Solitons attract a great deal of interest in many fields, ranging from optics to fluid mechanics, cosmology, particle physics and condensed matter. However, solitons of these very different types rarely coexist and interact with each other. Here we develop a system that hosts optical solitons coexisting with topological solitonic structures localised in the molecular alignment field of a soft birefringent medium. We experimentally demonstrate and theoretically explain optomechanical interactions between such optical and topological solitons, mediated by the local transfer of momentum between light and matter and the nonlocal orientational elasticity of the liquid-crystal phase used in our system. We show that the delicate balance arising from these different contributions to the optomechanical force enables facile dynamical control and spatial localisation of topological solitons. Our findings reveal unusual solitonic tractor beams and emergent light-matter self-patterning phenomena that could aid in creating new breeds of nonlinear photonic materials and devices.

The interfacial region formed in a polymer matrix around nanoparticles (NPs) controls many macroscopic properties of polymer nanocomposites (PNCs). However, understanding the factors controlling the structure and properties of the interfacial region remains a challenge. We demonstrated that the initial trapping of polymer chains at surfaces of NPs in solution strongly affects the macroscopic properties of PNCs. The most surprising result is that the differences in properties of PNCs persist even after an extremely long thermal annealing time. We ascribe the observed changes to the formation of an interfacial layer that is trapped in a deep metastable state already in solution. Furthermore, the presented analysis suggests that the PNC equilibration time is defined by the chain desorption time that can be extremely long and, in some cases, even not accessible on a reasonable experimental time scale. These results highlight the importance of polymer solution concentrations on the formation of an interfacial layer and the macroscopic properties of PNCs.

The key parameter controlling the glass transition of colloidal suspensions is ϕ, the fraction of the sample volume occupied by the particles. Unfortunately, changing ϕ by varying an external parameter, e.g. temperature T as in molecular glass formers, is not possible, unless one uses thermosensitive colloidal particles, like the popular poly(Nisopropylacrylamide) (PNiPAM) microgels. These however have several drawbacks, including high deformability, osmotic deswelling and interpenetration, which complicate their use as a model system to study the colloidal glass transition. Here, we propose a new system consisting of a colloidal suspension of non-deformable spherical silica nanoparticles, in which PNiPAM hydrogel spheres of ∼ 100 − 200 µm size are suspended. These non-colloidal 'mesogels' allow for controlling the sample volume effectively available to the silica nanoparticles and hence their ϕ, thanks to the T-induced change in mesogels volume. Using optical microscopy, we first show that the mesogels retain their ability to change size with T when suspended in Ludox suspensions, similarly as in water. We then show that their size is independent of the sample thermal history, such that a well-defined, reversible relationship between T and ϕ may be established. Finally, we use space-resolved dynamic light scattering to demonstrate that, upon varying T , our system exhibits a broad range of dynamical behaviors across the glass transition and beyond, comparable with those exhibited by a series of distinct silica nanoparticle suspensions of various ϕ.

Aggregation of amyloid β peptides is known to be one of the main processes responsible for Alzheimer’s disease. The resulting dementia is believed to be due in part to the formation of potentially toxic oligomers. However, the study of such intermediates and the understanding of how they form are very challenging because they are heterogeneous and transient in nature. Unfortunately, few techniques can quantify, in real time, the proportion and the size of the different soluble species during the aggregation process. In a previous work (Deleanu et al. Anal. Chem. 2021, 93, 6523−6533), we showed the potential of Taylor dispersion analysis (TDA) in amyloid speciation during the aggregation process of Aβ (1−40) and Aβ (1−42). The current work aims at exploring in detail the aggregation of amyloid Aβ (1− 40):Aβ (1−42) peptide mixtures with different proportions of each peptide (1:0, 3:1, 1:1, 1:3, and 0:1) using TDA and atomic force microscopy (AFM). TDA allowed for monitoring the kinetics of the amyloid assembly and quantifying the transient intermediates. Complementarily, AFM allowed the formation of insoluble fibrils to be visualized. Together, the two techniques enabled us to study the influence of the peptide ratios on the kinetics and the formation of potentially toxic oligomeric species.

Wheat gluten includes two major proteins classes, gliadin (25–60 kg/mol) and glutenin polymers (100 to > 2,000 kg/mol) each comprising several polypeptides routinely identified by size-exclusion chromatography and electrophoresis. Gluten proteins are rich in glutamine (30%) and contain several repeated sequences, linking them to the wide class of intrinsically disordered protein (IDP). Here we showed that an ethanol/water (EtOH/W, 50/50, v/v) extract of an industrial gluten, comprising 1/3 of glutenin polymers and 2/3 of gliadin, underwent liquid-liquid phase separation (LLPS) below 14 °C, leading to two coexisting phases, respectively rich and poor in protein. As the quenching depth increased, proteins of lower and lower molecular weight joined the rich phase, akin to what would have been obtained for a polydisperse polymer sample. Within the rich phase the mass ratio of glutenin over gliadin decreased from 2.5 to 0.5 as the temperature dropped from 14 °C to −0.8 °C. Concomitantly the concentration in glutenin polymers increased up to 143 ± 6 g/L (at 9 °C) and then stopped to evolve, suggesting that the binodal line intersected the gelation line below this temperature. Applying the Flory-Huggins (FH) lattice model for each gluten protein classes, we demonstrated that their partitioning in the coexisting phases followed a same temperature dependency. However, some gliadin species joined the rich phase above their critical temperature. Here, specific interactions with the glutenin polymers through weak forces were exemplified. The study demonstrated the relevance of the Flory-Huggins (FH) lattice model in predicting phase behavior even when applied to complex protein mixtures.