Electrical Detection Of DNA Research Articles

Electrical detection of DNA via nanoparticles under light-induced assembly

Rapid, simple, and label-free detection of DNA without fluorescent dyes is desired in the fields of medical diagnosis and food inspection. Electrical measurement using microelectrodes is a promising method for the detection of DNA, whereas it requires multiple pre-treatment processes. In this study, omitting these processes, we demonstrated the possibility of rapid electrical detection of DNA-modified gold nanoparticles and target DNA transported and accumulated between electrodes by photothermal assembly (PTA) under the laser irradiation to a microelectrode. Two types of target DNA molecules with different base sequences were detected within 10 min through the change of electric resistance before and after PTA. The obtained results will be a foundation of a rapid and simple genetic screening method and the detection of various biological nanomaterials based on the electrical measurement mediated by a light-induced assembly.

Bacterial detection based on polymerase chain reaction and microbead dielectrophoresis characteristics.

In this study, an electrical DNA detection method was applied to bacterial detection. DNA was extracted from bacteria and amplified by polymerase chain reaction. The microbeads were labelled with amplicons, altering their surface conductance and therefore their dielectrophoresis characteristics. Amplicon-labelled microbeads could thus be trapped within a high-strength electric field, where they formed a pearl chain between the electrodes, resulting in an increased conductance between the electrodes. This method reduces the amplicon detection time from 1-2 h to 15 min, compared with the conventional method. The presented method realised quantitative detection of specific bacteria at concentrations above 1 × 105 and 2.4 × 104 CFU/ml for bacterial solutions with and without other bacterial presence, respectively.

Double-Gate Graphene Nanoribbon Field-Effect Transistor for DNA and Gas Sensing Applications: Simulation Study and Sensitivity Analysis

In this paper, new sensors based on a double-gate (DG) graphene nanoribbon field-effect transistor (GNRFET), for high-performance DNA and gas detection, are proposed through a simulation-based study. The proposed sensors are simulated by solving the Schrodinger equation using the mode space non-equilibrium Green’s function formalism coupled self-consistently with a 2D Poisson equation under the ballistic limits. The dielectric and work function modulation techniques are used for the electrical detection of DNA and gas molecules, respectively. The behaviors of both the sensors have been investigated, and the impacts of variation in geometrical and electrical parameters on the sensitivity of sensors have also been studied. In comparison to other FET-based sensors, the proposed sensors provide not only higher sensitivity but also better electrical and scaling performances. The obtained results make the proposed DG-GNRFET-based sensors as promising candidates for ultra-sensitive, small-size, low-power and reliable CMOS-based DNA, and gas sensors.

DNA Detection Using SiC Nanowire Based Transistor

The fast and direct detection of small quantities of biomolecules improves early medical diagnosis of certain serious diseases as cancers and can be used to detect in situ the presence of pathogenic viruses or GMOs for food industry, protection environmental and bio-defense. Numerous research projects are conducted on nanoelectronic devices that can perform such detection with high sensitivity using nanostructures. Currently, these devices are made from Silicon nanowires [1]. For these applications, Silicon Carbide (SiC) material can advantageously replace Silicon as this semiconductor is now known to be biocompatible and to show a high chemical inertness [2]. Here, we present the electrical detection of DNA using a SiC Nanowire Field Effect Transistor (NWFET). The NWFETs are fabricated and then functionalized with DNA molecules. Between each step of the functionalization process, I-V characteristic measurements are performed. Comparative and simultaneous measurements are carried out on two SiC NWFETs: one is the sensor and the second one is used as a reference. Some interesting properties of the sensor are studied for the first time which opens the way to future developments of SiC nanowire based sensors.

