Patrícia Figueiredo

Pickering emulsions have attracted significant interest due to their superior stability compared to surfactant-stabilized emulsions. Particle size is a key parameter in the stabilization of Pickering emulsions. However, a fundamental understanding of how particle size influences emulsion stabilization across different homogenization methods remains unclear. In this study, the effects of silica nanoparticle size on Pickering emulsion formation and stability were investigated under different processing methods, including rotor-stator homogenization, ultrasonication, and high-pressure homogenization. Emulsion structure and stability were evaluated using droplet size analysis, interfacial adsorption measurements, ζ-potential characterization, and Turbiscan stability analysis. Multivariate Partial Least Squares (PLS) regression was further applied to assess the relative importance of particle size. The results show that the effect of particle size on emulsion stability strongly depends on the processing method. Under rotor-stator homogenization, stability was governed by a balance between droplet size reduction and particle sedimentation, resulting in optimal stability for intermediate-sized nanoparticles. Under ultrasonication, smaller nanoparticles enhanced stability primarily through increased interfacial adsorption. In contrast, for high-pressure homogenization, particle size effects on droplet structure were largely masked, and stability was mainly constrained by limited coalescence during storage and sedimentation of larger particles. These findings show that particle size influences Pickering emulsion stability through distinct mechanisms under different homogenization methods, providing guidance for the rational design of particle-stabilized emulsions.

Liquid–liquid interfaces and interfacially entrapped nanoparticles are ubiquitous in nature and technology. Their importance in the industry is rising because nanoparticle‐stabilized emulsions can be designed to be more stable, ecological, and safe for human health than conventional emulsions stabilized by molecular surfactants. The properties of these “Pickering emulsions” depend on the particle sizes and shapes, droplet coverage, and particle behavior in the interface, among other factors, some of which are yet to be understood better or even identified. Here, we present the first workflow for analyzing real Pickering emulsions in the nanoscale. Two case materials were chosen for the nanoparticles: silica and lignin to represent hard inorganic and soft biobased materials, respectively. The particle movements, deformation of interfacial particles, droplet movement, and droplet coalescence were inflicted and measured simultaneously at high forces. Our method opens a new analytical pathway to analyze and manipulate real‐world 3D nanostructures with fluid components, which are under intense research for self‐assembly, interfacial nanoarchitectonics, and functional devices. Furthermore, our results show that the interfacial behavior of a soft biomatter can be distinguished from that of a rigid inorganic particle, which is relevant for the green shift across multiple materials‐related industries.Summary: AFM workflow is introduced to measure the topography, adhesion, and stiffness of emulsion droplets and their interfacial nanoparticles under liquid. The droplets and interfacial nanoparticles can be mechanically manipulated at high interaction forces. Lignin particles do not keep their size and shape in the emulsion interface.

Functionalizing lignin nanoparticles (LNPs) is an attractive strategy to improve their properties and expand their range of applications. However, conventional approaches to achieve such modifications are done using environmentally and energy‐demanding methods. Here, a green synthetic approach through spontaneous adsorption and laccase‐induced reactions to functionalize LNPs with hemicelluloses is introduced. Structurally varying lignin and hemicellulose grades isolated from different sources and several fungal laccases are systematically compared. Specifically, the residual lignin content in hemicelluloses is hypothesized to determine their adsorption efficacy on LNPs. Results reveal that the LNPs can be coated with hemicelluloses by physical adsorption, which greatly increases their colloidal stability at acidic pH, compared to plain LNPs. Furthermore, fungal laccases can play an active role in attaching lignin moieties of the hemicelluloses at the LNP surface, confirmed by the enriched lignin‐derived compounds and monosaccharide composition of the laccase‐treated hybrid LNPs, compared to the physical adsorption of hemicellulose on the LNP surface. Overall, this study provides new insights on the mechanism of laccase‐assisted functionalization of LNPs with other ligands (e.g., hemicelluloses). Furthermore, the increased colloidal stability of LNPs can greatly increase the application of such hemicellulose–lignin hybrid nanosystems for different areas, such as health sciences.

Nanomedicine’s advent has promised to revolutionize different biomedical fields, including oncology. Silver Nanoparticles (AgNPs) showed promising results in different tumor models. Clear cell Renal Cell Carcinoma (ccRCC) is especially challenging due to its late diagnosis, poor prognosis and treatment resistance. Therefore, defining new therapeutic targets and regimens could improve patient management. This study intends to evaluate AgNPs’ effect in ccRCC cells and explore their potential combinatory effect with Everolimus and Radiotherapy. AgNPs were synthesized, and their effect was evaluated regarding their entering pathway, cellular proliferation capacity, ROS production, mitochondrial membrane depolarization, cell cycle analysis and apoptosis assessment. AgNPs were combined with Everolimus or used to sensitize cells to radiotherapy. AgNPs are cytotoxic to 786-O cells, a ccRCC cell line, entering through endocytosis, increasing ROS, depolarizing mitochondrial membrane, and blocking the cell cycle, leading to a reduction of proliferation capacity and apoptosis. Combined with Everolimus, AgNPs reduce cell viability and inhibit proliferation capacity. Moreover, 786-O is intrinsically resistant to radiation, but after AgNPs’ administration, radiation induces cytotoxicity through mitochondrial membrane depolarization and S phase blockage. These results demonstrate AgNPs’ cytotoxic potential against ccRCC and seem promising regarding the combination with Everolimus and sensitization to radiotherapy, which can, in the future, benefit ccRCC patients’ management.

The production of lignin nanoparticles (LNPs) has emerged as a way to overcome the highly variable and complex molecular structure of lignin. It can offer morphological control of the lignin polymer, allowing the formation of stable LNP dispersions in aqueous media, while increasing the potential of lignin for high‐value applications. However, the polydispersity and morphology of LNPs varies depending on the lignin grade and preparation method, and a systematic comparison using different technical lignins is lacking. In this study, it was attempted to find a green fabrication method with a distinct solvent fractionation of lignin to prepare LNPs using three different technical lignins as starting polymers: BLN birch lignin (hardwood, BB), alkali Protobind 1000 (grass, PB), and kraft LignoBoost (softwood, LB). For that, three anti‐solvent precipitation approaches to prepare LNPs were systematically compared: 70 % aqueous ethanol, acetone/water (3 : 1) and NaOH as the lignin solvent, and water/aqueous HCl as the anti‐solvent. Among all these methods, the acetone/water (3 : 1) approach allowed production of homogeneous and monodisperse LNPs with a negative surface charge and also spherical and smooth surfaces. Overall, the results revealed that the acetone/water (3 : 1) method was the most effective approach tested to obtain homogenous, small, and spherical LNPs from the three technical lignins. These LNPs exhibited an improved stability at different ionic strengths and a wider pH range compared to the other preparation methods, which can greatly increase their application in many fields, such as pharmaceutical and food sciences.