The Studies Of New PEG Block-copolymer Carries

The dissertation is chiefly concentrated on the studies of new PEG block-copolymer carries, including the activations of the well water-soluble and biocompatible polyethylene glycol(PEG) by preparing the derivatives with functional groups. The derivatives were used to modify diethylenetriaminepentaacetic acid (DTPA) to produce macromolecular ligands in order to improve the relaxivities of gadolinium complexs. To achieve tumor specificity, the liver tumor-targeting polypeptides have been linked to PEG block-copolymer carries. In this paper, the studies are summarized as follows:The new PEG block-copolymer ligand (â…¢) with functional amino group was prepared. Ligand (â…¢) has two important functions: â‘ . (â…¢) can be complexed with Gd^â…¢ ion to prepare macromolecular contrast agent. In this paper, the macromolecular contrast agent (â…£ ) was synthesized and the relaxivity of (â…£ ) was studied. It proved that, relative to Gd-DTPA contrast agent, the relaxivity of (â…£ ) showed an approximately 38.40% increase in R₁. The MR imaging showed that the macromolecular contrast agent (â…£) greatly enhanced the contrast of MR images of liver in the mice and had a longer circulation half-life. â‘¡. (â…¢) can be modified with a tumor-targeting group to achieve tumor specificity. In this thesis, the liver tumor-targeting polypeptides were linked to the macromolecular ligand (â…¢) and got the product ( â…§) . The results showed that ( â…§) can be endowed with liver tumor-specific property.The new PEG block-copolymer ligand (â…¥b) with functional aldehyde group was prepared. Since the aldehyde group can react with amines easily, ( â…¥b) can be modified with a tumor-targeting compound which have an amino group to achieve tumor specificity. And the ligand (â…¥b) can be complexed with Gd^â…¢ ion to prepare a macromolecular contrast agent. The macromolecular contrast agent ( â…¦b) was synthesized and the relaxivity of (â…¦b) was studied. The relaxivity of (â…¦b) was 10.63 (mmol/ L)^-1·s(-1). Compared to Gd-DTPA contrast agent, the relaxivity of (Vflb) showed an approximately 79.30% increase in R₁.The new methoxy-polyoxyethylene amine derivative (â…¨) was prepared, and (â…¨) was purified using CM-25-Sephadex ion-exchange column and Sephadex G-25 desalting column. (â…¨) has the flexible N-terminal , so it is easy to modify the proteins. The...