聚苯乙烯纳米塑料-植物蛋白冠的形成与特征

Formation and characteristics of polystyrene nanoplastic-plant protein corona

为探究聚苯乙烯纳米塑料-植物蛋白冠的形成过程以及蛋白冠的形成对植物可能造成的影响,本研究选用3种平均粒径为200nm不同表面修饰的聚苯乙烯纳米塑料微球和新几内亚凤仙(Impatiens hawkeri)为对象,将3种聚苯乙烯纳米塑料分别与新几内亚凤仙的叶蛋白提取物进行反应,反应时间分别为2、4、8、16、24、36 h。利用扫描电镜(scanning electron microscopy, SEM)观察其形貌变化,原子力显微镜(atomic force microscopy, AFM)进行表面粗糙度测定,使用纳米粒度和zeta电位分析仪测定水合粒径及zeta电位,液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry, LC-MS/MS)鉴定蛋白冠的蛋白成分。从生物学过程、细胞组分以及分子功能3个方面对蛋白进行分类,研究不同表面修饰的纳米塑料对蛋白的吸附选择,探究聚苯乙烯纳米塑料-植物蛋白冠的形成与特征,预测蛋白冠对植物造成的可能影响。结果表明:随着反应时间增加,纳米塑料的形貌变化越发明显,表现为尺寸和粗糙度的增加和稳定性的增强,由此证明了蛋白冠的形成;在相同蛋白浓度条件下,3种聚苯乙烯纳米塑料与叶蛋白形成蛋白冠的过程中,由软蛋白冠到硬蛋白冠的转化速度基本一致;在与叶蛋白进行反应时,3种纳米塑料对不同等电点和分子量蛋白的吸附选择存在差异,最终形成的蛋白冠的粒径和稳定性也存在差异,氨基修饰纳米塑料对蛋白质的吸附能力更强,形成的硬蛋白冠的稳定性强于羧基修饰纳米塑料和无修饰纳米塑料;由于蛋白冠的蛋白组分中很大一部分参与植物的光合作用,由此推测,蛋白冠的形成可能对新几内亚凤仙的光合作用产生影响。

To investigate the formation of polystyrene nanoplastic-plant protein corona and its potential impact on plants, three differently modified polystyrene nanoplastics with an average particle size of 200 nm were taken to interact with the leaf proteins of Impatiens hawkeri for 2 h, 4 h, 8 h, 16 h, 24 h, and 36 h, respectively. The morphological changes were observed by scanning electron microscopy(SEM), the surface roughness was determined by atomic force microscopy(AFM), the hydrated particle size and zeta potential were determined by nanoparticle size and zeta potential analyzer, and the protein composition of the protein corona was identified by liquid chromatography-tandem mass spectrometry(LC-MS/MS). The proteins were classified in terms of biological processes, cellular components, and molecular functions to study the adsorption selection of nanoplastics to proteins, investigate the formation and characteristics of polystyrene nanoplastic-plant protein corona and predict the potential impact of protein corona on plants. The results showed that the morphological changes of the nanoplastics became clearer as the reaction time extends, as evidenced by the increase in size and roughness and the enhancement of stability, thus demonstrating the formation of protein corona. In addition, the transformation rate from soft to hard protein corona was basically the same for the three polystyrene nanoplastics in the formation of protein corona with leaf proteins under the same protein concentration conditions. Moreover, in the reaction with leaf proteins,the selective adsorption of the three nanoplastics to proteins with different isoelectric points and molecular weights differed, and the particle size and stability of the final formed protein corona also differed. Since a large portion of the protein fraction in protein corona is involved in photosynthesis, it is hypothesized that the formation of the protein corona may affect photosynthesis in I. hawkeri.