Enhancement of polar phases in PVDF by forming PVDF/SiC nanowire composite

Different contents of silicon carbide (SiC) nanowires were mixed with Poly(vinylidene fluoride) (PVDF) to facilitate the polar phase crystallization. It was shown that the annealing temperature and SiC content affected on the phase and crystalline structures of PVDF/SiC samples. Furthermore, the addition of SiC nanowire enhanced the transformation of non-polar α phase to polar phases and increased the relative fraction of β phase in PVDF. Due to the nucleating agent mechanism of SiC nanowires, the ion-dipole interaction between the negatively charged surface of SiC nanowires and the positive CH2 groups in PVDF facilitated the formation of polar phases in PVDF

Development of novel layered nanoparticles for more efficient cancer treatment.

Cancer is the second-most leading cause of death in the United States, with 1.66 million new cases expected to be diagnosed and over 580,000 Americans expected to die of cancer in 2013 alone. (American Cancer Society 2013) Current treatments result in damage to the healthy tissues and incomplete resections of solid tumors, but by harnessing nanotechnology, more effective treatments can be constructed. Gold nanoshells present a promising option for targeted cancer therapy. The anatomy of tumors causes the “enhanced permeability and retention” effect, which means that nano-scale particles will extravasate from the bloodstream and accumulate in the tumors. However, small nanoparticles must still diffuse from the tumor vasculature into the tumor tissue. Due to impaired vascularization, the particles are unable to reach into the entire tumor region. The purpose of our project is to create a “two-layer” nanoshell coated with alkanethiol and phosphatidlycholine and a “three-layer” nanoshell that coats the “two-layer” system with a layer of high-density lipoprotein. It is proposed that these coatings will allow for better penetration of solid tumors compared to the standard nanoshells modified with poly(ethylene glycol) (PEG). In addition to the nanoshells, citrate-gold nanoparticles were investigated as a control. Size, zeta potential, and morphology were optimized, and the penetration of the particles into solid tumors was investigated using dark-field microscopy. It was discovered that the “two-layer” nanoshells exhibited significantly more uptake into the solid tumors compared to PEGylated nanoshells, and should be further investigated as a platform for targeted cancer therapies

Electroless Deposition of Plasmonic Nanostructures on Star Polymer Templates

As an alternative technique, electroless deposition is gaining interest due to its simplicity (solution-based process, no complex instrumentation), economical aspect, and effectiveness to form certain desired film thicknesses and morphologies on a wide variety of substrates. This work describes the use of water-soluble, polyvalent star polymer templates to form spontaneous self-limiting monolayers on complimentary functionalized substrates that act as efficient adhesion layers for the electroless deposition of thin gold films. The resulting gold films display outstanding thickness control, uniformity, reproducibility, and plasmon resonance generation, as evaluated by Rutherford backscattering spectroscopy (RBS), surface plasmon resonance (SPR) spectroscopy, and atomic force microscopy (AFM). The adaptation of this technique to the formation of core-shell gold nanoparticles was also shown to be feasible. The synthesized star polymer-templated gold nanoshells display a tunable NIR absorption depending on their size. By utilizing star polymers as templates, other materials such as drugs or chromophores can be effortlessly embedded inside the star polymer via self-assembled occlusion complex formation. This ability coupled with the efficacy of gold nanoshells in absorbing NIR light and transferring the light energy as heat to their surrounding environment can lead to an integrated form of imaging contrast, drug-delivery system, and photothermal ablation agent

