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 本项目的目标是开发一种新的纤维取样方法。目前用于航空航天的方法 碳纳米管（CNT）的取样是从微米级石棉取样改进而来的。实现我们 目标，我们将研究不同的碳纳米管和采样过滤器的表面特性有助于效率，开发一个 新的图像分析协议与我们的算法，使用新开发的纳米粒子（NP）等速扩散 采样器，模拟和阐明颗粒的行为，并提出了一种新的方法，适用于碳纳米管采样。 负担：暴露于空气中的碳纳米管一直是最令人关注的，因为它们被指定为潜在的 人类致癌物质。碳纳米管对健康的潜在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，CNT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是CNT纤维取样的推荐方法。CNTs 含有直径为石棉纤维的十分之一到百分之一的单个纤维。关于NIOSH 方法7402被发现是非常具有挑战性和耗时的识别一些非常细的碳纳米管纤维 在电子显微镜下的网格样品上。这一挑战提出的问题包括， 通过7402方法收集的CNT纤维的尺寸代表空气中的那些，无论这些尺寸是 影响的取样和广泛的处理所需的方法，以及如何暴露于细纤维 可以适当量化，以评估相关的健康影响时，该方法尚未验证CNT。 需求：一种新的细纤维取样方法和技术，以1）有效收集取样空气中的纤维 无损失，2）直接分析收集的纤维，对样品进行最少的处理，以及3）容易计数 获得纤维的浓度和尺寸，这将解决曝光测量缺乏准确性的问题 以及样品分析的显著时间要求。当用于CNT时，收集效率和 必须评估取样和分析的性能。设计一种新的采样基底是至关重要的 因为目前使用的用于收集石棉的混合纤维素酯（MCE）过滤器可能不适合于 收集碳纳米管在MCE过滤器上收集的纤维需要被处理以转移到网格进行分析， 较小的纤维可能聚集或损失。能有效收集纤维的新取样方法和基底 直接分析将防止收集的纤维在转移过程中的损失或变化。 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 纳米颗粒可以采用开发的协议和方法来有效地量化暴露水平， 纤维/颗粒浓度。该信息可以改变CNT的当前测量度量，从质量测量到质量测量。 纤维/颗粒数浓度。使用更精确的计数可以表征暴露 浓度非常低，难以测量质量浓度，并提供相关的关联 健康影响的测量低于目前的限制质量量化的碳纳米管。