Graphene and its Derivatives-Based Optical Sensors

Abstract

Being the first successfully prepared two-dimensional material, graphene has attracted extensive attention from researchers due to its excellent properties and extremely wide range of applications. In particular, graphene and its derivatives have displayed several ideal properties, including broadband light absorption, ability to quench fluorescence, excellent biocompatibility, and strong polarization-dependent effects, thus emerging as one of the most popular platforms for optical sensors. Graphene and its derivatives-based optical sensors have numerous advantages, such as high sensitivity, low-cost, fast response time, and small dimensions. In this review, recent developments in graphene and its derivatives-based optical sensors are summarized, covering aspects related to fluorescence, graphene-based substrates for surface-enhanced Raman scattering (SERS), optical fiber biological sensors, and other kinds of graphene-based optical sensors. Various sensing applications, such as single-cell detection, cancer diagnosis, protein, and DNA sensing, are introduced and discussed systematically. Finally, a summary and roadmap of current and future trends are presented in order to provide a prospect for the development of graphene and its derivatives-based optical sensors.

Keywords: fluorescence; graphene; optical fiber; optical sensors; surface-enhanced Raman scattering.

FIGURE 1

The application of graphene and its derivatives in optical sensors.

FIGURE 2

The application of graphene and its derivatives in fluorescence sensing. (A) Fluorescence spectra corresponding to GO and GO treated with KOH and HNO₃; inset: the different electronic transitions (Li et al., 2012). (B) The pH-dependent photoluminescence of GO. (C) The intensities of photoluminescence at different wavelengths (λ = 683, 506, and 479 nm) and its corresponding pH value (Galande et al., 2011). (D) Fluorescence mechanism of GO (Cushing et al., 2014). (E) Tunable excitation-wavelength-dependent two-photon imaging. (F) Two-photon fluorescence imaging technique based on aptamer-modified GO and its application (Pramanik et al., 2014b). (G) High-sensitivity detection of dopamine by using GO as a fluorescence quencher (Chen et al., 2011). (H) MicroRNA (miRNA) detection based on GO and peptide nucleic acid (PNA) (Ryoo et al., 2013).

FIGURE 3

The graphene-based substrates for surface-enhanced Raman scattering (SERS). (A) Schematic illustration of the graphene only substrates. (B) Raman spectra of Pc molecules on monolayer graphene and on a blank SiO₂/Si substrate (Ling et al., 2010). (C) Schematic of SERS enhancement from a crumpled graphene–Au nanoparticles hybrid structure (Leem et al., 2015). (D) Graphene-covered nanoparticles or nanohole arrays for SERS enhancement (Hao et al., 2012). (E) Graphene-covered Au nanovoid arrays (Zhu et al., 2013). (F) Graphene-separated metal nanostructure substrates (Zhao et al., 2017). (G) Schematic illustration of the SERS detection of DNA based on graphene (Duan et al., 2015). (H) Optical and Raman images of HeLa 229 cells. The scale bar is 10 µm (Zhang et al., 2015).

FIGURE 4

The graphene based fiber optical sensors. (A) Schematic diagram of the graphene/microfiber hybrid waveguide (Shivananju et al., 2017). (B) Scanning electron microscopy (SEM) image of the graphene-coated microfiber waveguide (Yao et al., 2014a). (C) Graphene-coated microfiber waveguide used for high-sensitivity gas sensing (Yao et al., 2014b). (D) Schematic model of the fiber-to-graphene coupler based on a side-polished optical fibre. (E) Optical images of a laterally polished optical fiber and of a planar section of the optical fiber covered by few-layer graphene (Bao et al., 2011). (F) The fiber-to-graphene coupler were used for high-sensitivity protein sensing (Kim et al., 2013). (G) Illustration of graphene-coated optical microring resonator (Gan et al., 2015). (H) Schematic of the end of an optical fiber pigtail with a graphene coating on pinhole (Shivananju et al., 2017). (I) Comparative plots of the sensing responses of GO and RGO-coated polymer optical fibers (Some et al., 2013).

FIGURE 5

(A) Ultrasensitive sensing of single cell using graphene-based optical sensor (Xing et al., 2014). (B) Optical images of the RGO detection window as lymphocytes roll across it. The scale bar is 15 μm. (C) Discrete time-dependent changes in signal that correspond to mixed lymphocytes and Jurkat cells as they roll across the detection window. (D) The RGO-based optical sensor for detecting specific protein (Jiang et al., 2017b). (E) Signal changes caused by the interaction of antigen and antibody. (F) Optical microscopy and SEM image of reduced graphene oxide microshell (RGOM) (Jiang et al., 2017a). (G) Schematic diagram of the photothermal detection experimental setup (Gao et al., 2018b). (H) Time-dependent changes in photothermal signal when different kinds of liquid medium are injected.