Progress in Silicon Nanowire‐Based Field‐Effect Transistor Biosensors for Label‐Free Detection of DNA

AbstractSilicon nanowire (SiNW), as one‐dimensional semiconducting nanomaterial, has been incorporated into the filed‐effect transistor (FET) devices to increase the efficacy and signal‐to‐noise in DNA sensing applications. Due to the advantages of high sensitivity, excellent selectivity, label‐free detection, direct electrical readout, and miniaturization, SiNW FET‐based DNA sensors have been regarded as an important tool in applications of molecular diagnostics, DNA sequencing, gene expressions, and drug discovery. Here, we review the recent progress in SiNW‐FET sensors for label‐free electrical DNA detection. We first introduce the working principle of SiNW‐FET DNA sensors, SiNW fabrication technologies, bio‐functionalization on nanowire surface, and enhancement of device sensitivity. Then we sum up the applications of SiNW sensors in detection of DNA hybridization, infectious viruses, microRNA, genetic change (DNA mutation, DNA methylation, and DNA repair), and protein‐DNA interactions. We address several crucial points of sensing performance including sensitivity, selectivity, and limit of detection. Finally, the perspectives, challenges, and some solutions of the field are also discussed.

Gold Nanowire Based Electrical DNA Detection Using Rolling Circle Amplification

We present an electrical sensor that uses rolling circle amplification (RCA) of DNA to stretch across the gap between two electrodes, interact with metal nanoparticle seeds to generate an electrically conductive nanowire, and produce electrical signals upon detection of specific target DNA sequences. RCA is a highly specific molecular detection mechanism based on DNA probe circularization. With this technique, long single-stranded DNA with simple repetitive sequences are produced. Here we show that stretched RCA products can be metalized using silver or gold solutions to form metal wires. Upon metallization, the resistance drops from TΩ to kΩ for silver and to Ω for gold. Metallization is seeded by gold nanoparticles aligned along the single-stranded DNA product through hybridization of functionalized oligonucleotides. We show that combining RCA with electrical DNA detection produces results in readout with very high signal-to-noise ratio, an essential feature for sensitive and specific detection assays. Finally, we demonstrate detection of 10 ng of Escherichia coli genomic DNA using the sensor concept.

Cyclic enzymatic amplification method (CEAM) based on exonuclease III for highly sensitive bioanalysis

Nucleic acid molecular probes (NAMPs) have been widely used in the sensing of various chemical and biological substances, as well as physical parameters. However, for traditional nucleic acid molecular probes, the stoichiometric 1:1 binding ratio limits the signal enhancement and thus the sensitivity of the assay. In order to overcome this problem, the cyclic enzymatic amplification method (CEAM) based on exonuclease III has been applied in optical and electrical detection of DNA, proteins and small molecules with excellent sensitivity, selectivity, versatility and simplicity. In this review, the working principle of CEAM is first introduced, followed by the applications of CEAM using different output signals for various analytes. Finally, experimental designs and procedures of CEAM are discussed in detail using displacing probes-based CEAM and linear molecular beacons (LMBs)-based CEAM as two examples.

An electrostatic micromechanical biosensor for electrical detection of label-free DNA

An electrostatic micromechanical biosensor is demonstrated for the label-free electrical detection of DNA, based on electrostatic actuation of a double-clamped micromechanical cantilever by driving gate electrodes to establish a current path through drain and source electrodes. Intrinsic charges in DNA alter surface charges on the gate by pre-charging concept and change the pull-in voltage (VPI), the voltage required to bring the suspended cantilever into contact with the drain electrode by induced electrostatic force. Its operation principle is verified by a numerical simulation and a capacitive model. The proposed biosensor represents a breakthrough for practical exploitation of electro-mechanical based sensors.

Oligonucleotide-based signal amplification for ultrasensitive electrochemical biosensor

There is a need for an inexpensive, non-invasive and quick investigation with high sensitivity and specificity for early and accurate diagnosis of cancers. The present amplified bioassay takes advantage of the state-of-the-art electrical DNA detection methods, including the highly sensitive stripping response based on the intrinsic electroactivity of guanine and adenine nucleobases, and the amplification potential of latex microspheres carrying numerous oligonucleotide tags. The dramatic signal amplification advantage of this type of detection has been combined with efficient magnetic removal of non-complementary DNA for maximum selectivity, use of microlitre sample volumes and disposable transducers. The advantages of this procedure were demonstrated by its application in the detection of DNA segments related to the BRCA1 breast cancer gene.

Label-free electrical detection of DNA hybridization using carbon nanotubes and graphene.

