scholarly journals Nanogap Capacitors for Label Free DNA Analysis

2002 ◽  
Vol 729 ◽  
Author(s):  
Joon Sung Lee ◽  
Yang-Kyu Choi ◽  
Michael Pio ◽  
Jeonggi Seo ◽  
Luke P. Lee
Keyword(s):  
Self Assembly ◽  
Dna Hybridization ◽  
Dna Analysis ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Detection Sensitivity ◽  
Label Free ◽  
Double Stranded Dna ◽  
The Difference ◽  
Dielectrical Properties

AbstractNanogap capacitors are fabricated for DNA hybridization detection. Without labeling, the nanogap capacitors on a chip can function as DNA microarray sensors. The difference in dielectric properties between single-stranded DNA and double-stranded DNA permits use of capacitance measurements to detect hybridization. To obtain high detection sensitivity, a 50 nm gap capacitor was fabricated using a Si-nanotechnology. To ensure proper measurement of DNA's dielectrical properties, the probe ssDNA was first immobilized onto the electrode surface using self-assembly monolayers and allowed to hybridize with the target ssDNA. The capacitance changes were measured for 35-mer homonucleotides. The self-assembly monolayer and DNA immobilization events were verified independently by contact angle measurement and FTIR. Capacitance values are measured at frequencies ranging from 75 kHz to 5 MHz, using 0 VDC bias and 25 mVAC signals. Approximately 9% change in capacitance was observed after DNA hybridization at 75 kHz.

scholarly journals Concentration-driven phase transition and self-assembly in drying droplets of diluting whole blood

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anusuya Pal ◽  
Amalesh Gope ◽  
John D. Obayemi ◽  
Germano S. Iannacchione
Keyword(s):  
Phase Transition ◽  
Self Assembly ◽  
Whole Blood ◽  
Morphological Analysis ◽  
Hierarchical Structures ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Colloidal Systems ◽  
Functional Complexity ◽  
Sharp Phase Transition

Abstract Multi-colloidal systems exhibit a variety of structural and functional complexity owing to their ability to interact amongst different components into self-assembled structures. This paper presents experimental confirmations that reveal an interesting sharp phase transition during the drying state and in the dried film as a function of diluting concentrations ranging from 100% (undiluted whole blood) to 12.5% (diluted concentrations). An additional complementary contact angle measurement exhibits a monotonic decrease with a peak as a function of drying. This peak is related to a change in visco-elasticity that decreases with dilution, and disappears at the dilution concentration for the observed phase transition equivalent to 62% (v/v). This unique behavior is clearly commensurate with the optical image statistics and morphological analysis; and it is driven by the decrease in the interactions between various components within this bio-colloid. The implications of these phenomenal systems may address many open-ended questions of complex hierarchical structures.

Fabrication of Composite Carbon Nanotubes With Different Oxidation Levels by a Self-Assembly Surface Modification

2006 ◽  
Author(s):  
Chien-Te Hsieh ◽  
Kuen-Song Lin ◽  
Shih Hung Chan ◽  
Ay Su
Keyword(s):  
Carbon Nanotubes ◽  
Metal Oxide ◽  
Metal Ions ◽  
Self Assembly ◽  
Carbon Composite ◽  
Atomic Ratio ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Hydroxyl Group ◽  
Surface Oxides

An efficient technique to fabricate metal-oxide/carbon composite nanotubes has been developed through a self-assembly processing that includes implantation of acidic groups and interaction between surface oxides and metal ions or hydration molecules. To functionalize carbon nanotubes, gaseous oxidation at 300 °C was firstly employed to build functional oxygen groups including carboxyl, carbonyl and hydroxyl group, on the ends or sidewalls of the nanotubes. It revealed that the oxidized nanotubes express a slight improvement of surface hydrophilicity, which was demonstrated by contact angle measurement. X-ray photoelectron spectroscope investigation indicated that the ratio of attached metal-oxide onto the oxidized nanotubes gradually increases with oxidation level, i.e., surface O/C atomic ratio. This evidence reflected that the surface oxides act as an adsorption center that strongly interacts with metal ions or hydration molecules in aqueous phase. Applying this method, SnO2, RuO2, NiO and PtRu nanoparticles having an average size of 5 nm were assembled on the oxidized carbon nanotubes.

Effect of Microcellulose on Wettability of Reservoir Rock Surface Model

2019 ◽  
Vol 811 ◽  
pp. 55-61
Author(s):  
Mia Ledyastuti ◽  
Galuh Sukmarani
Keyword(s):  
Contact Angle ◽  
Oil Recovery ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Reservoir Rock ◽  
Rock Surface ◽  
Surface Model ◽  
Particle Sizes ◽  
Produce Water ◽  
The Difference

Wettability is one factor that influences the enhanced oil recovery. Water-wet surfaces are predicted increasing the oil recovery from the reservoir. Microcellulose has the potential to produce water-wet surfaces. In this experiment, two types of microcellulose were used with different particle sizes of 2.9 μm and 14 μm. Both types of microcellulose are then applied to the reservoir rock surface model, i.e the surface of bentonite which has been soaked in crude oil for one week at 60 °C. Contact angle measurement shows that there is a decrease in water-the reservoir rock surface model contact angle from ~ 90 ° to ~ 80 ° when applied microcellulose solution 0.5% w/w. The difference in microcellulose size causes a difference in contact angle of about 5° at microcellulose solution 2.5%. This shows the application of microcellulose on the reservoir rock surface model causing the surface to be more water-wet.

scholarly journals Prediction of Dielectric Breakdown of OHTL Insulators Using Contact Angle Measurements

