Fabrication of Uniform Hierarchical Mesoporous Wrinkled Silica Nanoparticles and Their Applications : Chemical Mechanical Planarization, Solar Cell, and Electrorheological Fluid

유재훈 서울대학교 대학원 2018 국내박사

Mesoporous silica nanomaterials have received much attention due to their dramatic increased surface to volume ratio. These porous structures have been used extensively in a variety of applications such as catalyst supporters, adsorption, separation, drug delivery, electrodes, and hard templates for fabrication of nanocomposites due to their unique features. Among various structures of mesoporous silica nanomaterials, spherical mesoporous silica nanoparticles have attracted much attention because they provide excellent pore accessibility and smooth molecular diffusion. Therefore, various methods for the fabrication of spherical mesoporous silica nanoparticles with a range of pore structure types have been reported, and have contributed to the development of fields such as packing materials for chromatography, drug delivery, cosmetics, and adsorption. However, despite the variety of methods for preparing spherical mesoporous silica nanoparticles, it should be still required to develop fabrication methods of spherical mesoporous silica nanoparticles with uniformity and high yields. This dissertation introduces a method for fabricating uniform hierarchical mesoporous wrinkled silica nanoparticles. Furthermore, formation mechanism of the uniform spherical mesoporous silica naoparitcles was discussed by investigating the factors affecting the particle size and pore size of the naoparitcles. Thus, a complete method for high-yield production of uniform hierarchical mesoporous wrinkled silica nanoparticles with tunable particle size and pore size is provided. The prepared uniform mesoporous silica nanoparticles manifested better performance than non-porous silica nanoparticles of the same size in applications of abrasives in chemical mechanical planarization, scattering materials in dye sensitized solar cells, and hard templates for fabricating nanocomposite of ER fluids, demonstrating the superiority of the mesoporous structure. This dissertation suggests that silica nanoparticles with mesoporous structure offer the potential for performance enhancement in applications where non-porous silica spheres are currently used.

Synthesis of large pore sized mesoporous silica nanoparticles for bioapplication

차봉근 성균관대학교 일반대학원 2015 국내석사

Mesoporous silica nanoparticles (MSNs) have been applied to delivery carriers for various guest molecules based on their large surface area and high pore volume. However, most MSNs have small pore size (~ 3 nm) which is a limitation to load relatively large sized proteins in many bioapplication. Although there have been reports on the preparation of large pore-sized MSNs, it is still challenging to control pore structure of MSNs with large pores and to combine with functional nanoparticles. In this study, we demonstrate the integration of large pore sized MSNs with superparamagnetic nanoparticles. The large pore-sized MSNs encapsulating magnetic nanoparticles were prepared by using water-dispersed magnetic nanoparticles as cores and co-solvent as pore expander in the silica sol-gel reaction in the presence of structure directing agents. The resulting large pore-sized MSNs have a bimodal pore structure composed of 3 nm sized small mesopores and ~ 30 nm sized large mesopores. The pore size, pore morphology, and surface area of the resulting MSNs could be controlled by changing the ratio of co-solvents and/or the amounts of silica precursor. To enhance the adsorption of several types of biomolecules typically used in cancer immunotherapy, the surface of large pore-sized MSNs were modified with amine groups, which resulted in higher loading of model antigen protein and immune adjuvant compared to pristine MSNs with surface unmodified and small pores. The resulting MSNs were tested as delivery vehicles of antigenic protein and immune adjuvant to dendritic cells, showing the potential of the large pore-sized MSNs as delivery vehicles for cancer immunotherapy.

Antifungal effect of poly(methyl methacrylate) containing zinc doped mesoporous silica nanoparticles

