MoS₂ and MoSe₂ Nanosheets as Triggers for Glutathione Dimerization in Solution and Glutathione Oxidation in Live Cells

Abstract

Sulfur vacant sites in MoS2 nanosheets (NSs) have been confirmed to be effective in reacting with thiol molecules in solution. However, little-to-no information is known about the molar ratio of the remaining thiols and the produced disulfides in the reaction of MoS2 NSs and thiol molecules. Additionally, the MoSe2 NS-mediated conversion of thiol molecules has not been explored at present. Herein, we conducted a comparative study regarding the very-few-layer (VFL; layer number ∼ 3) MoS2 and VFL-MoSe2 NS-induced conversion of glutathione (GSH) to GSH disulfide (GSSG) in phosphate-buffered saline and the oxidation of GSH in live cells. Compared to traditional colorimetric assays for determining the percentage loss of GSH, liquid chromatography and mass spectroscopy were introduced to confirm and accurately quantify the molar ratio of the remaining GSH to produced GSSG from the reaction of the present VFL-MoS2 and VFL-MoSe2 NSs with GSH at pH 4.0–10 and 25–70 °C. The produced GSSG molecules were the leading product in the above-discussed reaction, and most of them were liberated into the solution rather than adsorbed on the NS surface. Additionally, it was found that VFL-MoSe2 converted more efficiently GSH to GSSG than VFL-MoS2 NSs. These findings were also valid for 5-thio-2-nitrobenzoic acid, which was well-suited to evaluate the difference in the rate constant of thiol conversion among the proposed two-dimensional NSs. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell viability assay, GSH-specific fluorescent probe, and live/dead cell staining kit demonstrated that the cellular cytotoxicity of the proposed two-dimensional NSs was highly correlated with the oxidation of intracellular GSH. The presence of selenocysteine filling selenium vacancies in VFL-MoSe2 NSs suppressed the conversion of GSH to GSSG in solution and the oxidation of GSH in live cells. Our findings point out that the reaction pathway of MoS2 and MoSe2 NSs with thiols not only involves vacant site repairing and thiol conjugation but also includes thiol dimerization.

Chemically Engineered Sulfur Vacancies on Few-Layered Molybdenum Disulfide Nanosheets for Remarkable Surface-Enhanced Raman Scattering Activity

“…FL-MoS 2 NSs were prepared by the direct ultrasonic exfoliation of bulk MoS 2 material in an isopropanol solvent. 26 In brief, 2 g of bulk MoS 2 was added to 100 mL of an isopropanol-containing glass container, and it was allowed to ice bath sonicate for 12 h at 150 W. In each 1 h, it was quivered for effective exfoliation. The gray-colored dispersion (initial stage) evolved into a greenish stable dispersion solution, indicating successful exfoliation of MoS 2 .…”

Reversible light-controlled fluorescence switch of block polymer-grafted carbon dots and cellular imaging

“…HEK-293 cells (human embryonic kidney cells) were purchased from Editgene China. Primary HEK-293 cells need to be thawed 26 and then dispersed in 4 mL culture medium (DMEM-H medium, 90%; fetal bovine serum, 10%). These cells were cultivated in an incubator (5% CO 2 , 37 1C) for 24 h. When the cell density reached 80%, cells were rinsed with PBS.…”

Facile and Green Fabrication of Highly Competent Surface-Modified Chlorogenic Acid Silver Nanoparticles: Characterization and Antioxidant and Cancer Chemopreventive Potential

“…34 Some nanoparticles produce ROS 35 and can cause efficient conversion of GSH to GSSG in phosphate-buffered saline and also induce oxidation of GSH in live cells. 36 Therefore, the focus of the current study is to synthesize and characterize surface-modified chlorogenic acid silver nanoparticles (AgNPs-CGA-BSA) and to investigate their in vitro antioxidant potential and antineoplastic efficacy against Dalton's lymphoma ascites (DLA). We also examined the in vivo anticancer potential in DLA-bearing Swiss albino mice to detect whether there is any capability of AgNPs-CGA-BSA to enhance the host antioxidant status which can antagonize the cancer ailments.…”

“…Some nanoparticles produce ROS and can cause efficient conversion of GSH to GSSG in phosphate-buffered saline and also induce oxidation of GSH in live cells . Therefore, the focus of the current study is to synthesize and characterize surface-modified chlorogenic acid silver nanoparticles (AgNPs-CGA-BSA) and to investigate their in vitro antioxidant potential and antineoplastic efficacy against Dalton’s lymphoma ascites (DLA).…”