The role of non-linear viscoelastic hydrogel mechanics in cell culture and transduction.

The mechanical complexity of the extracellular matrix (ECM) is central to how cells sense and respond to their environment, yet hydrogel design has often focused narrowly on stiffness. Emerging evidence highlights the importance of viscoelastic stress relaxation and plasticity in cell mechanotransduction. However, a key aspect remains underexplored: non-linear viscoelasticity, where stress relaxation and plasticity depend on the magnitude of applied stress or strain.

Pickering double emulsions stabilized by acylated cellulose nanocrystals for oral co-delivery of macromolecules and permeation enhancers.

Double emulsions are potential oral delivery systems for the simultaneous administration of hydrophilic drugs and hydrophobic permeation enhancers to enable effective intestinal absorption of macromolecular drugs. Emulsions stabilized by solid particles, i.e.

Versatile Mechanically Tunable Hydrogels for Therapeutic Delivery Applications.

Hydrogels provide a versatile platform for biomedical material fabrication that can be structurally and mechanically fine-tuned to various tissues and applications. Applications of hydrogels in biomedicine range from highly dynamic injectable hydrogels that can flow through syringe needles and maintain or recover their structure after extrusion to solid-like wound-healing patches that need to be stretchable while providing a selective physical barrier. In this study, a toolbox is designed using thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) polymeric matrices and nanocelluloses as reinforcing agent to obtain biocompatible hydrogels with altering mechanical properties, from a liquid injectable to a solid-like elastic hydrogel.

3D Hydrogel Encapsulation Regulates Nephrogenesis in Kidney Organoids.

Stem cell-derived kidney organoids contain nephron segments that recapitulate morphological and functional aspects of the human kidney. However, directed differentiation protocols for kidney organoids are largely conducted using biochemical signals to control differentiation. Here, the hypothesis that mechanical signals regulate nephrogenesis is investigated in 3D culture by encapsulating kidney organoids within viscoelastic alginate hydrogels with varying rates of stress relaxation.

A Modular Platform for Cytocompatible Hydrogels with Tailored Mechanical Properties Based on Monolithic Matrices and Particulate Building Blocks.

We establish a versatile hydrogel platform based on modular building blocks that allows the design of hydrogels with tailored physical architecture and mechanical properties. We demonstrate its versatility by assembling (i) a fully monolithic gelatin methacryloyl (Gel-MA) hydrogel, (ii) a hybrid hydrogel composed of 1:1 Gel-MA and gelatin nanoparticles, and (iii) a fully particulate hydrogel based on methacryloyl-modified gelatin nanoparticles. The hydrogels were formulated to exhibit the same solid content and comparable storage modulus but different stiffness and viscoelastic stress relaxation.

Controlling lipid crystallization across multiple length scales by directed shear flow.

The crystallization behavior of lipids is relevant in many fields such as adipose tissue formation and regeneration, forensic investigations and food production. Using a lipid model system composed of triacylglycerols, we study the formation of crystalline structures under laminar shear flows across various length scales by polarized light-, scanning electron-, and atomic force microscopy, as well as laser diffraction spectroscopy. The shear rate during crystallization γ̇ influences the acyl-chain length structure and promotes domain growth into the flow direction thereby transforming the crystallites from oblate into prolate particles.

Lipid emulsion interfacial design modulates human digestion and satiation hormone response.

Lipid emulsions (LEs) with tailored digestibility have the potential to modulate satiation or act as delivery systems for lipophilic nutrients and drugs. The digestion of LEs is governed by their interfacial emulsifier layer which determines their gastric structuring and accessibility for lipases. A plethora of LEs that potentially modulate digestion have been proposed in recent years, however, validations of altered LE digestion remain scarce.

Self-Healing Injectable Hydrogels for Tissue Regeneration.

Biomaterials with the ability to self-heal and recover their structural integrity offer many advantages for applications in biomedicine. The past decade has witnessed the rapid emergence of a new class of self-healing biomaterials commonly termed injectable, or printable in the context of 3D printing. These self-healing injectable biomaterials, mostly hydrogels and other soft condensed matter based on reversible chemistry, are able to temporarily fluidize under shear stress and subsequently recover their original mechanical properties.

Physiological fluid interfaces: Functional microenvironments, drug delivery targets, and first line of defense.

Fluid interfaces, i.e. the boundary layer of two liquids or a liquid and a gas, play a vital role in physiological processes as diverse as visual perception, oral health and taste, lipid metabolism, and pulmonary breathing.

Surfactant Adsorption to Different Fluid Interfaces.

