scholarly journals An Enzyme- and Label-Free Fluorescence Aptasensor for Detection of Thrombin Based on Graphene Oxide and G-Quadruplex

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4424 ◽  
Author(s):  
Yani Wei ◽  
Luhui Wang ◽  
Yingying Zhang ◽  
Yafei Dong
Keyword(s):  
Graphene Oxide ◽  
Cost Effective ◽  
Target Pair ◽  
Label Free ◽  
Detection Scheme ◽  
G Quadruplex ◽  
Universal Detection ◽  
Dna Strand ◽  
Aptamer Sequence

An enzyme- and label-free aptamer-based assay is described for the determination of thrombin. A DNA strand (S) consisting of two parts was designed, where the first (Sa) is the thrombin-binding aptamer and the second (Se) is a G-quadruplex. In the absence of thrombin, Sa is readily adsorbed by graphene oxide (GO), which has a preference for ss-DNA rather than for ds-DNA. Upon the addition of the N-methyl-mesoporphyrin IX (NMM), its fluorescence (with excitation/emission at 399/610 nm) is quenched by GO. In contrast, in the presence of thrombin, the aptamer will bind thrombin, and thus, be separated from GO. As a result, fluorescence will be enhanced. The increase is linear in the 0.37 µM to 50 µM thrombin concentration range, and the detection limit is 0.37 nM. The method is highly selective over other proteins, cost-effective, and simple. In our perception, it represents a universal detection scheme that may be applied to other targets according to the proper choice of the aptamer sequence and formation of a suitable aptamer-target pair.

scholarly journals Immobilization-Free Electrochemical Sensor Coupled with a Graphene-Oxide-Based Aptasensor for Glycated Albumin Detection

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 85
Author(s):  
Wassa Waiwinya ◽  
Thitirat Putnin ◽  
Dechnarong Pimalai ◽  
Wireeya Chawjiraphan ◽  
Nuankanya Sathirapongsasuti ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Sensor ◽  
Detection Method ◽  
Limit Of Detection ◽  
Glycated Albumin ◽  
Cost Effective ◽  
Logarithmic Scale ◽  
Electrochemical Aptasensor ◽  
Alternative Approach

An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels.

scholarly journals Paper-based potentiometric sensing devices modified with chemically reduced graphene oxide (CRGO) for trace level determination of pholcodine (opiate derivative drug)

RSC Advances ◽  
2021 ◽  
Vol 11 (20) ◽  
pp. 12227-12234
Author(s):  
Hisham S. M. Abd-Rabboh ◽  
Abd El-Galil E. Amr ◽  
Elsayed A. Elsayed ◽  
Ahmed Y. A. Sayed ◽  
Ayman H. Kamel
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Cost Effective ◽  
Trace Level ◽  
Ion Sensing ◽  
Reduced Graphene ◽  
Chemically Reduced Graphene Oxide ◽  
Trace Level Determination ◽  
Analytical Device

Robust, reliable and cost-effective paper-based analytical device for potentiometric pholcodine (opiate derivative drug) ion sensing has been prepared and characterized.

A label-free fluorescent sensor for Pb2+based on G-quadruplex and graphene oxide

2014 ◽  
Vol 6 (20) ◽  
pp. 8120-8123 ◽  
Author(s):  
Yunfeng Bai ◽  
Lu Zhao ◽  
Zezhong Chen ◽  
Haiyan Wang ◽  
Feng Feng
Keyword(s):  
Graphene Oxide ◽  
Fluorescent Sensor ◽  
Label Free ◽  
G Quadruplex

scholarly journals A label-free biosensor based on graphene and reduced graphene oxide dual-layer for electrochemical determination of beta-amyloid biomarkers

2020 ◽  
Vol 187 (5) ◽  
Author(s):  
Jagriti Sethi ◽  
Michiel Van Bulck ◽  
Ahmed Suhail ◽  
Mina Safarzadeh ◽  
Ana Perez-Castillo ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Limit Of Detection ◽  
Electrochemical Techniques ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Label Free ◽  
Reduced Graphene ◽  
Electrochemically Reduced Graphene Oxide

AbstractA label-free biosensor is developed for the determination of plasma-based Aβ1–42 biomarker in Alzheimer’s disease (AD). The platform is based on highly conductive dual-layer of graphene and electrochemically reduced graphene oxide (rGO). The modification of dual-layer with 1-pyrenebutyric acid N-hydroxysuccinimide ester (Pyr-NHS) is achieved to facilitate immobilization of H31L21 antibody. The effect of these modifications were studied with morphological, spectral and electrochemical techniques. The response of the biosensor was evaluated using differential pulse voltammetry (DPV). The data was acquired at a working potential of ~ 180 mV and a scan rate of 50 mV s−1. A low limit of detection (LOD) of 2.398 pM is achieved over a wide linear range from 11 pM to 55 nM. The biosensor exhibits excellent specificity over Aβ1–40 and ApoE ε4 interfering species. Thus, it provides a viable tool for electrochemical determination of Aβ1–42. Spiked human and mice plasmas were used for the successful validation of the sensing platform in bio-fluidic samples. The results obtained from mice plasma analysis concurred with the immunohistochemistry (IHC) and magnetic resonance imaging (MRI) data obtained from brain analysis.

