Editorial

2 pages, 145 KiB

Open AccessEditorial

by Xin Zhao and Mo Yang

Molecules 2019, 24(13), 2440; https://doi.org/10.3390/molecules24132440 - 03 Jul 2019

Cited by 9 | Viewed by 2512

Integrating graphene with other nanomaterials has created a variety of graphene nanocomposites with extraordinary chemical, optical, mechanical, and electrical properties [...] Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

Research

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9 pages, 2801 KiB

Open AccessArticle

Zero-Bias Visible to Near-Infrared Horizontal p-n-p TiO₂ Nanotubes Doped Monolayer Graphene Photodetector

by Zehua Huang, Chunhui Ji, Luhua Cheng, Jiayue Han, Ming Yang, Xiongbang Wei, Yadong Jiang and Jun Wang

Molecules 2019, 24(10), 1870; https://doi.org/10.3390/molecules24101870 - 15 May 2019

Cited by 12 | Viewed by 2925

Abstract

We present a p-n-p monolayer graphene photodetector doped with titanium dioxide nanotubes for detecting light from visible to near-infrared (405 to 1310 nm) region. The built-in electric field separates the photo-induced electrons and holes to generate photocurrent without bias voltage, which allows the [...] Read more.

We present a p-n-p monolayer graphene photodetector doped with titanium dioxide nanotubes for detecting light from visible to near-infrared (405 to 1310 nm) region. The built-in electric field separates the photo-induced electrons and holes to generate photocurrent without bias voltage, which allows the device to have meager power consumption. Moreover, the detector is very sensitive to the illumination area, and we analyze the reason using the energy band theory. The response time of the detector is about 30 ms. The horizontal p-n-p device is a suitable candidate in zero-bias optoelectronic applications. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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13 pages, 4382 KiB

Open AccessArticle

Graphene-Like Porous ZnO/Graphene Oxide Nanosheets for High-Performance Acetone Vapor Detection

by Hongwu Wang, Ding Wang, Liang Tian, Huijun Li, Ping Wang, Nanquan Ou, Xianying Wang and Junhe Yang

Molecules 2019, 24(3), 522; https://doi.org/10.3390/molecules24030522 - 31 Jan 2019

Cited by 21 | Viewed by 3808

Abstract

In order to obtain acetone sensor with excellent sensitivity, selectivity, and rapid response/recovery speed, graphene-like ZnO/graphene oxide (GO) nanosheets were synthesized using the wet-chemical method with an additional calcining treatment. The GO was utilized as both the template to form the two-dimensional (2-D) [...] Read more.

In order to obtain acetone sensor with excellent sensitivity, selectivity, and rapid response/recovery speed, graphene-like ZnO/graphene oxide (GO) nanosheets were synthesized using the wet-chemical method with an additional calcining treatment. The GO was utilized as both the template to form the two-dimensional (2-D) nanosheets and the sensitizer to enhance the sensing properties. Sensing performances of ZnO/GO nanocomposites were studied with acetone as a target gas. The response value could reach 94 to 100 ppm acetone vapor and the recovery time could reach 4 s. The excellent sensing properties were ascribed to the synergistic effects between ZnO nanosheets and GO, which included a unique 2-D structure, large specific surface area, suitable particle size, and abundant in-plane mesopores, which contributed to the advance of novel acetone vapor sensors and could provide some references to the synthesis of 2-D graphene-like metals oxide nanosheets. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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11 pages, 4192 KiB

Open AccessArticle

Ultrasensitive and Multifunction Plasmonic Temperature Sensor with Ethanol-Sealed Asymmetric Ellipse Resonators

by Jun Zhu and Jian Lou

Molecules 2018, 23(10), 2700; https://doi.org/10.3390/molecules23102700 - 19 Oct 2018

Cited by 15 | Viewed by 3105

Abstract

In order to improve the low temperature sensitivity of conventional sensors, a plasmonic multifunction temperature sensor with high sensitivity is proposed and investigated systematically in this paper. The sensor consists of two metal layers and two ethanol-sealed elliptical resonators connected to a straight [...] Read more.

