Carbon nanomaterial-derived lung burden analysis using UV-Vis spectrophotometry and proteinase K digestion

Dong-Keun Lee,Kyung Seuk Song,Wan-Seob Cho,Jiyoung Jeong,Soyeon Jeon

doi:10.1186/s12989-020-00377-9

Dong-Keun Lee, Kyung Seuk Song + Show 3 more

Open Access

https://doi.org/10.1186/s12989-020-00377-9

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Abstract

BackgroundThe quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. However, some types of nanomaterials, including carbon nanomaterials (CNMs), are difficult to quantify in a biological matrix. Therefore, developing improved methodologies for quantification of CNMs in vital organs is instrumental in their continued modification and application.ResultsIn this study, carbon black, nanodiamond, multi-walled carbon nanotube, carbon nanofiber, and graphene nanoplatelet were assembled and used as a panel of CNMs. All CNMs showed significant absorbance at 750 nm, while their bio-components showed minimal absorbance at this wavelength. Quantification of CNMs using their absorbance at 750 nm was shown to have more than 94% accuracy in all of the studied materials. Incubating proteinase K (PK) for 2 days with a mixture of lung tissue homogenates and CNMs showed an average recovery rate over 90%. The utility of this method was confirmed in a murine pharyngeal aspiration model using CNMs at 30 μg/mouse.ConclusionsWe developed an improved lung burden assay for CNMs with an accuracy > 94% and a recovery rate > 90% using PK digestion and UV-Vis spectrophotometry. This method can be applied to any nanomaterial with sufficient absorbance in the near-infrared band and can differentiate nanomaterials from elements in the body, as well as the soluble fraction of the nanomaterial. Furthermore, a combination of PK digestion and other instrumental analysis specific to the nanomaterial can be applied to organ burden analysis.

Highlights

The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics
We developed an efficient and reliable protocol for measuring the lung burden of various carbon nanomaterials (CNMs) including carbon black (CB), nanodiamond (ND), multi-walled carbon nanotube (MWCN T), carbon nanofiber (CNF), and graphene nanoplatelet (GNP) using proteinase K (PK) tissue digestion and quantification of the recovered CNMs using a UV-Vis spectrophotometer
Five types of CNM including CB, ND, Multi-walled carbon nanotube (MWCNT), CNF, and GNP were selected as test materials, which allowed us to cover most of the available CNMs currently employed in research and industries

Summary

Introduction

The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. There are various methods which can be used to measure the lung burden of non-labelled nanomaterials. Lee et al Particle and Fibre Toxicology (2020) 17:43 steps: (1) collection of nanomaterials from the lung and (2) quantification of nanomaterials using instrumental analysis. Chemical or enzymatic digestion methods are commonly used to collect nanomaterials from the lung tissue. Chemical digestion methods using acids, alkalis, and oxidants are all common but chemical digestion reagents can damage the structure of the nanomaterials resulting in defects, dissolution and oxidation [9]. Enzymatic digestion uses proteinase or collagenase with a chemical lysis buffer and has been proposed as an alternative to chemical lysis, as this degradation approach seems to limit structural damage of the nanomaterials [9, 10]. There are calls for the development of more efficient and reliable measurement methods or protocols for CNMs in an organ

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