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Over the recent years, various materials have been introduced as potential 3D cell culture scaffolds. These include protein extracts, peptide amphiphiles, and synthetic polymers. Hydrogel scaffolds without human or animal borne components or added bioactive components are preferred from the immunological point of view. Here we demonstrate that native nanofibrillar cellulose (NFC) hydrogels derived from the abundant plant sources provide the desired functionalities. We show 1) rheological properties that allow formation of a 3D scaffold in-situ after facile injection, 2) cellular biocompatibility without added growth factors, 3) cellular polarization, and 4) differentiation of human hepatic cell lines HepaRG and HepG2. At high shear stress, the aqueous NFC has small viscosity that supports injectability, whereas at low shear stress conditions the material is converted to an elastic gel. Due to the inherent biocompatibility without any additives, we conclude that NFC generates a feasible and sustained microenvironment for 3D cell culture for potential applications, such as drug and chemical testing, tissue engineering, and cell therapy.

Renewable high‐performance macroscopic functional fibers are prepared by a simple wet‐extrusion and coagulation process of hydrogels of native cellulose nanofibrils. The fibers are functionalized to be transparent, conducting, or magnetic and they can host and release guests as payloads. These biobased macrofibers provide a sustainable approach for high‐performance and functional fiber technology in 21st century technologies.

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The effect of temperature on aqueous solutions of poly(N-vinylcaprolactam) (PVCL) samples of molecular weights ranging from 21 000 to 1.5 × 106 g mol-1 was monitored by dynamic light scattering (DLS), high-sensitivity microcalorimetry (HS DSC), and pressure perturbation calorimetry (PPC) from 10 to 80 °C. The polymer was soluble in cold water and underwent phase separation at T CP ∼ 31−38 °C, depending on the molecular weight. The phase transition was endothermic, with an enthalpy change of 4.4 ± 0.4 kJ mol-1. Stable particles of average diameters 80 nm (high molecular weight PVCL) and ∼ 180 nm (low molecular weight PVCL) formed above the phase transition temperature. The coefficient of thermal expansion of PVCL in water (αpol), determined by PPC, underwent a sharp decrease at the temperature corresponding to the onset of phase transition, then it passed through a maximum, and decreased continuously with increasing temperature. The stability of the particles formed in PVCL solutions kept at temperatures exceeding T CP suggests that their surfaces possess a hydrophilic character. Results of microcalorimetric measurements carried out with solutions of PVCL in D2O add further strength to this conclusion. The thermodynamic and volumetric changes associated with the phase transition of aqueous PVCL solutions are compared to those of aqueous solutions of poly(N-isopropylacrylamide) (PNIPAM), a polymer that also undergoes a phase transition in water at ∼ 31 °C, and of poly(vinylpyrrolidone) (PVP), a polymer structurally related to PVCL, which is soluble in water at all the temperatures investigated here.