A comparative study on the enzymatic biodegradability of covalently functionalized double- and multi-walled carbon nanotubes

Abstract

International audienceThe assessment of the biodegradability potential of carbon nanotubes (CNTs) is a fundamental point towards their applications in materials science and biomedicine. Due to the continuous concerns about the fate of such type of nanomaterials, it is very important to understand if they can undergo degradation under certain conditions and if the morphology and structure of the nanotubes play a role in this process. For this purpose we have decided to undertake a comparative study on the enzymatic degradation of CNTs with concentric multilayers. Double-walled (DW) and multi-walled (MW) CNTs of various lengths, degrees of oxidation and functionalizations using different methods were treated with horseradish peroxidase (HRP). While all tested DWCNTs resulted resistant to the biodegradation, some of the MWCNTs were partially degraded by the enzyme. We have found that short oxidized multi-walled CNTs functionalized by amidation were reduced in length and presented a high amount of defects at the end of the period of treatment with HRP. This comparative study holds its importance in the understanding of the structural changes of different types of nanotubes towards the catalytic enzymatic degradation and will help to design safer CNTs for future applications

Wall Thickness of Industrial Multi-Walled Carbon Nanotubes Is Not a Crucial Factor for Their Degradation by Sodium Hypochlorite

“…Degradation of CNTs proceeded to a high extent if they had oxygenated groups (i.e., hydroxyl, carbonyl, carboxyl) on their surface [ 10 , 15 , 18 ]. MWCNT covalent functionalization was shown to affect the rate and extent of MWCNT enzymatic degradation [ 22 , 23 ], and the degradation of MWCNTs by macrophage-like microglia cells both in a culture model and in in vivo experiments [ 24 , 25 ].…”

Polymer Composites Containing Functionalized Nanoparticles and the Environment

“…The point is oxidation of graphite creates defect sites on the structure promoting the biodegradation of graphene. However, excessive functionalization with larger functional groups may prevent their biodegradation [72,73]. Nevertheless, the number of effective enzymes to be used in…”

Ligninolytic activity of the Penicillium chrysogenum and Pleurotus ostreatus fungi involved in the biotransformation of synthetic multi-walled carbon nanotubes modify its toxicity

“…In the last decade, in vitro studies report that oxidative enzymes from human, microbial, or plant can catalyze CNT degradation ( Modugno et al, 2016 ). Additionally, peroxidase isolated from Armoracia rusticana in presence of H 2 O 2 or FeCl 3 partially degrades CNTs structures of a single thick layer or single-walled carbon nanotubes (SWCNTs) ( Allen et al, 2009 ; Magrez et al, 2006 ) and multi-walled carbon nanotubes (MWCNTs) ( Petersen, Huang & Weber, 2008 ; Zhao, Allen & Star, 2012 ).…”