The interface between biosystems and nanomaterials is emerging for detection of various biomolecules and subtle cellular activities. In particular, the development of cost-effective and sequence-selective DNA detection is urgent for the diagnosis of genetic or pathogenic diseases. Graphene-based nanocarbon materials, such as carbon nanotubes and thin graphene layers, have been employed as biosensors because they are biocompatible, extraordinarily sensitive, and promising for large-area detection. Electrical and label-free detection of DNA can be achieved by monitoring the conductance change of devices fabricated from these carbon materials. Here, the recent advances in this research area are briefly reviewed. The key issues and perspectives of future development are also discussed.

A disposable and cost efficient microfluidic device for the rapid chip-based electrical detection of DNA

Requirements for a point-of-care device are an easy and robust read-out and – above all – a simple handling. We integrated an established robust electrical read-out for DNA-chips into a microfluidic device, thereby creating an automated analysis system that combines the necessary steps for a chip-based analysis. It is based on the electrical detection of biotin-labeled DNA in a gap between two microstructured electrodes on the surface of a DNA-chip. The biotin serves as binding molecule for streptavidin-conjugated horseradish peroxidase. A following enzyme-induced silver deposition bridges the gap by a conductive layer. The miniaturized chip gives the possibility to realize a durable system suitable for point-of-care applications. To enable an initial automation, all corresponding process steps were executed in a miniaturized silicone flow cell. The required defined temperatures for the hybridization and the washing steps can be adjusted by a heating foil. This paper characterizes the performance of the flow cell based system in terms of reaction speed and analysis time, sensitivity as well as specificity, and the comparison to a conventional system, without flow cell. These first steps of automation and integration will help to realize a laboratory-independent bioanalytical tool, for the use outside of specialized laboratories for fast analysis of different chemical and biological applications.

Fabrication of the nanogapped gold nanoparticles film for direct electrical detection of DNA and EcoRI endonuclease

In situ seeding growth of gold nanoparticles (AuNPs) by the reaction of HAuCl 4 and NH 2OH has been employed in the fabrication of the nanogapped AuNPs film for direct electrical detection of DNA hybridization and DNA cleavage by EcoRI endonuclease. The distance between neighboring gold nanoparticles is less than the length of the probe DNA, implying that the DNA strand could bridge the AuNPs to provide an electron tunneling path between microelectrodes. The double-stranded DNA (dsDNA) formed by hybridization of probe and target DNA is detected by current–voltage ( I– V) curve measurements. When dsDNA is cleaved by restriction endonuclease EcoRI, the electron tunneling path can be cut off, which is reflected from the different slopes of I– V curves between dsDNA and dsDNA cleavage by EcoRI in the label-free electrical measurements. The novel and simple method of fabricating the nanogapped AuNPs film by in situ seeding growth could provide a promising bioanalytical platform for studying both DNA–DNA and DNA–protein interactions.

Electrical Detection of Oligonucleotide Using an Aggregate of Gold Nanoparticles as a Conductive Tag

Sequence-specific DNA detection is a routine job in medical diagnostics and genetic screening. Alternative to a fluorescence readout scheme or electrophoresis approach, various kinds of rapid, low-cost, facile, and label-free methods have also been developed in last decades. Among these, direct electrical detection of DNA received increasing attention but more research is desirable. Particularly, enhancement with high discrimination must be employed to selectively amplify the responding signal. A chip-based biosensor was developed in this work to electrically detect 22-mer oligonucleotide DNA at low concentration, from 50 fM to 10 pM. First, a gold nanoparticle (NP) was capped with 3-mercaptopropionic acid through a thiol-gold bond. The derivatized carboxylic acid group showed strong complex interaction with an inorganic linker, Zr(4+). As a result, Zr(4+) could link several hundreds of individual gold NPs together to form an aggregate of nanoparticles (ANP), which was capable of being used as a conductive tag for the electrical detection of DNA. Second, in order to achieve the discriminative localization of ANP to bridge two comb-shaped electrodes (with height of approximately 50 nm and interdistance of 300-350 nm) gapped with insulative material of silicon oxide, peptide nucleic acids were covalently bonded to the silicon oxide in the gap as capture sites for DNA. After hybridization with target DNA, the charged phosphate-containing backbone of DNA was introduced into the gap. Phosphate groups also exhibited strong complex interaction with the linker of Zr(4+) and could react with the residual Zr(4+) on the ANP surface. As a consequence, the conductive tags were linked to the phosphate groups and localized into the gap, which could modify the conductance between the two comb-shaped electrodes in turn. The degree of modification correlated directly to the amount of hybridized DNA and to the concentration of target DNA in sample solution. Compared with the individual NPs used as the tag, a strong enhancement from the gold ANP was obtained.

