Morpholino monolayers: preparation and label-free DNA analysis by surface hybridization

Area of Science:

• Biochemistry
• Materials Science
• Nanotechnology

Background:

• Surface hybridization is crucial in life sciences, typically using charged DNA probes requiring high salt conditions.
• High salt concentrations impede label-free monitoring and can cause secondary structures in target nucleic acids.
• Existing methods face limitations in sensitivity and control due to salt dependency.

Purpose of the Study:

• To introduce morpholinos, uncharged DNA analogues, as an alternative for surface hybridization.
• To investigate the efficiency and specificity of morpholino probes for nucleic acid detection.
• To explore label-free monitoring of hybridization using electrochemical methods.

Main Methods:

• Fabrication of morpholino probe monolayers on gold supports.
• Surface hybridization experiments with complementary target strands.
• Electrochemical analysis (interfacial capacitance) to monitor hybridization.
• Comparison with DNA probe monolayers.
• Numerical Poisson-Boltzmann calculations for mechanistic interpretation.

Main Results:

• Morpholino monolayers demonstrated efficient and sequence-specific hybridization.
• Hybridization induced measurable changes in interfacial charge organization.
• Electrochemical responses (capacitance) correlated linearly with target coverage.
• Sensitivity in the picogram per square millimeter range was achieved.
• Observed both positive and negative capacitive responses, controllable by applied potential.

Conclusions:

• Morpholinos offer a viable, uncharged alternative to DNA for surface hybridization applications.
• Electrochemical monitoring of morpholino hybridization provides sensitive, label-free detection capabilities.
• The study elucidates the relationship between hybridization state and interfacial capacitance, offering insights into molecular mechanisms.