scholarly journals Improvement of Detection Limit of Nanomechanical Deflection Using Optical Interferometry for Label-free Molecular Detection

2019 ◽  
Vol 31 (9) ◽  
pp. 2895 ◽  
Author(s):  
Satoshi Maruyama ◽  
Yong Joon Choi ◽  
Kazuhiro Takahashi ◽  
Kazuaki Sawada
Keyword(s):  
Detection Limit ◽  
Molecular Detection ◽  
Optical Interferometry ◽  
Label Free

Label-Free Electrochemical Detection of DNA Hybridization Related to Anthrax Lethal Factor by using Carbon Nanotube Modified Sensors

2019 ◽  
Vol 15 (4) ◽  
pp. 502-510 ◽  
Author(s):  
Hakan Karadeniz ◽  
Arzum Erdem
Keyword(s):  
Detection Limit ◽  
Dna Hybridization ◽  
Lethal Factor ◽  
Modified Electrodes ◽  
Label Free ◽  
Carbon Paste ◽  
Chip Technology ◽  
Anthrax Lethal Factor ◽  
Hybridization Time ◽  
Electrochemical Monitoring

Background: Anthrax Lethal Factor (ANT) is the dominant virulence factor produced by B. anthracis and is the major cause of death of infected animals. In this paper, pencil graphite electrodes GE were modified with single-walled and multi-walled carbon nanotubes (CNTs) for the detection of hybridization related to the ANT DNA for the first time in the literature. Methods: The electrochemical monitoring of label-free DNA hybridization related to ANT DNA was explored using both SCNT and MCNT modified PGEs with differential pulse voltammetry (DPV). The performance characteristics of ANT-DNA hybridization on disposable GEs were explored by measuring the guanine signal in terms of optimum analytical conditions; the concentration of SCNT and MCNT, the concentrations of probe and target, and also the hybridization time. Under the optimum conditions, the selectivity of probe modified electrodes was tested and the detection limit was calculated. Results: The selectivity of ANT probes immobilized onto MCNT-GEs was tested in the presence of hybridization of probe with NC no response was observed and with MM, smaller responses were observed in comparison to full-match DNA hybridization case. Even though there are unwanted substituents in the mixture samples containing both the target and NC in the ratio 1:1 and both the target and MM in the ratio 1:1, it has been found that ANT probe immobilized CNT modified graphite sensor can also select its target by resulting with 20.9% decreased response in comparison to the one measured in the case of full-match DNA hybridization case Therefore, it was concluded that the detection of direct DNA hybridization was performed by using MCNT-GEs with an acceptable selectivity. Conclusion: Disposable SCNT/MCNT modified GEs bring some important advantages to our assay including easy use, cost-effectiveness and giving a response in a shorter time compared to unmodified PGE, carbon paste electrode and glassy carbon electrode developed for electrochemical monitoring of DNA hybridization. Consequently, the detection of DNA hybridization related to the ANT DNA by MCNT modified sensors was performed by using lower CNT, probe and target concentrations, in a shorter hybridization time and resulting in a lower detection limit according to the SCNT modified sensors. In conclusion, MCNT modified sensors can yield the possibilities leading to the development of nucleic acid sensors platforms for the improvement of fast and cost-effective detection systems with respect to DNA chip technology.

Microsphere-enhanced label-free high-throughput molecular detection

2008 ◽  
Author(s):  
Cheng Deng ◽  
Guoliang Huang ◽  
Shukuan Xu ◽  
Jing Zhu ◽  
Rui Ma ◽  
...  
Keyword(s):  
High Throughput ◽  
Molecular Detection ◽  
Label Free

scholarly journals Label-Free Split Aptamer Sensor for Femtomolar Detection of Dopamine by Means of Flexible Organic Electrochemical Transistors

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2577 ◽  
Author(s):  
Yuanying Liang ◽  
Ting Guo ◽  
Lei Zhou ◽  
Andreas Offenhäusser ◽  
Dirk Mayer
Keyword(s):  
Detection Limit ◽  
Electrochemical Sensors ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Label Free ◽  
Dopamine Detection ◽  
Electrochemical Transistor ◽  
Sensitivity And Selectivity

The detection of chemical messenger molecules, such as neurotransmitters in nervous systems, demands high sensitivity to measure small variations, selectivity to eliminate interferences from analogues, and compliant devices to be minimally invasive to soft tissue. Here, an organic electrochemical transistor (OECT) embedded in a flexible polyimide substrate is utilized as transducer to realize a highly sensitive dopamine aptasensor. A split aptamer is tethered to a gold gate electrode and the analyte binding can be detected optionally either via an amperometric or a potentiometric transducer principle. The amperometric sensor can detect dopamine with a limit of detection of 1 μM, while the novel flexible OECT-based biosensor exhibits an ultralow detection limit down to the concentration of 0.5 fM, which is lower than all previously reported electrochemical sensors for dopamine detection. The low detection limit can be attributed to the intrinsic amplification properties of OECTs. Furthermore, a significant response to dopamine inputs among interfering analogues hallmarks the selective detection capabilities of this sensor. The high sensitivity and selectivity, as well as the flexible properties of the OECT-based aptasensor, are promising features for their integration in neuronal probes for the in vitro or in vivo detection of neurochemical signals.