서영빈 Graduate School, Yonsei University 2024 국내박사

Denture stomatitis is caused by the accumulation of biofilm on the oral tissues and denture surface, characterized by inflammation and erythema of the oral mucosa beneath dentures, affecting many denture wearers. Zinc oxide nanoparticles (ZnO NPs) are known for their antifungal effects against Candida albicans, a common cause of denture stomatitis. However, incorporating ZnO NPs can negatively impact the mechanical properties of denture base resins. To address this issue, mesoporous silica nanoparticles (MSNs) are introduced due to their ability to enhance mechanical properties by forming a micromechanical interlocking interface between the fillers and the resin matrix. In this study, we incorporated Zn-doped mesoporous silica nanoparticles (Zn-MSNs) into poly(methyl methacrylate) (PMMA) and assessed their impact on surface properties, mechanical strength, and antifungal effects against C. albicans. MSNs and Zn-MSNs were synthesized by a sol–gel method and characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). N2 adsorption/desorption measurements were conducted to obtain the specific surface area and pore size. PMMA specimens were prepared by incorporating ZnO NPs, MSNs, and Zn-MSNs at 1.0 and 5.0 weight percentages (wt.%). The PMMA surface gloss was evaluated using a gloss meter with a 2 mm × 2 mm area and a 60° geometry. Translucency was measured using a spectrophotometer operating in reflectance mode and calibrated using a white tile and a black trap following standard procedures. The flexural strength and flexural modulus were measured by a universal mechanical testing machine according to the International Standard ISO 20795–1. The anti-adhesion assessment was performed by a colony-forming unit (CFU) against C. albicans. TEM images of MSNs and Zn-MSNs were successfully prepared and exhibited spherical morphology with a well-ordered mesoporous structure. ZnO NPs were found to be irregular in shape and had varying sizes and aspect ratios, with some of the particles agglomerating. EDS mapping results of the Zn-MSNs showed the composition and distribution of the Si, O, and Zn elements. Zn was successfully doped with an amount of approximately 7.34 wt.% and homogeneously distributed. According to the IUPAC classification, the N2 adsorption–desorption curves showed typical characteristics of the type IV isotherm of mesoporous materials. BET analysis confirmed the porosity of the Zn-MSNs with a pore size of 3.41 nm, pore volume of 0.77 cm3/g, and surface area of 848 m2/g. The surface gloss observed no significant difference between the control group, the 1% MSN, and the 1% Zn-MSN groups. In contrast, the 