Quantification of Zn(ii) using a label-free sensor based on graphene oxide and G-quadruplex

2015 ◽  
Vol 7 (22) ◽  
pp. 9615-9618 ◽  
Author(s):  
Yahui Guo ◽  
Yan Sun ◽  
Xiaoqiang Shen ◽  
Xing Chen ◽  
Weirong Yao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Fluorescence Assay ◽  
Label Free ◽  
G Quadruplex

A label-free fluorescence assay was developed for the detection of Zn2+ using GO and a guanine-rich sequence H22.

scholarly journals Design of a High-Sensitivity Dimeric G-Quadruplex/Hemin DNAzyme Biosensor for Norovirus Detection

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7352
Author(s):  
Yun Zhang ◽  
Xinao Ma ◽  
Jingtian Zhang ◽  
Feixian Luo ◽  
Wenshu Wang ◽  
...  
Keyword(s):  
Nucleic Acids ◽  
Operating Cost ◽  
High Sensitivity ◽  
Cost Effective ◽  
Sequence Detection ◽  
Conserved Sequence ◽  
Synergistic Enhancement ◽  
Target Dna ◽  
G Quadruplex ◽  
Dna Strand

G-quadruplexes can bind with hemin to form peroxidase-like DNAzymes that are widely used in the design of biosensors. However, the catalytic activity of G-quadruplex/hemin DNAzyme is relatively low compared with natural peroxidase, which hampers its sensitivity and, thus, its application in the detection of nucleic acids. In this study, we developed a high-sensitivity biosensor targeting norovirus nucleic acids through rationally introducing a dimeric G-quadruplex structure into the DNAzyme. In this strategy, two separate molecular beacons each having a G-quadruplex-forming sequence embedded in the stem structure are brought together through hybridization with a target DNA strand, and thus forms a three-way junction architecture and allows a dimeric G-quadruplex to form, which, upon binding with hemin, has a synergistic enhancement of catalytic activities. This provides a high-sensitivity colorimetric readout by the catalyzing H2O2-mediated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline -6-sulfonic acid) diammonium salt (ABTS). Up to 10 nM of target DNA can be detected through colorimetric observation with the naked eye using our strategy. Hence, our approach provides a non-amplifying, non-labeling, simple-operating, cost-effective colorimetric biosensing method for target nucleic acids, such as norovirus-conserved sequence detection, and highlights the further implication of higher-order multimerized G-quadruplex structures in the design of high-sensitivity biosensors.

scholarly journals A Label-Free Immunosensor Based on Graphene Oxide/Fe3O4/Prussian Blue Nanocomposites for the Electrochemical Determination of HBsAg

Biosensors ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 24 ◽  
Author(s):  
Shanshan Wei ◽  
Haolin Xiao ◽  
Liangli Cao ◽  
Zhencheng Chen
Keyword(s):  
Graphene Oxide ◽  
Hepatitis B ◽  
Prussian Blue ◽  
Hepatitis B Surface Antigen ◽  
Electrochemical Determination ◽  
Detection Sensitivity ◽  
Label Free ◽  
Serum Samples ◽  
Highly Sensitive

In this article, a highly sensitive label-free immunosensor based on a graphene oxide (GO)/Fe3O4/Prussian blue (PB) nanocomposite modified electrode was developed for the determination of human hepatitis B surface antigen (HBsAg). In this electrochemical immunoassay system, PB was used as a redox probe, while GO/Fe3O4/PB nanocomposites and AuNPs were prepared and coated on screen-printed electrodes to enhance the detection sensitivity and to immobilize the hepatitis B surface antibody (HBsAb). The immunosensor was fabricated based on the principle that the decrease in peak currents of PB is proportional to the concentration of HBsAg captured on the modified immunosensor. The experimental results revealed that the immunosensor exhibited a sensitive response to HBsAg in the range of 0.5 pg·mL−1 to 200 ng·mL−1, and with a low detection limit of 0.166 pg·mL−1 (S/N = 3). Furthermore, the proposed immunosensor was used to detect several clinical serum samples with acceptable results, and it also showed good reproducibility, selectivity and stability, which may have a promising potential application in clinical immunoassays.

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