Research On The Interaction Of Doxorubicin-SPION With Bovine Serum Albumin Or Bovine Hemoglobin

As an anticancer chemotherapeutic agent utilized therapeutically, the anthracycline antibiotic adriamycin or doxorubicin shows high efficacy with a variety of solid tumous,but it may cause strong side effects and has a deleterious influence on metabolic activity.Because of its non-specific interaction with nonmal tissues,DOX leads to significant nonmal tissue toxicity and limits dosages of it far below the tumor sites required to destroy most malignant lesions.To overcome the problem,the concept of Targeting Drug Delivery System(TDDS) has been proposed.Among kinds of targeted drug deliverers,nanoFe3O4has shown great prospct due to its biocompatibility and unique magnetic properties.Using cells as vehicles is a common approach that evaluates the toxic effect of drug delivery. However, little word is focused on investigating the interaction mechanism between the drug-loaded delivery complex and protein at the molecular level,such as interaction mode,binding constant,and binding site number.Here,we prepare Fe3O4nanoparticles by coprecipitation of Fe3+and Fe2+in alkaline medium under nitrogen atmosphere,and combine DOX to nanoparticles using a pre-formed Fe2+-DOX complex.Then the synthetic DOX-loaded SPION is employed as the reactant to protein.The dissertation consists of the following three parts.In the first part,we prepare Fe3O4nanoparticles by coprecipitation of Fe3+and Fe2+in alkaline medium under nitrogen atmosphere, and combine DOX to nanoparticles using a pre-formed Fe2+-DOX complex.In addition,the characterization of the drug delivery is presented using XRD patterns,Magnetic hysteresis loop,TEM and FTIR. In the second part, we explored the interaction mechanism between DOX-loaded SPION and BSA depending on the combination of spectroscopic and molecular modeling methods. The results indicate that the drug-loaded delivery could unfold the conformation of protein and increase the exposure of chromophore group in the internal hydrophobic region, leading to a microenvironment change of amino acid residues. The content of a-helix decreases from68.62%to62.76%with the addition of DOX-SPION. They finally generated a stable bioconjugate via hydrogen bonds. The interaction constant was5.2×1010and the binding site is located at the domains IIn the third part, we investigated the interaction of BHb with DOX-loaded SPION depending on the combination of spectroscopic and molecular modeling methods. The results indicate that there are two steps in the interaction. First, the drug delivery bond at the external region of BHb (Site1), leading to the lossening of the protein’s skeletal conformation. As the result of the Site1, the conformation of protein has been unfold, leading to the increasing the exposure of chromophore group in the nonpolar hydrophobic cavities, which make chance for the particles to bond at the original hemoglobin central cavity (Site2). They finally generated a stable bioconjugate via hydrogen bonds.In the face of the effect on proteins, the biocompatibility of this drug-loaded delivery should be given more concerns. This work not only clarifies that the mechanism of proteins interacts with DOX-SPION but also provides an approach for the evaluation of protein conformation.