Equilibrium mechanisms of self-limiting assembly.

Area of Science:

• Physical Chemistry
• Soft Matter Physics
• Biophysics

Background:

• Self-assembly, the spontaneous organization of subunits into ordered structures, is fundamental to both biological and synthetic systems.
• Most equilibrium self-assembly processes yield either dispersed subunits or bulk-condensed phases of unlimited size.
• Self-limiting assembly, resulting in finite-size structures, presents a unique thermodynamic challenge regarding size selection.

Purpose of the Study:

• To elucidate the physical mechanisms by which equilibrium self-assembly processes terminate at finite dimensions.
• To classify and analyze diverse self-limiting assembly systems based on their size-selection principles.
• To contrast self-limiting mechanisms with alternative strategies for achieving finite-size control.

Main Methods:

• Review of statistical mechanical frameworks for assembly thermodynamics.
• Analysis of physical ingredients enabling termination of assembly at finite sizes.
• Classification of self-limiting assemblies into 'self-closing' and 'open-boundary' categories.

Main Results:

• Identified key thermodynamic principles governing finite-size selection in self-assembly.
• Categorized self-limiting assemblies, including micellization, shell/tubule formation, short-range attraction/long-range repulsion systems, and geometrically-frustrated assemblies.
• Described size-selection mechanisms and limitations for various self-limiting systems.

Conclusions:

• Self-limiting assembly provides a thermodynamic basis for the formation of finite-sized structures from identical subunits.
• Diverse mechanisms, including self-closing and open-boundary approaches, contribute to size control in equilibrium assemblies.
• Understanding these principles is crucial for designing novel materials and comprehending biological organization.