Surfactant adsorption to fluid interfaces is ubiquitous in biological systems, industrial applications, and scientific fields. Herein, we unravel the impact of the hydrophobic phase (air and oil) and the role of oil polarity on the adsorption of surfactants to fluid interfaces. We investigated the adsorption of anionic (sodium dodecyl sulfate), cationic (dodecyltrimethylammonium bromide), and non-ionic (polyoxyethylene-(23)-monododecyl ether) surfactants at different interfaces, including air and oils, with a wide range of polarities.

Globular protein assembly and network formation at fluid interfaces: effect of oil.

The formation of viscoelastic networks at fluid interfaces by globular proteins is essential in many industries, scientific disciplines, and biological processes. However, the effect of the oil phase on the structural transitions of proteins, network formation, and layer strength at fluid interfaces has received little attention. Herein, we present a comprehensive study on the effect of oil polarity on globular protein networks.

Adsorption of proteins to fluid interfaces: Role of the hydrophobic subphase.

Adsorption of proteins to fluid interfaces is critical in many industries, scientific disciplines, and biological processes. However, the structural transitions of proteins upon adsorption and the effect of the hydrophobic subphase, such as oil, have received little attention. Herein, we present a comprehensive study on the effect of the hydrophobic subphase on the adsorption behavior of globular and random-coil proteins.

Crystallization-Induced Network Formation of Tri- and Monopalmitin at the Middle-Chain Triglyceride Oil/Air Interface.

Crystalline glycerides play an important role in the formation of multiphase systems such as emulsions and foams. The stabilization of oil/water interfaces by glyceride crystals has been extensively studied compared to only few studies which have been dedicated to oil/air interfaces. This study investigates the crystallization and network formation of tripalmitin (TP) and monopalmitin (MP) at the middle-chain triglyceride (MCT) oil/air interface.

Adsorption and interfacial structure of nanocelluloses at fluid interfaces.

Nanocelluloses (NCs), more specifically cellulose nanocrystals and nanofibrils, are a green alternative for the stabilization of fluid interfaces. The adsorption of NCs at oil-water interfaces facilitates the formation of stable and biocompatible Pickering emulsions. In contrast, unmodified NCs are not able to stabilize foams.

Coupling of long-wavelength density fluctuations to orientations in cellulose nanocrystal suspensions under external fields.

Motivated by the development of cellulose-based functional materials, we investigate the microscopic dynamics of suspensions of cellulose nanocrystals (CNCs) at different ionic strengths, both in the absence and in the presence of AC electric fields and for various temperatures. A concentration of 5 wt % of the CNCs is chosen for which the dispersions are in the full chiral-nematic state at low ionic strengths. Dynamic light scattering is used to characterize the wave vector-dependent decay rates of number-density fluctuations.

A Rat Model of Human Lipid Emulsion Digestion.

A better understanding of how dietary lipids are processed by the human body is necessary to allow for the control of satiation and energy intake by tailored lipid systems. To examine whether rats are a valid model of human dietary lipid processing and therefore useful for further mechanistic studies in this context, we tested in rats three lipid emulsions of different stability, which alter satiety responses in humans. Different sets of 15 adult male Sprague Dawley rats, equipped with gastric catheters alone or combined with hepatic portal vein (HPV) and vena cava (VC) catheters were maintained on a medium-fat diet and adapted to an 8 h deprivation/16 h feeding schedule.

Designing Cellulose Nanofibrils for Stabilization of Fluid Interfaces.

Particles of biological origin are of increasing interest for the Pickering stabilization of biocompatible and environmentally friendly foams and emulsions. Cellulose nanofibrils (CNFs) are readily employed in that respect; however, the underlying mechanisms of interfacial stabilization remain widely unknown. For instance, it has not been resolved why CNFs are unable to stabilize foams while efficiently stabilizing emulsions.

Adsorption of charged anisotropic nanoparticles at oil-water interfaces.

The adsorption of nanoparticles at fluid interfaces is of profound importance in the field of nanotechnology. Recent developments aim at pushing the boundaries beyond spherical model particles towards more complex shapes and surface chemistries, with particular interest in particles of biological origin. Here, we report on the adsorption of charged, shape-anisotropic cellulose nanocrystals (CNCs) for a wide range of oils with varying chemical structure and polarity.

Injectable Biocompatible Hydrogels from Cellulose Nanocrystals for Locally Targeted Sustained Drug Release.

Injectable hydrogels from biocompatible materials are in demand for tissue engineering and drug delivery systems. Here, we produce hydrogels from mere cellulose nanocrystals (CNCs) by salt-induced charge screening. The injectability of CNC hydrogels was assessed by a combination of shear and capillary rheology, revealing that CNC hydrogels are conveyed via plug flow in capillaries allowing injection with minimal impact on mechanical properties.