Browsing by Author "Wang, Xiaoju"

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    Injectable thiol-ene hydrogel of galactoglucomannan and cellulose nanocrystals in delivery of therapeutic inorganic ions with embedded bioactive glass nanoparticles
    (ELSEVIER SCI LTD, 2022-01-15) Wang, Qingbo; Xu, Wenyang; Koppolu, Rajesh; van Bochove, Bas; Seppälä, Jukka; Hupa, Leena; Willför, Stefan; Xu, Chunlin; Wang, Xiaoju; Department of Chemical and Metallurgical Engineering; Polymer technology; Åbo Akademi University
    We propose an injectable nanocomposite hydrogel that is photo-curable via light-induced thiol-ene addition between methacrylate modified O-acetyl-galactoglucomannan (GGMMA) and thiolated cellulose nanocrystal (CNC-SH). Compared to free-radical chain polymerization, the orthogonal step-growth of thiol-ene addition allows a less heterogeneous hydrogel network and more rapid crosslinking kinetics. CNC-SH reinforced the GGMMA hydrogel as both a nanofiller and a crosslinker to GGMMA resulting in an interpenetrating network via thiol-ene addition. Importantly, the mechanical stiffness of the GGMMA/CNC-SH hydrogel is mainly determined by the stoichiometric ratio between the thiol groups on CNC-SH and the methacrylate groups in GGMMA. Meanwhile, the bioactive glass nanoparticle (BaGNP)-laden hydrogels of GGMMA/CNC-SH showed a sustained release of therapeutic ions in simulated body fluid in vitro, which extended the bioactive function of hydrogel matrix. Furthermore, the suitability of the GGMMA/CNC-SH formulation as biomaterial resin to fabricate digitally designed hydrogel constructs via digital light processing (DLP) lithography printing was evaluated.
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    On Laccase-Catalyzed Polymerization of Biorefinery Lignin Fractions and Alignment of Lignin Nanoparticles on the Nanocellulose Surface via One-Pot Water-Phase Synthesis
    (AMERICAN CHEMICAL SOCIETY, 2021-07-05) Wang, Luyao; Tan, Liping; Hu, Liqiu; Wang, Xiaoju; Koppolu, Rajesh; Tirri, Teija; van Bochove, Bas; Ihalainen, Petri; Sobhana Seleenmary Sobhanadhas, Liji; Seppälä, Jukka V.; Willför, Stefan; Toivakka, Martti; Xu, Chunlin; Department of Chemical and Metallurgical Engineering; Polymer technology; Åbo Akademi; Åbo Akademi University; MetGen Oy
    Two series of well-defined lignin fractions derived from birch and spruce alkaline lignin (AL) by sequential solvent fractionation (i-PrOH-EtOH-MeOH) were engaged in a structure–property-application relationship study. The bacterial-derived alkaliphilic laccase (MetZyme) extensively catalyzed the oxidation and polymerization of AL fractions in an aqueous alkaline solution (pH 10). Lignin fractions with low molar mass reached a higher polymerization degree due to more phenolic-OH groups serving as reactive sites of oxidation and better lignin-laccase accessibility arose from a lower lignin condensation degree than the high molar mass ones. In comparison, AL fractions from spruce were found to be less reactive toward the laccase-catalyzed polymerization than those from birch, which was attributed to the much pronounced aryl-vinyl moieties’ oxidation. Furthermore, in situ polymerization of birch AL fractions using microfibrillated cellulose as a structural template was conducted in an aqueous medium and a dispersion of nanocellulose with its fiber network evenly coated by aligned lignin nanoparticles was obtained. The present study not only provides fundamental insights on the laccase-assisted oxidation and polymerization of lignin but also presents a new perspective for valorizing lignin in biobased fiber products through green processing of solvent fractionation and enzymatic treatment.
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    Robust shape-retaining nanocellulose-based aerogels decorated with silver nanoparticles for fast continuous catalytic discoloration of organic dyes
    (Elsevier Science B.V., 2020-07-01) Zhang, Weihua; Wang, Xiaoju; Zhang, Yongchao; van Bochove, Bas; Mäkilä, Ermei M.; Seppälä, Jukka; Xu, Wenyang; Willför, Stefan; Xu, Chunlin; Department of Chemical and Metallurgical Engineering; Polymer technology; Åbo Akademi University; University of Turku
    In this work we present a green method to prepare aerogel membranes based on cellulose nanofibers (CNFs) crossed-linked with poly (ethylene imine) (PEI) and further decorated with silver nanoparticles (Ag NPs). The nanosized Ag NPs were reduced and immobilized on the surface of the pore walls inside the aerogel. The as-prepared composite aerogel membrane showed excellent continuous catalytic discoloration of aqueous cationic and anionic dye solutions in batch and flow filtration tests. Moreover, the aerogel membrane exhibited very stable catalytic activity with discoloration efficiency at as high as 98% after 10 times reuse and the water permeance was high, up to 5 × 10 4 L·m −2 h −1. Interestingly, the aerogel membrane showed excellent shape recovery in water and no obvious deterioration of the structure was observed during long time testing. Therefore, the obtained aerogel membranes showed great potential in waste water treatment and catalytic applications.
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    Surface Engineered Biomimetic Inks Based on UV Cross-Linkable Wood Biopolymers for 3D Printing
    (AMER CHEMICAL SOC, 2019-04-03) Xu, Wenyang; Zhang, Xue; Yang, Peiru; Långvik, Otto; Wang, Xiaoju; Zhang, Yongchao; Cheng, Fang; Österberg, Monika; Willför, Stefan; Xu, Chunlin; Department of Bioproducts and Biosystems; Materials Chemistry of Cellulose; Bioproduct Chemistry; Åbo Akademi University
    Owing to their superior mechanical strength and structure similarity to the extracellular matrix, nanocelluloses as a class of emerging biomaterials have attracted great attention in three-dimensional (3D) bioprinting to fabricate various tissue mimics. Yet, when printing complex geometries, the desired ink performance in terms of shape fidelity and object resolution demands a wide catalogue of tunability on the material property. This paper describes surface engineered biomimetic inks based on cellulose nanofibrils (CNFs) and cross-linkable hemicellulose derivatives for UV-aided extrusion printing, being inspired by the biomimetic aspect of intrinsic affinity of heteropolysaccharides to cellulose in providing the ultrastrong but flexible plant cell wall structure. A facile aqueous-based approach was established for the synthesis of a series of UV cross-linkable galactoglucomannan methacrylates (GGMMAs) with tunable substitution degrees. The rapid gelation window of the formulated inks facilitates the utilization of these wood-based biopolymers as the feeding ink for extrusion-based 3D printing. Most importantly, a wide and tunable spectrum ranging from 2.5 to 22.5 kPa of different hydrogels with different mechanical properties could be achieved by varying the substitution degree in GGMMA and the compositional ratio between GGMMA and CNFs. Used as the seeding matrices in the cultures of human dermal fibroblasts and pancreatic tumor cells, the scaffolds printed with the CNF/GGMMA inks showed great cytocompatibility as well as supported the matrix adhesion and proliferative behaviors of the studied cell lines. As a new family of 3D printing feedstock materials, the CNF/GGMMA ink will broaden the map of bioinks, which potentially meets the requirements for a variety of in vitro cell-matrix and cell-cell interaction studies in the context of tissue engineering, cancer cell research, and high-throughput drug screening.