1% ZnO group showed a lower gloss value than the 5% MSN and 5% Zn-MSN groups. Moreover, the 5% ZnO group had the lowest surface gloss value among all the groups. Regarding translucency results, no significant difference was observed among all groups with the incorporation of MSNs and Zn-MSNs. However, the 1 wt% ZnO and 5 wt% ZnO groups showed significant differences from the control group. The flexural strength showed no significant difference in the incorporation of 1 wt% of MSN and Zn-MSN groups compared to the control group. However, when the concentration of MSN and Zn-MSN groups was increased to 5 wt%, a significant decrease in flexural strength was observed. Among all groups, the lowest flexural strength value was observed in the 5% ZnO group. Nevertheless, the flexural strength of all groups fulfilled the minimum requirements (60 MPa) specified in ISO 20795-1. As a result of fungal anti-adhesion, the control group showed the highest value, and the denture base resin containing 5 wt% ZnO, 5 wt% MSN, and 5 wt% Zn-MSN showed a significant difference from the control group. Among all values, 5 wt% Zn-MSN showed the lowest value. In this study, denture base resins incorporating ZnO NPs, MSNs, and Zn-MSNs were prepared, and the antifungal effect against C. albicans and clinical applicability were investigated. Incorporating Zn-MSNs into denture base resin exhibited acceptable surface properties, mechanical strength, and effective antifungal activity against C. albicans. Therefore, the denture base resin containing 5 wt% Zn-MSN is expected to be a valuable material for denture. 의치 구내염은 의치 착용자에게 흔하게 발병하는 질환으로, 구강 점막의 염증과 홍반을 특징으로 한다. 산화아연나노입자 (ZnO NPs)는 의치 구내염의 주요 원인 중 하나인 칸디다 알비칸스(Candida albicans)에 대한 항진균 효과를 가지고 있지만, 의치 레진에 직접 첨가할 경우 기계적 특성에 부정적인 영향을 미칠 수 있다. 한편, 메조포러스 실리카 나노입자(MSNs)는 필러와 레진 기질 사이에 미세 기계적 연동 인터페이스를 형성하여 기계적 특성을 향상시키는 능력으로 인해 다양한 분야에서 연구가 활발히 진행되고 있다. 따라서 본 연구에서는 아연이 도핑된 메조포러스 실리카 나노입자(Zn-MSNs)를 폴리메틸 메타크릴레이트(PMMA)에 첨가하여 표면 특성, 기계적 강도, 및 항진균 효과에 미치는 영향을 평가하였다. MSNs과 Zn-MSNs은 졸-겔 방법으로 합성되었으며, 합성된 입자는 메조다공성 구조를 갖는 구형 형태를 나타냈다. PMMA에 준비된 MSNs, ZnO NPs, Zn-MSNs 나노입자를 각각 1 wt%, 5 wt% 첨가하여 실험군을 제작하였고, 아무것도 첨가하지 않은 PMMA를 대조군으로 하였다. 반투명도 결과에서 MSNs과 Zn-MSNs을 첨가한 그룹에서는 대조군과 유의한 차이를 보이지 않았으나 1% ZnO과 5% ZnO은 모두 유의한 차이를 나타냈다(p<0.05). 기계적 특성 실험 결과, 대조군이 가장 높은 값을 보였으며 1% ZnO, 5% MSN, 5% Zn-MSN, 5% ZnO 군과 유의한 차이를 나타냈다(p<0.05). 그 중 5% ZnO은 모든 그룹 중에서 가장 낮은 값을 나타냈다(p<0.05). C. albicans에 대한 항진균 실험 결과 대조군이 가장 높은 균 생존율을 보였으며, 5% ZnO, 5% Zn-MSN과 유의한 차이를 나타냈다(p<0.05). 5 wt% Zn-MSN을 의치상 레진에 첨가하면 5 wt% ZnO를 함유한 의치상 레진에 비해 우수한 표면 특성과 기계적 강도를 나타냈다. 또한 C. albicans에 대한 항진균 실험 결과, 효과적인 항진균 활성을 나타냈다. 결과적으로 Zn-MSN을 5 wt% 함유한 의치상 레진은 의치용 재료로 활용할 수 있는 잠재력이 있음을 시사한다.

