Abstract
We proposed a simple method to process hydrogels containing polyvinyl alcohol and cellulose nanofibrils (PVA/CNF) to prepare volumetric architectures by direct ink writing (DIW). The presence of CNF in the aqueous PVA suspensions conferred rheology profiles that were suitable for extrusion and solidification in pre-designed shapes. The viscoelastic behavior of the hybrid inks enabled precise control on processability and shape retention, for instance, as demonstrated in multilayered lattice structures of high fidelity. After lyophilization, the obtained 3D-printed hydrogels presented a very high porosity, with open and interconnected pores, allowing a high-water uptake capacity (up to 1600%). The mechanical strength of the composite 3D-printed materials matched those of soft tissues, opening opportunities for skin applications. As such, drug-loaded samples revealed a controlled and efficient delivery of an antioxidant (ascorbic acid) in PBS buffer media at 23 °C (~80% for 8 h). Altogether, PVA/CNF hydrogels were introduced as suitable precursors of 3D-lattice geometries with excellent physical and mechanical characteristics.
Highlights
Additive manufacturing enables customized fabrication of 3D structures directly from computer-aided designs
This is favorable for direct ink writing (DIW) since the ink can extrude without clogging the nozzle tip due to the high shear rates subjected to the 3D printing materials
It is worth mentioning that a 10 wt% Polyvinyl alcohol (PVA) solution displayed the slight shear-thinning behavior with a final viscosity of approximately 120 mPa.s (Fig. S2b) [5]; the observed rheological performance of the composite inks could be attributed to the incorporation of cellulose nanofibrils (CNF)
Summary
Additive manufacturing enables customized fabrication of 3D structures directly from computer-aided designs. Jiang et al [5] reported DIW of hybrid hydrogel inks composed of PVA and κ-carrageenan They revealed the outstanding rheology of the developed hydrogels, and their excellent mechanical properties, which arose from freezing and thawing processes. They proved excellent cytocompatibility of the printed samples and offered them for tissue engineering, drug delivery, bone regeneration, and implant medicine. Another important component in DIW, cellulose nanofibrils (CNF), has been considered given that it is a natural polysaccharide with a native crystalline structure. The biocompatible 3D structures are demonstrated for their excellent promise as far as their mechanical performance and controlled drug release properties
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