Creating Ultrastrong and Osteogenic Chitin Nanocomposite Hydrogels via Chitin Whiskers with Different Surface Chemistries

Abstract

The commonly used chitin whiskers (CHWs) prepared by the acid hydrolysis method are easy to agglomerate in an alkaline matrix, which limits their applications in many aspects. Herein, maleation chitin whiskers (mCHWs) with lots of −COOH groups were designed, which can stably exist and homogeneously disperse in the alkaline chitin matrix due to their relatively strong electronegativities. Subsequently, the CHWs and mCHWs were utilized as reinforcing fillers to enhance the mechanical strength of the chitin hydrogel. As expected, the CHWs played an extremely limited role in reinforcing the chitin hydrogel. Conversely, due to good dispersibility and strong interfacial interaction, the mCHWs exhibited a significantly superior enhancement effect on the chitin hydrogel. Moreover, the tensile strength and modulus of the asprepared mCHW/chitin composite hydrogels were strongly dependent on the content of mCHWs, and the highest values of 5.8 ± 0.2 and 5.2 ± 0.6 MPa were obtained with 3 wt % mCHW content, which are higher than those of polysaccharide hydrogels reported in the most literature. Importantly, both CHWs and mCHWs can facilitate the adhesion, proliferation, and differentiation of mouse embryo osteoblast precursor (MC3T3-E1) cells. Moreover, the mCHWs also play these promoting effects in a contentdependent manner. Interestingly, CHWs and mCHWs mainly contain −NH 2 and −COOH groups, respectively; as a result, surface protein adsorption and calcium-phosphate mineralization are different. But there are very small differences in cell adhesion, proliferation, and differentiation between the corresponding 3%CHW/chitin and 3%mCHW/chitin composite hydrogels. This work provides a promising strategy to construct a polysaccharide nanocomposite hydrogel with robust mechanical strength and osteogenesis for potential application as an artificial periosteum.

Nanochitin: Chemistry, Structure, Assembly, and Applications

“…625,627 Therein, covalent cross-linking occurred between the amino groups present on the surface of ChNF and the quinone rings, derived from the oxidation of phenol. 622 The obtained hydrogels displayed a nearly 10-fold higher tensile strength compared to the hydrogels formed by nondeacetylated ChNF, indicating the extended cross-linking between quinone and amino groups. Genipin, a natural product extracted from gardenia fruit, has shown low cytotoxicity and has been demonstrated to efficiently cross-link β-ChNF, forming strong hydrogels.…”

“…After filling the void space of the template with a ChNF hydrogel, the template was dissolved in alkaline media (Figure a2), resulting in a ChNF system that retained the visual appearance of the original design (Figure a3) and led to an aligned internal porous structure (Figure a4). On the other hand, in order to control the interactions leading to nanofiber interconnections, a gas phase coagulation was applied by exposing the system to a volatile alkaline (e.g., ammonium hydroxide) or acid (e.g., hydrochloric acid) vapor, leading to physically cross-linked ChNF hydrogels containing PD-ChNF or TEMPO-ChNF (Figure b). − Besides hydrogels produced from pure nanochitin, blending of nanochitin with other components allows composite hydrogels with enhanced performances. , For instance, loading alginate into a ChNC suspension improved the mechanical properties and swelling stability of the hydrogels due to strong electrostatic interactions between the nanocrystals and alginate molecules …”

“…The obtained hydrogel retained its integrity after a number of dehydration (compression) and swelling (immersion) cycles, which demonstrates the advantage of covalent cross-linking to generate high-performance nanochitin hydrogels. Recently, inspired by a naturally occurring quinone hardening process during insect cuticle sclerotization, a quinone-cross-linked hydrogel was produced from surface-deacetylated ChNF in neutral aqueous phase. , Therein, covalent cross-linking occurred between the amino groups present on the surface of ChNF and the quinone rings, derived from the oxidation of phenol . The obtained hydrogels displayed a nearly 10-fold higher tensile strength compared to the hydrogels formed by nondeacetylated ChNF, indicating the extended cross-linking between quinone and amino groups.…”

“…619−621 Besides hydrogels produced from pure nanochitin, blending of nanochitin with other components allows composite hydrogels with enhanced performances. 622,623 For instance, loading alginate into a ChNC suspension improved the mechanical properties and swelling stability of the hydrogels due to strong electrostatic interactions between the nanocrystals and alginate molecules. 624 Although physical cross-linking generates nanochitin hydrogels with robust structures and strength, further enhancement of the performance and functions of nanochitin-based hydrogels requires chemical cross-linking, leading to covalently entangled networks.…”

Dual-Cross-linked Liquid Crystal Hydrogels with Controllable Viscoelasticity for Regulating Cell Behaviors

“…Due to its good biocompatibility, cell affinity, biodegradation and excellent osteogenic activity, chitin is widely considered a good candidate for bone repair materials. − Chitin whisker (CHW), prepared by the acid hydrolysis of chitin, not only retains the structure and properties of chitin but also shows a high aspect ratio. Ascribing to electrostatic interactions, van der Waals forces, and other interaction forces, the aqueous suspension of CHW can exhibit a typical cholesteric LC texture similar to that of liquid crystalline collagen in a specific concentration range. − Moreover, due to its ultrahigh strength and modulus, CHW has also been widely used as enhanced fillers to improve the mechanical properties, biocompatibility, and osteogenic activity of hydrogels. , Our previous work proved the positive effects of the CHW on improving the mechanical properties and guiding the cell behaviors of chitin/CHW composite hydrogels . However, few studies have focused on the LC properties of composite hydrogels doped with CHW, and there are also no reports considering the effects of LC properties caused by CHW on cell behaviors and osteogenic activity.…”