Effect of surface electrostatics on adsorption behavior and biospecific interactions of DNA oligonucleotides

Alexander N. Asanov; Igor Y. Sarkisov; Philip B. Oldham

doi:10.1117/12.346739

21 April 1999 Effect of surface electrostatics on adsorption behavior and biospecific interactions of DNA oligonucleotides

Alexander N. Asanov, Igor Y. Sarkisov, Philip B. Oldham

Author Affiliations +

Proceedings Volume 3603, Systems and Technologies for Clinical Diagnostics and Drug Discovery II; (1999) https://doi.org/10.1117/12.346739
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

A total internal reflection fluorescence (TIRF) flow system was used to detect DNA adsorption and hybridization of a single stranded target DNA with a surface immobilized DNA probe. A transparent SnO₂ or indium tin oxide (ITO) film served as a spectroscopic surface in the TIRF flow system and simultaneously as a working electrode for electrochemical (EC) control. The SnO₂ and ITO electrodes were chemically modified to provide hydrophilic or hydrophobic surfaces with different functional groups. Charge of the sensor surface was modulated by external electrochemical polarization. Results indicate that DNA oligonucleotides exhibit higher adsorption affinity to positively charged aminated sensor surfaces, while negative polarization stimulates desorption of DNA molecules. To investigate DNA hybridization at the TIRF EC sensor surface, a thiolated probe oligonucleotide, with the complementary sequence to that of the target DNA, was covalently attached to the aminated sensor surface using a heterobifunctional crosslinker. A solution phase 27-base target DNA labeled by fluorescein was exposed to the sensor surface. The kinetics of heterogeneous hybridization between target DNA and surface immobilized probe was studied at different electrode potentials. The results show that cathodic polarization can accelerate hybridization and, at the same time, suppress nonspecific DNA adsorption.

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Alexander N. Asanov, Igor Y. Sarkisov, and Philip B. Oldham "Effect of surface electrostatics on adsorption behavior and biospecific interactions of DNA oligonucleotides", Proc. SPIE 3603, Systems and Technologies for Clinical Diagnostics and Drug Discovery II, (21 April 1999); https://doi.org/10.1117/12.346739

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