Breaking the Size Barrier: Surface Roughness Enables Oversized Chromium Colloids to Penetrate Plant Cell Walls

Area of Science:

• Plant Biology
• Materials Science
• Biophysics

Background:

• Plant cell walls act as physical barriers with size exclusion limits.
• The mechanism of oversized particle entry into plant tissues is poorly understood.
• Traditional models fail to explain particle accumulation within plant tissues.

Purpose of the Study:

• To elucidate the mechanism of oversized particle penetration across the plant cell wall apoplastic barrier.
• To investigate the role of interfacial dynamics and physicochemical forces in particle transport.
• To challenge the conventional size-threshold paradigm of biological barriers.

Main Methods:

• Utilized oversized chromium (Cr) colloids and rice as a model system.
• Integrated cross-scale characterizations, molecular dynamics simulations, and molecular biological assays.
• Analyzed interfacial dynamics and physicochemical interactions between colloids and cell walls.

Main Results:

• Oversized particle penetration is driven by dynamic cell wall remodeling, not pore-size matching.
• High microscopic roughness of colloids amplifies interfacial contact and affinity.
• Physicochemical forces induce adaptive loosening and structural deformation of the cell wall polysaccharide network.
• A physical pathway is opened for oversized particle entry.

Conclusions:

• Challenges the traditional size-threshold paradigm for biological barriers.
• Surface topography of colloids is a critical determinant for cross-barrier bioavailability.
• Colloid-cell wall interactions trigger systemic growth-defense metabolic trade-offs in plants.