Electrochemical detection of homovanillic acid, a breast cancer biomarker, using Pluronic-modified MoS₂ nanosheets

Abstract

Two-dimensional transition metal dichalcogenides (2D TMDs) have gained considerable attention from the scientific community for their various applications thanks to their remarkable chemical, physical, optical and electronic properties. In this study, MoS2 nanosheets were synthesized using a kitchen blender with the assistance of a surfactant so-called Pluronic F127 through a shear-exfoliation process. Different techniques were used to characterize the chemical composition, nanostructure, and electrochemical properties of the synthesized MoS2-F127 as well as Pt modified with MoS2-F127 (Pt/MoS2-F127) electrode. The Pt/MoS2-F127 electrode combined with differential pulse voltammetry was used for the electrochemical detection of homovanillic acid (HVA) in the presence of common interferents in urine. The study provides a new approach to discriminate the electrochemical signal of HVA and UA which lead to higher selectivity of the sensor.

Quaternary Pullulan-Functionalized 2D MoS2 Glycosheets: A Potent Bactericidal Nanoplatform for Efficient Wound Disinfection and Healing

“…The presence of a sharp peak at 2θ = 14.4°in the XRD pattern of both bulk MoS 2 and MCP is a characteristic of MoS 2 and corresponds to the (002) lattice plane (Figure 3c). 53 The intensity of this peak was low for MCP as compared to that of bulk MoS 2 . The reduction in peak intensity validates the well-exfoliated nature of MCP nanosheets.…”

“…The two characteristic Raman modes of MoS 2 at 380 cm −1 (E 2g 1 ) and 402 cm −1 (A 1g ), which arises from the in-plane and out-ofplane vibrations of sulfur/molybdenum atoms, respectively, are clearly evident in the spectra of both bulk and exfoliated nanosheets. 53 Further, Raman spectroscopy acts as a powerful tool to differentiate between bulk and exfoliated states of layered materials. The process of exfoliation of layered materials reduces the number of layers in the bulk material, which gets reflected in the Raman spectra in the form of shifts in phonon modes.…”

“…Pristine MoS 2 nanosheets underwent decomposition between 450 and 550 °C due to MoS 2 oxidation to MoO 3 . 21,53 CP showed a characteristic degradation profile corresponding to pullulan with a sharp weight loss of around 300 °C due to the degradation of pullulan chain structure. 55 The TGA spectra of MCP nanosheets showed a similar degradation profile as that of CP, with a gradual weight loss starting at 300 °C and continuing up to 500 °C, thereby supporting the presence of CP on the surface of the nanosheets.…”

“…Similarly, the high-resolution S 2p spectrum of MCP showed peaks at 162.47 and 163.30 eV corresponding to S 2p 3/2 and S 2p 1/2 (Figure g). The position of all of these peaks agrees very well with that of typical MoS 2 material. ,, Zeta-potential analysis of the synthesized MCP nanosheets gave more insights into the successful functionalization of MoS 2 nanosheets with CP (Figure h). Pristine MoS 2 nanosheets showed a net negative surface charge of −15 mV in PBS (pH = 7.4) and −24.2 mV in DI water, whereas CP owing to the presence of quaternary ammonium groups in its structure showed a net positive surface charge of +10.4 mV in PBS (pH = 7.4) and +19.2 mV in DI water.…”

“…The position of all of these peaks agrees very well with that of typical MoS 2 material. 21,53,56 Zeta-potential analysis of the synthesized MCP nanosheets gave more insights into the successful functionalization of MoS 2 nanosheets with CP (Figure 3h). Pristine MoS The presence of a positive charge on the surface of MCP nanosheets again validates its functionalization with CP.…”