Preparation Of Deoxycholate Acid-carboxymethyl Chitosan Micelles As Co-loading Carrier Of Doxorubicin And Cisplatin For Tumor Inhibition

In present thesis, carboxymethyl chitosan (CMCS) was hydrophobicallymodified by deoxycholate acid (DOCA) to form amphiphilic polymeric micelles forthe co-delivery of doxorubicin hydrochloride (DOX) and cisplatin (CDDP). Theinhibition of tumor cell by co-delivery of therapeutants was accessed.Firstly, deoxycholate hydrophobically-carboxymethyl chitosan (DOCA-CMCS)was synthesized with1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC) and N-Hydroxysuccinimide (NHS) as catalyst. The structure of the productwas characterized by infrared spectroscopy (IR) and1H-nuclear magnetic resonance(1H-NMR). The results showed that the conjugation of DOCA with CMCS increasewith the dosage of DOCA. And the degrees of substitution were ranged from1.6,2.8to4.3per100sugar units.Secondly, the critical aggregation concentration (CAC) of DOCA-CMCS wasmeasured by fluorescence spectrum with pyrene as fluorescence probe. The resultshowed that the CAC of amphiphilic polymer, which ranged from9.55×10-2mg/mL to6.31×10-2mg/mL, increased with the degree of substitution ratio. DOCA-CMCSself-aggregated micelles were prepared by ultrasonic above the CAC concentration.The morphologies and size of self-aggregated micelles were determined by scanningelectron microscopy (SEM) and dynamic light scattering (DLS), respectively. And thezeta potential was also measured. The results showed that the micelles exhibited aspherical morphology, and the size of the self-aggregated particles decreased from364nm to229nm with the increase of substitution degree. The zeta potential ofmicelles also changed along with the substitution degree, increasing from-28.7mV to-7.9mV.Third, DOX was loaded in DOCA-CMCS micelles by the method of solventremoved. Then CDDP were conjugated onto the micelles via their reaction withcarboxyl group of CMCS. The results of SEM and DLS showed that the dosage ofCDDP had a great impact to the morphologies and particles size. When the dosage ofCDDP was small, it has little effect on particles size. But the excessive dosage leadedto the aggregation of micelles, which formed uneven particles with size of about1μm.The optimal drug loaded rates of drug co-loaded nanoparticles were4.29%(DOX) and9.47%(CDDP). The DOX released faster in acidic environments than in neutralenvironments. In contrast, pH had little effect on the release of CDDP. The CDDPcould be released quickly when Cl-were presented. Inhibition of tumor cells bydrug-loaded nanoparticles is measured by MTT. And the results showed that blankdrug carriers have low cytotoxicity with the cell proliferation rate of95.24%. The cellproliferation rate of drug co-loaded nanoparticles was26.51%. While the cellproliferation rates of nanoparticles loading DOX and CDDP alone were31.95%and36.89%, respectively, indicating that drug co-loading had a stronger inhibitory effecton tumor cells.