A DNA aptamer sensor for 8-oxo-7,8-dihydroguanine

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Abasic sites in DNA duplexes are key for designing aptamers and sensors.
• 8-oxoG is a significant product of DNA base excision repair, indicating oxidative stress.

Purpose of the Study:

• To develop a specific sensor for detecting free 8-oxoG.
• To investigate modifications of abasic sites for selective 8-oxoG binding.

Main Methods:

• Incorporation of pyrrolo-dC as a fluorescent reporter opposite the abasic site.
• Quantification of fluorescence quenching upon 8-oxoG binding.
• Determination of aptamer binding affinity (dissociation constant).

Main Results:

• 8-oxoG binding quenched pyrrolo-dC fluorescence by up to 70%.
• Adenine, guanine, thymine, and cytosine showed minimal fluorescence quenching.
• The best aptamer exhibited a dissociation constant of 5.5±0.8μM for 8-oxoG.

Conclusions:

• A novel DNA sensor utilizing an abasic site and pyrrolo-dC reporter has been successfully developed.
• This sensor demonstrates high specificity and sensitivity for 8-oxoG detection.
• The sensor is capable of accurately quantifying 8-oxoG in the presence of guanine, valuable for DNA repair studies.