitro release showed that DOX/LA-CMBC micelles had sustained release and pH sensitivity. Cytotoxicity tests showed that DOX/LA-CMBC micelles had significant inhibitory effect on the growth of HepG2 hepatoma cells. Conclusion The prepared DOX/LA-CMBC micelles have uniform particle size, good drug loading capacity, improved water solubility of BC, and have good pH sensitivity and anticancer activity.