A high affinity modified DNA aptamer containing base-appended bases for human β-defensin

Area of Science:

• Biochemistry
• Molecular Biology
• Biotechnology

Background:

• Human β-defensin 2 (HBD-2) is a biomarker associated with physical stress, often found in saliva.
• Developing specific and high-affinity detection methods for biomarkers like HBD-2 is crucial for diagnostic applications.

Purpose of the Study:

• To develop a novel nucleic acid aptamer capable of specifically binding to human β-defensin 2.
• To investigate the efficacy of modified DNA libraries containing adenine analogs for aptamer selection.

Main Methods:

• A new adenine analog was synthesized and incorporated into a DNA library.
• Systematic Evolution of Ligands by Exponential Enrichment (SELEX) was employed to select aptamers.
• The binding affinity and specificity of the selected aptamer (A^ad1) to HBD-2 were evaluated using dissociation constant measurements and pull-down assays.

Main Results:

• A novel aptamer, designated A^ad1, was successfully selected using the modified DNA library.
• A^ad1 demonstrated strong binding affinity to human β-defensin 2 with a dissociation constant (K_d) of 6.8 nM.
• Specific binding of A^ad1 to HBD-2 in spiked saliva samples was confirmed, indicating its potential for real-world sample analysis.

Conclusions:

• The study successfully developed the first reported nucleic acid aptamer, A^ad1, that specifically targets human β-defensin 2.
• Modified DNA libraries incorporating adenine analogs are highly effective for generating high-affinity aptamers.
• The A^ad1 aptamer holds promise for the development of sensitive diagnostic tools for physical stress detection.