High-Sensitivity DNA Aptasensors for Detecting Salivary Biomarker S100A7 in Heart Failure

Area of Science:

• Biochemistry
• Molecular Biology
• Biomedical Engineering

Background:

• Early detection of heart failure (HF) is crucial for patient management and reducing hospital readmissions.
• Current diagnostic methods for HF can be invasive or lack sufficient sensitivity.
• S100A7 is identified as a potential salivary biomarker for heart failure.

Purpose of the Study:

• To develop a high-affinity DNA aptamer targeting the salivary heart failure biomarker S100A7.
• To evaluate the aptamer's performance in sensitive and noninvasive diagnostic assays.
• To establish a foundation for portable aptamer-based biosensors for heart failure monitoring.

Main Methods:

• Iterative truncation and dimerization were used to optimize the DNA aptamer sequence (17-43).
• G-quadruplex structure confirmation via biochemical and mutational studies.
• Integration of the aptamer into sandwich aptamer-ELISA, hybrid aptamer-antibody ELISA, and biolayer interferometry (BLI) sensors.

Main Results:

• A 43-nt DNA aptamer (17-43) with a 5.5 nM binding affinity for S100A7 was generated.
• The aptamer demonstrated G-quadruplex structure essential for S100A7 recognition and saliva stability.
• ELISA assays achieved limits of detection as low as 29 pg/mL, outperforming commercial assays.
• BLI sensor detected S100A7 in patient saliva with a LOD of 3.2 ng mL-1 in under 20 minutes.
• The hybrid assay showed stability for 2.5 months at room temperature.

Conclusions:

• The developed DNA aptamer is a stable, specific, and versatile tool for S100A7 detection.
• This aptamer facilitates highly sensitive, noninvasive heart failure diagnostics using saliva.
• The findings pave the way for developing portable biosensors for multiplexed heart failure biomarker monitoring.