Multifunctional mesoporous silica nanoparticles for immunotherapy

Cha, Bonggeun Sungkyunkwan university 2019 국내박사

The term ‘immune-nano-bioengineering’ is used to describe to design materials, delivery vehicles and molecules both to manipulate and to better understand the immune system. The field is rapidly evolving along with advances in understanding of immunology and is also contributing to knowledge of basic immunology. Over the past decade, particulate carriers have emerged as an attractive means for enhancing the delivery efficacy and potency of vaccines and associated immunomodulatory molecules. Specifically, engineered nanomaterials are being extensively studied for a wide variety of applications. Recently, a lot of researches focus on the immunotherapy for overcoming cancer, chronic viral disease, infection, allergy, and autoimmunity. Along with the development of nanotechnology, these research trends are accomplished progression to immune-nano-bioengineering. To apply nano-engineered materials to immunotherapy is accompanied delivery property. Especially, multi-functional inorganic nanocomposite can be proposed for the application to immunotherapy, subdividing immunoactivation, suppression, and modulation. For example, in case of based on mesoporous silica nanoparticles, changes of physical and chemical properties, different surface engineering, and composition of theragnostic function can affect the immunoengineering properties. Furthermore, both interior and exterior side of mesoporous silica nanoparticles can be decorated with various functional inorganic nanomaterials simultaneously. These multi-functional inorganic nanomaterials become one of the best candidates to apply various immunotherapy areas. In this thesis, the four parts of ‘immune-nano-bioengineeging’ are investigated the synthesis of multifunctional mesoporous silica nanoparticles, included changing of pore structure, immunosuppression through ROS scavenging, immunoactivation by cancer vaccine, and immunomodulation to macrophage polarization. Firstly, a facile method to expand pore size of mesoporous silica nanoparticles embedding superparamagnetic nanocrystals is demonstrated. Uniform extra-large pore mesoporous silica nanoparticles (XL-MSNs) with 30 nm pores were synthesized using organic additives to form extra-large pores in the presence of inorganic seed nanoparticles to generate uniform particles. Furthermore, XL-MSNs show a simple size and pore morphology controlling. Furthermore, XL-MSNs showed significantly higher loading capacity for the model proteins with different molecular weights compared to conventional small pore MSNs. Secondly, the use of XL-MSNs as a cancer vaccine through the delivery of protein antigen and danger signal was demonstrated. Additional surface modification of XL-MSNs resulted in significantly higher loading of antigenic protein and toll-like receptor 9 (TLR9) agonist compared with conventional small-pore MSNs. In vitro culture of bone marrow-derived DCs (BMDCs) in the presence of XL-MSNs loaded with antigen and TLR9 agonist led to enhanced DC activation and antigen presentation and increased secretion of proinflammatory cytokines. An in vivo study demonstrated efficient targeting to draining lymph nodes, induction of antigen-specific CTLs, enhanced suppression of tumor growth after vaccination, and prevention of tumor growth after rechallenge of cancer cells into vaccinated mice due to a significant generation memory T cells. Thirdly, XL-MSNs as delivery carrier of IL-4 for macrophage polarization were demonstrated. XL-MSNs showed significantly higher loading capacity for IL-4 compared to conventional small pore MSNs. XL-MSNs did not induce the secretion of proinflammatory cytokines in vitro or in vivo, which is advantageous for polarization of anti-inflammatory M2 macrophages. Finally, their ability to deliver the M2-polarizing cytokine IL-4 to macrophages in vivo via uptake by phagocytes was demonstrated. These results suggest that XL-MSNs are an effective platform for delivery of cytokines to MPS cells for in vivo modulation and the subsequent treatment of inflammation-associated diseases. Finally, anti-inflammatory nanoparticle assembly on the MSNs is developed. Cerium oxide (ceria) nanoparticles, inorganic ROS scavenging catalyst, synthesized in an aqueous media were electrostatically bound on the surface of MSNs that had magnetic nanoparticles for MR imaging contrast agents. In intracerebral hemorrhage (ICH) model, MRI clearly showed that the intracerebrally injected ceria nanoparticles doped MSNs was effectively delivered to the peri-hematomal area where secondary brain injury occurred. Furthermore, the lipid bilayer supported the multifunctional nanocomposition for increasing dispersity and circulation in body fluid. In the peri-hematomal area, multifunctional nanocomposition was internalized by macrophages and attenuated inflammatory cell infiltration through ROS scavenging capacity of ceria nanoparticles, which is required for resolving the intense inflammation induced after ICH. Furthermore, multifunctional nanocomposition significantly reduced brain edema induced by ICH and enhanced neurologic outcomes in treated rats. Taken together enhanced loading capacity and multifunctionalities of MSNs suggest that MSNs can be used as an attractive platform for immunotherapy in the future.

Engineering Mesoporous Silica Nanocomposite for Efficient Drug Delivery Against Cancer

Karmacharya, Prajeena 영남대학교 대학원 2024 국내박사

Hollow mesoporous silica nanoparticles with extra-large mesopores for enhanced cancer vaccine

