First characterization of a biphasic, switch-like DNA amplification.

Area of Science:

• Molecular Biology
• Biochemistry
• Synthetic Biology

Background:

• Oligonucleotide amplification reactions are crucial for molecular detection.
• Existing methods like exponential amplification reaction (EXPAR) have limitations, including premature termination.
• A need exists for highly sensitive and switchable DNA amplification chemistries.

Purpose of the Study:

• To report a novel biphasic DNA amplification chemistry with switch-like characteristics.
• To investigate the reaction mechanism and thermodynamic drivers of this new chemistry.
• To demonstrate the potential of this reaction for detecting various target molecules.

Main Methods:

• Development of a DNA amplification reaction initiated by an oligonucleotide trigger binding to a palindromic looped DNA template.
• Characterization of the biphasic reaction kinetics, including distinct initial and high-gain phases.
• Thermodynamic analysis to correlate DNA association with reaction acceleration.
• Investigation of reaction behavior without a palindromic sequence, comparing it to EXPAR.

Main Results:

• A novel biphasic DNA amplification chemistry was developed, exhibiting switch-like behavior.
• The reaction shows an initial phase followed by a high-gain burst (10-100x more product).
• Reaction acceleration in the second phase is linked to DNA association thermodynamics.
• A previously unknown cause of early reaction cessation in EXPAR was identified.

Conclusions:

• This new chemistry provides an endogenous switch-like output responsive to ~1 pM oligonucleotide triggers.
• The isothermal reaction is adaptable for detecting diverse targets including proteins, DNA, and microRNA.
• Potential applications span synthetic biology, biosensors, DNA computing, and clinical diagnostics.