Binding between particles and proteins in extracts: implications for microrheology and toxicity

Area of Science:

• Biomaterials Science
• Cell Biology
• Nanotechnology

Background:

• Understanding foreign material interactions with cytoplasmic proteins is vital for intracellular probe design and nanoparticle toxicity.
• Protein adsorption onto micro/sub-micron particles influences their behavior within cells.

Purpose of the Study:

• To characterize protein adsorption onto various particles from cell extracts.
• To measure particle Brownian motion in live cells and reconstituted networks as a proxy for association.
• To investigate the impact of particle surface chemistry on protein binding and cellular interactions.

Main Methods:

• Tested SiO2, TiO2, and polystyrene particles with varied surface chemistries and coatings.
• Characterized protein adsorption from cell extracts.
• Measured particle Brownian motion in live cells and reconstituted actin networks.
• Utilized phalloidin to functionalize particles for targeted actin binding.

Main Results:

• Cellular associations and protein binding are strongly dependent on particle surface chemistry.
• Cytoskeletal proteins, including actin and intermediate filaments (like vimentin), are highly concentrated on particle surfaces.
• Microinjected particles binding vimentin showed larger movements than those binding actin; this difference was masked upon endocytosis.
• Identified carboxylated SiO2 particles resistant to protein binding, which became actin-binding upon phalloidin conjugation.

Conclusions:

• Particle surface chemistry is a critical determinant of protein adsorption and cellular interactions.
• Cytoskeletal protein binding influences particle dynamics within cells, with endocytosis potentially masking surface interactions.
• Surface modification strategies, like phalloidin conjugation, can predictably alter particle-protein binding for specific applications.