In order to improve the low temperature sensitivity of conventional sensors, a plasmonic multifunction temperature sensor with high sensitivity is proposed and investigated systematically in this paper. The sensor consists of two metal layers and two ethanol-sealed elliptical resonators connected to a straight waveguide by two rectangular tubes. We numerically analyzed the transmission characteristics of the Nano-device to assess its performance with the finite element method and achieved great optical properties. The results show that an obvious blue shift of the transmission spectrum appears by varying temperatures, exhibiting a great sensing effect. Sensitivity of the sensor reaches −3.64 nm/°C, far greater than conventional temperature sensors. Our research also demonstrates that the transmission spectrum could be modulated efficiently by the ratio of semi-short axis to semi-major axis of the ellipse resonators and the width of two same rectangular tubes. Furthermore, the Nano-device has a filtering characteristic. The transmittances of pass-band and stop-band are 96.1% and 0.1%, respectively. The results of this study can pave the way for low-cost sensing application in high-density photonic circuits and biosensors. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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16 pages, 7315 KiB

Open AccessArticle

Synthesis and Application of Scaffolds of Chitosan-Graphene Oxide by the Freeze-Drying Method for Tissue Regeneration

by Cesar Valencia, Carlos H. Valencia, Fabio Zuluaga, Mayra E. Valencia, José H. Mina and Carlos David Grande-Tovar

Molecules 2018, 23(10), 2651; https://doi.org/10.3390/molecules23102651 - 16 Oct 2018

Cited by 110 | Viewed by 8711

Abstract

Several biomaterials, including natural polymers, are used to increase cellular interactions as an effective way to treat bone injuries. Chitosan (CS) is one of the most studied biocompatible natural polymers. Graphene oxide (GO) is a carbon-based nanomaterial capable of imparting desired properties to [...] Read more.

Several biomaterials, including natural polymers, are used to increase cellular interactions as an effective way to treat bone injuries. Chitosan (CS) is one of the most studied biocompatible natural polymers. Graphene oxide (GO) is a carbon-based nanomaterial capable of imparting desired properties to the scaffolds. In the present study, CS and GO were used for scaffold preparation. CS was extracted from the mycelium of the fungus Aspergillus niger. On the other hand, GO was synthesized using an improved Hummers-Offemann method and was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Subsequently, three formulations (GO 0%, 0.5%, and 1%) were used to prepare the scaffolds by the freeze-drying technique. The scaffolds were characterized by FTIR, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), to determine their thermal stability and pore size, demonstrating that their stability increased with the increase of GO amount. Finally, the scaffolds were implanted, recollected 30 days later, and studied with an optical microscope, which evidenced the recovery of the tissue architecture and excellent biocompatibility. Hence, these results strongly suggested the inherent nature of chitosan/graphene oxide (CS/GO) scaffolds for their application in bone tissue regeneration. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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11 pages, 4613 KiB

Open AccessArticle

Novel High-Sensitivity Racetrack Surface Plasmon Resonance Sensor Modified by Graphene

by Jun Zhu, Zhengjie Xu and Yuanmin Huang

Molecules 2018, 23(7), 1726; https://doi.org/10.3390/molecules23071726 - 14 Jul 2018

Cited by 1 | Viewed by 2971

Abstract

In order to overcome the existing challenges presented by conventional sensors, including their large size, a complicated preparation process, and difficulties filling the sensing media, a novel high-sensitivity plasmonic resonator sensor which is composed of two graphene-modified straight waveguides, two metallic layers, and [...] Read more.

In order to overcome the existing challenges presented by conventional sensors, including their large size, a complicated preparation process, and difficulties filling the sensing media, a novel high-sensitivity plasmonic resonator sensor which is composed of two graphene-modified straight waveguides, two metallic layers, and a racetrack nanodisk resonator is proposed in this study. The transmission characteristics, which were calculated by the finite element theory, were used to further analyze the sensing properties. The results of quantitative analysis show that the proposed plasmonic sensor generates two resonance peaks for the different incident wavelengths, and both resonance peaks can be tuned by temperature. In addition, after optimizing the structural parameters of the resonator, the Q value and the refractive sensitivity reached 21.5 and 1666.67 nmRIU⁻¹, respectively. Compared with other studies, these values translate to a better performance. Furthermore, a temperature sensitivity of 2.33 nm/5 °C was achieved, which allows the sensor to be easily applied to practical detection. The results of this study can broaden the useful range for a nanometer-scale temperature sensor with ultrafast real-time detection and resistance to electromagnetic interference. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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8 pages, 3005 KiB

