scholarly journals Highly Sensitive Uric Acid Detection Based on a Graphene Chemoresistor and Magnetic Beads

Biosensors ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 304
Author(s):  
Wangyang Zhang ◽  
Xiaoqiang Zhao ◽  
Lina Diao ◽  
Hao Li ◽  
Zhonghao Tong ◽  
...  
Keyword(s):  
Uric Acid ◽  
High Performance ◽  
Magnetic Beads ◽  
Point Of Care ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Test Time ◽  
Film Material ◽  
Ph Change ◽  
Highly Sensitive

In this study, we developed a low-cost, reusable, and highly sensitive analytical platform for the detection of the human metabolite uric acid (UA). This novel analysis platform combines the graphene chemoresistor detection technique with a magnetic bead (MB) system. The heterojunction (single-layer graphene and HfO2 thin-film material) of our graphene-based biosensor worked as a transducer to detect the pH change caused by the specific catalytic reaction between UA and uricase, and hence acquires a UA concentration. Immobilization of uricase on MBs can decouple the functionalization steps from the sensor surface, which allows the sensor to be reusable. Our microsensor platform exhibits a relatively lower detection limit (1 μM), high sensitivity (5.6 mV/decade), a linear range (from 1 μM to 1000 μM), and excellent linearity (R2 = 0.9945). In addition, interference assay and repeatability tests were conducted, and the result suggests that our method is highly stable and not affected by common interfering substances (glucose and urea). The integration of this high-performance and compact biosensor device can create a point-of-care diagnosis system with reduced cost, test time, and reagent volume.

Well-Aligned Graphene Oxide Nanosheets Decorated with Zinc Oxide Nanocrystals for High Performance Photocatalytic Application

2015 ◽  
Vol 14 (03) ◽  
pp. 1550007 ◽  
Author(s):  
K. Kaviyarasu ◽  
C. Maria Magdalane ◽  
E. Manikandan ◽  
M. Jayachandran ◽  
R. Ladchumananandasivam ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Graphene Oxide ◽  
High Performance ◽  
Chemical Reduction ◽  
Visible Region ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Graphene Oxides ◽  
X Ray ◽  
Nanoscale Structures

Graphene oxide (GO) nanosheets modified with zinc oxide nanocrystals were achieved by a green wet-chemical approach. As-obtained products were characterized by XRD, Raman spectra, XPS, HR-TEM, EDS, PL and Photocatalytic studies. XRD studies indicate that the GO nanosheet have the same crystal structure found in hexagonal form of ZnO . The enhanced Raman spectrum of 2D bands confirmed formation of single layer graphene oxides. The gradual photocatalytic reduction of the GO nanosheet in the GO : ZnO suspension of ethanol was studied by using X-ray photoelectron (XPS) spectroscopy. The nanoscale structures were observed and confirmed using high resolution transmission electron microscopy (HR-TEM). The evolution of the elemental composition, especially the various numbers of layers were determined from energy dispersive X-ray spectra (EDS). PL properties of GO : ZnO nanosheet were found to be dependent on the growth condition and the resultant morphology revealed that GO nanosheet were highly transparent in the visible region. The photocatalytic performance of GO : ZnO nanocomposites was performed under UV irradiation. Therefore, the ZnO nanocrystals in the GO : ZnO composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the graphene oxide nanosheet.

Inking Elastomeric Stamps with Micro-Patterned, Single Layer Graphene to Create High-Performance OFETs

2011 ◽  
Vol 23 (31) ◽  
pp. 3531-3535 ◽  
Author(s):  
Seok Ju Kang ◽  
Bumjung Kim ◽  
Keun Soo Kim ◽  
Yue Zhao ◽  
Zheyuan Chen ◽  
...  
Keyword(s):  
High Performance ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene

scholarly journals Reflection Enhancement and Giant Lateral Shift in Defective Photonic Crystals with Graphene

2019 ◽  
Vol 9 (10) ◽  
pp. 2141 ◽  
Author(s):  
Dong Zhao ◽  
Fangmei Liu ◽  
Peng Meng ◽  
Jie Wen ◽  
Siliu Xu ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Interband Transition ◽  
Single Layer ◽  
Defect Layer ◽  
Lateral Shift ◽  
Single Layer Graphene ◽  
Intraband Transition ◽  
Highly Sensitive ◽  
Highly Sensitive Sensors ◽  
Periodic Number

