Single-chain nanoparticles (SCNPs) are soft nano-objects synthesized via intramolecular cross-linking of individual polymer chains (precursors). These structures hold significant promise for applications in nanomedicine, bioimaging, biosensing, catalysis, and rheology, among others. Under standard good solvent conditions of synthesis —where precursor chains adopt self-avoiding conformations— long-loop cross-links are rare, limiting intramolecular compaction. As a result, most SCNPs adopt sparse, multi-loop architectures with scaling exponents close to 0.5, resembling the behavior of intrinsically disordered proteins.
In this contribution, we examine theoretical and computational insights into how SCNP topology influences their scaling behavior, as well as the structure and dynamics of SCNP-based systems. These include fluids, gels, melts, and nanocomposites featuring either reversible or irreversible bonds. We also explore strategies for synthesizing globular SCNPs, the impact of crowding on their conformations, and their unique glassy dynamics. Additionally, we discuss their shear flow properties, their topological interactions in nanocomposites, and the behavior of SCNP-based vitrimer networks.