One route has been employed to prepare dendritic-linear block copolymer modified superparamagnetic iron oxide nanoparticles (SPIONs), which consist of a Fe3O4 magnetic nanoparticle core and a dendritic-linear block copolymer, the focal point polyamidoamine-type dendron-b-poly(2-dimethylaminoethyl methacrylate)-b-poly(N-isopropylacrylamide) (PAMAM-b-PDMAEMA-b-PNIPAM) shell by two-step atom transfer radical polymerization (ATRP). Firstly, Fe3O4 nanoparticles were prepared by a high-temperature solution phase reaction in the presence of iron(III) acetylacetonate [Fe(acac)3], oleic acid and oleylamine. Then propargyl focal point PAMAM-type dendron (generation 2.0, denoted as propargyl-D2.0) with four carboxyl acid end groups as a cap displaced the oleic acid and oleylamine on the surfaces. Subsequently, an initiator for ATRP was introduced onto the propargyl-D2.0-modified Fe3O4 nanoparticle surfaces via click chemistry with 2′-azidoethyl-2-bromoisobutylate (AEBIB). PDMAEMA and PNIPAM were grown gradually from nanoparticle surfaces using two-step copper-mediated ATRP. Finally, a crosslinking reaction between PDMAEMA block with 1,2-bis(2-iodoethoxy)ethane (BIEE) was used to stabilize the nanoparticles and reverse aggregation. The modified nanoparticles were subjected to detailed characterization using FT-IR, DLS, XRD and TGA. Magnetization measurements confirmed the characteristic superparamagnetic behavior of all magnetic nanoparticles under room temperature. In addition, doxorubicin (DOX) as an anticancer drug model was loaded into the dendritic-linear block copolymer shell of the modified nanoparticles, and subsequently the drug release was performed in phosphoric acid buffer solution (pH 7.4) at 25 °C or 37 °C. The results verify that dendritic-linear block copolymer-modified nanoparticles as a drug carrier possess thermosensitive drug release behaviors. Furthermore, a methyl tetrazolium (MTT) assay of DOX-loaded dendritic-linear block copolymer-modified nanoparticles against Hela cells was evaluated. The results show that the modified nanoparticles can be used for drug delivery.
一种方法被用来制备树枝状线性嵌段共聚物修饰的超顺磁性
氧化铁纳米粒子(
SPIONs),
SPIONs 由
Fe3O4 磁性纳米粒子核心和树枝状线性嵌段共聚物组成、通过两步原子转移自由基聚合(ATRP)法制备的焦点聚
氨基胺型树枝状-b-聚(2-二甲基
氨基乙基
甲基丙烯酸酯)-b-聚(N-异丙基
丙烯酰胺)(P
AM-b-PD
MAEMA-b-
PNIP
AM)外壳。首先,在
乙酰丙酮铁(III)[Fe(acac)3]、
油酸和
油胺存在下,通过高温溶液相反应制备出 纳米粒子。然后,以四个
羧酸末端基团为帽的
丙炔焦点 PAMAM 型树枝状化合物(第 2.0 代,称为
丙炔-D2.0)将
油酸和
油胺置换到表面。随后,通过与 2′-
叠氮乙基-2-
溴异丁酸酯(AEBIB)的点击
化学反应,在
丙炔基-D2.0 改性的 纳米粒子表面引入了 ATRP 的
引发剂。通过两步
铜介导的 ATRP,PD
MAEMA 和
PNIP
AM 从纳米粒子表面逐渐生长出来。最后,PD
MAEMA 嵌段与 1,2-双(2-
碘乙氧基)
乙烷(BIEE)发生交联反应,以稳定纳米颗粒并逆转聚集。利用 FT-IR、DLS、XRD 和 TGA 对改性纳米粒子进行了详细表征。磁化测量证实了所有磁性纳米粒子在室温下的超顺磁性特征。此外,将抗癌药物模型
多柔比星(DOX)装入改性纳米粒子的树枝状线性嵌段共聚物外壳中,然后在 25 ℃ 或 37 ℃ 的
磷酸缓冲溶液(pH 值为 7.4)中进行药物释放试验。结果验证了树枝状线性嵌段聚合物修饰的纳米颗粒作为药物载体具有热敏药物释放行为。此外,还评估了树枝状线性嵌段共聚物改性纳米颗粒负载 DOX 后对 Hela 细胞的甲基
四氮唑(M
TT)检测。结果表明,改性纳米颗粒可用于药物递送。