<p>MWCNT interactions with protein: surface-induced changes in protein adsorption and the impact of protein corona on cellular uptake and cytotoxicity</p>

Abstract

PurposeProtein adsorption onto nanoparticles in the form of protein corona, affects properties of nanomaterials and their behavior in the biological milieu. This study aims at exploring the effects of multiwalled carbon nanotubes (MWCNTs) surface chemistry on bovine serum albumin (BSA) and immunoglobulin G (IgG), including their adsorption behavior and spatial configurations, as well as the impact on cellular uptake, cytotoxicity, and cellular responses.MethodsThree types of MWCNTs (pristine MWCNTs, MWCNTs-COOH, and MWCNTs-PEG) were synthesized by classical chemical reduction. The size, morphology, hydrodynamic size, and zeta potential were characterized using transmission electron microscopy and dynamic light scattering. MWCNTs were exposed to BSA and IgG solutions, then the amount of MWCNT absorption was performed by bicinchoninic acid assay, and the effects were assessed by utilizing fluorescence spectroscopy, circular dichroism (CD) spectroscopy. Quantitative measurement of MWCNTs uptake with or without protein corona was performed as turbidity method. CCK assay and a microdilution method were performed to evaluate the effects of protein corona on cytotoxicity and pro-inflammatory cytokines release.ResultsThe BSA and IgG adsorption capacities of MWCNTs followed the order pristine MWCNTs>MWCNTs-COOH and MWCNTs-PEG. MWCNT binding can cause fluorescence quenching and conformational changes in BSA and IgG, indicating that both the physicochemical properties of MWCNTs and protein properties play critical roles in determining their adsorption behavior. Further study showed time-dependent increases in MWCNT cellular uptake and internalization. Hydrophobicity is the major factor increasing cellular uptake of pristine MWCNTs, but a protein corona enriched with dysoposnins is the main factor reducing uptake of MWCNT-COOH by RAW264.7 cells. The cytotoxicity and pro-inflammatory response related to physicochemical properties of MWCNTs, and frustrated phagocytosis is a key initiating event in the pro-inflammatory response of MWCNT-exposed macrophages.ConclusionThese findings shed light on how functionalized MWCNTs interact with protein coronas and provide useful insight into the dramatic effect of protein coronas on different functionalized MWCNTs. These events affect cellular uptake and cytotoxicity, which could inform how to enhance MWCNT biocompatibility and develop approaches for managing MWCNT hazards.

Cytotoxicity-Related Bioeffects Induced by Nanoparticles: The Role of Surface Chemistry

“…PEG decoration on ZnO NPs (39 nm) reduced the internalization into THP-1 and differentiated THP-1 cells compared to levels of NPs with APTES decoration that were internalized (Luo et al, 2014). Regarding MWCNTs (average diameter of 10-20 nm and length of 5-15 µm), PEG decoration reduced the number taken up by RAW264.7 cells (Zhang T. et al, 2019).…”

“…The absence of serum in the medium did not affect the uptake of positively charged amine-SWCNTs; however, the absence of serum significantly enhanced the internalization of negatively charged carboxy-SWCNTs in HeLa cells (Budhathoki-Uprety et al, 2017). In RAW264.7 cells, the cellular uptake of carboxyl-MWCNTs (average diameter of 10-20 nm and length of 5-15 µm) was greater than that of pristine MWCNTs, and the BSA and IgG corona could alleviate the internalization of the carboxy-MWCNTs and enhance the uptake of the pristine MWCNTs (Zhang T. et al, 2019). The internalization of carbon NPs (CNPs) smaller than 50 nm was systematically investigated in breast cancer cells in different stages (including the early and late metastatic stages).…”

“…Compared to NPs with glucose decoration, PEG-iron oxide NPs (12 nm) bound fewer proteins (Stepien et al, 2018). PEG decoration was also found to reduce the adsorption of BSA and IgG compared to pristine multi-walled carbon nanotubes (MWCNTs, with an average diameter of 10-20 nm and length of 5-15 µm) (Zhang T. et al, 2019).…”

“…With BSA coronas, pristine MWCNTs induced higher levels of IL-1β than did COOH-MWCNTs, and both kinds of MWCNTs induced similar levels of TNF-α. With IgG coronas, pristine MWCNTs induced higher levels of TNF-α than did COOH-MWCNTs, and both kinds of MWCNTs induced similar levels of IL-1β (Zhang T. et al, 2019). Except for these in vitro investigations mentioned above, a series of in vivo experiments were also conducted to investigate the impact of surface charge on inflammation.…”

“…For example, a decoration comprising positively charged and hydrophobic ligands on NPs can enhance the cellular uptake level (Su et al, 2012;Li et al, 2015a). A decoration consisting of poly(ethylene glycol) (PEG) can reduce protein binding in the blood and avoid recognition by the reticular endothelial system (RES) (Zhang T. et al, 2019). Moreover, surface chemistry is one of the key factors that can trigger adverse effects in biosystems.…”