Graphene/MoS2 Nanohybrid for Biosensors

Abstract

Graphene has been studied a lot in different scientific fields because of its unique properties, including its superior conductivity, plasmonic property, and biocompatibility. More recently, transition metal dicharcogenide (TMD) nanomaterials, beyond graphene, have been widely researched due to their exceptional properties. Among the various TMD nanomaterials, molybdenum disulfide (MoS₂) has attracted attention in biological fields due to its excellent biocompatibility and simple steps for synthesis. Accordingly, graphene and MoS₂ have been widely studied to be applied in the development of biosensors. Moreover, nanohybrid materials developed by hybridization of graphene and MoS₂ have a huge potential for developing various types of outstanding biosensors, like electrochemical-, optical-, or surface-enhanced Raman spectroscopy (SERS)-based biosensors. In this review, we will focus on materials such as graphene and MoS₂. Next, their application will be discussed with regard to the development of highly sensitive biosensors based on graphene, MoS₂, and nanohybrid materials composed of graphene and MoS₂. In conclusion, this review will provide interdisciplinary knowledge about graphene/MoS₂ nanohybrids to be applied to the biomedical field, particularly biosensors.

Keywords: MoS2; biosensors; graphene; hybrid nanomaterials; transition metal dichalcogenide (TMD) nanomaterials.

Figure 1

(a) Characteristics of graphene, molybdenum disulfide (MoS₂), and graphene/MoS₂ nanohybrid, and (b) their utilization to develop graphene/MoS₂ nanohybrid-based biosensors.

Figure 2

(a) Schematic of graphene and graphene oxide (GO) with various chemical property modification methods (reproduced with permission from [43], published by Elsevier, 2013), (b) the desorption of DNA from GO either via hybridization with cDNA on the surface of the GO or by nonspecific simple displacement by non-cDNA (reproduced with permission from [47], published by the American Chemical Society, 2014), (c) the detailed atomic structure of a MoS₂ nanosheet (reproduced with permission from [66], published by Elsevier, 2016), and (d) the synthesis process of the MoS₂ QD to improve the photoluminescence property (reproduced with permission from [69], published by Elsevier, 2015).

Figure 3

Graphene in biosensors: (a) Schematic of the electrochemical prostate-specific antigen (PSA) biosensor based on the GO/AgNP hybrid through the peptide cleavage strategy and a linear sweep voltammogram for PSA detection (Reprinted with permission from [88], published by Elsevier, 2019), (b) Schematic illustration of the synthesis process of AuNS on the surface of the GO and label-free detection of the bilirubin (Reprinted with permission from [96], published by Elsevier, 2019), (c) Schematic illustration of the boron-doped graphene QD (BQD) synthesis process for detecting Fe³⁺, Cyt C, and Pi and the fluorescence signal of BQD with the addition of a different concentration of Fe³⁺ and its linear response curve (Reprinted with permission from [104], published by Elsevier, 2019).

Figure 4

MoS₂ in biosensors: (a) Schematic illustration of the fabrication process of the HIV biosensor based on an Au/MoS₂/Au multilayer on a polyethylene terephthalate (PET) substrate; the square wave voltammogram for detecting gp120 with its linear response curve (Reprinted with permission from [122], published by MDPI, 2019), (b) Schematic illustration of the let-7b miRNA detection mechanism using a fluorescent biosensor composed of the MoS₂ nanosheet, ssDNA with fluorescein amidite (FAM), and duplex-specific nuclease (DSN); the measured fluorescence signal with different concentrations of the let-7b miRNA and its linear response curve (Reprinted with permission from [125], published by American Chemical Society, 2018), (c) Schematic illustration of the MC–LR detection process using MoS₂ quantum dots (QDs) and aptamer-modified AuNPs; the fluorescence signals of MoS₂ QDs by with different added concentrations of microcystin–LR (MC–LR) with its linear response curve (Reprinted with permission from [130], published by American Chemical Society, 2020).

Figure 5

Graphene/MoS₂ nanohybrid in biosensors: (a) TEM image of the MoS₂ nanoparticles (NPs) encapsulated by GO, cyclic voltammogram of Mb modified GO@MoS₂, and its selective and sensitive H₂O₂ sensing performance by amperometric I-T measurement (reproduced with permission from [30], published by Elsevier, 2017), (b) schematic diagram of the fluorescent epithelial cell adhesion molecule (EpCAM) biosensor based on the graphene QD and MoS₂ nanosheet, and its fluorescent sensing of EpCAM depending on the concentration of EpCAM (reproduced with permission from [76], published by Elsevier, 2017), (c) schematic images of W-MoS₂ nanosheet decorated with graphene micro-flowers (GMFs) fabrication and its surface-enhanced Raman spectroscopy (SERS)-enhancing effects for target detection (reproduced with permission from [77], published by Elsevier, 2020).