2025/08/20 by Sida Wang, Wang, Sida, Angela Le +5
Biochemistry, Genetics and Molecular Biology · Chemistry · Physics and Astronomy · #Biological Physics (physics.bio-ph) #Chemical Physics (physics.chem-ph) #Electrostatics and Colloid Interactions #FOS: Physical sciences #Force Microscopy Techniques and Applications #Lipid Membrane Structure and Behavior #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2508.14652
openalex publication_date 2025/08/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/03
In solution, electrically like-charged particles can experience a strong and long-ranged attraction that leads to the formation of stable, slowly reorganizing clusters. The attractive force underpinning this spontaneous organization process has been shown to depend on both the sign of charge of the particle and the nature of the solvent medium. The origin of the attraction has been ascribed to the preferential orientation of solvent molecules at the object-electrolyte interface. Here, we use optical imaging to directly measure the spatial profile of the potential of mean force between isolated pairs of charged microspheres. Working with particles carrying a variety of surface chemistries we find that the range of the electrosolvation attraction is substantially longer than previously held. In particular we show that particles carrying strongly anionic surface coatings composed of DNA or phospholipid bilayers display long-range attraction. We further find that the length scale governing the decay of the attractive force can depend on the properties of the interacting particles. This contrasts with the canonical expectation that the screening length governing the interaction of charged particles in solution depends exclusively on the properties of the intervening electrolyte medium. The observations point to significant departures from current thinking, and the likely need for a model of interactions that accounts for the molecular nature of the solvent, its interfacial behaviour, and spatial correlations. Finally, a strong and long-ranged attraction mediated by anionic matter constituting lipid membranes and chromatin could carry far-reaching implications for biological organization and structure formation.