A Thixotropic, Cell-Infiltrative Nanocellulose Hydrogel That Promotes in Vivo Tissue Remodeling

Recent perspective of synthesis and modification strategies of cellulose nanocrystals and cellulose nanofibrils and their beneficial impact in scaffold-based tissue engineering: A review

Outstanding properties of nanocellulose provide opportunities for novel applications in various fields, particularly tissue engineering. Despite of numerous useful characteristics of nanocellulose, its production methods suffer from the lack of control of morphology, high cost, and the use of organic solvents. On the other hand, hydrophilicity of nanocellulose is a significant challenge for its dispersion as a reinforcement in hydrophobic polymers matrix. Therefore, sustainable production methods and well-tuning interfacial characteristics of nanocellulose have been identified as critical steps in their development. This review article discusses the numerous preparation methods and surface modification strategies of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) to help nanocellulose users obtain the appropriate material for their desired application. We also cover various polymer/nanocellulose scaffolds that are reported in the literature and investigate the effect of CNC and CNF on their mechanical, thermal and biological properties. Moreover, we provide several scientific figures and tables for a better understanding of the explored topics. Finally, we evaluate the opportunities and challenges of nanocellulose industrialization in the field of tissue engineering. Overall, this review guides researchers towards a deeper understanding of nanocellulose production processes, changing their properties using surface modification methods, and subsequently their performance in scaffold-based tissue engineering.

Effect of active carbonyl-carboxyl ratio on dynamic Schiff base crosslinking and its modulation of high-performance oxidized starch-chitosan hydrogel by hot extrusion 3D printing

The quest to develop 3D starch-based printing hydrogels for the controlled release of active substances with excellent mechanical and printing properties has gained significant attention. This work introduced a facile method based on crosslinking via Schiff base reaction for preparing bicomponent hydrogels. The method involved the utilization of customizable oxidized starch (OS) and chitosan (CS), enabling superior printing performance through the precise control of various active carbonyl-carboxyl ratios (ACR, 2:1, 1:1, and 2:3, respectively) of OS. OS-CS hydrogel (OSC) with an ACR level of 2:1 (OS-2-y%CS) underwent rearrangement during printing environment, fostering increased Schiff base reaction with a higher crosslinking degree and robust high structural recovery (>95 %). However, with decreasing ACR levels (from 2:1 to 2:3), the printing performance and mechanical strength of printed OSC (POSC) declined due to lower Schiff base bonds and increased phase separation. Compared with printed OS, POS-2-2%CS exhibited a remarkable 1250.52 % increase in tensile strength and a substantial 2424.71 % boost in compressive strength, enhanced shape fidelity and notable self-healing properties. Moreover, POS-2-2%CS exhibited stable diffusive drug release, showing potential application in the pH-responsive release of active substances. Overall, controlling the active carbonyl-carboxyl ratios provided an efficient and manageable approach for preparing high-performance 3D-printed hydrogels.

Recent advances in nanocellulose based hydrogels: Preparation strategy, typical properties and food application

Nanocellulose has been favored as one of the most promising sustainable nanomaterials, due to its competitive advantages and superior performances such as hydrophilicity, renewability, biodegradability, biocompatibility, tunable surface features, excellent mechanical strength, and high specific surface area. Based on the above properties of nanocellulose and the advantages of hydrogels such as high water absorption, adsorption, porosity and structural adjustability, nanocellulose based hydrogels integrating the benefits of both have attracted extensive attention as promising materials in various fields. In this review, the main fabrication strategies of nanocellulose based hydrogels are initially discussed in terms of different crosslinking methods. Then, the typical properties of nanocellulose based hydrogels are comprehensively summarized, including porous structure, swelling ability, adsorption, mechanical, self-healing, smart response performances. Especially, relying on these properties, the general application of nanocellulose based hydrogels in food field is also discussed, mainly including food packaging, food detection, nutrient embedding delivery, 3D food printing, and enzyme immobilization. Finally, the safety of nanocellulose based hydrogel is summarized, and the current challenges and future perspectives of nanocellulose based hydrogels are put forward.

