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Leveraging Hydration Forces for Size-Specific Nanoparticle Enrichment with a Redox-Responsive Silica-Binding
Zhixing Lin1, François Baneyx1
1Departments of Materials Science and Engineering1 and Chemical Engineering2, University of Washington, Seattle, Washington 98195, United States.
ACS Nano
|January 5, 2026
Summary
Elastin-like polypeptides (ELPs) reversibly aggregate silica nanoparticles (SiNPs) below their transition temperature. This protein-based nanoparticle assembly is tunable by ELP design and particle size, enabling selective separation.
Area of Science:
- Materials Science
- Biomaterials Science
- Nanotechnology
Background:
- Elastin-like polypeptides (ELPs) are known for their thermoresponsive coacervation above a lower critical solution temperature (LCST).
- Their application in nanoparticle assembly below LCST, particularly for silica nanoparticles (SiNPs), is underexplored.
- ELPs offer potential for novel bioinspired colloidal design and separation strategies.
Purpose of the Study:
- To investigate the ability of unmodified ELPs to mediate reversible nanoparticle assembly below their transition temperature.
- To explore how ELP characteristics and nanoparticle properties influence assembly and flocculation.
- To demonstrate size-selective nanoparticle separation and expand the concept to other oxide nanoparticles.
Main Methods:
- Utilized unmodified ELPs to induce reversible flocculation of silica nanoparticles (SiNPs) via hydrogen bonding with surface silanols.
- Engineered redox-responsive ELP-based fusion proteins with silica-binding peptides (Car9) for controlled nanoparticle stabilization and flocculation.
- Investigated the impact of ELP length, concentration, anchoring groups, and nanoparticle size on assembly dynamics.
Main Results:
- ELPs reversibly flocculate SiNPs below their LCST by forming hydrogen bonds with surface silanols.
- Particle assembly is modulated by ELP length, concentration, and terminal anchoring groups (e.g., Car9).
- Demonstrated size-selective SiNP enrichment based on particle size (20-60 nm) and controlled flocculation of titania nanoparticles using pH-responsive ELPs.
Conclusions:
- Unmodified ELPs can reversibly assemble and disassemble nanoparticles below their transition temperature.
- The study provides a tunable strategy for nanoparticle assembly, separation, and bioinspired colloidal design.
- These findings are applicable to the separation of various oxide nanoparticles and their polymorphs.
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