Interactions of Transition Metal Dichalcogenide Nanosheets With Mucin: Quartz Crystal Microbalance With Dissipation, Surface Plasmon Resonance, and Spectroscopic Probing.

Wei Qi,Renliang Huang,Zhimin He,Boshi Liu,Rongxin Su,Tao Yu

doi:10.3389/fchem.2019.00166

Abstract

Ultrathin 2-dimensional transition metal dichalcogenides (TMDs) have become a class of high-potential materials in biomedicine due to their intriguing properties. They have been applied to solve biomedical challenges, such as biosensing, bioimaging, drug delivery, and cancer therapy. However, studies of the interactions between these materials and biomolecules are insufficient. Mucous tissue serves as a barrier to foreign hazardous substances and a gel layer for substance exchange. The main organic matter of mucous tissue is mucin, so it was selected as a model biomolecule to study its interactions with six different TMD nanosheets (NSs), including single-layered (SL), few-layered (FL), and small few-layered (SFL) MoS2 and WS2 NSs, using quartz crystal microbalance (QCM) with a dissipation monitor (QCM-D) and surface plasmon resonance (SPR). Additionally, UV absorption, fluorescence, and circular dichroism (CD) spectroscopy were applied to investigate the mechanism of the interactions and to study the conformational change of mucin. We found that the TMD NSs could adsorb on the mucin layer and affect its viscoelasticity. The results indicated that the SL WS2 NSs exhibited the highest initial absorption rate and the maximum absorption amount, while the SL MoS2 NSs exhibited the highest initial desorption rate. During the adsorption, the viscoelasticity variations of the mucin layer caused by the WS2 nanosheets were weaker than those caused by the MoS2 nanosheets. Furthermore, the conformational changes of mucin caused by the SL MoS2, SL WS2, and SFL MoS2 NSs were higher than those resulting from other TMD NSs. These findings provide important information on the interactions between TMD NSs and mucin and provide useful insights into the interfacial behavior of TMD NSs before they enter tissues.

Highlights

Mucus is secreted by specialized goblet cells in the columnar epithelium and serves many functions including lubrication, maintenance of a hydrated layer over the epithelium, a barrier to hazardous substances, and a permeable gel layer for the exchange of gases and nutrients with the underlying cells and tissues (Bansil and Turner, 2006; Linden et al, 2008; McGuckin et al, 2011; Demouveaux et al, 2018)
In stage I, when the mucin aqueous solution flowed over the gold chip surface, the F value descended while the D value ascended owing to the increase of the mass and viscoelasticity of the materials on the surface, which indicated the adsorption of mucin on the surface of the quartz crystal microbalance (QCM) sensing module and the formation of a mucin layer
When the MoS2 NS dispersions flowed over the mucin layer (Figures 2A–C), slight increases of the F values were recorded at the beginning, and the D values continued to increase

Summary

Introduction

Mucus is secreted by specialized goblet cells in the columnar epithelium and serves many functions including lubrication, maintenance of a hydrated layer over the epithelium, a barrier to hazardous substances, and a permeable gel layer for the exchange of gases and nutrients with the underlying cells and tissues (Bansil and Turner, 2006; Linden et al, 2008; McGuckin et al, 2011; Demouveaux et al, 2018). Mucin is closely related to many mucus-related diseases, the intake of nutrients, and the adsorption and delivery of drugs through the mucus barrier (Bansil and Turner, 2006; Boya et al, 2017). MoS2 has been shown to be toxic toward planktonic cells, biofilms, and mammalian cells in the presence of electron donors (Fan et al, 2015), to bind to the K+ channels and disturb their functions (Gu et al, 2018), to activate TGF-beta/Smad pathways and perturb the metabolome of human dermal fibroblasts (Yu et al, 2017), and to exhibit cytotoxicity and impact inflammation (Moore et al, 2017)

Methods

Results

Conclusion