Browsing by Author "Liu, Liang"

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    Chirality from Cryo-Electron Tomograms of Nanocrystals Obtained by Lateral Disassembly and Surface Etching of Never-Dried Chitin
    (AMERICAN CHEMICAL SOCIETY, 2020-06-23) Bai, Long; Kämäräinen, Tero; Xiang, Wenchao; Majoinen, Johanna; Seitsonen, Jani; Grande, Rafael; Huan, Siqi; Liu, Liang; Fan, Yimin; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Department of Applied Physics; Bio-based Colloids and Materials; Biohybrid Materials; Nanjing Forestry University
    The complex nature of typical colloids and corresponding interparticle interactions pose a challenge in understanding their self-assembly. This specifically applies to biological nanoparticles, such as those obtained from chitin, which typically are hierarchical and multidimensional. In this study, we obtain chitin nanocrystals by one-step heterogeneous acid hydrolysis of never-dried crab residues. Partial deacetylation facilitates control over the balance of electrostatic charges (ζ-potential in the range between +58 and +75 mV) and therefore affords chitin nanocrystals (DE-ChNC) with axial aspect (170-350 nm in length), as determined by cryogenic transmission electron microscopy and atomic force microscopy. We find that the surface amines generated by deacetylation, prior to hydrolysis, play a critical role in the formation of individual chitin nanocrystals by the action of a dual mechanism. We directly access the twisting feature of chitin nanocrystals using electron tomography (ET) and uncover the distinctive morphological differences between chitin nanocrystals extracted from nondeacetylated chitin, ChNC, which are bundled and irregular, and DE-ChNC (single, straight nanocrystals). Whereas chitin nanocrystals obtained from dried chitin precursors are known to be twisted and form chiral nematic liquid crystals, our ET measurements indicate no dominant twisting or handedness for the nanocrystals obtained from the never-dried source. Moreover, no separation into typical isotropic and anisotropic phases occurs after 2 months at rest. Altogether, we highlight the critical role of drying the precursors or the nanopolysaccharides to develop chirality.
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    High Axial Ratio Nanochitins for Ultrastrong and Shape-Recoverable Hydrogels and Cryogels via Ice Templating
    (AMERICAN CHEMICAL SOCIETY, 2019-03-26) Liu, Liang; Bai, Long; Tripathi, Anurodh; Yu, Juan; Wang, Zhiguo; Borghei, Maryam; Fan, Yimin; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Biohybrid Materials; Nanjing Forestry University
    High yield (>85%) and low-energy deconstruction of never-dried residual marine biomass is proposed following partial deacetylation and microfluidization. This process results in chitin nanofibrils (nanochitin, NCh) of ultrahigh axial size (aspect ratios of up to 500), one of the largest for bioderived nanomaterials. The nanochitins are colloidally stable in water (ζ-potential = +95 mV) and produce highly entangled networks upon pH shift. Viscoelastic and strong hydrogels are formed by ice templating upon freezing and thawing with simultaneous cross-linking. Slow supercooling and ice nucleation at -20 °C make ice crystals grow slowly and exclude nanochitin and cross-linkers, becoming spatially confined at the interface. At a nanochitin concentration as low as 0.4 wt %, highly viscoelastic hydrogels are formed, with a storage modulus of ∼16 kPa, at least an order of magnitude larger compared to those measured for the strongest chitin-derived hydrogels reported so far. Moreover, the water absorption capacity of the hydrogels reaches a value of 466 g g -1 . Lyophilization is effective in producing cryogels with a density that can be tailored in a wide range of values, from 0.89 to 10.83 mg·cm -3 , and corresponding porosity, between 99.24 and 99.94%. Nitrogen adsorption results indicate reversible adsorption and desorption cycles of macroporous structures. A fast shape recovery is registered from compressive stress-strain hysteresis loops. After 80% compressive strain, the cryogels recovered fast and completely upon load release. The extreme values in these and other physical properties have not been achieved before for neither chitin nor nanocellulosic cryogels. They are explained to be the result of (a) the ultrahigh axial ratio of the fibrils and strong covalent interactions; (b) the avoidance of drying before and during processing, a subtle but critical aspect in nanomanufacturing with biobased materials; and (c) ice templating, which makes the hydrogels and cryogels suitable for advanced biobased materials.
