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Nanocellulose has lately emerged as one of the most promising "green" materials due to its unique properties. Nanocellulose can be mainly divided into three types, i.e., cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose (BC). With the rapid development of technology, nanocellulose has been designed into multidimensional structures, including 1D (nanofibers, microparticles), 2D (films), and 3D (hydrogels, aerogels) materials. Due to its adaptable surface chemistry, high surface area, biocompatibility, and biodegradability, nanocellulose-based composite materials can be further transformed as drug delivery carriers. Herein, nanocellulose-based composite material used for drug delivery was reviewed. The typical drug release behaviors and the drug release mechanisms of nanocellulose-based composite materials were further summarized, and the potential application of nanocellulose-based composite materials was prospected as well. [ABSTRACT FROM AUTHOR]

A humidity sensor is a crucial device in daily life; therefore, in the present study, a novel humidity sensor was designed to increase its specific surface area to improve its humid sensing capacity and conductivity. Titanium dioxide nanoparticles (TiNP) consisting of zero-dimensional nanospheres and one-dimensional nanotubes were prepared by anodic oxidation. Rod-shaped cellulose nanocrystals (CNCs) with average length and diameter of 60 nm and 800 nm, respectively, were obtained by enzymatic hydrolysis and high pressure homogenization. TiNP/CNC composite films exhibited superior hydrophilicity and large specific surface areas based on Fourier transform infrared spectroscopy and nitrogen adsorption–desorption results. The humidity sensing characteristics of sensors based on TiNP/CNC flexible composite films with varying contents of TiNP were investigated under a relative humidity range of 11–97%. The 6% TiNP/CNC-based humidity sensor exhibited high humidity response, rapid response/recovery speed, and high stability. Furthermore, the humidity sensing mechanism of TiNP/CNC composite films was analyzed based on the density functional theory. TiNP/CNC-based humidity sensors could be applied in flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

• Starch was oxidized under the control of cellulose nanocrystals/NaClO. • The PVA based blends showed enhanced film-forming ability with oxidized starch. • The coating formula showed good penetration effect in paper structure. Cellulose and starch are main chemical components of plant biomass, and can be used to produce value-added materials. Herein, cellulose nanocrystals (CNC) was used along with NaClO to prepare oxidized corn starch. Subsequently, the oxidized starch was blended with PVA/glycerol to prepare oxidized starch-based blends for film formation and coating paper. The properties of oxidized starch and film formability were modified by addition of CNC and PVA/glycerol. The oxidized starch showed the highest oxidizing degree at 1.10% with 0.5 wt% CNC and 8.0 wt% NaClO. Oxidized starch-based blends had lower viscosity and better uniformity than that of corn starch. The oxidized starch-based composite film showed the optimal water resistance, surface free energy and air permeability. Blending with 30 wt% PVA, the oxidized starch-based composite film showed the best tensile strength, and a simple structural model was simulated. The three-dimensional structure of coated paper was visualized using computed tomography scan (CT-Scan), and verified the good penetration of starch-based blends. The coated paper showed a more dense structure compared to the control paper, and had better waterproof performance and physical strength properties with oxidized starch with the highest oxidizing degree. [ABSTRACT FROM AUTHOR]

A cellulose nanocrystal based oxidation system is developed for oxidizing starch in the presence of NaClO, and provides an alternative and green method to improve the oxidizing degree of oxidized starch. The underlying mechanism for the oxidation was studied with confocal laser scanning microscopy. It was found that cellulose nanocrystal would penetrate into the starch microparticles and contribute to oxidation. The function of cellulose nanocrystal on the physicochemical properties of oxidized starch was investigated. With the incorporation of the oxidized starch into starch/polyvinyl alcohol/glyceryl composite films, the mechanical property and transparency of the films improved substantially. The highest oxidation level of starch was attained at 0.5 wt% cellulose nanocrystal dosage and the carboxylate content was 1.10%, the composite film showed the maximum transparency of 0.66 and highest contact angle of 102.0°. Meanwhile, the best film was obtained with oxidized starch containing 1.0 wt% cellulose nanocrystal. Compared to native starch and TEMPO-oxidated starch, the cellulose nanocrystal-based oxidized starch improved the hydrophobicity of film more substanially. In conclusion, cellulose nanocrystal acts as prooxidant and reforcing agent in this starch-based composite film, which makes them promising materials in the preparation of novel composite materials. [Display omitted] [ABSTRACT FROM AUTHOR]