Influence of Biocorona Formation on the Transformation and Dissolution of Cobalt Nanoparticles under Physiological Conditions.

Nanxuan Mei,Eva Blomberg,Inger Odnevall Wallinder,Jonas Hedberg

doi:10.1021/acsomega.9b02641

Abstract

Cobalt (Co) nanoparticles (NPs) are produced in different applications and unintentionally generated at several occupational and traffic settings. Their diffuse dispersion may lead to interactions with humans and aquatic organisms via different exposure routes that include their transformation/dissolution in biological media. This paper has investigated the particle stability and reactivity of Co NPs (dispersed by sonication prior to exposure) interacting with selected individual biomolecules (amino acids, polypeptides, and proteins) in phosphate-buffered saline (PBS). No or minor adsorption of amino acids (glutamine, glutamic acid, lysine, and cysteine) was observed on the Co NPs, independent of the functional group and charge. Instead, phosphate adsorption resulted in the formation of a surface layer (a corona) of Co phosphate. The adsorption of larger biomolecules (polyglutamic acid, polylysine, lysozyme, and mucin) was evident in parallel with the formation of Co phosphate. The dissolution of the Co NPs was rapid as 35–55% of the particle mass was dissolved within the first hour of exposure. The larger biomolecules suppressed the dissolution initially compared to exposure in PBS only, whereas the dissolution was essentially unaffected by the presence of amino acids, with cysteine as an exception. The formation of Co phosphate on the NP surface reduced the protective properties of the surface oxide of the Co NPs, as seen from the increased levels of the released Co when compared with the nonphosphate-containing saline. The results underline the diversity of possible outcomes with respect to surface characteristics and dissolution of Co NPs in biological media and emphasize the importance of surface interactions with phosphate on the NP characteristics and reactivity.

Highlights

Co metal is widely used in high wear-resistant alloys and as a binder in hard metals because of its excellent wear resistance, magnetic and catalytic properties, as well as strength at high temperatures
This paper focuses on the interaction between Co NPs and different biomolecules of varying structure and properties under simulated physiological conditions with the aims to: (i) deduce the trends in the adsorption of biomolecules of different characteristics, (ii) explore if the formation of a biocorona prevents the agglomeration of Co NPs in solution and, influence their stability and mobility, and (iii) investigate the influence of biomolecule characteristics and biocorona formation on the dissolution of Co NPs
This paper focuses on the interaction between Co NPs and biomolecules of different properties in phosphate-buffered saline (PBS) in order to understand their potential adsorption and biocorona formation and how it influences particle stability, particle characteristics, and the dissolution of Co NPs

Summary

Introduction

Co metal is widely used in high wear-resistant alloys and as a binder in hard metals because of its excellent wear resistance, magnetic and catalytic properties, as well as strength at high temperatures. Nanoparticles (NPs) of Co and Co oxides are further used as pigments, as catalysts, in magnetic fluids, and as contrast agents for medical imaging.[1] Their use and potential dispersion via, for example, wear processes at occupational settings, from implant materials, or tire studs at traffic settings may result in adverse effects on humans and the environment. Repeated exposure to Co ion concentrations exceeding 20 μg/L is reported to result in risks for systemic toxicity.[2] Exposure to Co can induce asthma and acute illness including fever, anorexia, malaise, breathing difficulties, and interstitial pneumonitis.[3] Co is a vital component of vitamin B12, an essential compound for the wellbeing of humans, plants, and animals.[4]

Methods

Results

Conclusion