【introduction】
Nanocellulose is a kind of renewable high aspect ratio nanoparticles with high mechanical properties, and its surface has chemically reactive groups that can be functionalized. In an effort to develop sustainable advanced functional materials, nanocellulose has recently attracted widespread attention. Nanocellulose ranges from rod-shaped cellulose nanocrystals with high crystallinity to longer, more entangled cellulose nanofibers, previously also known as microfibrillated cellulose and bacterial cellulose. In recent years, research on a wide range of applications has been promoted, from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural colors, gels, aerogels and foams, and energy applications to filtration membranes, etc. Become a key area of science and technology. We list the high-quality articles published in the top issue of nanocellulose in the past month to sort out the recent research progress of this material.

1. Monica Ek (ACS Sustainable Chemistry & Engineering), Royal Institute of Technology, Sweden: Nano cellulose is separated from bark by biorefining, which can be used as a variety of materials

The production of nanocellulose is in a state of continuous development, with emphasis on reducing production costs and introducing different functional groups into the cellulose structure. Cellulose oxalate (COX) is made by reacting cellulose fibers with molten oxalic acid dihydrate, and the relatively low melting point of oxalic acid dihydrate at 102°C makes solvent-free reactions possible and makes the The method has become a green substitute for other methods. Nanocellulose can be separated by cellulose oxalate for bleaching kraft pulp and dissolving pulp from wood, where most of the lignin, hemicellulose and impurities are removed. When wood pulp and materials are produced in the forest products industry, a large number of by-products, especially bark, are also produced. Reasonable use of bark will make the benefits even better.

Monica Ek of the Royal Institute of Technology in Sweden applies the concept of biorefining, using acetone and pressurized hot water extraction method to achieve the extraction of Norwegian spruce bark components, followed by mild peracetic acid treatment to delignify the bark, and then react in a solvent-free Cellulose oxalate is formed in the cellulose, and nanocellulose is finally separated. During the extraction and separation process, its chemical composition and thermal properties were monitored. The results showed that the yield of cellulose oxalate was 82%, the degree of substitution was 0.3, and the surface charge was 1.53 mmol g-1. The isolated nanocellulose is a mixture of rod-shaped nanocrystals and nanofibers. Finally, a preliminary thermal analysis was performed on the separated nanocellulose, which showed good performance. The morphology and thermal properties of nanocellulose make it a very promising material. The material comes from renewable resources and is a sustainable alternative to fossil-based materials. Cellulose oxalate and its derived nanocellulose can be used as an enhancer in nanocomposites, transparent films or cosmetics.



Reference: Rietzler B and Ek M. Adding Value to Spruce Bark by the Isolation of Nanocellulose in a Biorefinery Concept. ACS Sustainable Chemistry & Engineering 2021.

2. Muhammad Moniruzzaman (ACS Sustainable Chemistry & Engineering), University of Petroleum Malaysia: Overview——Ionic liquid as a sustainable platform for processing nanocellulose from biological resources

In the past few decades, the need to find environmentally friendly and sustainable alternative chemicals and materials with petroleum sources has become increasingly important. Nanocellulose (NC) is a product or extract of natural cellulose, which exists in a variety of resources, such as plants, animals, and bacteria. At present, NC can be divided into three categories according to its size and processing method: cellulose nanocrystal (CNC), nanofibrillated cellulose (NFC) and bacterial nanocellulose (BNC). However, high energy consumption, low yield, and health and environmental hazards associated with the use of high concentrations of acids and other chemicals are the main disadvantages of these methods. Moreover, acid hydrolysis seriously deteriorates the thermal integrity of nanocellulose, which is disadvantageous for the manufacture of nanocomposite materials. In order to solve the above limitations, researchers have focused their attention on using ionic liquids (ILs) as potential solvents, swelling agents and catalysts in NC production.

The University of Petroleum Malaysia Muhammad Moniruzzaman focused on the latest technological developments assisted by ionic liquids, which have been successfully used in the nanocellulose processing of biological resources including cellulosic biomass. When performing NC extraction from renewable resources, ionic liquids (ILs) are used as excellent compounds with outstanding combinatorial chemical diversity and unique properties, covering at least 2 key elements in 12 green chemical principles. At the same time, IL can also induce the extraction of ultra-thin nanocellulose fibers with high crystallinity and high yield. At the same time, the potential development of IL-mediated NC can be based on imidazole-based IL. Significant progress is being made in the process of using IL to give NC fibers new functions and open up new ways and markets. Further exploring the emerging aspects of IL, such as nano IL derived from low-cost renewable raw materials, coupled with novel recycling technologies, will make IL promising for large-scale NC processing.


