Bioinspired Thermoresponsive Xyloglucan–Cellulose Nanocrystal Hydrogels

Abstract

Thermoresponsive hydrogels present unique properties, such as tunable mechanical performance or changes in volume, which make them attractive for applications including wound healing dressings, drug delivery vehicles, and implants, among others. This work reports the implementation of bioinspired thermoresponsive hydrogels composed of xyloglucan (XG) and cellulose nanocrystals (CNCs). Starting from tamarind seed XG (XGt), thermoresponsive XG was obtained by enzymatic degalactosylation (DG-XG), which reduced the galactose residue content by ∼50% and imparted a reversible thermal transition. XG with native composition and comparable molar mass to DG-XG was produced by an ultrasonication treatment (XGu) for a direct comparison of behavior. The hydrogels were prepared by simple mixing of DG-XG or XGu with CNCs in water. Phase diagrams were established to identify the ratios of DG-XG or XGu to CNCs that yielded a viscous liquid, a phase-separated mixture, a simple gel, or a thermoresponsive gel. Gelation occurred at a DG-XG or XGu to CNC ratio higher than that needed for the full surface coverage of CNCs and required relatively high overall concentrations of both components (tested concentrations up to 20 g/L XG and 30 g/L CNCs). This is likely a result of the increase in effective hydrodynamic volume of CNCs due to the formation of XG-CNC complexes. Investigation of the adsorption behavior indicated that DG-XG formed a more rigid layer on CNCs compared to XGu. Rheological properties of the hydrogels were characterized, and a reversible thermal transition was found for DG-XG/CNC gels at 35 °C. This thermoresponsive behavior provides opportunities to apply this system widely, especially in the biomedical field, where the mechanical properties could be further tuned by adjusting the CNC content.

Review of Applications and Future Prospects of Stimuli-Responsive Hydrogel Based on Thermo-Responsive Biopolymers in Drug Delivery Systems

“…A histological study showed that the administration of xyloglucan gel did not show any damage to nasal mucosa [ 44 ]. The bioinspired thermo-responsive hydrogels composed of xyloglucan and cellulose nanocrystals showed a reversible thermal transition at 35 °C, and exhibited tunable mechanical performance or changes in volume that made them suitable for biomedical applications including drug delivery, wound healing dressings, and implants [ 45 ]. The thermo-responsive property of xyloglucan was obtained by enzymatic de-galactosylation of tamarind seed xyloglucan, which reduced the galactose residue content by ∼50%, and the adsorption behavior indicated that de-galactosylated xyloglucan formed a more rigid layer on cellulose nanocrystals than that of native xyloglucan [ 45 ].…”

“…The bioinspired thermo-responsive hydrogels composed of xyloglucan and cellulose nanocrystals showed a reversible thermal transition at 35 °C, and exhibited tunable mechanical performance or changes in volume that made them suitable for biomedical applications including drug delivery, wound healing dressings, and implants [ 45 ]. The thermo-responsive property of xyloglucan was obtained by enzymatic de-galactosylation of tamarind seed xyloglucan, which reduced the galactose residue content by ∼50%, and the adsorption behavior indicated that de-galactosylated xyloglucan formed a more rigid layer on cellulose nanocrystals than that of native xyloglucan [ 45 ]. The de-galactosylated xyloglucan was applied to develop thermo-responsive hydrogel for the intraperitoneal administration of mitomycin C and in vitro drug release from the hydrogel following the Higuchi rate model over the time period of 5 h [ 46 ].…”

Broad Specific Xyloglucan:Xyloglucosyl Transferases Are Formidable Players in the Re-Modelling of Plant Cell Wall Structures

“…Examining these novel relationships will spur a better understanding of the roles of XTH enzymes in plant CWs from macro to atomic levels. Thus, it is imperative to use the knowledge of XTHs in a CW context, amongst other applications, for the rational design of economically important crops using genetic engineering and more broadly bio-technology to increase stress tolerance, tackle drought and other abiotic stresses [105], and produce modified (thermo-responsive) XG hydrogels for bio-medicine [142] and wound healing [143].…”

Cellulose Nanocrystals for Environment-Friendly Self-Assembled Stimuli Doped Multisensing Photonics

“…(A) Polarized optical microscopy images of DG-XG/CNC mixtures at low and high temperatures for ratios of 20:1 and 20:10 (XG/CNC). Reprinted with permission from ref . Copyright 2020 American Chemical Society.…”