2021 ◽  
Author(s):  
Taeyong Kim ◽  
Simpy Sanyal ◽  
Seongho Jeon ◽  
Junsin Yi
Keyword(s):  
Contact Angle ◽  
Transmission Lines ◽  
Dielectric Breakdown ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Salt Deposit ◽  
Voltage Drops ◽  
Flashover Voltage ◽  
Deposit Density ◽  
The Difference

Abstract Porcelain insulators used in overhead transmission lines (OHTL) are exposed to pollution when operational. To observe the effect of external pollution on these insulators, the relationship between the flashover voltage and surface contamination was studied. The flashover voltage drops sharply when contaminants in the wind are deposited on the surface of the insulators in a humid environment. Under wet conditions, the flashover voltage demonstrates a difference of approximately 10 kV depending on the contamination levels. The higher the equivalent salt deposit density, the lower the contact angle. In particular, the flashover voltage under wet conditions decreases exponentially when the contact angle is below 30°. In this case, the condensation area becomes considerably wider, thus exhibiting the difference in the area of the electrolytic conductive film layer forming the leakage path on the surface. Depending on the equivalent salt deposit density and contact angle, the area of condensation is more than doubled. To measure the level of contamination on the surface using this principle, a contact angle measurement method was adopted to predict the dielectric breakdown of the insulator.

scholarly journals Correlation between Contact Angle and Surface Roughness of Silicon Carbide Wafers

2021 ◽  
Author(s):  
Jung Gon Kim ◽  
Woo Sik Yoo ◽  
Woo Yeon Kim ◽  
Won Jae Lee
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Surface Polarity ◽  
Force Microscopy ◽  
Water Drops ◽  
The Difference ◽  
Sic Wafer

Abstract Two-inch diameter 6H-SiC wafers were sliced from a SiC ingot and the wafers were ground and polished using different diamond slurries (1 m and 0.1 m in particles size) to investigate their dependence on wetting on surface roughness (Ra) and polarity using precisely dispensed de-ionized (DI) water drops. The Ra of the Si-face (0001) SiC wafer, after grinding and polishing, was 5.6 and 1.6 nm, respectively, as measured by atomic force microscopy (AFM). For C-face (000-1) SiC wafers, the Ra was 7.2 nm after grinding and 3.3 nm after polishing. The average contact angle measurement of the SiC wafers after final polishing showed clear differences between surface polarity; the contact angle for the Si-face (0001) was ~7o greater than that for the C-face (000-1). The difference in contact angles between the Si-face (0001) and the C-face (000-1) tends to increase as the reduction of surface roughness approaches the final stage of polishing. The uniformity of Raman peak intensity in the folded transverse optical phonon band at ~780 cm-1 in scanned areas correlated well with the surface roughness measured by AFM. The contact angle measurement can be used as a convenient surface polarity and surface roughness testing technique for SiC wafers.

Fabrication of Transparent Hydrophilic Nanosized TiO2 Films via Layer-by-Layer Self-Assembly

2016 ◽  
Vol 852 ◽  
pp. 1075-1079
Author(s):  
Zhi Yong Zeng ◽  
Ying Shi ◽  
Su Jun Yuan ◽  
Jian Jun Xie
Keyword(s):  
Contact Angle ◽  
Self Assembly ◽  
Hydrothermal Process ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Layer By Layer ◽  
Water Contact ◽  
Assembly Method ◽  
Oppositely Charged ◽  
Positively Charged

The transparent nanosized TiO2 film was fabricated by a layer-by-layer assembly method starting from the highly dispersed anatase oppositely charged TiO2 nanoparticles without using anypoly electrolytes. The positively charged TiO2 nanoparticles (ca.7 nm) and negatively charged TiO2 nanoparticles (ca.7 nm) were synthesized by a subsequently hydrothermal process. Field-emission scanning electron microscopy, UV-vis transmittance spectra and Contact angle measurement were employed to characterize TiO2films.By the treatment of 500°C for 2hrs, the nanostructured TiO2 film showed a water contact angle of below 10°andthe relative transmittance to quartz glass of over 90%.

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.

scholarly journals Ultrasensitive and label free electrochemical immunosensor for detection of ROR1 as an oncofetal biomarker using gold nanoparticles assisted LDH/rGO nanocomposite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rozita Abolhasan ◽  
Balal Khalilzadeh ◽  
Hadi Yousefi ◽  
Sahar Samemaleki ◽  
Forough Chakari-Khiavi ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Flexible Structures ◽  
Modified Electrodes ◽  
Electrochemical Immunosensor ◽  
Lymphocytic Leukemia ◽  
Orphan Receptor ◽  
Detection Sensitivity ◽  
Label Free ◽  
Serum Samples ◽  
Limit Of Quantification

AbstractIn the present article, we developed a highly sensitive label-free electrochemical immunosensor based on NiFe-layered double hydroxides (LDH)/reduced graphene oxide (rGO)/gold nanoparticles modified glassy carbon electrode for the determination of receptor tyrosine kinase-like orphan receptor (ROR)-1. In this electrochemical immunoassay platform, NiFe-LDH/rGO was used due to great electron mobility, high specific surface area and flexible structures, while Au nanoparticles were prepared and coated on the modified electrodes to improve the detection sensitivity and ROR1 antibody immobilizing (ROR1Ab). The modification procedure was approved by using cyclic voltammetry and differential pulse voltammetry based on the response of peak current to the step by step modifications. Under optimum conditions, the experimental results showed that the immunosensor revealed a sensitive response to ROR1 in the range of 0.01–1 pg mL−1, and with a lower limit of quantification of 10 attogram/mL (10 ag mL−1). Furthermore, the designed immunosensor was applied for the analysis of ROR1 in several serum samples of chronic lymphocytic leukemia suffering patients with acceptable results, and it also exhibited good selectivity, reproducibility and stability.

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