Dual-Valve and Counter-Flow Surface Plasmon Resonance

Area of Science:

• Analytical Chemistry
• Biochemistry
• Biotechnology

Background:

• Surface Plasmon Resonance (SPR) is a label-free optical sensing technique widely used for studying biomolecular interactions.
• Traditional SPR instruments often face limitations in analysis speed and surface reaction efficiency due to single-injector systems.
• Efficient ligand immobilization and stable surfaces are critical for sensitive SPR detection, especially for small molecules.

Purpose of the Study:

• To develop and demonstrate a novel alternate injection mode for SPR instruments.
• To enhance the speed and efficiency of surface reactions, including ligand immobilization and regeneration.
• To improve the sensitivity and reliability of SPR-based kinetic and affinity measurements.

Main Methods:

• Integration of two six-port injector valves and one selector valve with an SPR instrument.
• Implementation of a counter-flow system within the flow cell for simultaneous or sequential solution introduction.
• Utilizing the alternate injection mode for rapid (<1 s) exchange of solutions between fluidic channels.
• Demonstration with binding studies of acetazolamide to human carbonic anhydrase II and microglobulin to immobilized antibodies.

Main Results:

• The alternate injection mode significantly reduces analysis time and facilitates efficient ligand immobilization.
• Achieved higher ligand densities and more stable surfaces, crucial for SPR detection of small molecules.
• Demonstrated successful kinetic and affinity measurements without repeated dissociation and regeneration steps, as shown in acetazolamide-HCA and microglobulin-antibody binding assays.

Conclusions:

• The developed alternate injection mode offers a versatile and efficient approach for SPR analysis.
• This method enhances surface reaction capabilities, leading to improved sensitivity and reduced analysis time.
• The system is well-suited for kinetic and affinity studies, particularly for small molecule interactions and antibody-based assays.