Immobilization, of DNA probe

Y. Ishige, M. Shimoda, and M. Kamahori, Immobilization of DNA probes onto gold surface and its application to fully electric detection of DNA hybridization using field-effect transistor sensor. Jpn. J. Appl. Phys. 45, 3776-3783 (2006). 

As it is well known, the immobilization of DNA probes onto electrode surfaces is one of the key steps in DNA sensor development. It has been widely demonstrated that the DNA sensor performance (e.g., sensitivity, selectivity, and stability) is highly dependent on the characteristics of DNA probes immobilization approaches. One of these relies on the use of nanomaterials such as gold nanoparticles (Au-NPs), taking advantage of their unique electrical conductivity, biocompatibility, and ease of self-assembly through... 

Figure 13. The magnetoresistor chip is covered with a flow cell for the introduction of sample after immobilization of an array of DNA probes. The photo shows a diffuser channel placed over the 65 magnetoresistor sensors on the chip54.

Fig. 16.10 Reaction scheme for immobilization of DNA onto functionalized Si02 substrates. Plasma treated Si02 substrates are denoted as Si OH, APTMS functionalized substrates are denoted as Si NH2, dendrimer functionalized substrates are denoted as Si G(4.5)COOH, and substrates to which DNA capture probes have been immobilized are denoted as Si DNA. Inset Repeat unit of PAMAM dendrimer possessing terminal carboxylic acid functionality...

Second, we tried the immobilization of DNA molecules as a potential target material for the immobilization of biological macromolecules. An aqueous solution of 1 mg/mL A.-DNA was spotted onto the surface of an azopolymer and covered with a cover glass, where the A.-DNA was stained with a fluorophore (YOYO-1 iodide, Molecular Probes Inc., Eugene, OR) in advance and the surface was then irradiated with the linearly shaped laser beam for 5 min, as shown in Fig. 3b. The surface was washed for 5 min in an aqueous solution and was then observed using... 

Typically, the design of a genosensor involves the following steps [7] (1) modification of the sensor surface to create an activated layer for the attachment of the DNA probe (2) immobilization of the probe... 

DNA can be easily immobilized on GEC by simple wet-adsorption onto GEC surface (Fig. 21.1(A2)). A small drop of DNA probe in acetate saline solution pH 4.8 [58] is put onto the surface of a GEC electrode in upright position. The immobilization of the probe was allowed to proceed for 15 min without applying any potential under static conditions. After the inosine-modified DNA probe immobilization, the DNA target was detected by the intrinsic DNA oxidation signal coming from the guanine moieties. Briefly, the procedure consists of the following... 

Four spots of DNA probes were applied in a PMMA microchannel (500 pm wide, 50 pm deep). This is intended for detection of low-abundant point mutation in the K-ras gene, which is diagnostic for colorectal cancer. Aminated 24-mer DNA probes were immobilized via glutaraldehyde hnkage on the amine groups... 

A membrane for a DNA-probe of a microelectronic biosensor based on Langmuir-Blodgett (LB) diacetylene film with covalently bonded DNA has been developed [86]. Diacetylene films formed on the surface of oxidized silicon by the LB method were used for covalent immobilization of DNA molecules, using the standard W./V -dicyclohexylcarbodiimide... 

DNA chip technology is based on the hybridization of DNA probe sequences. For a proper hybridization, the probes have to be immobilized selectively on a modified 5 -end or 3 -cnd and in high yields. Since probes will be immobilized in large excess relative to the labeled targets, the kinetics of hy-... 

DNA immobilization chemistry on the beads used in these systems is presented in Fig. 2. Two main techniques were used, a direct immobilization of the probe sequence bearing a 5 -amino-C6 modifier (Fig. 2A), or an affinity procedure using avidin modified beads and biotinylated probes (Fig. 2B). 

An electrochemical DNA hybridization biosensor basically consists of an electrode modified with a single stranded DNA called probe [109]. Usually the probes are short oligonucleotides (or analogues such as peptide nucleic acids). The first and most critical step in the preparation of an electrochemical DNA biosensor is the immobilization of the probe sequence on the electrode. The second step is the hybrid formation under selected conditions of pH, ionic strength and temperature. The next step involves the detection of the double helix... 

Heme TM, Tarlov MJ (1997) Characterization of DNA probes immobilized on gold surfaces. J Am Chem Soc 38 2016-2020... 

A DNA optical sensor system was proposed by Cass and co-workers [35] based on the combination of sandwich solution hybridization, magnetic bead capture, flow injection and chemiluminescence for the rapid detection of DNA hybridization. Sandwich solution hybridization uses two sets of DNA probes, one labelled with biotin, the other with an enzyme marker and hybridization is performed in solution where the mobility is greater and the hybridization process is faster, rather than on a surface. The hybrids were bound to the streptavidin-coated magnetic beads through biotin-streptavidin binding reaction. A chemiluminescence fibre-optic biosensor for the detection of hybridization of horseradish peroxidase-labelled complementary DNA to covalent immobilized DNA probes was developed by Zhou and co-workers [36]. 

In another study also, electrochemical impedance technique has been shown to be a useful method for a DNA biosensor using a multinuclear nickel(II) salicylaldimine metallodendrimer platform [164], Both the preparation of the dendrimer-modified GCE surface and the immobilization of DNA have been effectively done by simple drop-coating procedures. The metallodendrimer is electroactive exhibiting two redox couples in phosphate buffer solution. The impedance study demonstrated that the DNA biosensor responded well to 5 nM of target DNA by displaying a decrease in charge transfer resistance in phosphate buffer solution and increase in charge transfer resistance in the presence of the [Fe(CN)6]3/4" redox probe. 

Figure 4-15 Examples of DNA biosensor configurations (A) direct electrooxidation detection of guanosine bases in target DNA after hybridization with immobilized capture probe on electrode surface (B) electrochemical detection of hybridization using exogenous redox species that intercalates into hybridized complex between immobilized capture DNA probe and target DNA.

Abstract Recent advances in nucleic acid-based detection coupled to piezoelectric transduction will be reported here. The main aspects involved in the development of nucleic acid sensors are considered the immobilization of the probe, the sample pretreatments (DNA extraction, amplification, denaturation of the amplified material), the sensitivity and specificity, etc. 

DNA can be easily immobilized on GEC by simple wet adsorption onto GEC surface. A small drop of DNA probe in acetate saline... 

The maximum percentage change of charge transfer resistance upon hybridization with fully complementary target oligonucleotides was obtained with samples prepared by co-immobilization of oligonucleotide probes and mercaptohexanol with a DNA mole fraction of 20%. This corresponds to a mean probe surface density of 5.4 X 10 cm . ... 

The adsorption method at controlled potential or without potential application called "wet adsorption" [16, 17] is the easiest way to immobilize DNA (or probes) onto carbon transducers [2, 18, 19]. There is no need of special reagents, expensive labeled nucleic acids, or long experimental steps in adsorption-based immobilization technique. Hovewer, random immobilization of DNA were obtained with this technique and nucleic acids bound weakly to the surface as parallel layers. Additionally, it is possible to aglomerate DNA onto the surface and when the electrode is rinsed stringently, noncovalently bound DNA can be removed from the transducer surface. 

---