Polysaccharide-mediated stabilization of bacterial nanocellulose dispersions: Experimental and molecular dynamics study

Abstract

Colloidal dispersions of pristine cellulose (nano- or microsized; fibrillar or particulate), are typically unstable in water due to interfiber/interparticle interactions. Carboxymethyl cellulose (CMC) is known to effectively stabilize these dispersions, allowing for full recovery of the properties upon redispersion after drying. However, the underlying mechanism has been unclear. This study investigated why CMC effectively stabilized cellulose and whether other polysaccharides could perform similarly. Mixtures of bacterial nanocellulose (BNC) with chia mucilage (ChM), hyaluronic acid (HA), pectin (Pec), xanthan gum (XG), locust bean gum (LBG), salep, alginate (Alg), and polyol glycerol (Gly) were compared to mixtures of BNC:CMC. The stability and redispersibility after drying of each mixture were analyzed. Only ChM produced homogeneous and stable BNC dispersions similar to CMC. The polysaccharides adsorption onto cellulose films was studied using quartz crystal microbalance with dissipation (QCM-D). CMC and ChM showed stronger and more stable adsorption, with higher retained mass after washing (10.0 ± 0.3 and 7.8 ± 2.3 mg/m2, respectively), compared to Alg, HA, or XG (3.6 ± 0.6, 1.0 ± 0.3 and 0.2 ± 0.1 mg/m2, respectively). Molecular dynamics simulations confirmed the stronger interactions of CMC and ChM with cellulose surfaces, characterized by hydrogen bonding and perpendicular orientation.