다조성계 플라즈몬 나노 구조의 화학 및 전기적 산란 신호 조절

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 화학부, 2022.2. 남좌민.Plasmon resonance, which is a coherent collective oscillation of conductive electrons in the presence of an external electromagnetic field, effectively enhances various optical processes by means of strong light-matter interactions. Especially, plasmonic nanomaterials scatter light with extraordinary efficiency and the increased far-field radiation intensity can be exploited for the advanced design of biosensors, colorimetric methods for naked-eye detection, and smart displays. However, the full potential of the scattering from plasmonic nanomaterials cannot be fully realized by single component-based nanostructures with monotonic and confined properties. On the contrary, multi-component-based systems exhibit diverse properties and opportunities owing to the synergistically combined physicochemical functions of individual components or new features arising from the integrated structures. In this thesis, I present a chemical and an electrical strategy to modulate scattering response of plasmonic multi-component nanostructures and optimal examples of which showing benefits from the multicomponent systems. Chapter 1 introduces plasmonic properties of multicomponent nanostructures and following advantages of enhanced and modulated plasmonic scattering on applications. In Chapter 2, I developed a highly specific, well-defined Cu polyhedral nanoshell (CuPN) overgrowth chemistry and introduced to enhance light-scattering signal of Au nanoparticle probes for bio-detection. The CuPNs are exclusively formed on the surface of Au nanoparticles in a controllable manner without any noticeable non-specific signal amplification. This newly developed polymer-mediated multicomponent core-shell formation chemistry was shown as a means of the development of the naked-eye-based highly sensitive and quantitative detections of DNA and viruses. Chapter 3 includes new-found anomalous electrochromic behaviors of Au nanocubes. Plasmon scattering of the nanocubes showed higher shift rate of resonance frequency at the highly negative potential range in reversible manner. This unexpected change beyond classical understandings was attributed to the material-specific quantum mechanical electronic structures of the plasmonic materials. The substantial role of quantum capacitance in plasmonic material, which can be derived from the density of states of the composing metals, was able to be verified for the first time by means of altering the surface element by forming Ag-Au core-shell nanocubes.플라즈몬 공명은 외부 전기장에 따른 전도성 전자들의 정합 진동이며, 물질과 빛의 강력한 상호작용을 통하여 다양한 광학적 과정을 효과적으로 증대한다. 특히 플라즈모닉 나노물질은 비범할 정도의 효율로 빛을 산란하며, 증가된 원거리장 방사 세기는 바이오센서, 육안 검출을 위한 비색분석, 스마트 디스플레이 등의 발전된 설계를 위해 활용할 수 있다. 그러나 단조롭고 제한된 특성을 보이는 단일 조성의 나노 구조만으로는 플라즈모닉 나노물질의 산란이 갖는 모든 잠재력을 충분히 발휘할 수 없다. 반면 다조성계 기반 체계에서는 개별 요소로부터 오는 물리 화학적 특성의 상승적 조합이나 결합된 구조로부터 오는 새로운 특성과 같은 다양한 성질과 가능성을 보일 수 있다. 이 논문에서는 플라즈모닉 다조성계 나노구조의 산란 신호를 조절하기 위한 화학적 및 전기적 전략과 다조성계 시스템의 이점을 보여주는 최적의 예를 제시한다. 제1 장에서는 다조성계 나노구조의 플라즈몬 특성과 이를 응용할 때 플라즈모닉 산란의 조절 및 증강으로부터 기대할 수 있는 장점을 소개한다. 제2 장에서는 매우 특이적이고 잘 정의된 구리 다면체 나노쉘(CuPN)의 과성장을 위한 화학적 접근법 개발을 소개한다. 새로운 과성장 법은 바이오 검지를 위해 사용되는 금 나노입자 프로브의 빛 산란에 적용하였다. CuPN은 금 나노입자 표면에서만 선택적이고 제어 가능하도록 형성되었으며 비 특이적 신호 증폭을 나타내지 않았다. 이렇게 새로 개발된 다조성계 코어-쉘을 형성하는 고분자 기반 화학적 합성법이 DNA와 바이러스의 정량 가능한 고감도 육안 검출법의 개발에 사용됨을 보였다. 제3 장은 금 나노 큐브의 색전현상에서 새롭게 발견한 비정상적 거동을 포함한다. 나노 큐브의 플라즈몬 산란은 높은 음전위 영역에서 더 높은 진동수 변화율을 보였다. 고전적인 이해를 벗어나는 이러한 예기치 않은 변화는 플라즈모닉 재료의 물질 특이적인 양자 역학적 전자 구조에 기인한다. 플라즈모닉 재료를 구성하는 금속의 상태 밀도로부터 유도될 수 있는 양자 정전용량의 상당한 역할은, 은-금 코어-쉘 나노 큐브를 형성하여 표면 원소를 바꾸는 방법을 통해 처음으로 증명할 수 있었다.Abstract i Self-Citations of the Prior Publications iv Chapter 1. Introduction: Plasmonic Scattering of Multicomponent Nanostructures 1 1.1. Light Scattering of Plasmonic Nanomaterials 2 1.2. Plasmonic Multicomponent Nanostructures 7 1.3. Plasmonic Scattering Modulation for Applications 14 Chapter 2. Polyhedral Cu Nanoshell Formation Chemistry for Bio-Detections 23 2.1. Introduction 24 2.2. Experimental Methods 28 2.3. Results and Discussion 40 2.4. Conclusion 66 Chapter 3. Unconventional Electrochromic Behaviors of Plasmonic Au and Au-Ag Core-Shell Nanocubes 71 3.1. Introduction 72 3.2. Experimental Methods 81 3.3. Results and Discussion 90 3.4. Conclusion 115 Bibliography 119 Abstract in Korean 126박

The Optical Properties of Spiky Gold Nanoshells

Plasmonic nanoparticles are a powerful and versatile tool for molecular sensing, drug delivery, and cancer treatment. When exposed to incident light, these nanoparticles have greatly increased far-field scattering and near-field enhancement. Spiky gold nanoshells are a recently developed class of nanoparticles composed of sharp gold spikes decorating a polystyrene core. Spiky nanoshells are synthesized using the templated surfactant-assisted seed growth method, which enables extensive control of the nanoparticle morphology. Here, it is shown that these particles have a tailorable far-field resonance, extremely uniform single-particle surface enhanced Raman scattering, and modal interference in dark-field microscopy measurements. Finite-difference time-domain simulations are performed to determine the morphological features which control these unusual behaviors. Additionally, a T-matrix method was developed to use finite-difference time-domain simulations to analyze mode mixing in these particles. These studies show that the lengths of spikes are critical in determining the far-field scattering peak. Additionally, simulation of the electric field near the particle surface show that the near-field Raman surface enhancement is dominated by the quadrupole modes, resulting in Quadrupole Enhanced Raman Scattering. Due to the large number of spikes, the near-field enhancement is relatively insensitive to variations in individual spikes, resulting in emergent homogeneity in optical properties due to heterogeneity in the structure. The disorder induced asymmetry of the spiky nanoshell enables mode-mixing between the dipole and quadrupole modes, which is observed experimentally in dark-field measurements and predicted theoretically in a T-matrix analysis of finite-difference time-domain simulations. This mode mixing was found to be of the order of 5% between the quadrupole and dipole modes. Such mode mixing is responsible for the broadening of the quadrupole modes towards the infrared and for the activation of all six quadrupole moments, partially explaining how heterogeneity can result in reliable and robust near-field enhancement