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Traditional radiation therapy is limited by the radiotoxic effects on surrounding healthy tissues. This project investigated the use of a gold nanoparticle (AuNP) conjugated to a cell-penetrating peptide (CPP) to increase tumour cell death during radiotherapy by maximizing the cellular import of the gold nanoparticles. ~8300 octaarginine CPPs were coupled per 30 nm AuNP through poly(ethylene glycol) spacers (AuNP-PEG-CPP). The CPPs enhanced the internalization of the AuNPs into three human breast cancer cell lines by a factor >2 as compared to untargeted AuNPs. Cells were treated with AuNP-PEG-CPP for 24 hours, prior to radiotherapy and their long-term proliferation was assessed in clonogenic assays. The increased internalization of AuNPs by the CPPs resulted in greater cell death following exposure to 300 kVp radiotherapy, by a dose enhancement factors between 1.3 and 2.1 depending on the cell line. These findings illustrate the potential of using AuNP-CPPs to enhance radiotherapy in patients.

Traditional radiation therapy is limited by the radiotoxic effects on surrounding healthy tissues. This project investigated the use of a gold nanoparticle (AuNP) conjugated to a cell-penetrating peptide (CPP) to increase tumour cell death during radiotherapy by maximizing the cellular import of the gold nanoparticles. ~8300 octaarginine CPPs were coupled per 30 nm AuNP through poly(ethylene glycol) spacers (AuNP-PEG-CPP). The CPPs enhanced the internalization of the AuNPs into three human breast cancer cell lines by a factor >2 as compared to untargeted AuNPs. Cells were treated with AuNP-PEG-CPP for 24 hours, prior to radiotherapy and their long-term proliferation was assessed in clonogenic assays. The increased internalization of AuNPs by the CPPs resulted in greater cell death following exposure to 300 kVp radiotherapy, by a dose enhancement factors between 1.3 and 2.1 depending on the cell line. These findings illustrate the potential of using AuNP-CPPs to enhance radiotherapy in patients.

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Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17583号 / 工博第3742号 / 新制||工||1570(附属図書館) / 30349 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 平尾 一之, 教授 田中 勝久, 教授 三浦 清貴 / 学位規則第4条第1項該当

Des nanoparticules d’or fonctionnelles ont été synthétisées avec pour objectifs l’élaboration de nanomatériaux pour applications biomédicales et propriétés physiques originales. L’étude de la fonctionnalisation a conduit à utiliser le chimie “click” entre des nanoparticules d’or portant des ligands thiolates azoturés et des alcynes terminaux en utilisant un catalyseur au cuivre (I) renforcé par un ligand polyazoté, ce qui a permis d’introduire des fonctions très variées. En particulier le récepteur folate a été greffé de cette façon pour la synthèse de nouveaux vecteurs du docétaxel, un puissant agent anti-cancéreux dont l’étude est menée en collaboration. Des nanoparticules d’or fonctionnelles ont aussi servi de support pour le greffage de complexes du fer (II) à transition de spin, ce qui a permis de réaliser l’étude en 2D par différentes techniques physiques en collaboration. Enfin un nouveau ligand azoté a été mis au point pour la synthèse de nanoparticules d’or originales. / The thesis concerns functionalizations and applications of gold nanoparticles (AuNPs). In the aspects of functionalization of AuNPs, we concentrated on efficiently functionalized AuNPs by “Click” chemistry. In the aspects of applications, the PEG capped AuNPs was prepared to encapsulate vitamins, which has a potential use in hydrophobic part of human body; the folate functionalized AuNPs was used for docetaxel delivery for cancer therapy; the novel synthesis of triazole stabilized AuNPs used for biosensors; and the citrate capped AuNPs introduced into the silica thin films to check the SERS effect and spin crossover of iron complexes.

Chemotherapy regimens, one of the most common cancer treatments, are often dictated by dose-limiting toxicities. Also, the largest hurdle for translating novel biological therapies such as siRNA into the clinic is lack of an efficient delivery mechanism to get the therapeutic into malignant cells. Both of these situations would benefit from a minimally-invasive controlled release system that only delivers a therapeutic to the site of malignant tissue. This thesis presents work towards the creation of such a delivery platform using two novel material components: a thermally responsive poly[N-isopropylacrylamide-co-acrylamide] (NIPAAm-co-AAm) hydrogel and gold-silica nanoshells. Thermally responsive hydrogels undergo a physical property transition at their lower critical solution temperature (LCST). When transitioning from below to above the LCST, the hydrogel material expels large amounts of water and absorbed molecules. This phase change can be optically triggered by embedded gold-silica nanoshells, which rapidly transfer near-infrared (NIR) light energy into heat energy due to the surface plasmon resonance phenomena. When this material is loaded with absorbed drug molecules, drug release can be externally triggered by exposure to an NIR laser. Initial characterization of this material was accomplished using bulk hydrogel-nanoshell composites. Poly(NIPAAm-co-AAm)-nanoshell composites were synthesized via free radical polymerization. The LCST of the poly(NIPAAm-co-AAm) hydrogels was determined to be from 39-45 deg C, or slightly above physiologic temperature. The material was swollen in a drug solution of either doxorubicin (a common chemotherapeutic) or a 21bp dsDNA olgio (a model molecule for siRNA). Composites were then exposed to an 808 nm laser, which was found to trigger release of the therapeutics from the composite material. Further work has been done in translating this composite material to nano-scale sized particles, such that it could be injected intravenously, passively accumulate in tumor tissue, and be externally triggered to release therapeutics by exposure to an NIR laser. Sub-micron composite particles were synthesized using dissolvable gelatin templates with 500 nm wells. Analysis by transmission electron microscopy (TEM) indicates that these particles consist of gold nanoshells surrounded by a hydrogel coating. Dynamic light scattering (DLS) measurements were used to show that these particles display the same thermal properties as seen in the bulk material: collapsing in response to increased temperatures or NIR light exposure. Ultimately, the work in this thesis advances the development of a minimally-invasive, optically-triggered drug delivery platform.

