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Abstract：
This study investigated the role of ultraviolet (UV) radiation and oxidation in high-density polyethylene microplastics (2-15 μm) and nanoplastics (0.2-9.9 μm) (NMPs) on particle chemistry, morphology, and reactivity with cadmium (Cd). Additionally, toxicity of NMPs alone and with Cd was evaluated using RTgutGC cells, a model of the rainbow trout (Oncorhynchus mykiss) intestine. The role on NMPs on Cd bioaccumulation in RTgutGC cells was also evaluated. Dynamic light scattering indicated that after UV radiation NPs agglomerated size increased from 0.8 to 28 µm, and to 8 µm when Cd was added. Oxidized MPs agglomerated size increased from 11 and 7 to 46 and 27 µm in non-UV- and UV-aged oxidized MPs when adding Cd, respectively. Cd-coated particles exhibited generally significantly higher zeta potential than non-Cd-coated particles, while attenuated total reflectance-Fourier transform infrared spectroscopy showed that the functional chemistry of the particles was oxidized and modified after being exposed to UV radiation. Presence of NMPs resulted in a significant decrease in Cd bioaccumulation in RTgutGC cells (100.5-87.9 ng Cd/mg protein) compared to Cd alone (138.1 ng Cd/mg protein), although this was not quite significant for co-exposures with UV-aged NPs (105.7 ng Cd/mg protein). No toxicity was observed in RTgutGC cells exposed to NMPs alone for 24 h. Moreover, co-exposures with Cd indicated that NMPs reduce the toxicity of Cd. Altogether these results show that UV aging enhances NMP surface reactivity, increasing Cd absorption in solution, which resulted in a reduction in Cd bioavailability and toxicity.
摘要：
这项研究调查了紫外线（UV）辐射和氧化在高密度聚乙烯微塑料（2-15μm）和纳米塑料（0.2-9.9μm）（NMPs）颗粒化学中的作用，形态学,和与镉（Cd）的反应性。此外,使用RTgutGC细胞评估NMPs单独和Cd的毒性，虹鳟鱼（Oncorhynchusmykiss）肠的模型。还评估了NMP对RTgutGC细胞中Cd生物积累的作用。动态光散射表明，紫外线辐射后，NPs的团聚尺寸从0.8微米增加到28微米，添加Cd时达到8µm。当添加Cd时，非UV和UV老化的氧化MPs中的氧化MPs团聚尺寸从11和7增加到46和27µm，分别。Cd包覆的颗粒通常比非Cd包覆的颗粒表现出明显更高的zeta电位，而衰减全反射-傅里叶变换红外光谱表明，暴露于紫外线辐射后，颗粒的功能化学被氧化和改性。与单独的Cd（138.1ngCd/mg蛋白）相比，NMP的存在导致RTgutGC细胞中Cd生物积累（100.5-87.9ngCd/mg蛋白）显着降低，尽管这对于与紫外线老化的NP（105.7ngCd/mg蛋白）的共同暴露并不十分重要。在单独暴露于NMP24小时的RTgutGC细胞中未观察到毒性。此外，与Cd的共同暴露表明NMP降低了Cd的毒性。总之，这些结果表明，紫外线老化增强NMP表面反应性，增加溶液中的Cd吸收，导致Cd生物利用度和毒性降低。
