Ice-Confinement Overcomes the Diffusion-Reaction Limitation in Surface Assays.

Area of Science:

• Biotechnology and Biosensing
• Surface Chemistry and Nanotechnology

Background:

• Diffusion-reaction coupling at solid-liquid interfaces limits molecular assay performance, especially for surface-based DNA assays.
• Existing methods struggle with efficient mass transport and reaction control at interfaces.

Purpose of the Study:

• To develop an ice-confinement strategy to reprogram mass transport at solid-liquid interfaces for enhanced molecular assays.
• To achieve ultrasensitive detection of microRNA (miRNA) by optimizing interfacial reaction kinetics.

Main Methods:

• Utilized directional freezing to create an ice-confined liquid layer at the solid-liquid interface.
• Employed in situ electrochemistry and finite-element modeling to analyze DNA oligonucleotide behavior.
• Integrated PEGylated passivation to modify the electrical double layer and enhance binding.

Main Results:

• Directional freezing concentrated DNA oligonucleotides, shifting reactions from diffusion-controlled to surface-confined.
• Ice confinement lowered interfacial energy barriers and enabled kinetic trapping of overequilibrium binding states.
• Achieved ultrasensitive miRNA detection down to 100 aM within 30 minutes, with suppressed amplification leakage.

Conclusions:

• The ice-confinement strategy effectively modulates interfacial kinetics through phase-transition-enabled physical confinement.
• This approach significantly enhances biosensing capabilities, offering broad applicability across substrates and signal outputs.
• The strategy holds promise for advancing surface engineering and molecular diagnostics.