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Detection of DNA immobilisation and hybridisation on a silanised support by Dual polarization interferometry (DPI) (CAT#: STEM-MB-0441-WXH)

Introduction

DNA microarrays and DNA biosensors have emerged as a key enabling technology for the functional interrogation of genetic information. Such sensors are based upon the inherent ability of a target DNA in solution to bind to a complementary probe molecule immobilised on a solid support. A key step that is pivotal to the process is the attachment of the single-stranded probe molecule to the substrate. The covalent attachment of probe molecules to self-assembled silane layers is a commonly employed method with such sensors for the formation of highly reactive, robust probe layers on a variety of substrates such as glass and silicon.




Principle

Dual polarization interferometry (DPI) is an analytical technique that allows the simultaneous determination of thickness, density, and mass of a biological layer on a sensing waveguide surface in real time. DPI focuses laser light into two waveguides. One of these functions as the "sensing" waveguide having an exposed surface while the second one functions to maintain a reference beam. A two-dimensional interference pattern is formed in the far field by combining the light passing through the two waveguides. The DPI technique rotates the polarization of the laser, to alternately excite two polarization modes of the waveguides. Measurement of the interferogram for both polarizations allows both the refractive index and the thickness of the adsorbed layer to be calculated. These measurements can be used to infer conformational information about the molecular interactions taking place, as the molecule size (from the layer thickness) and the fold density (from the RI) change.

Applications

Detection of DNA immobilisation and hybridisation on a silanised support

Procedure

1. Setting of dual polarization interferometry
2. Preparing the DPI sensor chip
3. Immobilization of target on DPI biosensor
4. Reagent was injected to react
5. Quantitative analysis

Materials

• DPI biosensor
• DPI sensor chip
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