A facile low-cost paper-based SERS substrate for label-free molecular detection

2019 ◽  
Vol 291 ◽  
pp. 369-377 ◽  
Author(s):  
Vo Thi Nhat Linh ◽  
Jungil Moon ◽  
ChaeWon Mun ◽  
Vasanthan Devaraj ◽  
Jin-Woo Oh ◽  
...  
Keyword(s):  
Molecular Detection ◽  
Low Cost ◽  
Sers Substrate ◽  
Label Free

Label-Free Aptamer Fluorescence Determination of Trace Pb2+ Using AuPd Nanoalloy Probe as Catalyst

2013 ◽  
Vol 631-632 ◽  
pp. 18-21 ◽  
Author(s):  
Zhi Liang Jiang ◽  
Mei Ling Tang ◽  
Qing Ye Liu ◽  
Ai Hui Liang
Keyword(s):  
Detection Limit ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Water Samples ◽  
Catalytic Effect ◽  
Rhodamine 6G ◽  
Label Free ◽  
Double Stranded Dna ◽  
Fluorescence Determination

In the condition of 1.24 mmol/L EDTANa2, 16.7 mmol/L NaCl and 0.17 mmol/L Tris, the substrate chain of double-stranded DNA (dsDNA) could be cracked by Pb2+ to release single-stranded DNA (ssDNA) that adsorb onto AuPd nanoparticle (AuPdNP) and form stable AuPdNP-ssDNA, but the dsDNA can not protect AuPdNP that were aggregated to big AuPdNP aggregations (AuPdNPA) under the action of NaCl. The AuPdNP-ssDNA and AuPdNPA could be separated by centrifugation. With the concentration of Pb2+ increased, the released ssDNA increased, the AuPdNP-ssDNA in centrifugation solution increased and the catalytic effect enhanced on the fluorescence quenching reaction of Rhodamine 6G (Rh6G) and NaH2PO2, which led the fluorescence intensity at 552nm to decrease. The decreased fluorescence intensity (ΔF552nm) was linear to the concentration of Pb2+ in the range of 0.33-8.00 nmol/L, a detection limit of 0.21 nmol/L. The proposed method was applied to detect Pb2+ in water samples, with satisfactory results.

scholarly journals Fast Detection of Chloramphenicol in Raw Milk Using a Hairpin Aptamer-templated Silver Nanoclusters

2021 ◽  
pp. 8-21
Author(s):  
Hengchao Li ◽  
Bin Hu ◽  
Yuliang Cheng ◽  
Hang Yu ◽  
Yunfei Xie ◽  
...  
Keyword(s):  
Detection Limit ◽  
Raw Milk ◽  
Hairpin Structure ◽  
Silver Nanoclusters ◽  
Structure Transformation ◽  
Label Free ◽  
Fast Detection ◽  
New Strategy ◽  
Potential Applicability ◽  
Induced Structure

In this presented work, a facile and efficient method was established for the detection of chloramphenicol (CAP) based on target-induced structure transformation of aptamer. This aptamer DNA with a hairpin structure can coincidentally serve as a template for the synthesis of bright silver nanoclusters (quantum yield 16.36%). The binding of CAP with aptamer DNA could cause the destruction of the hairpin structure, resulting in the quenching of the fluorescence of silver nanoclusters (AgNCs). It costs less than 10 minutes to complete the assay, and excellent sensitivity was achieved with detection limit of 0.052 nmol/L. The selectivity and recovery experiments also demonstrated satisfactory results of this proposed protocol. The method has potential applicability, and provides a new strategy for the development of label-free sensors based on aptamer and AgNCs.

scholarly journals Imaging action potential in single mammalian neurons by tracking the accompanying sub-nanometer mechanical motion

2017 ◽  
Author(s):  
Yunze Yang ◽  
Xian-Wei Liu ◽  
Hui Yu ◽  
Yan Guan ◽  
Shaopeng Wang ◽  
...  
Keyword(s):  
Detection Limit ◽  
Patch Clamp ◽  
Action Potential ◽  
Fluorescence Detection ◽  
Action Potentials ◽  
Single Cells ◽  
Detection Methods ◽  
Imaging Method ◽  
Label Free ◽  
Mechanical Motion

AbstractAction potentials in neurons have been studied traditionally by the patch clamp and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with sub-nanometer detection limit and sub-millisecond temporal resolution. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2 - 0.4 nm. The work indicates that action potentials may be studied non-invasively in single mammalian neurons by label-free imaging of the accompanying subnanometer mechanical motion.

Fiber-optics: a new route towards ultra-low detection limit label-free biosensing

2019 ◽  
Author(s):  
Pablo Zubiate ◽  
Desiree Santano ◽  
Aitor Urrutia ◽  
Carlos R. Zamarreño ◽  
Silvia Díaz ◽  
...  
Keyword(s):  
Detection Limit ◽  
Fiber Optics ◽  
Label Free ◽  
Low Detection Limit
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