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Due to the severe environmental pollution the paper-making process often causes, the rewritten paper has emerged as a key research area to replace traditional paper. However, it is challenging to achieve application control and maximize resource utilization in various occasions when using the recently reported photochromic papers, which have low fading efficiency and poor regeneration effect. In this study, a composite film made of sodium alginate (SA) and polyvinyl alcohol (PVA) with ammonium molybdate serving as the photochromic component was prepared. The film had mechanical properties similar to paper, good resolution, and visible color after 50 days. With a magnification of 20 times, the distinct borders were still discernible. Through water-soluble-regeneration of the damaged film, the photochromic film can be faded, regenerated and reused, which has a lengthy storage time for information. The film quality and resolution do not considerably degrade after ten cycles of the "information writing—dissolution (fading)—regenerative writing" closed-loop process, exhibiting excellent recycling performance and high recovery rate. Hence, the photochromic film presents a refreshing approach to the design of rewriteable paper. [ABSTRACT FROM AUTHOR]

• SAG hydrogel was modified by the multilayer electrospinning membrane of cellulose. • SAG-C showed excellent mechanical and biocompatibility properties. • M-SAG-C showed better mechanical and biocompatibility properties due to mineralization. • No hazardous materials were used in obedience to the features of green and sustainable chemistry. Sodium alginate (SA) hydrogel has a broad prospect in tissue engineering and other biomedical fields due to its biocompatibility. However, the single SA hydrogel has shown poor mechanical properties and cell adhesion, which seriously limited its application and development in tissue engineering scaffolds. Herein, the SA/gelatin (SAG) hydrogel was modified by the multilayers electrospinning membrane of cellulose (SAG-C). It showed excellent mechanical properties when the layer number of electrospinning membrane got to three. After mineralization (M-SAG-C), the mechanical and biocompatible properties have been further improved. The SAG, SAG-C, and M-SAG-C series hydrogels all had good water retention, swelling rates, and good degradation performance. The fluorescence staining and cell proliferation experiments showed that M-SAG, SAG-C, and M-SAG-C hydrogel materials had no apparent cytotoxicity. Simultaneously, the introduction of bone-like apatite in the M-SAG-C hydrogel material allowed the cells to have better adhesion and proliferation ability on the composite surface. And the higher the degree of mineralization, the better the cell compatibility of the hydrogel material. Therefore, such hydrogels had excellent biocompatibility and mechanical properties, which could be widely used in tissue engineering. [ABSTRACT FROM AUTHOR]

Cellulose-based hydrogel electrolytes have important application prospects in flexible solid-state supercapacitors due to the renewability and high toughness of their raw materials. Currently, cellulose-based hydrogel electrolytes are generally prepared by a bottom-up strategy, which also has poor mechanical properties and low capacitance of the hydrogel electrolytes. These issues need to be further solved. Herein, employed an innovative top-down fabrication approach, utilizing meticulously organized delignified wood as a structural framework, and concurrently integrated polyacrylamide (PAM) and sodium alginate (SA) within this framework, creating a continuous conductive network. Furthermore, multi-walled carbon nanotubes (CNTs) have been introduced as conductive additives. This addition has imparted substantial mechanical robustness and exceptional electrical performance to the wood-based hydrogel. When the concentration of CNTs in the hydrogel precursor solution is 10 mg/ml, the resulting hydrogel electrolyte, denoted as CWH-10, demonstrates a remarkable enhancement in both mechanical strength and electrical conductivity compared to hydrogels modified using conventional techniques. This straightforward fabrication method presents an innovative and promising approach for producing high-strength, bio-based hydrogel electrolytes, with potential applications spanning various fields. • Wood-based hydrogels: Enhanced mechanical strength. • Top-down approach for cellulose scaffold extraction. • The addition process of carbon nanotubes is environmentally friendly. • Notable electrochemical performance in supercapacitors. • Exceptional stability during bending and charge-discharge cycles. [ABSTRACT FROM AUTHOR]