Thin film micro arrays with immobilized DNA for hybridization analysis
- PDF / 402,278 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 82 Downloads / 203 Views
Thin film micro arrays with immobilized DNA for hybridization analysis F. Fixe1,2, A. Faber1, D. Gonçalves1, D.M.F. Prazeres1, R. Cabeça2, V. Chu2, G. Ferreira3 and J.P. Conde4 1 Center for Biological & Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal 2 INESC Microsystems and Nanotechnologies, Lisbon, Portugal 3 Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, Faro, Portugal 4 Department of Materials Engineering, Instituto Superior Técnico, Lisbon, Portugal ABSTRACT In this work, a procedure to immobilize DNA probes on a microarray patterned on a flexible plastic substrate is developed. The method involves the chemical activation of a thin film surface, the introduction of amine functionality via a silanization step, the coupling of an adequate crosslinker and finally the immobilization of the DNA probe. The response of different thin-film materials and plastic substrates to the immobilization procedure is discussed. The DNA probes immobilized in the patterned pixels were then allowed to hybridize with complementary target DNA labeled with a fluorescent molecule. A prototype array of thin film pixels of SiO2 functionalized by silanization deposited over a polyimide substrate is demonstrated. INTRODUCTION Biochips, particularly those based on DNA, are powerful devices that integrate the specificity and selectivity of biological molecules with electronic control and parallel processing of information. This combination will potentially increase the speed and reliability of biological analysis [1]. Thin-film microelectronic technology is especially suited for this purpose since it enables low-temperature processing and thus allows fabrication of electronic devices on a wide variety of substrates (glass, stainless steel, plastic, etc. [2]). Examples of current applications of DNA chips include genomic analysis to screen and identify single nucleotide polymorphisms (SNPs) or to sequence gene fragments, pathogen identification, and gene expression profiling [1]. The core of a DNA chip is a surface, usually flat, with DNA probe molecules spatially resolved and attached to it. This separation can be accomplished by using immobilization procedures that localize the probes to their exact site such as fine spotting [3], piezoelectric printing [4], electronic [5] and electrochemical addressing [6]. Alternatively, thin-film microelectronics technology can be used to deposit a material suitable for DNA attachment on an inert surface according to a given pattern. The use of passivation layers, although not described so often, can also be considered [7]. Other possible features of a DNA chip surface include the presence of microelectrodes beneath the DNA-containing areas. These can be used as sensing devices and to generate electric fields that promote the migration of oligonucleotides [5], hybridization and covalent binding [8]. Overall, the structure of a DNA chip is complex and its fabrication may include surface activation, passivation, patterning, and introduction of sensing devices and i
Data Loading...
