DNA Hybridization Detection Using 5-nm Polysilicon Nanogap Structure

DNA hybridization detection using less than 10-nm gap silicon nanogap structure

The detection of DNA hybridization can be either complicated or require expensive devices. Some methods use a fluorescence signal to investigate hybridization. Here, we present an optical probe based on optical fibers both for illumination and for fluorescence collection. The detection is made with a microspectrophotometer and the signal is then treated with a PC. We also developed the DNA biochips (glass plate with a gold layer functionalized with target DNA) as well as a dedicated microtank which maintains a constant flow of probe DNA over the target one. Finally, the detection of hybridization with this simple and versatile system is presented.

Simple and label-free detection of DNA hybridization on a modified graphene nanosheets electrode

This work presents miniaturized CMOS (complementary metal oxide semiconductor) impedimetric sensors for detection of avian influenza virus (AIV) in the femtomolar level. The sensing resolution is significantly enhanced owing to monolithic sensor integration to reduce the parasitic effect and the use of sub-μm interdigitated microelectrodes to promote signal coupling efficiency. The 4×4 sensor array contains four electrode designs of different sizes. Capacitance changes associated with surface modification, functionalization, and DNA hybridization were extracted from measured frequency responses based on an equivalent circuit. Hybridization of AIV H5 capture and target DNA produced a percentage capacitance change of −12.8+3% among the four designs for target DNA concentrations from 1 fM to 10 fM, while capacitance increases were observed for non-specific binding of the H5 and H7 DNA probes.

Colorimetric detection of DNA hybridization based on a dual platform of gold nanoparticles and graphene oxide

A label-free electrochemical biosensor for highly sensitive and selective detection of DNA via a dual-amplified strategy

The present work deals with a non-clinical scheme to develop a system-on-chip for the detection and identification of the malignant cells in a known volume of white blood cells (WBC) using MEMS capacitive sensor. In presence of cancerous cells, the sensor produces a change in the value of capacitance which reflects a significant variation of dielectric permittivity. For this purpose, a double shell electrical model of WBC is designed and analyzed in frequency range 20 kHz–10 MHz due to the polarization of cell membrane. The polarization is induced using electroporation process where the plasma membrane of the blood cell is polarized to a membrane potential of about 0.5–1 V with a supply of 1 V which makes cell membrane semi permeable for the exchange of ions, thus producing change in dielectric permittivity. In order to determine the change in dielectric permittivity, an electrostatic MEMS capacitive sensor is virtually fabricated with a pair of rectangular electrodes in which the second electrode is further divided into four sub-plates in same plane. This change in permittivity results in change of output capacitance, finally differentiate a malignant cell from a normal one.

Multiplex and quantifiable detection of nucleic acid from pathogenic fungi using padlock probes, generic real time PCR and specific suspension array readout

This research aims to develop DNA chip array without an indicator. We fabricated microelectrode array by photolithography technology. Several DNA probes were immobilized on an electrode. Then, indicator-free target DNA was hybridized by an electrical force and measured electrochemically. Cyclic-voltammograms (CVs) showed a difference between DNA probe and mismatched DNA in an anodic peak. Immobilization of probe DNA and hybridization of target DNA could be confirmed by fluorescent. This indicator-free DNA chip microarray resulted in the sequence-specific detection of the target DNA quantitatively ranging from <TEX>$10^{-18}\;M\;to\;10^{-5}$</TEX> M in the buffer solution. This indicator-free DNA chip resulted in a sequence-specific detection of the target DNA.

Surface plasmon resonance (SPR) spectroscopy is employed for the study of biotinylated DNA assembly on streptavidin modified gold surfaces for target DNA hybridization. Two immobilization strategies are involved for constructing streptavidin films, namely, (1) physical adsorption on biotin-containing thiol treated surfaces through biotin-streptavidin links and (2) covalent attachment to 11-mercaptoundecanoic acid (MUA) treated surfaces through amine coupling. To understand the structural properties of the streptavidin films, a quartz crystal microbalance with energy dissipation monitoring (QCM-D) is used to monitor the streptavidin immobilization procedures. The simultaneously measured frequency (Deltaf) and dissipation factor (DeltaD) changes, together with the SPR angle shifts (Deltatheta), suggest that the streptavidin film assembled on the biotin-containing surface is highly rigid with a well-ordered structure while the streptavidin film formed through amine coupling is highly dissipative and less structured. The subsequent biotinylated DNA (biotin-DNA) assembly and target hybridization results show that the streptavidin film structure has distinct effects on the biotin-DNA binding amount. On the streptavidin matrix, not only the probe DNA density but also the strand orientation mediated by the streptavidin films has distinct effects on hybridization efficiency. Particularly, the molecularly ordered streptavidin films formed on the biotin-containing surfaces ensure a well-ordered DNA assembly, which in turn allows for a higher efficiency in target DNA capture and for a higher sensitivity in the hybridization analysis when compared to the biotin-DNA assembled on the less structured streptavidin films formed through amine coupling.

Scalable production of all-electronic DNA biosensors with high sensitivity and selectivity is a critical enabling step for research and applications associated with detection of DNA hybridization. We have developed a scalable and very reproducible (>90% yield) fabrication process for label-free DNA biosensors based upon graphene field effect transistors (GFETs) functionalized with single-stranded probe DNA. The shift of the GFET sensor Dirac point voltage varied systematically with the concentration of target DNA. The biosensors demonstrated a broad analytical range and limit of detection of 1 fM for 60-mer DNA oligonucleotide. In control experiments with mismatched DNA oligomers, the impact of the mismatch position on the DNA hybridization strength was confirmed. This class of highly sensitive DNA biosensors offers the prospect of detection of DNA hybridization and sequencing in a rapid, inexpensive, and accurate way.

An ultrasensitive nanogap junction is developed for label-free biomolecular detection. The nanogap junction can minimize the effects of electrode polarization. Without any label, dielectric detection of DNA hybridization is accomplished: the 70% and 12% changes of capacitance after hybridization were accomplished at 100 Hz for 10 /spl mu/M and 10 fM concentrations of target DNA, respectively. The nanogap junction-based dielectric DNA detection method and the batch fabrication method of nanogap junctions might able to change the paradigm of functional genomics and proteomics.

This research aims to develop the multiple channel electrochemical DNA chip using microfabrication technology. At first, we fabricated a high integration type DNA chip array by lithography technology. Several probe DNAs consisting of thiol group at their 5-end were immobilized on the gold electrodes. Then target DNAs were hybridized and reacted. Cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. Therefore, it is able to detect a plural genes electrochemically after immobilization of a plural probe DNA and hybridization of non-labeling target DNA on the electrodes simultaneously. It suggested that this DNA chip could recognize the sequence specific genes.

Comparison of DNA, aminoethylglycyl PNA and pyrrolidinyl PNA as probes for detection of DNA hybridization using surface plasmon resonance technique

Calcium-Dependent Synaptic Vesicle Trafficking Underlies Indefatigable Release at the Hair Cell Afferent Fiber Synapse