| Summary: | 博士 === 國立清華大學 === 化學工程學系 === 104 === The objectives of this research are the preparation of drug / gene delivery vector and the biological sensor electrode materials by utilizing different modified graphenes, which can be applied to cancer therapy and diagnosis. The performances of different modified graphenes for the treatment of brain tumors and the detection ability of prostate cancer, brain tumors have been investigated.
There are six chapters in this dissertation.
The first chapter describes the development of a statistical analysis of cancer, cancer treatment and diagnosis, and the proposed method for preparation the graphene material.
The second chapter introduces the basic theory of graphene composites and reviews the related literatures redarding the brain tumor therapy and magnetic graphene biosensor.
The third chapter focuses on the research on the gadolinium-functionalized nanographene oxide for combined drug and microRNA delivery and magnetic resonance imaging.
The fourth chapter discusses on the study on the combined detection of cancer cells and a tumor biomarker using an immunomagnetic sensor for the improvement of prostate-cancer diagnosis.
The fifth chapter studies the investigation on the use a magnetic graphene biosensor to detect blood levels of vascular endothelial growth factor as the diagnosis of brain tumors.
The sixth chapter is the general conclusions of this dissertation.
1.Gadolinium-functionalized nanographene oxide for combined drug and microRNA delivery and magnetic resonance imaging
The delivery of anti-cancer therapeutics to tumors at clinically effective concentrations, while avoiding nonspecific toxicity, remains a major challenge for cancer treatment. The first part of this thesis presents the nanoparticles of gadolinium-functionalized nanographene oxide (Gd-NGO) can be used as effective carriers to deliver both chemotherapeutic drugs and highly specific gene-targeting agents such as microRNAs (miRNAs) to cancer cells. The positively charged surface of Gd-NGO was capable of simultaneous adsorption of the anti-cancer drug epirubicin (EPI) and interaction with negatively charged Let-7g miRNA. Using human glioblastoma (U87) cells as a model, we found that this conjugate of Let-7g and EPI (Gd-NGO/Let-7g/EPI) not only exhibited considerably higher transfection efficiency, but also induced better inhibition of cancer cell growth than Gd-NGO/Let-7g or Gd-NGO/EPI. The concentration of Gd-NGO/Let-7g/EPI required for 50% inhibition of cellular growth (IC50) was significantly reduced (to the equivalent of 1.3 mg mL−1 EPI) compared to Gd-NGO/EPI (3.4 mg mL−1 EPI). In addition, Gd-NGO/Let-7g/EPI could be used as a contrast agent for magnetic resonance imaging to identify the location and extent of blood-brain-barrier opening and quantitate drug delivery to tumor tissues. These results suggest that Gd-NGO/Let-7g/EPI is a promising non-viral vector for chemogene therapy and molecular imaging diagnosis in future clinical applications.
2.Combined detection of cancer cells and a tumor biomarker using an immunomagnetic sensor for the improvement of prostate-cancer diagnosis
Prostate cancer (PCa) is the second most common cancer in men worldwide. In addition, the incidence of prostate carcinoma increases with age-more rapidly than any other cancers. The development of assays for the early and accurate detection of PCa is therefore of utmost importance. The second part of this thesis introduce a simple, low-cost method for Capture and detection of both a relevant PSMA and CWR22R PCa cells are demonstrated using magnetic graphene oxide (MGO) possessing conjugated antibodies. By simply dropping the MGO onto the surface of Pt electrodes while in a magnetic field, MGO-PSMAab-modified Pt sensor is rapidly constructed. The detection limit for PSMA was 10 pg mL−1 and 46 CWR22R PCa cells per sensor, and the amount of PSMA detected was close to that measured by ELISA. The dual approach of the sensor potentially offers a more accurate, rapid platform than current tests based on immunological methods.
3.Using a magnetic graphene biosensor to detect blood levels of vascular endothelial growth factor as the diagnosis of brain tumors
Currently, the diagnosis of brain tumors in the body examination with medical diagnostic imaging. However, it is great needed to develop a technology in vitro diagnosis rapidly for early diagnosis of brain tumors. The third part of this thesis, a reusable biosensor was proposed based on a magnetic graphene oxide (MGO)-modified Au electrode to detect vascular endothelial growth factor (VEGF) in human plasma for brain tumor diagnosis. In this biosensor, Avastin is used as the VEGF biorecognition element, and MGO is used as the carrier for Avastin loading. The use of MGO enables rapid purification due to its magnetic properties, which prevents the loss of bioactivity. Moreover, the biosensor can be constructed quickly, without requiring a drying process, which is convenient for proceeding to detection. Our reusable biosensor provides the appropriate sensitivity for clinical diagnostics and has a wide range of linear detection, from 31.25-2000 pg mL−1, compared to ELISA analysis. In addition, 100% serum of experiments were obtained from clinical samples, readouts from the sensor and an ELISA for VEGF showed good correlation within the limits of the ELISA kit. The relative standard deviation (RSD) of the change in current (ΔC) for reproducibility of the Au biosensor was 2.36% (n=50), indicating that it can be reused with high reproducibility. Furthermore, the advantages of the Avastin-MGO-modified biosensor for VEGF detection are that it provides an efficient detection strategy that not only improves the detection ability but also reduces the cost and decreases the response time by 10-fold, indicating its potential as a diagnosis product for brain tumor.
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