Beyond molecular recognition: using a repulsive field to tune interfacial valency and binding specificity between...

Area of Science:

• Materials Science
• Colloid Science
• Biophysics

Background:

• Smart materials utilize surface-bound biomolecules for selective recognition of cells and particles.
• Current smart surfaces are limited by biomolecular selectivity, restricting design possibilities.
• Nonbiological systems offer a platform to explore alternative selectivity mechanisms.

Purpose of the Study:

• To demonstrate how specificity in particle binding can be achieved using entirely nonselective nanoscale adhesion elements.
• To illustrate fundamental principles of tunable interfacial valency in a nonbiological model system.
• To provide a generalized mechanism for selective binding applicable to both engineered surfaces and biological systems.

Main Methods:

• Utilized a model system of cationic nanoparticles on a silica surface interacting with anionic silica microspheres.
• Investigated particle binding dynamics under varying ionic strengths to tune electrostatic repulsions.
• Defined and manipulated interfacial valency (number of cross-bonds for capture) as a key parameter.

Main Results:

• At high ionic strength (univalent regime), single nanoparticles captured microspheres due to screened repulsions.
• At low ionic strength, multiple nanoparticles were required for capture (multivalent regime) due to weakened adhesion.
• Demonstrated that multivalency enables interfacial-scale selectivity, tunable via ionic strength.

Conclusions:

• Nonselective adhesion elements can achieve specific particle binding through controlled multivalency.
• Interfacial valency offers a tunable mechanism for designing selective surfaces, analogous to biological cell recognition.
• This approach broadens the design principles for smart materials and understanding natural adhesion processes.