DNA microarrays fabrication

The second platform for DNA microarray fabrication involves controlled in situ synthesis of oligonucleotides (on-chip). This technology, implemented by Affymetrix in the manufacture of GeneChips, uses photolithographic... 

The third advantage, the chemical stability of DNA aptamers, can solve the main problem of protein-based biosensors. The chemical and physical instability of protein-based biosensors is always claimed in practical use, and this limits the range of biosensor application. However, DNA is chemically stable. It is stable within the pH range 2 to 12 and is thermally renaturable Even if it is denatured at 100°C, it is refolded at room temperature. Even RNA aptamers can gain stability upon 1 modification therefore, aptamers have the potential to enhance the applicability of biosensors in practical contexts. Additionally, aptamers can be immobilized onto substrates using DNA microarray fabrication technology, and aptamer microarrays can be created. 

Biological molecules and structures are assumed to be fragile and sensitive. However, deoxyribonucleic acid (DNA) molecules could be directly printed onto glass slides using commercially available inkjet printers for high-density DNA microarray fabrication (9,10). 

Wang L, Xia Y, Ju J, Fan Y, Mo Y, Shi W (2000) Efficient luminescence from CVD diamond film-coated porous silicon. J Phys Condens Matter 12 L257 Wang C, Jia XM, Jiang C, Zhuang GN, Yan Q, Xiao SJ (2012) DNA microarray fabricated on poly (acrylic acid) brushes-coated porous silicon by in situ rolling circle amplification. Analyst 137 4539... 

One crucial and hence central step in the design, fabrication and operation of DNA chips, DNA microarrays, genosensors and further DNA-based systems described here (e.g. nanometer-sized DNA crafted beads in microfluidic networks) is the immobilization of DNA on different soHd supports. Therefore, the main focus of these two volumes is on the immobilization chemistry, considering the various aspects of the immobihzation process itself, since different types of nucleic acids, support materials, surface activation chemistries and patterning tools are of key concern. 

Cell microarrays have also been fabricated. Ziauddin and Sabatini (2001) demonstrated the ability to transfect cells cultured onto plasmid DNA arrayed in gelatin on a standard DNA microarray slide. Xu (2002) printed down cells in the form of high density microarrays on permeable membranes and demonstrated phenotypic assay performance with the immobilized cells. The commercialization of viable cell arrays will permit an even closer look at cell-mediated events during the drug discovery process. 

Call, D.R., Chandler, D.R, and Brockman, R, Fabrication of DNA microarrays using unmodified oligonucleotide probes. Biotechniques, 30, 368-379, 2001. 

Okamoto, T., Suzuki, T., and Yamamoto, N., Microarray fabrication with covalent attachment of DNA using Bubble Jet technology, Nat. Biotechnol., 18,438 41, 2000. 

Okamoto T, Suzuki T, Yamamoto N. Microarray fabrication with covalent attachment of DNA using bubble jet technology [see comments]. Nat Biotech-nol 2000 18(4) 438—441. 

A typical gene expression profiling experiment takes place in five separate processes. They are (i) microarray fabrication, (ii) purification and labeling of the target material, (iii) hybridization, (iv) detection and (v) data analysis. The characteristics of each step were briefly discussed in the introduction. A closer look at each of these steps is the object of this section. Here we mainly refer to biochips where the probe is constituted by nucleic acids (DNA microarrays). 

In both the cases decribed above, the second step in microarray fabrication involves ordered deposition of the probes on the surface (spotting). The purified DNA probes (PCR fragment or oligonucleotides) are spotted on a modified glass slide in an ordered grid, by means of array spotters and robotic instruments that allow for precise deposition of a few nanoliters of DNA... 

Charles, P.T., et al. Fabrication and surface characterization of DNA microarrays using amine- and thiol-terminated oligonucleotide probes. Langmuir, 2003, 19, p. 1586-1591. 

Wacker R, Schroder H, Niemeyer CM (2004) Performance of antibody microarrays fabricated by either DNA-directed immobilization, direct spotting, or streptavidin-biotin attachment a comparative study. Anal Biochem 330 281-287... 

Soper et al. [211] presented the fabrication of DNA microarrays onto PMMA surfaces using a UV modification protocol as shown in Fig. 11. Briefly, the PMMA surface was first activated via exposure to UV irradiation, which produced carboxylic acid functional groups onto its surface. EDC/NHS coupling chemistry was then used to facilitate the formation of succinimidyl ester intermediates on the surface, which allowed for the covalent attachment of amine-terminated... 

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