Nanocellulose Source and Morphology Impact on Properties of Composite Gelatin Hydrogel Scaffolds

Abstract

Nanocellulose has emerged as a promising biomaterial for development of scaffolds for tissue engineering. Incorporation of nanocellulose into a polymer scaffold can increase its stiffness, allowing it to better mimic the mechanical properties of native extracellular matrix. Plant-derived nanocellulose is classified as either cellulose nanofibrils (CNFs) or cellulose nanocrystals (CNCs) depending on particle characteristics and extraction methods. Although both materials have been used in hydrogel composites, the impact of nanocellulose source and morphology on scaffold properties remains unclear. Here, we isolated high aspect ratio CNFs from two macroalgae species and compared them with conventional wood pulp-derived CNFs and CNCs in the preparation of composite gelatin hydrogels. All nanocellulose types increased hydrogel stiffness in a concentration-dependent manner; however, the greatest increase was achieved using brown algae CNF, where the addition of 1.25 wt.% nanocellulose resulted in a 5.2-fold increase in compression modulus relative to neat gelatin. Bioassays showed that nanocellulose improved keratinocyte adhesion and spreading on gelatin scaffolds, with a positive correlation between nanocellulose concentration and surface coverage and inverse with cell circularity. These findings demonstrate the influence of nanocellulose source and morphology on the mechanical and biological properties of composite scaffolds and highlight the potential of novel nanocellulose sources for scaffold development.

Impact Statement

Nanocellulose has been used as a scaffolding material for many different types of tissues, where it is employed as a reinforcing phase in composite scaffolds. This study investigated how nanocellulose origin (algal vs wood pulp), type (nanofibrils vs nanocrystals), and concentration influence the mechanical properties of gelatin hydrogel composites. We demonstrate that nanocellulose morphology and concentration impact both mechanical properties and cell growth. The greatest reinforcing effect was delivered by the kelp-derived nanofibrils, whereas wood-derived nanofibrils and nanocrystals had the smallest effect. Nanocellulose reinforcement also enhanced keratinocyte attachment and spreading on gelatin hydrogels in a concentration-dependent manner.