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    Microfibers synthesized by wet-spinning of chitin nanomaterials : Mechanical, structural and cell proliferation properties
    (ROYAL SOC CHEMISTRY, 2020-08-11) Wang, Ling; Ezazi, Nazanin Zanjanizadeh; Liu, Liang; Ajdary, Rubina; Xiang, Wenchao; Borghei, Maryam; Santos, Helder A.; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Nanjing Forestry University; University of Helsinki
    Partially deacetylated chitin nanofibers (ChNF) were isolated from shell residues derived from crab biomass and used to prepare hydrogels, which were easily transformed into continuous microfibers by wet-spinning. We investigated the effect of ChNF solid content, extrusion rate and coagulant type, which included organic (acetone) and alkaline (NaOH and ammonia) solutions, on wet spinning. The properties of the microfibers and associated phenomena were assessed by tensile strength, quartz crystal microgravimetry, dynamic vapor sorption (DVS), thermogravimetric analysis and wide-angle X-ray scattering (WAXS). The as-spun microfibers (14 GPa stiffness) comprised hierarchical structures with fibrils aligned in the lateral direction. The microfibers exhibited a remarkable water sorption capacity (up to 22 g g(-1)), while being stable in the wet state (50% of dry strength), which warrants consideration as biobased absorbent systems. In addition, according to cell proliferation and viability of rat cardiac myoblast H9c2 and mouse bone osteoblast K7M2, the wet-spun ChNF microfibers showed excellent results and can be considered as fully safe for biomedical uses, such as in sutures, wound healing patches and cell culturing.
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    Nanochitin: Chemistry, Structure, Assembly, and Applications
    (AMERICAN CHEMICAL SOCIETY, 2022-07-13) Bai, Long; Liu, Liang; Esquivel, Marianelly; Tardy, Blaise L.; Huan, Siqi; Niu, Xun; Liu, Shouxin; Yang, Guihua; Fan, Yimin; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Nanjing Forestry University; National University of Costa Rica; Northeast Forestry University; University of British Columbia; Qilu University of Technology
    Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano-and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.
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    Self-Assembled Networks of Short and Long Chitin Nanoparticles for Oil/Water Interfacial Superstabilization
    (AMER CHEMICAL SOC, 2019-04-01) Bai, Long; Huan, Siqi; Xiang, Wenchao; Liu, Liang; Yang, Yang; Nugroho, Robertus Wahyu N.; Fan, Yimin; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of Helsinki; Nanjing Forestry University
    Highly charged (zeta potential ζ = +105 mV, acetate counterions) chitin nanoparticles (NCh) of three different average aspect ratios (∼5, 25, and >60) were obtained by low-energy deconstruction of partially deacetylated chitin. The nanoparticles were effective in reducing the interfacial tension and stabilized the oil/water interface via network formation (interfacial dilatational rheology data) becoming effective in stabilizing Pickering systems, depending on NCh size, composition, and formulation variables. The improved interfacial wettability and electrosteric repulsion facilitated control over the nanoparticle's surface coverage on the oil droplets, their aspect ratio and stability against coalescence during long-term storage. Emulsion superstabilization (oil fractions below 0.5) occurred by the microstructuring and thickening effect of NCh that formed networks at concentrations as low as 0.0005 wt %. The ultrasound energy used during emulsion preparation simultaneously reduced the longer nanoparticles, producing very stable, fine oil droplets (diameter ∼1 μm). Our findings indicate that NCh surpasses any reported biobased nanoparticle, including nanocelluloses, for its ability to stabilize interfaces at ultralow concentrations and represent a step-forward in efforts to fully replace surfactants in multiphase systems.
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    Simple synthesis of self-assembled nacre-like materials with 3D periodic layers from nanochitin via hydrogelation and mineralization
    (ROYAL SOC CHEMISTRY, 2022-02-07) Xu, Junhua; Liu, Liang; Yu, Juan; Zou, Yujun; Pei, Wenhui; Zhang, Lili; Ye, Wenbo; Bai, Long; Wang, Zhiguo; Fan, Yimin; Yong, Qiang; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials
    The superb mechanical properties of some natural materials usually result from highly ordered, multiscale and hierarchical architectures such as bone, nacre, exoskeleton, etc. Nonetheless, the involved gene regulated process cannot be realized artificially. Here we report bioinspired 3D structures with similar performance following a rapid, green, one-pot synthesis route based on the concept of "brick-and-mortar" biomineralization by introducing Ca2+ and PO43- into a nanochitin dispersion followed by ammonia vapor diffusion. The process leads to self-stratified, periodic assemblies formed under ion diffusion gradients and hydrogelation of nanochitin with simultaneous mineral coprecipitation. Specifically, an organic hydrogel network is formed from partially deacetylated chitin nanofibers together with hydroxyapatite. The components are structured in periodic bands by alternating (organic/inorganic) precipitation as layer-by-layer stacks. The layer space is adjustable by changing the ion concentration and temperature of regulators. Endowed with directional diffusion, customizable 3D forms are self-assembled and demonstrated to function as optical waveguides with selective light transmission. Upon hot pressing, the synthesized material shows structural similarity to natural nacre and displays exceptional strength. This artificial method can reduce the synthesis time from years in nature to a few days in a lab, with no need for complex treatments or facilities; moreover, the designable structure can be customized for uses ranging from structural support in biomedical implants to optical waveguides.