【introduction】
Nanocellulose is a kind of renewable high aspect ratio nanoparticles with high mechanical properties, and its surface has chemically reactive groups that can be functionalized. In an effort to develop sustainable advanced functional materials, nanocellulose has recently attracted widespread attention. Nanocellulose ranges from rod-shaped cellulose nanocrystals with high crystallinity to longer, more entangled cellulose nanofibers, previously also known as microfibrillated cellulose and bacterial cellulose. In recent years, research on a wide range of applications has been promoted, from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural colors, gels, aerogels and foams, and energy applications to filtration membranes, etc. Become a key area of science and technology. We list the high-quality articles published in the top issue of nanocellulose in the past month to sort out the recent research progress of this material.

1. Monica Ek (ACS Sustainable Chemistry & Engineering), Royal Institute of Technology, Sweden: Nano cellulose is separated from bark by biorefining, which can be used as a variety of materials

The production of nanocellulose is in a state of continuous development, with emphasis on reducing production costs and introducing different functional groups into the cellulose structure. Cellulose oxalate (COX) is made by reacting cellulose fibers with molten oxalic acid dihydrate, and the relatively low melting point of oxalic acid dihydrate at 102°C makes solvent-free reactions possible and makes the The method has become a green substitute for other methods. Nanocellulose can be separated by cellulose oxalate for bleaching kraft pulp and dissolving pulp from wood, where most of the lignin, hemicellulose and impurities are removed. When wood pulp and materials are produced in the forest products industry, a large number of by-products, especially bark, are also produced. Reasonable use of bark will make the benefits even better.

Monica Ek of the Royal Institute of Technology in Sweden applies the concept of biorefining, using acetone and pressurized hot water extraction method to achieve the extraction of Norwegian spruce bark components, followed by mild peracetic acid treatment to delignify the bark, and then react in a solvent-free Cellulose oxalate is formed in the cellulose, and nanocellulose is finally separated. During the extraction and separation process, its chemical composition and thermal properties were monitored. The results showed that the yield of cellulose oxalate was 82%, the degree of substitution was 0.3, and the surface charge was 1.53 mmol g-1. The isolated nanocellulose is a mixture of rod-shaped nanocrystals and nanofibers. Finally, a preliminary thermal analysis was performed on the separated nanocellulose, which showed good performance. The morphology and thermal properties of nanocellulose make it a very promising material. The material comes from renewable resources and is a sustainable alternative to fossil-based materials. Cellulose oxalate and its derived nanocellulose can be used as an enhancer in nanocomposites, transparent films or cosmetics.

Reference: Rietzler B and Ek M. Adding Value to Spruce Bark by the Isolation of Nanocellulose in a Biorefinery Concept. ACS Sustainable Chemistry & Engineering 2021.

2. Muhammad Moniruzzaman (ACS Sustainable Chemistry & Engineering), University of Petroleum Malaysia: Overview——Ionic liquid as a sustainable platform for processing nanocellulose from biological resources

In the past few decades, the need to find environmentally friendly and sustainable alternative chemicals and materials with petroleum sources has become increasingly important. Nanocellulose (NC) is a product or extract of natural cellulose, which exists in a variety of resources, such as plants, animals, and bacteria. At present, NC can be divided into three categories according to its size and processing method: cellulose nanocrystal (CNC), nanofibrillated cellulose (NFC) and bacterial nanocellulose (BNC). However, high energy consumption, low yield, and health and environmental hazards associated with the use of high concentrations of acids and other chemicals are the main disadvantages of these methods. Moreover, acid hydrolysis seriously deteriorates the thermal integrity of nanocellulose, which is disadvantageous for the manufacture of nanocomposite materials. In order to solve the above limitations, researchers have focused their attention on using ionic liquids (ILs) as potential solvents, swelling agents and catalysts in NC production.

The University of Petroleum Malaysia Muhammad Moniruzzaman focused on the latest technological developments assisted by ionic liquids, which have been successfully used in the nanocellulose processing of biological resources including cellulosic biomass. When performing NC extraction from renewable resources, ionic liquids (ILs) are used as excellent compounds with outstanding combinatorial chemical diversity and unique properties, covering at least 2 key elements in 12 green chemical principles. At the same time, IL can also induce the extraction of ultra-thin nanocellulose fibers with high crystallinity and high yield. At the same time, the potential development of IL-mediated NC can be based on imidazole-based IL. Significant progress is being made in the process of using IL to give NC fibers new functions and open up new ways and markets. Further exploring the emerging aspects of IL, such as nano IL derived from low-cost renewable raw materials, coupled with novel recycling technologies, will make IL promising for large-scale NC processing.



References: Haron GAS, Mahmood H, Noh MH, Alam MZ and Moniruzzaman M. Ionic Liquids as a Sustainable Platform for Nanocellulose Processing from Bioresources: Overview and Current Status. ACS Sustainable Chemistry & Engineering 2021.

