The Constuction Of Daunomycin Drug Delivery System Based On Apoferritin And Its Effect On Lung Cancer Cells

Due to the effects of the traditional mode of drugs administration are systemic rather than local, drug delivery system has always been of concern to solve the problems of traditional drugs and the pharmacology. In a host of excellent performance developed drug delivery carriers, apoferritin has attracted more and more attention due to its excellent properties.Apoferritin is a naturally derived protein cage. It composes of 24 polypeptide subunits which interact to form a hollow cage-like structure with a diameter of 12.5 nm and its lumen diameter is 8nm. Apoferritin has good biocompatibility and it is stable enough to suffer from a wide range of pH value (pH 2.8-10.6) and has fairly high heat resistance; its subunits can disaggregation and reorganization under the control of pH; and its isoelectric is 4.4, when the pH below 4.4, it is positively charged, and when the pH above 4.4, it is negatively charged. Nowadays, due to its unique structure and quality as well as favourable biocompatibility, apoferritin is widely used as drug delivery carrier to contain or attached delivery both insoluble and water soluble drugs.Daunomycin is an anthracycline antibiotic drug, its toxicity is tremendous to tissues and to the nervous system. It combines the DNA of cancer cells to slow down or stop its growth. In this paper, we used apoferritin as a carrier to delivery to cancer cells to alleviate its effect on normal tissues and cells. We set the pH of experiment conditions as 5.0. Apoferritin was swelling and the protein units were dispersed at the initial pH 5.0. The swelling channel took daunomycin into the protein cage when apoferritin mixed with the drug. Daunomycin carriers positive charge at pH 5.0. However, the electrostatic bonding between positive daunomycin and negative apoferritin cage interior is very weak to encapsulate enough drug molecules. What's more, daunomycin is easily to leak out from the channel of apoferritin cage due to it is a small molecular weight water soluble drug. Based on the above issues, the main contents of this thesis are summarized as follows:Firstly, we can take advantage of the carboxyl of graphene quantum dots (GQDs) and amino of apoferritin to form amido bond, thereby realizing the combination. Whereas, amido bond isn't easy to break, in this case, daunomycin can't release effectively. After discussion and consult literature, we know hydrazine bond can break under acid condition. So we let apoferritin and chloramine to react to form hydrazine bond firstly, then, I use EDC/NHS to activate the carboxyl of graphene quantum dots and combine with amino of hydrazine bond. In this case, we successfully introduced GQDs as blocker to the surface of apoferritin cage to avoid daunomycin from leakage, and at the same time, hydrazine bond can break in acidic conditions of cancer cells so that the drug daunomycin can be released.Secondly, PLAA is a biocompatible polypeptide, has a similar structure with the units of apoferritin, thus, does not increase the toxicity of the drug delivery system. PLAA carriers negative charge at pH 5.0, thus it can combine with daunomycin through electrostatic interaction and can exist stably in the apoferritin cage. Meanwhile, we learn about the surface of cancer cells can express much CD44 receptor through consulting a number of literatures, so we connect hyaluronic acid with the surface of apoferritin to meet the target goal.The main innovation points of this thesis are as follows:1?Currently, few people use both GQDs and apoferritin to applied to cancer cells, and this method supplies a certain way of thinking to future drug delivery.2?The study of based-apoferritin to encapsulate anti-cancer drug daunomycin and apply to actual cells is still relatively rare. Moreover, we have used hyaluronic acid to target, consequently, it laid a foundation for future clinical research.