Screen printing as cost-efficient fabrication method for DNA-chips with electrical readout for detection of viral DNA

The fast development in the field of DNA analytics is driven by the need for cost-effective and high-throughput methods for the detection of biomolecules. The detection of DNA using metal nanoparticles as labels is an interesting alternative to the standard fluorescence technique. Fluorescence is highly sensitive and broadly established, but shows limitations, for example instability of the signal and the requirement for sophisticated and high-cost equipment. A recently developed approach realizes a method for the electrical detection of DNA, based on the induction of silver nanoparticles growth in microelectrode gaps on the surface of a DNA-chip. This breakthrough towards robust and cost-effective detection was still hampered by the need for microstructured (and therefore expensive) substrates. We demonstrate that it is possible to utilize screen printed electrode structures for a chip-based electrical DNA detection. The electrode structures were produced on a glass substrate which made an additional optical readout possible. The screen printed structures show the required precision and are compatible with the applied biochemical protocols. A comparison with chip substrates produced by standard photolithography showed the same sensitivity and specificity for the screen printed chips. Screen printing of electrode structures for DNA-chip with electrical detection offers an interesting and cost-efficient possibility to produce DNA-chips with microstructured electrodes.

Open Bridge-Structured Gold Nanoparticle Array for Label-Free DNA Detection

We focused on changes in the electrical property of the open bridge-structured gold nanoparticles array consisting of 46-nm parent and 12-nm son gold nanoparticles by hybridization and applied it for a simple electrical DNA detection. Since a target DNA of a 24-mer oligonucleotide was added to the probe DNA modified 12-nm Au nanoparticles, which was arranged on the gap between the 46-nm Au particles, the response was read by an electrical readout system. Even in a simple measuring method, we obtained a rapid response to the cDNA with a high S/N ratio of 30 over a wide concentration range and a detection limit of 5.0 fmol. Moreover, the array discriminated 1-base mismatches, regardless of their location in the DNA sequence, which enabled us to detect single-nucleotide polymorphism, which is one of the important diagnoses, without any polymerase chain reaction amplification, sophisticated instrumentation, or fluorescent labeling through an easy-to-handle electrical readout system.

Critical factors for the performance of chip array-based electrical detection of DNA for analysis of pathogenic bacteria

Different factors influencing chip array-based electrical detection of DNA for analysis of pathogenic bacteria were examined. Both rehydration of capture probe layer of functionalized chip arrays and efficient hybridization of targets irrespective of their length resulted in signal enhancement when high-ionic phosphate-buffered saline (i.e., 600 mM sodium chloride and 40 mM disodium hydrogen phosphate) was used. Similarly, placement of two adjacent capture and detection probe-binding sites at a terminal part of the target strand resulted in significant signal increase. Moreover, 10-min ultrasonic fragmentation of targets amplified the signals up to twofold for longer DNA strands (i.e., >300 bp). No obvious effects on signals were visible for shorter than 400-bp PCR amplicons subjected to ultrasonication. For DNA strands of all sizes, more than 10 min ultrasonication diminished the specific electrical responses. Our results also demonstrate that target analytes are detected with discrimination against mismatches even for single nucleotide sequence alteration. The mismatch detection appeared in order of ease of recognition as follows: triple random > quintuple middle > triple middle > single middle mismatch. Among the three variants of one-base mismatches, a sequence variation was most remarkable for adenine. On the other hand, no benefits in assay sensitivity were recognized by the use of longer capture probe linkers as the 6-C linker.

