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Study the adsorption of DNA with some cationic complexes (Ca2+, Cu2+, and Co3+) on chip surfaces by Dual polarization interferometry (DPI) (CAT#: STEM-MB-0453-WXH)

Introduction

DNA adsorption on a solid surface is important in various fields, such as in DNA-based biosensing, DNA microarrays, DNA hybridization studies, a small molecule−DNA interaction study, mesoporous silica nanoparticle-based gene delivery, and DNA separation and purification through solid-phase extraction. Double-stranded DNA is a highly negatively charged biomacromolecule. Thus, studying DNA adsorption on a surface will help determine the adsorption process of highly negatively charged polyelectrolytes on the liquid−solid interface.<br />Double-stranded DNA can interact with cation, forming a DNA/cation complex. Different cations cause different interactions with the bases and phosphate groups of DNA.




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

Study the adsorption of DNA with some cationic complexes (Ca2+, Cu2+, and Co3+) on chip surfaces.

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