RUI: Liposome Bilayer-Embedded Hydrophobic Palladium Nanoparticles for Selective Catalytic Reactions in Water

模拟酶功能的分子多年来一直令人感兴趣。与天然酶相比，酶模拟物具有结构易修饰、稳定性好、成本低等优点。要模拟天然酶的化学反应活性，需要模型保持酶活性部位及其附近的复杂结构，因为这些部位负责这种反应。在这个项目中，加州州立大学长滩分校的Shon博士正在研究一种模拟酶的新方法，即将钯纳米颗粒嵌入脂质体的脂层中，脂质体类似于细胞膜。纳米粒子的表面反应性可以通过各种分子的附着来改变。所得到的构建体可以提供模拟酶活性部位的相互作用所需的控制水平。Shon博士在他的研究的基础上，积极参与教育项目和外联活动，以促进从高中生到科学、技术、工程和数学(STEM)学科的硕士研究生的参与。这些活动包括面向本科生的凯克能源与材料项目(KEMP)，以及面向高中生的Shon博士实验室的暑期材料研究实习。在化学系化学催化计划的资助下，加州州立大学长滩分校的Shon博士正在对纳米脂质体的包埋、脂相转变、膜流动性以及纳米颗粒的表面配体密度和组成如何影响底物和纳米颗粒之间的非共价相互作用以及决定脂质体双层嵌入的钯纳米颗粒的催化性能产生基本的了解。为了考察脂质体包封率的影响，用不同的脂类考察了不同的相变温度对包封率的影响。改变脂质与钯(Pd)纳米粒子的摩尔比，观察膜流动性的影响。具有可控核尺寸和不同封端配体密度和结构的催化Pd纳米颗粒被用来隔离表面配体的影响与其他因素，如纳米颗粒的尺寸、形状、形貌和脂质体结构。了解吸附在Pd纳米颗粒催化剂表面的二元硫酸盐配体的表面组成和分布的影响，可以区分和控制封端配体的电子和几何贡献。最终，这些发现被应用于基于前药物活化和生物正交酶反应的优化的脂质-纳米颗粒杂化治疗剂的开发。Shon博士积极参与STEM教育，让本科生和硕士研究生接触创造性的科学研究调查。他积极招募妇女和少数族裔学生，他们在STEM领域传统上代表人数较少，以促进研究和教育的平衡发展。他还扩大了一项高中生研究实习计划，以支持该项目的更广泛影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Molecules that mimic the function of enzymes have been of interest for many years. Enzyme mimics provide advantages over natural enzymes as they are easily modified structures, improve stability, and lower cost. Mimicking the chemical reactivity of natural enzymes requires models that maintain the complex structures at and near the enzyme active site as these sites are responsible for that reactivity. In this project, Dr. Shon of California State University Long Beach is investigating a new approach to enzyme mimics where palladium nanoparticles are embedded in the lipid layer of a liposome, which resembles a cell membrane. The nanoparticle surface reactivity is modified by the attachment of various molecules to it. The resulting constructs may provide the level of control needed to simulate the interactions at an enzyme active site. Dr. Shon is actively engaged in educational programs and outreach activities that build upon his research to promote engagement of students ranging from high school students to master-level graduate students in science, technology, engineering and mathematics (STEM) disciplines. These activities include the Keck Energy and Materials Program (KEMP) for undergraduates and summer materials research internships in Dr. Shon’s laboratory for high school students. With funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Shon of California State University Long Beach (CSULB) is developing a fundamental understanding of how nanoparticle liposome embedding, lipid phase transition, membrane fluidity, and surface ligand density and composition of nanoparticles influence the non-covalent interactions between substrates and nanoparticles and determine the catalytic properties of the liposome bilayer-embedded palladium nanoparticles. For the investigation of the influence of liposome encapsulation, various lipids are used to study the effects of different phase transition temperatures. The molar ratio of lipids to palladium (Pd) nanoparticles are varied to observe the influence of membrane fluidity. Catalytic Pd nanoparticles with controlled core size and varying capping ligand density and structure are used for isolating the effect of surface ligands from other factors such as nanoparticle size, shape, and morphology and liposome structure. Understanding the effects of the surface composition and distribution of binary thiolate ligands adsorbed on Pd nanoparticle catalyst surfaces may distinguish and control the electronic and geometric contributions by the capping ligands. Ultimately, the findings are applied to the development of optimized lipid-nanoparticle hybrid therapeutic agents based on pro-drug activation and bioorthogonal enzymatic reaction. Dr. Shon is actively engaged in STEM education by exposing undergraduate and master's-level graduate students to the creative scientific research investigations. He actively recruits women and minority students, traditionally underrepresented groups in the STEM fields, to enhance the balanced advancement of research and education. He is also expanding a high school student research internship program in support of the broader impacts of the project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.