Understanding Nanocellulose-Water Interactions: Turning a Detriment into an Asset

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose-water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Cellulose nanocrystals vs. cellulose nanospheres: A comparative study of cytotoxicity and macrophage polarization potential

Nanocellulose application has been increasing owing to its appealing physicochemical properties. Monitoring of the crystallinity, surface topography, and reactivity of this high-aspect-ratio nanomaterial is crucial for efficient tissue engineering. Controlling macrophage polarization phenotype remains a challenge in regenerative medicine and tissue engineering. Herein, we monitored the effects of shape-regulated (rod and spherical) nanocellulose on the macrophage modulatory potential of RAW 246.7 cells in vitro. Spherical nanocellulose (s-NC) exhibited higher thermal stability and biocompatibility than rod nanocellulose. Macrophage polarization was profoundly affected by nanocellulose topography and incubation period. M2 polarization was observed in vitro after 1 day of treatment with s-NC, followed by M1 polarization after treatment for longer periods. Transcriptome analysis similarly revealed that M1 polarization was dominant after 1 day h of incubation with both nanocellulose types. These findings demonstrate that macrophage polarization can be controlled by selecting suitable nanocellulose shape and incubation time for desired applications.

Nanocellulose-based hydrogels as versatile drug delivery vehicles: A review

Hydrogels designed with nanocellulose (i.e. cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and bacterial cellulose (BC)) have significant advantages as drug carriers due to their environmentally-benign features and excellent properties. Nanocellulose hydrogels have been demonstrated to sustainably deliver various kinds of drugs via different routes of administration, in which nanocellulose significantly improves the hydrogel properties and tunes the drug releasing profile. This article comprehensively summarizes the recent research progress on nanocellulose hydrogels in drug delivery. We carefully assessed the gelation methods for nanocellulose hydrogel design and highlighted the influence of nanocellulose on hydrogel properties and drug release behaviors. In particular, it is the first time to summarize the research on nanocellulose hydrogel-based drug carriers regarding specific routes of administration. This work provides a critical review of nanocellulose-based hydrogels as drug delivery vehicles, and also underlines the outlook in this field, with the objective to inspire/prompt future work, especially the practical applications of nanocellulose hydrogels in designing controlled drug delivery systems.

Nanocellulose-Based Composite Materials Used in Drug Delivery Systems

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.

Cellulose Hydrogels Containing Geraniol and Icaridin Encapsulated in Zein Nanoparticles for Arbovirus Control

The most important arboviruses are those that cause dengue, yellow fever, chikungunya, and Zika, for which the main vector is the Aedes aegypti mosquito. The use of repellents is an important way to combat mosquito-borne pathogens. In this work, a safe method of protection employing a repellent was developed based on a slow release system composed of zein nanoparticles containing the active agents icaridin and geraniol incorporated in a cellulose gel matrix. Analyses were performed to characterize the nanoparticles and the gel formulation. The nanoparticles containing the repellents presented a hydrodynamic diameter of 229 ± 9 nm, polydispersity index of 0.38 ± 0.10, and zeta potential of +29.4 ± 0.8 mV. The efficiencies of encapsulation in the zein nanoparticles exceeded 85% for icaridin and 98% for geraniol. Rheological characterization of the gels containing nanoparticles and repellents showed that the viscoelastic characteristic of hydroxypropylmethylcellulose gel was preserved. Release tests demonstrated that the use of nanoparticles in combination with the gel matrix led to improved performance of the formulations. Atomic force microscopy analyses enabled visualization of the gel network containing the nanoparticles. Cytotoxicity assays using 3T3 and HaCaT cell cultures showed low toxicity profiles for the active agents and the nanoparticles. The results demonstrated the potential of these repellent systems to provide prolonged protection while decreasing toxicity.

