Precise supramolecular control of surface coverage densities on polymer micro- and nanoparticles

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Surface Chemistry

Background:

• Surface functionalization is crucial for tailoring particle properties.
• Supramolecular chemistry offers modular approaches for molecular assembly.
• Controlling the density of surface-bound molecules remains a challenge.

Purpose of the Study:

• To demonstrate controlled surface functionalization of micro- and nanoparticles using supramolecular host-guest interactions.
• To exploit the competitive binding of high-affinity guests to cucurbit[7]uril (CB7) for precise surface coverage control.
• To establish a modular strategy for stable immobilization of application-relevant molecules.

Main Methods:

• Grafting poly(acrylic acid) onto polymethylmethacrylate particles and introducing azide groups.
• Coupling a propargyl derivative of cucurbit[7]uril (CB7) to the particle surface via click chemistry.
• Quantifying surface-bound CB7 using aminomethyladamantane (AMADA) and demonstrating functionalization with aminoadamantane-labeled rhodamine (Ada-Rho).

Main Results:

• Achieved high surface coverage densities of CB7 (around 0.3 nmol cm⁻²), forming a 3D layer of binding sites.
• Demonstrated precise control over surface functionalization by varying the mole fraction of a second high-affinity guest (Ada-Rho).
• Observed a linear relationship between Ada-Rho surface coverage and its mole fraction in the incubation mixture.

Conclusions:

• The developed supramolecular strategy enables modular and stable immobilization of molecules onto particle surfaces.
• Precise control over surface coverage densities of functional molecules is achievable.
• This method provides a versatile platform for designing functionalized nanomaterials.