Khandare Jayant, Kolhe Parag, Pillai Omathanu, Kannan Sujatha, Lieh-Lai Mary, Kannan Rangaramanujam M
Department of Chemical Engineering and Material Science, and Biomedical Engineering, Wayne State University, Detroit, Michigan 48202, USA.
Bioconjug Chem. 2005 Mar-Apr;16(2):330-7. doi: 10.1021/bc0498018.
Dendrimers have emerged as promising multifunctional nanomaterials for drug delivery due to their well-defined size and tailorability. We compare two schemes to obtain methylprednisolone (MP)-polyamidoamine dendrimer (PAMAM-G4-OH) conjugate. Glutaric acid (GA) was used as a spacer to facilitate the conjugation. In scheme A, PAMAM-G4-OH was first coupled to GA and then further conjugated with MP to obtain PAMAM-G4-GA-MP conjugates. This scheme yields a lower conjugation ratio of MP, presumably because of lower reactivity and steric hindrance for the steroid at the crowded dendrimer periphery. In scheme B, this steric hindrance was overcome by first preparing the MP-GA conjugate, which was then coupled to the PAMAM-G4-OH dendrimer. The (1)H NMR spectrum of the conjugate from scheme B indicates a conjugation of 12 molecules of MP with the dendrimer, corresponding to a payload of 32 wt %. In addition, conjugates were further fluorescent-labeled with fluoroisothiocynate (FITC) to evaluate the dynamics of cellular entry. Flow cytometry and UV/visible spectroscopic analysis showed that the conjugate is rapidly taken up inside the cell. Fluorescence and confocal microscopy images on A549 human lung epithelial carcinoma cells treated with conjugates show that the conjugate is mostly localized in cytosol. MP-GA-dendrimer conjugate showed comparable pharmacological activity to free MP, as measured by inhibition of prostaglandin secretion. These conjugates can potentially be further conjugated with a targeting moiety to deliver the drugs to specific cells in vivo.
由于其明确的尺寸和可定制性，树枝状大分子已成为一种很有前景的用于药物递送的多功能纳米材料。我们比较了两种制备甲基泼尼松龙（MP）-聚酰胺胺树枝状大分子（PAMAM-G4-OH）共轭物的方案。戊二酸（GA）用作间隔基以促进共轭反应。在方案A中，PAMAM-G4-OH首先与GA偶联，然后进一步与MP共轭以获得PAMAM-G4-GA-MP共轭物。该方案产生的MP共轭率较低，可能是因为在拥挤的树枝状大分子外围，类固醇的反应性较低且存在空间位阻。在方案B中，通过首先制备MP-GA共轭物来克服这种空间位阻，然后将其与PAMAM-G4-OH树枝状大分子偶联。方案B中共轭物的（1）H NMR光谱表明有12个MP分子与树枝状大分子共轭，对应于32 wt%的载药量。此外，共轭物用异硫氰酸荧光素（FITC）进一步进行荧光标记，以评估细胞摄取的动力学。流式细胞术和紫外/可见光谱分析表明，该共轭物能迅速被细胞摄取。用共轭物处理A549人肺上皮癌细胞后的荧光和共聚焦显微镜图像显示，共轭物主要定位于细胞质中。通过抑制前列腺素分泌测定，MP-GA-树枝状大分子共轭物显示出与游离MP相当的药理活性。这些共轭物有可能进一步与靶向部分共轭，以便在体内将药物递送至特定细胞。