Open AccessArticle

Wetting Properties of Defective Graphene Oxide: A Molecular Simulation Study

by Ke Xu, Jicheng Zhang, Xiaoli Hao, Chunbo Zhang, Ning Wei and Chao Zhang

Molecules 2018, 23(6), 1439; https://doi.org/10.3390/molecules23061439 - 13 Jun 2018

Cited by 33 | Viewed by 5785

Abstract

In the present work, the wettability of defective graphene oxide (GO) film is studied by molecular dynamics simulations. A water droplet is deposited on the surface of a graphene oxide membrane, and the contact angle is measured by fitting the liquid–vapor interface. Although [...] Read more.

In the present work, the wettability of defective graphene oxide (GO) film is studied by molecular dynamics simulations. A water droplet is deposited on the surface of a graphene oxide membrane, and the contact angle is measured by fitting the liquid–vapor interface. Although pristine graphene has few hydrophobic properties with a contact angle of 95°, graphene oxide presents more hydrophilic properties, due to the stronger hydrogen bonds interactions at the interface. Moreover, the introduction of vacancy defects at the graphene oxide surface decreases the wettability of graphene oxide. We find that the contact angle of graphene oxide increases from 70° to 82°, with a defective concentration from 0% to 10%. Our results will help provide a new method for controlling the wetting properties of GO and its additional capabilities in device design for applications. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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Review

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15 pages, 2693 KiB

Open AccessReview

Graphene-Based Nanocomposites for Neural Tissue Engineering

by Ho Pan Bei, Yuhe Yang, Qiang Zhang, Yu Tian, Xiaoming Luo, Mo Yang and Xin Zhao

Molecules 2019, 24(4), 658; https://doi.org/10.3390/molecules24040658 - 13 Feb 2019

Cited by 101 | Viewed by 10036

Abstract

Graphene has made significant contributions to neural tissue engineering due to its electrical conductivity, biocompatibility, mechanical strength, and high surface area. However, it demonstrates a lack of biological and chemical cues. Also, it may cause potential damage to the host body, limiting its [...] Read more.

Graphene has made significant contributions to neural tissue engineering due to its electrical conductivity, biocompatibility, mechanical strength, and high surface area. However, it demonstrates a lack of biological and chemical cues. Also, it may cause potential damage to the host body, limiting its achievement of efficient construction of neural tissues. Recently, there has been an increasing number of studies showing that combining graphene with other materials to form nano-composites can provide exceptional platforms for both stimulating neural stem cell adhesion, proliferation, differentiation and neural regeneration. This suggests that graphene nanocomposites are greatly beneficial in neural regenerative medicine. In this mini review, we will discuss the application of graphene nanocomposites in neural tissue engineering and their limitations, through their effect on neural stem cell differentiation and constructs for neural regeneration. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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23 pages, 2796 KiB

Open AccessReview

Graphene and Graphene-Based Nanomaterials for DNA Detection: A Review

by Xin Wu, Fengwen Mu, Yinghui Wang and Haiyan Zhao

Molecules 2018, 23(8), 2050; https://doi.org/10.3390/molecules23082050 - 16 Aug 2018

Cited by 64 | Viewed by 9041

Abstract

DNA detection with high sensitivity and specificity has tremendous potential as molecular diagnostic agents. Graphene and graphene-based nanomaterials, such as graphene nanopore, graphene nanoribbon, graphene oxide, and reduced graphene oxide, graphene-nanoparticle composites, were demonstrated to have unique properties, which have attracted increasing interest [...] Read more.

DNA detection with high sensitivity and specificity has tremendous potential as molecular diagnostic agents. Graphene and graphene-based nanomaterials, such as graphene nanopore, graphene nanoribbon, graphene oxide, and reduced graphene oxide, graphene-nanoparticle composites, were demonstrated to have unique properties, which have attracted increasing interest towards the application of DNA detection with improved performance. This article comprehensively reviews the most recent trends in DNA detection based on graphene and graphene-related nanomaterials. Based on the current understanding, this review attempts to identify the future directions in which the field is likely to thrive, and stimulate more significant research in this subject. Full article

(This article belongs to the Special Issue Graphene Nanocomposites)

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