Molecular beacon-metal nanowire interface: effect of probe sequence and surface coverage on sensor performance

Area of Science:

• Nanotechnology
• Biotechnology
• Materials Science

Background:

• DNA hairpin probes are crucial for biosensing applications.
• Immobilization of DNA probes on metal nanostructures is an active research area.
• Understanding surface interactions is vital for optimizing sensor performance.

Purpose of the Study:

• To investigate the impact of surface coverage and probe sequence on DNA hairpin probe performance.
• To evaluate the effectiveness of diluent molecules in improving sensor performance.
• To assess the feasibility of using these probes in multiplexed, wash-free assays.

Main Methods:

• Synthesized 5' thiolated, 3' fluorophore-labeled DNA hairpin probes.
• Assembled probes onto Au/Ag striped metal nanowires.
• Controlled surface coverage using probe concentration, ionic strength, and diluent molecules.
• Tested probe performance in the presence and absence of target sequences.

Main Results:

• Intermediate probe coverage (~10^12 molecules/cm^2) yielded optimal discrimination.
• Surface dilution with hydroxy-terminated alkanethiols did not significantly improve performance.
• Different probe sequences exhibited varying surface coverage and sensor performance.
• Multiplexed assays accurately identified target oligonucleotides despite probe performance variations.

Conclusions:

• Surface coverage and probe sequence are critical factors in DNA probe-based metal nanowire sensors.
• The findings are relevant for developing advanced biosensing platforms.
• Molecular beacon probes on metal surfaces offer potential for diverse diagnostic applications.