This study describes the use of human serum albumin (HSA)-modified gold nanoparticles (HSA-AuNPs) for the selective extraction and enrichment of high-pI protein, lysozyme (Lyz) prior to analysis by capillary electrophoresis (CE) with UV detection. HSA-AuNPs are capable of extracting Lyz from a complicated matrix because a HSA capping layer not only stabilizes gold nanoparticles in a high-salt environment but also exhibits strong electrostatic attraction with Lyz under neutral pH condition. Efficient separation of Lyz and other high-pI proteins has been successfully achieved by the filling of cationic polyelectrolyte, poly(diallydimethylammonium chloride) (PDDAC), to the background electrolyte. After capturing Lyz with HSA-AuNPs, PDDAC-filled CE can be directly used for the analysis of the extracted Lyz without the addition of the releasing agent into the extractor. The extraction efficiency relied on the pH of the solution and the concentration of HSA-AuNPs. Under optimal extraction conditions, the limits of detection at a signal-to-noise ratio of 3 for Lyz were down to 8 nM. The combination of HSA-AuNP extraction and PDDAC-filled CE has been applied the analyses of lysozyme in chicken egg white, white wine and human tear. Also, we reveal that this NP-based extraction can be coupled to matrix-assisted desorption/ionization time-of-flight mass spectrometry.

This study presents a simple process for producing resistance-based humidity sensors utilizing dopamine (DA) coated gold nano-particles (AuNPs) as the sensing material. The sensing material for typical humidity sensors are solid state metal oxides, graft-polymers or salt-doped polymers. However, these humidity sensors may suffer from low sensing response or slow time response since water molecules have to diffuse into the sensing materials to induce the electrical property changes. Alternatively, AuNPs have large surface area for water molecule absorption and can be potentially for high performance humidity sensing. Nevertheless, the surface property of AuNPs is hydrophobic and needs to be modified. In this regards, this work uses a highly hydrophilic molecule of dopamine to modify the surface of AuNP into hydrophilic to enhance the humidity sensing performance. Highly hydrophilic bio-molecule of dopamine is physically bonded onto 4-6 nm AuNPs to enhance the humidity sensing performance. Results show that the DA coated AuNPs have nice humidity sensing responses in the measuring range of 20-90%RH. The measured resistance response shows >1500 times greater than the sensor using the same AuNPs without DA coating. The developed humidity sensor shows rapid time responses for water absorption (13 s) and desorption (30 s), respectively. Moreover, a 3-day long-term measurement at low, medium and high humidity ranges also shows the good stability of the developed sensor. The method developed in this study provides a simple and low-cost method to produce high-performance humidity sensors with DA-coated AuNPs.

Gold Nanoparticle-Aided Radiation Therapy (GNRT) is a new paradigm in radiation therapy which seeks to make a tumor more susceptible to radiation damage by modifying its photon interaction properties with an infusion of a high-atomic-number substance. The purpose of this study was to quantify the energy deposition due to secondary electrons from gold nanoparticles on a micrometer scale and to calculate the corresponding microscopic dose enhancement factor during GNRT. The Monte Carlo code EGSnrc was modified to obtain the spectra of secondary electrons from atoms of gold and molecules of water under photon irradiation of a tumor infused with 0.7 wt. % gold. Six different photon sources were used: 125I, 103Pd, 169Yb, 192Ir, 50kVp, and 6MV x-rays. Treating the scored electron spectra as point sources within an infinite medium of water, the event-by-event Monte Carlo code NOREC was used to quantify the radial dose distribution, giving rise to gold and water electron dose point kernels. These kernels were applied to a scanning electron microscope (SEM) image of a gold nanoparticle distribution in tissue. The dose at each point was then calculated, enabling the determination of the microscopic dose enhancement at each point. For the lower energy sources 125I, 103Pd, 169Yb, and 50 kVp, the secondary electron fluence was increased by as much as two orders of magnitude, leading to a one-to-two order of magnitude increase in the electron dose point kernel over radial distances up to 50 um. The dose was enhanced by 100% within 5 um of the nanoparticles, and by 5% as far away as 30 um. This study demonstrates a remarkable microscopic dose enhancement due to gold nanoparticles and low energy photon sources. Given that the dose enhancement exceeds 100% within very short distances from the nanoparticles, the maximum radiobiological benefit may be derived from active targeting strategies that concentrate nanoparticles in close proximity to the cancer cell and/or its nucleus.