Structure and dynamics of single-chain nano-particles in solution

Abstract

Single-chain polymer nano-particles (SCNP's) obtained by intramolecular cross-linking of linear macromolecules (precursors) are emerging soft nano-objects showing unique and remarkable physicochemical, rheological, and sensing properties as a result of their locally collapsed structure and ultrasmall size. In principe, tuning the synthesis procedure, these SCNP's can exhibit tailor-made bio-mimetic properties. For example, through one of the possible routes - 'Michael' addition-mediated self-assembly- SCNPs can offer a controlled delivery of substances like vitamin B9 or even a combined delivery of dermal protective and anti-cancer bioactive cargos. recently, the topology of these nano-particles in solution (good solvent) has been found to strongly resemble that of intrinsically disordered proteins (IDP), currently believed to be a key ingredient in bioogical processes. In both cases, it is clear that the properties/functionally have to be determined not only by the structure but also by the dynamics of solutions of SCNPs obtained through two different synthesis methods, namely the above mentioned 'Michael' route and through cu-complexation. As reference, the precursor (the same for both kinds of SCNPs) in solution has also been characterized. In a first step, the form factor has been characterized by SANS experiments, determining thereby the degree of internal compaction achieved in each case. Then, NSE experiments have allowed us to hace unique insight into the internal modes of the SCNPs, while by means of DLS independent information about the diffusion of their center of mass has been obtained. we compare the outcome of this study with recently published results on the dynamics of the IDP myelin.