Electrical Detection of Femtomolar DNA via Gold‐Nanoparticle Enhancement in Carbon‐Nanotube‐Network Field‐Effect Transistors

The development of sequence-selective DNA sensors for diagnosis of genetic or pathogenic disease has attracted increasing interest. Most DNA detection methods rely on optical, piezoelectric, or electrochemical transductions. Alternative methods based on the resistance change of a single silicon nanowire or an individual carbon nanotube have been reported. However, these sensors may have significant deviceto-device variations and their fabrication requires high production costs. Recently, field-effect transistors (FETs) based on single-walled carbon nanotube (SWNT) networks have been fabricated, and their electrical properties depend on the percolation paths of SWNTs in conduction channels, where device variations are expected to be small. Label-free electrical detection of DNA and biomolecules using SWNT network FETs (SNFETs) has been successfully achieved, with typical detection limits on the order of ca. 1 nM of DNA. In this Communication, we report that the detection sensitivity of SNFETs for DNA can be further improved to ca. 100 fM by using a ‘‘nanoparticle enhancement’’ approach, in which the target DNAs are hybridized with probe DNAs on the device, and reporter DNAs labeled with Au nanoparticles (AuNPs) flank a segment of the target DNA sequence. We note that the enhancement of DNA detection by incorporating nanoparticles (e.g., CdS and Au) has been recently reported by using electrochemical approaches. On

Electrical DNA-chip-based identification of different species of the genus Kitasatospora

The identification of different Kitasatospora strains has been shown with a DNA-chip based on an electrical readout scheme. The 16S-23S rDNA internal transcribed spacer region of these Actinomycetes was used for identification. Two different capture probes per strain were immobilized on the chip. The capture probes were spotted on a DNA-chip with electrode structures for an electrical DNA detection. A biotinylated PCR product of the 16S-23S rDNA region was incubated on the chips and bound to its complementary capture sequences. Followed by a gold nanoparticle or enzyme labeling and a deposition of silver, the binding of the PCR product was detected by an increase of the measured conductivity on the chip. To show the applicability of this detection system, four strains of Kitasatospora were chosen for an identification using the DNA-chip with electrical detection. Each strain was clearly identified using the system. Concentrations of the polymerase chain reaction (PCR) products within the range of 1 ng/ml to 1 mug/ml were detected and identified. These tests are the first application of this novel electrical detection scheme for the identification and classification of microorganisms. The presented results show that the DNA-chip with electrical detection can be used for a robust and cost-efficient DNA analysis.

Electrical detection of DNA using gold and magnetic nanoparticles and bio bar-code DNA between nanogap electrodes

This paper presents an electrical detection method on a DNA biochip that employs a novel approach for ultra sensitive detection of DNA using self-assembled gold nanoparticles and bio-bar-code-based amplification (BCA) DNA. The experimental study relies on three-components oligonucleotide-modified gold nanoparticles, single-component oligonucleotide-modified magnetic nanoparticles and subsequent detection of amplified target DNA in the form of bio-bar-code ssDNA (single strand DNA) using a chip-based detection method. In this study, the BCA technique measures the bar-code DNA rather than the target DNA. There withal, the DNA chips with nanogap electrodes are fabricated by electron-beam lithography. The gap distance and an electrode height are 300 and 65 nm, respectively. Here, the surface between the electrodes and multilayer of gold nanoparticles is established by the hybridization among single strand BCA, the second capture DNA (C2DNA) and the second probe DNA (P2DNA). Measurable current through nanogap electrodes can be obtained over multilayer gold nanoparticles. In this way, magnetic nanoparticles and bio-bar-code DNA are used to amplify obtainable current through nanogap electrodes from the extremely low concentration of target DNA. The detective concentration of target DNA with electrical DNA biosensor is as low as 1 fM for the analysis of current-voltage curves.

Enzymatic Control of Metal Deposition as Key Step for a Low-Background Electrical Detection for DNA Chips

Electrical detection of DNA using nanoparticle labels in combination with metal enhancement represents an interesting alternative to fluorescence readout schemes. This electrical method is hampered by unspecific metal deposition, resulting in a lower sensitivity of the assay. A novel enhancement technique based on an enzymatic process is introduced. This approach enables highly specific metal deposition only at the enzyme label, without the background that is typical in the case of the conventional metal enhancement process of growing nanoparticles. The enzymatic enhancement leads to a significant increase in sensitivity, and the detection of single base mismatches demonstrates the high specificity of the novel enhancement approach.