Lee, Junyup Sungkyunkwan university 2020 국내석사

Due to the limitations of the conventional cancer therapy, the cancer immunotherapy has emerged to prevent the recurrence of cancer. In order to provoke the adaptive immune responses in antigen-specific manners, it is important to develop an efficient antigen delivery system that could enhance the activation and maturation of the dendritic cells (DCs) in the body. Mesoporous silica nanoparticles (MSNs) are one of the most promising nanocarriers for antigen delivery due to their mesopores, high surface area and large pore volume, easy modification of physical and chemical functionalities, their biocompatibility, and self-adjuvanticity. In this study, we have synthesized the hollow mesoporous silica nanoparticles with extra-large pores (H-XL-MSNs) with large mesopores (20~30 nm) and hollow interior void based on a single-step synthesis of core-shell mesoporous silica nanoparticles with a core composed of assembly of iron oxide nanoparticles. The hollow void inside the mesoporous silica nanoparticles with large mesopores allowed to have advantages for high loading efficiency of various model proteins with different sizes. The H-XL-MSNs were coated with the poly(ethyleneimine) solution (PEI) to provide immune adjuvant and to change the surface charge of the particles for loading and slow release of model antigen. In vitro study showed the enhanced activation of the DCs. The in vivo study demonstrated that the resulting cancer vaccine led to the increase of antigen-specific cytotoxic T cells, enhanced suppression of tumor growth, and improved survival rate after challenging cancer to mice. With this finding, the hollow MSNs with extra-large pores, can be used as superior antigen-carrier for immunotherapy. 지금까지의 전통적인 암 치료법의 한계로 인해 최근 암의 재발을 억제하는 암 면역 치료에 관한 연구가 많이 진행되고 있다. 항원 특이적 방식으로 적응 면역 반응을 유발하기 위해서는 체내의 수지상세포를 활성화시키고 성숙시키는 효율적인 항원 전달 시스템이 중요하다. 다공성 실리카 나노입자는 다공성 구조, 높은 표면적, 큰 기공 부피, 표면 화학적 기능기 개질의 수월성, 생체 적합성, 그리고 고유의 면역보조제 기능으로 인해 암백신 전달체로 적합한 특성을 지니고 있다. 본 연구에서는 내부에 빈 공간(중공)을 가지며 동시에 이를 감싸는 실리카 외벽에 상대적으로 큰 크기의 중형세공 (20~30 nm)을 갖는 다공성 실리카 나노입자 (H XL MSNs) 를 합성하고 이를 암백신에 적용하였다 먼저 수용액의 극성에 따라 제어되는 산화철 나노입자의 자기조립된 군집을 코어로 하여 계면활성제 존재 하에서 실리카 졸-겔 반응을 유도하여 산화철 나노입자 군집 코어와 다공성 실리카 쉘을 가진 나노입자를 합성하고, 이후 내부의 산화철 나노입자 군집 코어 부분을 낮은 pH에서 제거하여 최종적으로 H-XL-MSN을 합성하였다. H-XL-MSN 내부의 빈 공간과 외부의 큰 다공성 기공으로 인해 다양한 크기의 단백질 분자의 높은 담지량을 확인하였다. 이후 H-XL-MSN의 표면에 면역보조제 역할을 하는 poly(ethyleneimine) (PEI)를 코팅하여 입자 표면의 표면 전하를 양전하로 바꾸어 높은 양의 모델 항원의 담지 및 이의 서방형 방출이 가능한 암백신 나노입자를 합성하였다. 이 나노입자 암백신이 골수유래 수지상세포의 성숙을 촉진하며 생쥐에 피하주사한 이후 항원 특이적 세포독성 T 세포의 증가가 유도됨을 확인하였다. 마지막으로 나노입자 암백신의 피하주사 후 암세포를 다른 부위에 피하주사한 생쥐에서 암세포의 성장을 효과적으로 억제하여 쥐의 생존율이 증가하는 것이 확인되었다. 이와 같이 본 연구를 통해 개발된 내부 중공과 외부 큰 중형세공을 동시에 가지고 있는 다공성 실리카 나노입자는 향후 강화된 암면역 치료를 위한 항원 전달체로 사용될 수 있을 것이다.

Preparation and synergistic antitumor activity of a hydrogel formulation with doxorubicin/curcumin/perfluorocarbon-loaded nanoparticles

