[Formation and characteristics of polystyrene nanoplastic-plant protein corona]

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.