This study investigates the reflectance of the defective mode (DM) and the lateral shift of reflected beam in defective photonic crystals incorporated with single-layer graphene by the transfer matrix method (TMM). Graphene, treated as an equivalent dielectric with a thickness of 0.34 nm, was embedded in the center of a defect layer. The reflectance of the DM was greatly enhanced as the intraband transition of electrons was converted to an interband transition in graphene. The reflectance of the DM could be further enhanced by increasing the Bragg periodic number. Furthermore, a large lateral shift of the reflected beam could also be induced around the DM. This study may find great applications in highly sensitive sensors.

scholarly journals Bottom-up synthesis of graphene films hosting atom-thick molecular-sieving apertures

2021 ◽  
Vol 118 (37) ◽  
pp. e2022201118 ◽  
Author(s):  
Luis Francisco Villalobos ◽  
Cédric Van Goethem ◽  
Kuang-Jung Hsu ◽  
Shaoxian Li ◽  
Mina Moradi ◽  
...  
Keyword(s):  
High Performance ◽  
State Of The Art ◽  
Scale Up ◽  
Single Layer ◽  
Chemical Vapor ◽  
Single Layer Graphene ◽  
Bottom Up ◽  
Vacancy Defects ◽  
Graphene Lattice ◽  
Molecular Sieving

Incorporation of a high density of molecular-sieving nanopores in the graphene lattice by the bottom-up synthesis is highly attractive for high-performance membranes. Herein, we achieve this by a controlled synthesis of nanocrystalline graphene where incomplete growth of a few nanometer-sized, misoriented grains generates molecular-sized pores in the lattice. The density of pores is comparable to that obtained by the state-of-the-art postsynthetic etching (1012 cm−2) and is up to two orders of magnitude higher than that of molecular-sieving intrinsic vacancy defects in single-layer graphene (SLG) prepared by chemical vapor deposition. The porous nanocrystalline graphene (PNG) films are synthesized by precipitation of C dissolved in the Ni matrix where the C concentration is regulated by controlled pyrolysis of precursors (polymers and/or sugar). The PNG film is made of few-layered graphene except near the grain edge where the grains taper down to a single layer and eventually terminate into vacancy defects at a node where three or more grains meet. This unique nanostructure is highly attractive for the membranes because the layered domains improve the mechanical robustness of the film while the atom-thick molecular-sized apertures allow the realization of large gas transport. The combination of gas permeance and gas pair selectivity is comparable to that from the nanoporous SLG membranes prepared by state-of-the-art postsynthetic lattice etching. Overall, the method reported here improves the scale-up potential of graphene membranes by cutting down the processing steps.

Development of FETs and Resistive Devices Based on Epitaxially Grown Single Layer Graphene on SiC for Highly Sensitive Gas Detection

2012 ◽  
Vol 717-720 ◽  
pp. 687-690
Author(s):  
Ruth Pearce ◽  
R. Yakimova ◽  
L. Hultman ◽  
Jens Eriksson ◽  
Mike Andersson ◽  
...  
Keyword(s):  
Work Function ◽  
Elevated Temperatures ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Steady Increase ◽  
Fermi Level Pinning ◽  
Layer Graphene ◽  
Highly Sensitive ◽  
Grown Graphene ◽  
P Type

Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were characterised for NO2 response at room and elevated temperatures, with an n-p type transition observed with increasing NO2 concentrations for all sensors. The concentration of NO2 required to cause this transition varied with different graphene samples and is attributed to varying degrees of substrate induced Fermi-level pinning above the Dirac point. The work function of a single layer device demonstrated a steady increase in work function with increasing NO2 concentration indicating no change in reaction mechanism in the concentration range measured despite a change in sensor response direction. Epitaxially grown graphene device preparation is challenging due to poor adhesion of the graphene layer to the substrate. A field effect transistor (FET) device is presented which does not require wire bonding to contacts on graphene.

scholarly journals Highly sensitive UVA and violet photodetector based on single-layer graphene-TiO_2 heterojunction

2016 ◽  
Vol 24 (23) ◽  
pp. 25922 ◽  
Author(s):  
Feng-Xia Liang ◽  
Deng-Yue Zhang ◽  
Jiu-Zhen Wang ◽  
Wei-Yu Kong ◽  
Zhi-Xiang Zhang ◽  
...  
Keyword(s):  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene ◽  
Highly Sensitive

scholarly journals High-performance deformable photoswitches with p-doped graphene as the top window electrode

2015 ◽  
Vol 3 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Rongjin Li ◽  
Zhaoyang Liu ◽  
Khaled Parvez ◽  
Xinliang Feng ◽  
Klaus Müllen
Keyword(s):  
High Performance ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene ◽  
Doped Graphene

Deformable polymer photoswitches with p-doped single layer graphene as the top window electrode exhibit an on/off ratio as high as 8.5 × 105.

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