Method Development for Quantification of Physicochemical Properties of Engineered Nanoparticles and Their Local-Scale Biological Effects

1235166chen这项NSF奖支持研究工程纳米材料对细胞局部尺度表面物理化学性质的影响。提供纳米材料在纳米尺度上的毒性影响的基本知识，并帮助理解和区分大块或聚合材料和纳米尺度材料的风险，对公众来说是很重要的。智力优势：许多传统的纳米材料毒理学实验并没有在水介质中得到真正的纳米材料，很大程度上是因为大多数纳米材料在测试系统中会发生或快或慢的聚集。观察到的毒性及其相关机制可能与聚集团簇的性质及其扩大的大小有关。然而，未聚集的纳米级工程纳米颗粒（NPs）及其与异质细胞表面的局部相互作用会影响其随后的毒性作用，这一点尚未得到很好的证明。因此，工程NPs的毒性机制尚不清楚。我们要测试的假设是，单个NPs和细胞之间的局部相互作用不可避免地导致细胞在纳米尺度上的物理化学性质的变化。为了定量测量有和没有暴露于NPs的细胞的异质表面特性，我们将开发具有原子力显微镜（AFM）独特优势的新实验方法。该项目的目标包括量化：1)微生物细胞在局部尺度上的生物力学（即硬度和弹性）特性，这些特性会影响细胞的完整性、灵活性和运动性；2)粘附性，影响细胞对环境表面的粘附；3)疏水性，影响界面能和表面相互作用；局部表面静电势，影响细胞系统的稳定性和相互作用能。此外，在遗传水平上，我们还将通过液体成像研究NP-DNA相互作用，以显示NP与DNA之间的动态结合，暴露于NP后DNA的结构构象变化，以及NP结合潜在影响下的DNA转录。更广泛的影响：如果成功，拟议的研究将建立基于原子力显微镜的扫描探针方法，可以量化纳米粒子与生物系统（细胞和DNA分子）相互作用过程中的局部表面物理化学性质，并为探索工程纳米材料的毒性作用提供一个独特的角度。它将填补局部尺度NP相互作用影响的数据空白，并提高我们在工程纳米材料毒性方面的基础知识。这些发现最终将对工业制造商、监管机构和研究人员在可持续纳米材料设计、法规制定以及使用、处理和处置中的生态责任管理方面产生更广泛的影响。此外，我们将通过激励STEM研究领域的本科生和毕业生，引导他们走向纳米科学和纳米技术的前沿，在项目研究和大学教育之间建立协同效应。pi将提供资金，让代表性不足的本科生研究人员参与研究项目。

1235166ChenThis NSF award supports work to investigate the impacts of engineered nanomaterials on local scale surface physicochemical properties of cells. It is important to the general public by providing the fundamental knowledge about the toxic impacts of nanomaterials at nanometer scale and help understand and differentiate risks of bulk or aggregated and nanoscale materials. Intellectual Merit: Many traditional toxicological experiments on nanomaterials have not ended up with real nano-sized materials in aqueous media, largely because most nanomaterials are subject to slow or fast aggregation in the testing systems. The observed toxicity and related mechanisms are likely associated with the properties of aggregated clusters and their enlarged sizes. However, un-aggregated nanoscale engineered nanoparticles (NPs) and their local interactions with heterogeneous cell surfaces influence their subsequent toxic effects, which are not well documented yet. Thus, the toxicity mechanisms of engineered NPs are not clear yet. Our hypothesis to be tested is that local interactions between single NPs and cells inevitably result in changes in the physicochemical properties of cells at nanoscale. To perform quantitative measurements of heterogeneous surface properties of cells with and without exposure to NPs, we will develop novel experimental methods with the unique advantages of atomic force microscopy (AFM). The project objectives include the quantification of: 1) biomechanical (i.e., hardness and elasticity) properties of microbial cells at local-scale, which affect cellular integrity, flexibility, and motility; 2) adhesiveness, which influences cell adhesion to environmental surfaces; 3) hydrophobicity, which affects the interfacial energy and surface interactions; and 4) local surface electrostatic potential, which influences the stability of cell systems and interaction energy. Moreover, at the genetic level, we will also study NP-DNA interactions via imaging in liquid to show the dynamic binding between NPs and DNA, structural conformational changes in DNA upon exposure to NPs, and DNA transcription under the potential influence of NP binding. Broader Impacts: If successful, the proposed research will establish AFM-based scanning probe approaches that can quantify the local-scale surface physicochemical properties during the interactions between NPs and biological systems (cells and DNA molecules) and provide a unique angle for exploring the toxic effects of engineered nanomaterials. It will fill a data gap in the impacts of local scale NP interactions and improve our fundamental knowledge in toxicity of engineered nanomaterials. These findings will ultimately produce broader impacts on industrial manufacturers, regulatory authorities, and researchers for sustainable nanomaterial design, regulation formulation, and eco-responsible management in use, handling, and disposal. In addition, we will establish synergies between the project research and college education by motivating undergraduates and graduates in STEM research areas, and navigating them to the frontiers of nanoscience and nanotechnology. The PIs will provide funding to get underrepresented undergraduate researchers involved in the research project.