Browsing by Author "Kihara, S"

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    Exploring the biological identity of nanoplastics
    (Institut Laue Langevin, 2024-07-18) Kihara, S; Mata, JP; Domigan, L; Keoper, I; McGillivray, DJ
    Despite recent attention to nanoplastics, there is still much to learn about their surface coatings that give them their “bioidentity”, which is critical to their behaviour in biological contexts. These coatings, corona, form on the particle as a complex mixtures of proteins and other surface-active chemicals – some strongly bound, and others weakly attached and exceptionally hard to study– which depend on both the particle and its environment. We show that the nature of the protein corona in simple systems depends on the surface charge and particle size of the nanoplastics, and that nanoparticles with corona can aggregate to form higher order structures, which may trigger biological stress responses. We also show that model nanoplastics strongly associate with human alveolar epithelial cells, in a manner dependent on their protein corona. However, there is much still to be learnt about the impact of complex environmental systems on these coatings, which is critical to the development of mitigation strategies for nanoplastic contamination.
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    Nanoplastics – protein interaction: a scattering study of transition from soft and hard corona
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Kihara, S; Koeper, I; Seal, C; McGillivray, DJ; Mata, JP
    There is growing concern about plastic waste in the environment, and its impact on biological organisms. While bulk plastics are thought to be non-toxic, when the plastics break down to a sub-micron length scale (i.e. nanoplastics), they obtain extra mobility inside living things, and may cause various adverse effects [1,2]. This, coupled with a lack of knowledge surrounding the dangers from different types of plastics, prevents well-designed responses to the problem. Hypothetically, the potential adverse effects are caused by protein denaturation, oxidative stress and/or cellular mem brane damage. However, the inherent complexity of biological systems makes it challenging to gain a mechanistic understanding. Adding complexity to this problem, the potential adverse effects are highly dependent on the nature of nanoparticles (NPs) – the contributing factors could include elemental composition, chemistry of the plastic surface, and/or size of the plastic particle [3,2,4]. When in biological systems, nanoplastics are surrounded by various types of proteins5. The structure of proteins surrounding nanoplastics are important parameters to understand the interaction of nanoplastic/protein composite. We carried out light scattering and small angle neutron scattering (SANS) experiments to explore the structure of the protein corona on monodisperse polystyrene spheres using a model protein human serum albumin (HSA). The geometry of the PS/HSA complex was investigated with a contrast matching method. The transition from a “soft” to a “hard” interaction between the nanoparticle and the protein was observed when pH is lowered from 7.4, and the implications of this on nanoplastic toxicity is discussed. © The Authors.