Anharmonic surface interactions for biomolecular screening and characterization

Area of Science:

• Biomolecular engineering
• Analytical chemistry
• Materials science

Background:

• Conventional mechanical oscillators exhibit harmonic responses at low amplitudes.
• Attached analytes can introduce motional anharmonicity, altering the oscillator's response.
• Quartz crystal resonators are sensitive to mass changes but can suffer from nonspecific binding.

Purpose of the Study:

• To develop and validate an anharmonic detection technique (ADT) for biomolecular analysis.
• To investigate the influence of molecular tethers on the anharmonic response of quartz crystal resonators.
• To establish ADT as a method for enhancing selectivity in receptor-based detection.

Main Methods:

• Experiments utilized quartz crystal resonators with attached streptavidin-coated polystyrene microbeads in liquid.
• The electrical response of the resonators was analyzed for motional anharmonicity as a function of oscillation amplitude.
• The deviation of odd Fourier harmonics was quantitatively analyzed to identify molecular tether signatures.

Main Results:

• Significant motional anharmonicity was observed in the electrical response upon attachment of microbeads.
• The deviation of odd Fourier harmonics showed a unique signature dependent on the molecular tether and oscillation amplitude.
• The technique successfully differentiated between specific and nonspecific molecular interactions.

Conclusions:

• Anharmonic detection technique (ADT) provides a novel approach for sensitive and selective biomolecule screening.
• ADT offers enhanced selectivity in receptor-based detection, mitigating challenges posed by nonspecific interactions.
• The technique can be extended to extract mechanical properties of molecular tethers, such as force-extension characteristics and activation energy.