| Glioblastoma multiforme（GBM）is the most common primary malignant tumor in brain tumors,with a high mortality and recurrence rate.At present,the standard treatment strategy for glioblastoma is craniotomy and resection to the maximum extent,followed by adjuvant radiotherapy and chemotherapy.Temozolomide（TMZ）capsule is the main chemotherapy agents.However,the postoperative therapy for glioblastoma needs long-term administration.Temozolomide has a short half-life in vivo.The effective drug concentration through circulating blood to the site of the brain tumor is low.And long-term medication makes the intermediate products of temozolomide are accumulated in the heart,liver,lung and other organs.Therefore,the prognosis and therapeutic outcomes of GBM patients are poor,with high systemic toxicity.In order to reduce the toxicity of TMZ in vivo,prolong drug release span,improve the therapeutic effect and reduce the recurrence rate of cancer,this study aims to design a new formulation of temozolomide for the postoperative treatment of glioblastoma.In Chapter 1,the current situation of temozolomide in the treatment of glioblastoma is summarized.Some research progress of TMZ-loaded micro-nanocarriers are introduced.The application prospect of micro-nano-carrier combined with hydrogel is sketched.In Chapter 2,temozolomide loaded solid lipid nanoparticles（T-SLNs）were prepared by emulsion solvent evaporation and diffusion method.The preparation process and formulation were optimized.The optimized T-SLNs showed that the particle size was 190.8±15.3nm,Zeta potential was-20.2±1.7m V,encapsulation efficiency（EE%）was 99.3±0.5%,drug loading（DL%）was 15.1±2.7%.Differential thermogravimetric analysis（DTG）and X-ray diffraction analysis（XRD）were performed on the optimized T-SLNs.The storage stability of T-SLNs was studied.The results showed that the solid lipid had good encapsulation effect on temozolomide,and freeze-dried T-SLNs powder could be stored stably at low temperature for 3months.Then,the freeze-dried T-SLNs were incorporated into the MRI contrast agent hydroxypropyl chitosan（HPCS）/diarylaldehyde PEG（PEG-DF）in-situ hydrogel（T-SLNs@Gel）.The morphologies of solid lipid nanoparticles and hydrogel were observed through scanning electron microscopy（SEM）.And the in vitro drug release and cytotoxicity of solid lipid nanoparticles and hydrogel were studied.The results showed that T-SLNs was stabily filled in the three dimensional reticular pores of hydrogels.Compared with free drugs,the in vitro release time of T-SLNs was up to72 h,while the release time of T-SLNs@Gel was up to 144 h,which prolonged drug release.The in vitro drug release of T-SLNs follows the Higuchi model,while the drug release of T-SLNs@Gel follows the Hixson-Crowell model.In vitro cell experiments,the blank SLNs and hydrogel materials showed no cytotoxicity and retained the bioactivity of temozolomide.Compared with conventional oral administration,the designed hydrogel system containing temozolomide-loaded solid lipid nanoparticles has important potential in the local treatment of postoperative glioblastoma.In Chapter 3,temozolomide was loaded into PLLA by W/O emulsion solvent evaporation method.And the preparation process and formulation were optimized to obtain optimized temozolomide-loaded polylactic acid microspheres（T-PLLA-MS）.The T-PLLA-MS showed regular morphology,small particle size distribution and certain drug loading capacity.The average particle size was 625.4nm,and more than50% of the microspheres are in the range of 600nm~650nm.The microscope images showed that T-PLLA-MS were transparent sphere with smooth surface and poriferous inside.The encapsulation efficiency（EE%）and drug loading（DL%）of microspheres were 78.8±1.4% and 10.1±0.5%,respectively.In vitro drug release results showed that T-PLLA-MS continuously release drug within 15 days.In the early stages of drug release,drug was released rapidly within a short period of time.While this problem could be effectively improved by incorporating T-PLLA-MS into the injectable hydrogel（T-PLLA@Gel）.The drug release can be controlled by controlling the initial amount of drug.Both T-PLLA-MS and T-PLLA@Gel follow the Ritger-Pepper model.In addition,in vitro cytotoxicity studies showed that polylactic acid and hydrogel materials had no cytotoxicity.The obtained T-PLLA@Gel can be used as a drug delivery system with better sustained-release effect.To sum up,in this paper,the route of administration of temozolomide was changed.The drugs were first loaded with sustained-release micro/nano particles to prolong the release time.Then,the drug-loaded particles were combined with injectable and MRI visible in-situ hydrogels,so that they could be better fitted to the surgical residual cavity and further retard the release of the drug,so as to implement location-targeted therapy.In vitro experiments showed that the biological activity of temozolomide was basically maintained in the new carrier,and the drug release time was significantly prolonged.This hydrogels containing micro/nano particles is a promising new formulation of temozolomide in the treatment of glioma. |
