Chitin nanofibrils (NCh, ∼10 nm lateral size) were produced under conditions that were less severe compared to those for other biomass-derived nanomaterials and used to formulate high internal phase Pickering emulsions (HIPPEs). Pre-emulsification followed by continuous oil feeding facilitated a “scaffold” with high elasticity, which arrested droplet mobility and coarsening, achieving edible oil-in-water emulsions with internal phase volume fraction as high as 88%. The high stabilization ability of rodlike NCh originated from the restricted coarsening, droplet breakage and coalescence upon emulsion formation. This was the result of (a) irreversible adsorption at the interface (wettability measurements by the captive bubble method) and (b) structuring in highly interconnected fibrillar networks in the continuous phase (rheology, cryo-SEM, and fluorescent microscopies). Because the surface energy of NCh can be tailored by pH (protonation of surface amino groups), emulsion formation was found to be pH-dependent. Emulsions produced at pH from 3 to 5 were most stable (at least for 3 weeks). Although at a higher pH NCh was dispersible and the three-phase contact angle indicated better interfacial wettability to the oil phase, the lower interdroplet repulsion caused coarsening at high oil loading. We further show the existence of a trade-off between NCh axial aspect and minimum NCh concentration to stabilize 88% oil-in-water HIPPEs: only 0.038 wt % (based on emulsion mass) NCh of high axial aspect was required compared to 0.064 wt % for the shorter one. The as-produced HIPPEs were easily textured by taking advantage of their elastic behavior and resilience to compositional changes. Hence, chitin-based HIPPEs were demonstrated as emulgel inks suitable for 3D printing (millimeter definition) via direct ink writing, e.g., for edible functional foods and ultralight solid foams displaying highly interconnected pores and for potential cell culturing applications.

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Osteoblast cells were separated from the neonatal rat calvaria and co-cultured on a novel mineralized hydroxyapatite/collagen/poly(lactic acid) composite scaffold. By using this static cell culture, a three-dimensional osteoblasts/composite bone-like was constructed in vitro. The culture process was observed by scanning electron microscopy, fluorescence microscopy, confocal laser scanning microscopy, and histological analysis. Cells were observed to spread and proliferate throughout the inner-pores of the scaffold material. After a 12-day culture, the cells had grown into the interior scaffold about 200–400 μm depth of the composite by histological section observation. This mobile behavior of osteoblasts appeared to be similar to the composition and hierarchical structure of bone tissue. The adherence and migration of osteoblast cells in this three-dimensional composite is clinically important for large bone defect repair based on tissue engineering.

Ionic hydrogels are attractive for the protection, delivery and controlled release of charged biomacromolecules such as proteins, growth factors or DNA. We have prepared and characterized a series of photocrosslinked anionic hydrogels based on water soluble methacrylated (MA) O‐carboxymethylchitosan (OCMCS) and polyethylene glycol (PEG) diacrylate. OCMCS samples with varying degree of substitution of carboxymethyl group ranging from 0.69 to 1.86 were prepared by reacting native chitosan with different amounts of monochloroacetic acid. The OCMCS products demonstrated differences in solubility, zeta potential (–52.7 to –12.8 mV) and thermal decomposition temperature (260 to 283 °C). The OCMCS products were then reacted with glycidyl methacrylate to make ultra‐violet (UV) crosslinkable OCMCS‐MAs which were blended with PEG diacrylate, a photoinitiator and water and successfully photocrosslinked to create OCMCS‐MA/PEG hydrogels. Water uptake of the hydrogels varied between 226 % to 358 % and the porous structures of the prepared OCMCS‐MA/PEG hydrogels could be modulated by the degree of methacrylation. All the OCMCS‐MA/PEG hydrogel substrates similarly supported attachment and proliferation of Smooth Muscle Cells (SMCs). The in vitro biodegradation of these hydrogels, in the presence of SMCs, could be controlled by the degree of methacrylation; weight loss after 9‐week was (15±1) % and (19±2) % using OCMCS 4‐MA (12.7 % MA) and OCMCS 1‐MA (4.6 % MA), respectively. In addition, the hydrogel based on the most anionic OCMCS 1 showed higher adsorption of basic TGF‐β1 than similarly modified ‐agarose, ‐dextran, and ‐chondroitin sulfate hydrogels.