Fiber sampling technique and counting protocol development for carbon nanotubes

碳纳米管纤维采样技术和计数协议开发

• 批准号: 10593857
• 负责人: Candace SuJung Tsai
• 金额: $ 19.26万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10593857
• 关键词: Fiber; sampling; technique; counting; protocol

PROJECT ABSTRACT The goal of this project is to develop a new method for fiber sampling. The method currently used for airborne sampling of carbon nanotubes (CNTs) is adapted from micrometer-scale asbestos sampling. To achieve our goal, we will study surface properties of different CNTs and sampling filters contributing to efficiency, develop a novel image analysis protocol with our algorithms, use a newly developed nanoparticle (NP) isokinetic diffusion sampler, simulate and elucidate the particle behavior, and produce a new method suitable to CNTs sampling. Burden: Exposure to airborne CNTs has been of highest concern following their designation as a potential human carcinogen. The potential health effects of CNTs have shown some similarity to those of asbestos fibers in animal models. CNTs global market is projected to reach $103.2 billion by 2030 with 16.3% annual growth. The fiber sampling method used for asbestos has been a recommended method for sampling CNT fibers. CNTs contain individual fibers with diameters that are one tenth to one hundredth that of asbestos fibers. The NIOSH Methods 7402 was found to be very challenging and time consuming for identifying a few very fine CNT fibers on a grid sample under electron microscopy. Questions raised by this challenge include whether the number and size of CNT fibers collected by 7402 method are representative of those in the air, whether these sizes are affected by the sampling and extensive processing required by the method, and how the exposure to fine fibers can be quantified properly to evaluate associated health effects when this method is not yet validated for CNT. Need: A new method and technique for sampling fine fibers to 1) collect fibers efficiently in the sampled air without loss, 2) directly analyze the collected fibers with minimal processing of the sample, and 3) easily count the fibers to obtain the concentration and size, which will resolve the lack of accuracy of exposure measurements and the significant time requirement of sample analysis. When used for CNTs, the collection efficiency and performance of sampling and analysis must be evaluated. It is critical to design a new sampling substrate because the currently used mixed cellulose ester (MCE) filter for collecting asbestos may not be suitable for collecting CNTs. The fibers collected on the MCE filter need to be processed for transfer to a grid for analysis, small fibers can be agglomerated or lost. A new sampling method and substrate that can effectively collect fibers to be analyzed directly will prevent the loss or change of collected fibers through the transfer process. Impact: The wide range of applications that use fiber materials such as CNTs, asbestos and fiberglass and other NPs can employ the developed protocol and method to effectively quantify the exposure level in terms of fiber/particle concentration. This information may change the current measurement metric for CNTs from mass concentration to fiber/particle number concentration. Using more precise counting can characterize the exposure concentration at a very low and difficult to measure mass concentration and provide associations to related health effects for a measurement below the current limit of mass quantification for CNTs.

项目摘要 该项目的目标是开发一种新的纤维采样方法。目前用于机载的方法 碳纳米管（CNT）采样是根据微米级石棉采样改编的。为了实现我们的 目标，我们将研究不同碳纳米管的表面特性和有助于提高效率的采样过滤器，开发一种 采用我们算法的新颖图像分析协议，使用新开发的纳米颗粒 (NP) 等速扩散 采样器，模拟和阐明粒子行为，并产生适合碳纳米管采样的新方法。 负担：在被指定为潜在的碳纳米管之后，暴露于空气中的碳纳米管一直是最受关注的问题 人类致癌物。碳纳米管的潜在健康影响与石棉纤维有一些相似之处 在动物模型中。预计到2030年，碳纳米管全球市场将达到1032亿美元，年增长率为16.3%。 用于石棉的纤维取样方法已成为 CNT 纤维取样的推荐方法。碳纳米管 含有直径为石棉纤维十分之一到百分之一的单个纤维。美国国家职业安全与卫生研究所 发现方法 7402 对于识别一些非常细的 CNT 纤维非常具有挑战性且耗时 在电子显微镜下的网格样品上。这一挑战提出的问题包括是否有数量和 7402方法收集的CNT纤维的尺寸代表了空气中的那些尺寸，无论这些尺寸是 受该方法所需的取样和大量处理的影响，以及如何接触细纤维 当该方法尚未针对 CNT 进行验证时，可以正确量化以评估相关的健康影响。 需求：一种对细纤维进行采样的新方法和技术，以1）有效地收集采样空气中的纤维 无损失，2) 直接分析收集的纤维，对样品进行最少的处理，3) 轻松计数 纤维以获得浓度和尺寸，这将解决暴露测量缺乏准确性的问题 以及样品分析的大量时间要求。当用于碳纳米管时，收集效率和 必须评估采样和分析的性能。设计新的采样基底至关重要 因为目前用于收集石棉的混合纤维素酯（MCE）过滤器可能不适合 收集碳纳米管。 MCE 过滤器上收集的纤维需要进行处理，以便转移到网格进行分析， 小纤维可能会聚集或丢失。一种可有效收集纤维的新采样方法和基质 直接进行分析将防止收集的纤维在传输过程中丢失或变化。 影响：使用碳纳米管、石棉和玻璃纤维等纤维材料的广泛应用 NP 可以采用已开发的协议和方法来有效量化暴露水平： 纤维/颗粒浓度。该信息可能会改变碳纳米管当前的质量测量指标 浓度到纤维/颗粒数浓度。使用更精确的计数可以表征暴露情况 浓度非常低且难以测量质量浓度并提供与相关的关联 低于当前碳纳米管质量定量限制的测量对健康的影响。