Probing Facet Dependent Properties of Crystalline Nanomaterials and Interactions with Biomolecules using Hybrid AFM

二氧化铈、氧化锌和二氧化钛等金属半导体纳米材料或纳米颗粒的大量生产，在防晒霜、抗菌剂、太阳能转换和催化等商业产品和工艺中有着广泛的应用。这些纳米材料表现出对其工业应用非常重要的显著特性。然而，同样独特的性质也可能导致意想不到的生物学后果(例如，细胞损伤和细胞膜破坏)，这通常被归因于内在和/或外在性质。本征性质包括尺寸、形状、表面积、化学成分、结晶度、电子和表面反应性。外在性质包括自由基的形成和溶解，这取决于内在性质和环境因素。了解纳米材料特性在毒性机制中的作用对于建立安全和可持续的纳米技术的监管和制造框架至关重要。该项目将包括一套创新的扫描探头方法，以揭示小平面材料的特性和真正的“纳米”效果。最终，这些研究成果不仅可以促进纳米技术的设计安全性，还可以促进功能纳米材料在催化、生物医学、光疗和药物输送等广泛应用中的定制制造，其中纳米材料的晶体刻面工程发挥着关键作用。其他更广泛的影响包括(1)开发新的教学模块、实验室手册和针对不同学生群体的互动学习活动，以增加STEM劳动力。(2)组织纳米技术主题研讨会系列和扫描探针显微镜实践培训。这一努力将通过学术界和产业界的合作，为区域可持续纳米技术研究和教育联盟建立一个协调中心。远程参与者将通过现场直播研讨会和其他互动网络研讨会有效地参与其中；在分子水平上，纳米材料的尺寸或形状的任何变化都可能与其暴露的晶面或晶格面的变化有关。据报道，不同晶面的取向和分布会改变表面电荷、表面张力或疏水性、光催化活性和表面反应活性，从而最终改变纳米材料的生物效应。这项研究的中心假设是，通常表征的纳米材料的性能(例如，尺寸、形状和Zeta电位)及其对环境或生物的影响可能源于暴露的晶面或小平面及其相关表面结构、原子配置和特征的差异。为了验证这一假设，本项目试图实现以下具体目标：(1)研究具有不同形貌(立方体、八面体和片状)的高晶态半导体纳米材料对晶面分布的依赖关系。(2)定量刻面本征性质，如光反应性、能带结构和疏水性，以更好地揭示刻面相关或由刻面控制的表面性质。(3)展示了原子力显微镜结合拉曼光谱和红外光谱等混合扫描探针技术在纳米材料表面物理化学定位中的应用。(4)研究纳米材料暴露面上的生物分子相互作用(吸附、结合和降解)的机制，为潜在的生物学意义提供新的见解。此外，这些研究成果将被纳入STEM教育和劳动力发展。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。

Metallic semiconductor nanomaterials or nanoparticles, such as cerium dioxide, zinc oxide and titanium dioxide, are produced in high volume and have broad applications in commercial products and processes such as sunscreens, antimicrobial agents, solar energy conversion and catalysis. These nanomaterials exhibit remarkable properties important to their industrial applications. However, the same unique properties may also cause unexpected biological consequences (e.g., cellular injury and cell membrane disruption), which are commonly attributed to the intrinsic and/or extrinsic properties. Intrinsic properties include size, shape, surface area, chemical composition, crystallinity, electronic, and surface reactivity. Extrinsic properties include radical formation and dissolution, which depend on intrinsic properties and environmental factors. Understanding of the roles of nanomaterial properties in toxicity mechanisms is critical for establishing regulatory and manufacturing frameworks for safe and sustainable nanotechnology. This project will encompass a suite of innovative scanning probe approaches to unravel facet-level material properties and true "nano" effects. Ultimately, the research findings may not only promote the "safety-by-design" of nanotechnology, but also facilitate the tailored fabrication of functional nanomaterials in a wide array of applications such as catalysis, biomedicine, phototherapy, and drug delivery, where crystal facet engineering for nanomaterials plays a pivotal role. Other broader impacts include (1) developing new teaching modules, laboratory manuals, and interactive learning activities targeted at a diverse student population to increase the STEM workforce. (2) organizing nanotechnology themed workshop series and hands-on training on scanning probe microscopy. This effort will be made through academic-industrial collaborations to build a focal point for regional research and education consortium in sustainable nanotechnology. Remote participants will be effectively involved through live streaming the workshops and other interactive webinars; At a molecular level, any changes in the size or shape of nanomaterials could be associated with changes in their exposed crystallographic facets or lattice planes. Different orientations and distributions of crystal facets have been reported to vary surface charge, surface tension or hydrophobicity, photocatalytic activity and surface reactivity, which ultimately changes biological effects of nanomaterials. The central hypothesis of this research is that the commonly characterized nanomaterial properties (e.g., size, shape, and zeta potential) and their environmental or biological impacts may originate from differences in exposed crystallographic planes or facets and their associated surface structures, atomic configurations and characteristics. To validate this hypothesis, this project seeks to achieve the following specific objectives: (1) Investigate the dependence of crystal facet distribution on highly crystalline semiconductor nanomaterials with distinct morphologies (cube, octahedra and plate). (2) Quantify facet-level intrinsic properties such as photo reactivity, band structures, and hydrophobicity to better reveal facet-dependent or facet-controlled surface properties. (3) Demonstrate hybridized scanning probe techniques such as using an atomic force microscope combined with Raman and infrared spectrometry in localized surface physical and chemical mapping of nanomaterials. (4) Investigate mechanisms of biomolecular interactions (adsorption, binding and degradation) at exposed facets of nanomaterials to provide new insight into potential biological implications. Furthermore, these research outcomes will be incorporated into STEM education and workforce development.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.