An Overview on Recent Progress of the Hydrogels: From Material Resources, Properties to Functional Applications

Hydrogels, as the most typical elastomer materials with three-dimensional network structures, have attracted wide attention owing to their outstanding features in fields of sensitive stimulus response, low surface friction coefficient, good flexibility and bio-compatibility. Because of numerous fresh polymer materials (or polymerization monomers), hydrogels with various structure diversities and excellent properties are emerging, and the development of hydrogels is very vigorous over the past decade. This review focuses on state-of-the-art advances, systematically reviews the recent progress on construction of novel hydrogels utilized several kinds of typical polymerization monomers, and explores the main chemical and physical cross-linking methods to develop the diversity of hydrogels. Following the aspects mentioned above, the classification and emerging applications of hydrogels, such as pH response, ionic response, electrical response, thermal response, biomolecular response, and gas response, are extensively summarized. Finally, we have done this review with the promises and challenges for the future evolution of hydrogels and their biological applications. cross-linking methods; functional applications; hydrogels; material resources This article is protected by copyright. All rights reserved.

Hydrogel based on nanocellulose/polydopamine/gelatin are used for the treatment of MRSA infected wound with broad-spectrum antibacterial, antioxidant property and tissue suitability

Most wound dressings have a series of problems when dealing with bacterial infection of wounds, for example, for lack of sufficient antibacterial and antioxidant capacity, comfort and mechanical properties are...

Nanocellulose: Recent Fundamental Advances and Emerging Biological and Biomimicking Applications

In the effort toward sustainable advanced functional materials, nanocelluloses have attracted extensive recent attention. Nanocelluloses range from rod-like highly crystalline cellulose nanocrystals to longer and more entangled cellulose nanofibers, earlier denoted also as microfibrillated celluloses and bacterial cellulose. In recent years, they have spurred research toward a wide range of applications, ranging from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural color, gels, aerogels and foams, and energy applications, until filtering membranes, to name a few. Still, nanocelluloses continue to show surprisingly high challenges to master their interactions and tailorability to allow well-controlled assemblies for functional materials. Rather than trying to review the already extensive nanocellulose literature at large, here selected aspects of the recent progress are the focus. Water interactions, which are central for processing for the functional properties, are discussed first. Then advanced hybrid gels toward (multi)stimuli responses, shape-memory materials, self-healing, adhesion and gluing, biological scaffolding, and forensic applications are discussed. Finally, composite fibers are discussed, as well as nanocellulose as a strategy for improvement of photosynthesis-based chemicals production. In summary, selected perspectives toward new directions for sustainable high-tech functional materials science based on nanocelluloses are described.

Immunological aspects of nanocellulose

Cellulose is the most abundant natural polymer in the world. Nanoscale forms of cellulose, including cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and bacterial nanocellulose (BC), are very attractive in industry, medicine and pharmacy. Biomedical applications of nanocellulose in tissue engineering, regenerative medicine, and controlled drug delivery are the most promising. Nanocellulose is considered a biocompatible nanomaterial and relatively safe for biomedical applications. However, more studies are needed to prove this hypothesis, especially those related to chronic exposure to nanocellulose. Besides toxicity, the response of the immune system is of particular importance in this sense. This paper provides a comprehensive and critical review of the current-state knowledge of the impact of nanocellulose on the immune system, especially on macrophages and dendritic cells (DC), as the central immunoregulatory cells, which has not been addressed in the literature sufficiently. Nanocellulose, especially CNC, can induce the inflammatory response upon the internalization by macrophages, but this reaction may be significantly modulated by introducing different functional groups on their surface. Our original results showed that nanocellulose has a potent immunotolerogenic potential. Native CNF potentiated the capacity of DC to induce conventional Tregs. When carboxyl groups were introduced on the CNF surface, the tolerogenic potential of DC was shifted towards the induction of regulatory CD8⁺ T cells, whereas the introduction of phosphonates on CNF surface potentiated DCs' capacity to induce both regulatory CD8⁺ T cells and Type 1 regulatory (Tr-1) cells. These results are extremely important when considering the application of nanocellulose in vivo, especially for tissue regeneration and wound healing.