Towards a target label-free suboptimum oligonucleotide displacement-based detection system

Area of Science:

• Biotechnology
• Molecular Diagnostics
• Biosensor Technology

Background:

• Developing sensitive and rapid DNA detection methods is crucial for diagnostics.
• Existing DNA sensor assays can be time-consuming, limiting real-time applications.
• Label-free detection strategies offer advantages by simplifying assay procedures.

Purpose of the Study:

• To propose and evaluate a novel label-free DNA sensor based on oligonucleotide displacement.
• To investigate the hybridization kinetics and thermodynamics of labeled oligonucleotides with a biotin-capture probe.
• To demonstrate the efficiency of the displacement method for rapid DNA target detection.

Main Methods:

• A biotin-capture probe was immobilized and hybridized with a labeled, suboptimum mutated oligonucleotide.
• Target DNA complementary to the biotin-capture probe was introduced to displace the labeled oligonucleotide.
• Signal decrease was measured colorimetrically to quantify target presence and concentration.
• Kinetic and thermodynamic behaviors of hybridization were studied.

Main Results:

• The displacement method successfully detected DNA targets, indicated by a signal decrease.
• Signal decrease was found to be proportional to the DNA target concentration.
• Heterogeneous hybridization exhibited distinct kinetic and thermodynamic profiles for complementary vs. suboptimum oligonucleotides.
• Response time was reduced from 1 hour (direct assay) to 5 minutes (displacement assay) for micromolar concentrations.

Conclusions:

• The proposed oligonucleotide displacement method offers a rapid and label-free approach for DNA sensing.
• This method significantly enhances detection speed compared to traditional direct hybridization assays.
• The findings support the development of next-generation DNA sensors with improved performance characteristics.