In vitrolocalisation and degradation of few-layer MoS₂submicrometric plates in human macrophage-like cells: a label free Raman micro-spectroscopic study

Abstract

In-vitro localisation and degradation of few-layer MoS2 submicrometric plates in human macrophage-like cells: a label free Raman micro-spectroscopic study

Label-free screening of biochemical changes in macrophage-like cells following MoS2 exposure using Raman micro-spectroscopy

“…Notably, this concentration of particulate material resulted in no significant reduction of cell viability for THP-1 cells for 24, 48 or 72 h incubation time-points. Uptake of submicron/nanoplates following a 4 h incubation within the phagocytic macrophages was confirmed by both Transmission Electron Microscopy (TEM) and Raman micro-spectroscopy [16,17].…”

“…Whole cell Raman spectral mapping was previously employed to assess the capability of Raman micro-spectroscopy to identify material uptake in-vitro and to determine the fate and/or integrity of MoS2 following phagocytosis [17]. It was observed that, following internalisation, particulate material was localised to discrete regions of the cell, the majority of vesicles being located within the cytoplasm in the peri-nuclear region.…”

“…It was observed that, following internalisation, particulate material was localised to discrete regions of the cell, the majority of vesicles being located within the cytoplasm in the peri-nuclear region. Degradation of MoS2 plates in cells incubated for 24 h post-exposure could be observed, based on changes of the characteristic E 1 2g and A1g features of MoS2 [17,18]. A micro-environment rich in lipids from the phosphatidyl family was associated with material degradation, while non-degraded MoS2 plates were encompassed within an environment rich in the enzyme lysozyme [17].…”

“…Degradation of MoS2 plates in cells incubated for 24 h post-exposure could be observed, based on changes of the characteristic E 1 2g and A1g features of MoS2 [17,18]. A micro-environment rich in lipids from the phosphatidyl family was associated with material degradation, while non-degraded MoS2 plates were encompassed within an environment rich in the enzyme lysozyme [17]. It was suggested that the lipopolysaccharide (LPS) contaminant on the surface of particulate material inhibited the activity of the enzyme, formally known as muramidase [19].…”

“…As a result, prominent lipidic vesicles, which were previously identified as being involved in the catabolisation of particulate material, were selected to gain insight into the cellular response following exposure to MoS2. Notably, whereas the analysis of the previous study specifically targeted MoS2 containing vesicles in individual treated cells [17], using Raman point spectral analysis to sampling vesicles in multiple untreated and treated cells, in an unsupervised fashion, this study aims to further understand the response of the immune cell population following interactions with MoS2 and further identify any biochemical alterations between untreated cells and those exposed to the MoS2. The same pulse chase exposure method was applied for this study, whereby cells were incubated for 4 (T4), 24 (T24) and 72 h (T72) subsequent to an initial exposure of 4 h to 1 μg/ml MoS2 submicron/nano plates.…”