Huh, Sumin Sungkyunkwan University 2022 국내석사

A drug synergistic effect refers to the interaction of two or more drugs, in which the overall effect of the drug is larger than the individual effects of each drug added one by one. In this study, we researched the beneficial synergistic effect of two drugs in antitumor effect, and we expected an effective therapeutic effect even with a small amount of the drug. Through this, it is possible to increase the drug efficacy while reducing the dose of a drug with large side effects. The substances used in this study are doxorubicin, which is widely used as an anticancer agent, and curcumin, which has an antitumor effect. To show the synergistic antitumor effect by doxorubicin and curcumin, two different types of nanoparticles were loaded into the hydrogel system. The first were doxorubicin-loaded porous silica nanoparticles, and the other were albumin-bound curcumin nanoparticles using Nab™ technology. The porous silica nanoparticles had many pores on the superficies, and had a diameter of about 60 nm with a spherical form. The pore size of the porous silica nanoparticles was variously controlled, thereby confirming the difference in the loading amount and the release amount of the drug. When the pore size of the mesoporous silica nanoparticles increased, the loading amount increased, and the release amount over time also increased. And albumin with high in vivo stability and high tumor targeting was combined with curcumin to make nanoparticles. These nanoparticles had a size of 145 nm and a spherical shape. As a result of MTT, 2D, and 3D Live/Dead analysis, the two nanoparticles explained a larger cytotoxic effect on cancer cells compared to the individual nanoparticles. In addition, since the tumor is a hypoxic environment, a perfluorocarbon (PFC) nanoemulsion was used as an oxygen carrier to have a higher oxygen concentration, thereby reducing the negative effects of chemical anticancer drugs in a hypoxic environment. This effect was confirmed using CellROX® reagent and HIF-1α antibody. Additionally, the oxygenation by PFC was confirmed in tumors injected into mice through ultrasound images. Here, we believed that this unique hydrogel system can be a novel and promising platform to overcome hypoxic environments while synergistically regulating the release of doxorubicin and curcumin. 약물 상승효과는 두 가지 이상의 약물 간의 상호작용을 말하며, 각 약물의 개별 효과를 합한 것보다 약물의 총 효과가 더 크다. 이 연구에서 우리는 항종양 효과에서 두 약물의 유익한 시너지 효과를 알아보았고, 적은 양의 약물로도 효과적인 치료 효과를 기대한다. 이를 통해 부작용이 큰 약물의 용량은 줄이면서 약효는 증가시킬 수 있다. 이 연구에서 사용된 물질은 항암제로 널리 쓰이는 독소루비신과 항종양 효과를 가지는 커큐민이다. 독소루비신과 커큐민에 의한 상승적 항종양 효과를 보기 위해 두 가지 다른 유형의 나노입자를 하이드로겔 시스템에 로딩하였다. 첫 번째는 독소루비신이 로딩된 다공성 실리카 나노입자이고, 다른 하나는 Nab™ 기술을 사용한 알부민과 결합된 커큐민 나노입자였다. 다공성 실리카 나노입자는 표면에 많은 기공이 있고 60 nm 내외의 크기와 구형의 모양을 형성했다. 다공성 실리카 나노입자는 기공 크기를 다양하게 조절하여 이에 따른 약물의 로딩양과 방출량의 차이를 확인하였다. 다공성 실리카 나노입자는 기공 크기가 커질수록 로딩양이 많아지고, 시간에 따른 방출량도 증가했다. 그리고 생체 내 안정성이 높고 종양 표적성이 높은 알부민을 커큐민과 결합시켜 나노입자를 만들었다. 이 나노입자는 145 nm 의 크기와 구형의 모양을 가졌다. MTT 및 2D, 3D Live/Dead 분석 결과 각각의 나노입자들에 비해 두 나노입자가 함께 들어갔을 때 더 큰 암세포 사멸효과를 나타냈다. 또한 종양에서는 저산소 환경이므로 더 높은 산소 농도를 가지기 위해 과불화탄소(PFC) 나노에멀전을 산소 운반체로 사용하여 저산소 환경에서의 화학적 항암제의 부정적 영향을 줄였다. 이것의 효과는 CellROX® 시약과 HIF-1α 항체를 이용하여 확인하였다. 추가적으로 초음파 사진을 통해 쥐에 주입한 종양에서 PFC 에 의한 산소발생을 확인할 수 있었다. 여기에서 우리는 이 독특한 하이드로겔 시스템이 독소루비신과 커큐민의 방출을 조절하고 시너지 효과를 창출하면서 저산소 환경을 극복하는 새롭고 유망한 플랫폼이 될 수 있음을 보여준다.

Structure engineering of silica nanoparticles and application to display devices

엄기주 Graduate School, Yonsei University 2019 국내박사

실리카 나노입자는 인체에 대한 낮은 독성, 높은 기계적, 화학적 및 열적 안정성, 표면 기능화 용이성, 구조 제어 용이성 등 다양한 이점으로 인해 광범위하게 합성된 실리콘 옥사이드 기반 마이크로미터 이하의 입자다. 많은 종류의 실리카 나노입자들 중에서, 메조다공성 혹은 중공 구조의 실리카 입자들은 다양한 연구자들에 의하여, 그들의 목적을 맞게 합성되고 연구되어 왔다. 그러나, 이러한 구조의 입자를 합성하는 과정에서는 많은 시간과 비용을 필요로 한다. 그러므로, 이 논문은 그러한 시간적, 비용적 문제들을 해결하고자 했다. 이 논문은 중공형 실리카 나노입자를 만드는 새로운 방법을 제안한다. 첫째, 산화아연과 실리카의 반응 속도 차이를 이용하여 산화아연/실리카 코어/쉘 구조를 가진 메조다공성 입자를 합성하였다. 그런 다음 중공형 실리카를 얻기 위해 pH 4.0 의 산성 버퍼를 사용하여 산화 아연 성분을 쉽게 제거할 수 있었다. 이러한 기본 합성법을 기반으로 구조제어를 통해 다양한 구조의 실리카 기반 입자를 합성할 수 있었다. 또한, 새롭게 개발된 합성법을 기반으로, 추가적으로 양친성 고분자를도입함에 따라 메조다공성 중공형 산화 아연/실리카 입자를 단일 공정으로 합성하는 방법 또한 개발되었다. 위와 마찬가지로, 산화 아연 성분을 산성 버퍼를 통해 제거함으로써, 메조다공성 입자의 중공형 공간을 확대할 수 있었다. 이러한 실리카 입자의 형성 메커니즘 및 특징에 대한 이해를 바탕으로 디스플레이 장치에 사용되는 실리카 나노 입자에 대한 연구가 실시되었다. 주름진 표면을 가진 실리카 나노입자가 사용되었으며, 실리카 나노입자의 주름진 표면은 포토레지스트 필름 내에 양자점을 분산시키기 위한 분산체 역할뿐만 아니라, 제작된 필름의 광학적 효율성을 향상시키기 위한 산란 재료로 설계되고 사용되었다. 주름진 실리카와 양자점의 하이브리드 입자를 사용함에 따라, 양자점을 응집시키는 용매가 존재함에도 불구하고 양자점/포토레지스트 나노컴포지트를 제작할 수 있었다. 나아가, 이러한 필름을 마이크로 LED 칩에 올려 간단한 디바이스를 제작하고 그 특성을 분석함에 따라, 이러한 입자의 디스플레이 응용가능성을 입증하였다. Silica nanoparticles are silicon oxide based sub-micrometer particles which have been widely synthesized due to their many advantageous such as low toxicity to human body, high mechanical, chemical and thermal stabilities, ease surface functionalization, and availability to control their structure. Among many types of silica nanoparticles, the particles having mesopores and/or hollow core have been researched by many researchers for their purpose. However, process of synthesize the particles requires many times and costs. Therefore, this thesis tried to solve such problems. This thesis suggests new ways to produce hollow mesoporous silica nanoparticles. First, by using the rate difference of zinc oxide and silica, zinc silicate particles with core/shell structure of zinc oxide/silica were synthesized. The zinc oxide component was then easily eliminated by acid-etching method to obtain the hollow mesoporous silica. From this method, one-pot synthesis method for hollow mesoporous zinc silicate were developed. Through the elimination zinc component step, the hollow space of the particles was enlarged. Based on understanding of formation mechanism of the particles, studies were conducted on silica nanoparticles used in display devices. Silica nanoparticles with wrinkled surface were designed and used not only as templates for dispersing quantum dots in photoresist film and but also as scattering materials for enhancing optical efficiencies. By hybridizing wrinkled silica and quantum dots (QDs), QD/PR nanocomposite could be fabricated despite of presence of non-solvent for QDs. Furthermore, their applicability for display devices were proved by fabricating simple devices in which WSQs were placed on blue µ-LEDs.

Controlling the Properties of Solid-Liquid Interfaces in Silica Nanopores via Surface Functionalization

Singappuli-Arachchige, Dilini Iowa State University ProQuest Dissertations & The 2019 해외박사(DDOD)

This dissertation explores how functionalization of mesoporous silicas affects their solid-liquid interfacial properties. The research work is focused on carefully modifying pore surfaces of mesoporous silica with organic functional groups to create local environments that differ from the bulk medium. Chapter 1 is a general introduction to mesoporous silica nanoparticles (MSN) and a literature review of previous attempts to modify silica-water interface for different applications.Chapter 2 describes an effort to control local polarity at silica-water interface via surface functionalization of MSN. A local polarity scale was created using solvatochromic dye Prodan and interfacial polarity values were assigned to functionalized MSN pores. The effects of pore polarity on quenching of Nile Red fluorescence and on the vibronic band structure of pyrene were also studied. The results showed that the dielectric properties in the pores are different from the bulk water. We found that the catalytic activity of TEMPO for the aerobic oxidation of furfuryl alcohol in water improved when decreasing pore polarity. This work demonstrated that the activity of a nanoconfined catalyst can be modified by controlling the local polarity around it.Chapter 3 further explores the interfacial control of catalytic activity inside the nanometer pores of MSN. The activity of aminopropyl-functionalized mesoporous silica nanoparticles (AP-MSN) for the aldol condensation can be improved by using either a non-polar solvent or an aqueous media. In this work, a novel AP-MSN based catalytic system with combined action of water and low-local polarity environment is presented. Local polarity was tuned by introducing different surface densities of hexyl groups on AP-MSN. The dielectric constants of the hexyl modified silica-water interfaces were determined using the solvatochromic probe Prodan as discussed in Chapter 1. The activity of hexyl-modified AP-MSN in water increased with decreasing interfacial dielectric constants. In addition, aldol reactions with substituted substrates, and other C-C bond forming reactions such as Henry and Vinylogous aldol catalyzed by hexyl-modified AP-MSN in water were enhanced compared to those catalyzed by AP-MSN in water. An improved performance of AP-MSN for aldol condensation and similar reactions were achieved by combining the effects of hydrophobic environments and water at the catalyst-solvent interface.Chapter 4 demonstrates how the orientation and mobility of surface groups affects the strength of non-covalent interactions between a guest molecule and the mesoporous silica surface. In this study, we created different phenyl functionalized mesoporous silica samples with different orientations of phenyl groups relative to the pore surface, i.e. rigid perpendicular, variable orientation derived from a flexible ethylene linker, and rigid co-planar. The release of adsorbed Ibuprofen into simulated body fluid from these phenyl-functionalized silicas was analyzed using an adsorption-diffusion model. All phenyl-bearing materials showed lower Ibuprofen initial release rates than bare MSN. The materials with conformationally locked upright and co-planar phenyl groups had stronger interactions with Ibuprofen than those with mobile groups and bare MSN. The obtained results were consistent with DFT calculations. We demonstrated that we could control the kinetics and extent of Ibuprofen release by tuning the type and geometry of non-covalent interactions at the solid-liquid interface.Chapter 5 introduces an approach for controlling interfacial acid-based properties inside nanopores. We demonstrated that the silica-water interfacial pH of MSN can be tuned by functionalizing the pores with different acids and bases. To probe the interfacial pH, we grafted a modified pH sensitive dual emission fluorescent probe, SNARF-AP on silica surfaces. The fluorescence intensity ratio (I588/I635) of the probe at different bulk pH served as a calibration to assign pH values for functionalized mesoporous silica-water interfaces. We showed that interfacial pH varied as a function of the surface groups’ pKa and that it was different from the bulk pH. We attributed the differences to altering protonation/deprotonation equilibria on surface and to the interfacial potential that results from the surface charges. We demonstrated that effective screening of surface charges can be achieved by increasing the ionic strength of the solution. In addition, replacing MSN with a wider pore MSN-10 showed a similar effect. Both these factors affect the proton concentration in the vicinity of surface.

Colliodal mesoporous silica nanoparticles as strong adhesives for hydrogels and biological tissues

Kim, Hodae Sungkyunkwan university 2018 국내석사

Colloidal mesoporous silica (CMS) nanoparticles are evaluated as an adhesive for hydrogels or biological tissues. Because the adhesion energy is proportional to the surface area of the nanoparticles, the CMS nanoparticles could provide a stronger adhesion between two hydrogels than the nonporous silica nanoparticles. In the case of 50 nm CMS nanoparticles with a pore diameter of 6.45 nm, the maximum adhesion energy was approximately 35.0 J/m2 at 3.0 wt %, whereas the 10 wt % nonporous silica nanoparticle solution showed only 7.0 J/m2. Moreover, the CMS nanoparticle solution had an adhesion energy of 22.0 J/m2 at 0.3 wt %, which was 11 times higher than that of the nonporous nanoparticles at the same concentration. We also found optimal pore diameter from maximum adhesion energy of various CMS nanoparticles. Moreover, these CMS nanoparticles are demonstrated for adhering incised skin tissues of mouse, resulting in rapid healing even at a lower nanoparticle concentration. Finally, the CMS nanoparticles had added benefit of quick degradation in biological media because of their porous structure, which may prevent unwanted accumulation in tissues.