3. Huang Chongxing (Materials Today) of Guangxi University: Review——The latest progress in the color display of cellulose nanocrystalline material structure

Structural colors, also called physical colors, are colors produced by pure physical structures without any pigments. Conventional color displays use dyes or pigments to selectively absorb and reflect light to produce typical colors, while structural colors are periodically produced through ordered structures of light scattering, diffraction and interference. Compared with the method of using dyes or pigments, the production of structural colors has many advantages, including the efficient and efficient conversion of light sources to colors, environmental friendliness, and long-term stability if the structure of the material is not damaged or deformed colour. Cellulose nanocrystals (CNC) are harmless to the environment and are derived from plants, bacteria or membranes. CNC controller is the unique properties of spindle-shaped nano-level materials, such as high strength, high specific surface area, high thermal stability, light permeability, biodegradability, biocompatibility and self-assembly ability. The structure color display has good prospects.

Huang Chongxing of Guangxi University summarized the influence of various factors involved in the preparation of nanocellulose film on the structure color, the color response of nanocellulose film to environmental factors, and the structure design of cellulose nanomaterials in the field of color development. Describes the progress in the field of structural coloring of nano-cellulose materials in recent years. Finally, the expected future developments in the color of the nanocellulose material structure are discussed. As more and more countries begin to ban the use of disposable plastics, cellulose-based materials as biodegradable alternatives will become the subject of more extensive research, and the structural color of cellulose nanomaterials will become the key to various applications One of the parameters.



References: Xu C, Huang C and Huang H. Recent advances in structural color display of cellulose nanocrystal materials. Applied Materials Today 2021;22:100912.

4. Tsuguyuki Saito (ACS Nano), University of Tokyo: Mesoporous nano-cellulose xerogel with high mechanical strength and expandability, with light transmission, heat insulation and flame self-extinguishing properties

Scalability is a common challenge in the structuring of nano-scale particle dispersions, especially when drying these dispersions to produce functional porous structures such as aerogels. However, the production of aerogels relies on supercritical drying, which makes it exhibit poor scalability. The solution to this scalability limitation is to use evaporative drying under ambient pressure. However, the evaporative drying of wet gels containing nano-sized particles is accompanied by strong capillary forces. Therefore, it is challenging to produce evaporative drying gels or "xerogels" with specific structural characteristics of aerogels, such as mesoscale pores, high porosity, and high specific surface area (SSA).

Tsuguyuki Saito from the University of Tokyo reported on monolithic nanocellulose (CNF) xerogels with outstanding mechanical strength, moderate light transmittance, heat insulation and self-extinguishing functions. This xerogel is obtained through fine nanostructure engineering of CNF, and its width is 2-3 nm. CNF is prepared by TEMPO-oxidation, so that the surface of a single CNF is selectively carboxylated at a high density. The results show that CNF xerogel has versatility, excellent strength (compression E = 170 MPa, σ = 10 MPa; tensile E = 290 MPa, σ = 8 MPa), moderate light transmittance, and thermal insulation ( 0.06-0.07 W m–1 K–1), and has flame self-extinguishing performance. As a dry gel in lighting and heat insulation, it has broad prospects in the application of load-bearing wall components.

References: Sakuma, W., Yamasaki, S., Fujisawa, S., et al., Mechanically Strong, Scalable, Mesoporous Xerogels of Nanocellulose Featuring Light Permeability, Thermal Insulation, and Flame Self-Extinction[J]. Acs Nano, 2021.

5. Brazilian National Laboratory of Nanotechnology Juliana S. Bernardes (Carbohydrate Polymers): Preparation of nano-cellulose sponge by electrostatic complexation can improve its mechanical properties

Interest in the use of biomass to produce materials to develop a sustainable future with less environmental impact is growing rapidly. However, more environmentally friendly materials face challenges related to their inherent properties, which are very different from those of oil-based plastics in terms of mechanical properties and water resistance. The supramolecular assembly of bio-based components in aqueous media is a promising strategy that can overcome some of the shortcomings in the preparation of materials with desired characteristics. Nanocellulose is an excellent candidate for the preparation of various multifunctional bio-based materials, such as membranes, foams, hydrogels and nanoparticles.

The Brazilian National Laboratory of Nanotechnology, Juliana S. Bernardes, prepared cationic and anionic nanocellulose sponges (CNF) through a simple electrostatic complexation method. Small-angle X-ray scattering and low-temperature transmission electron microscopy experiments show that the oppositely charged nanocellulose suspension is a mixture of entangled fiber clusters and networks. The balance between these structures determines the colloidal stability and rheological properties of CNF in water. When the mass composition is 1:1 (approximately 0.12 MPa), the compressive modulus of the sponge prepared from the suspension reaches the maximum, and it plays a role of strengthening the structure in the material. In addition to electrostatic attraction, hydrogen bonding and hydrophobic contact may also occur inside the cluster, which improves the water stability of the cationic foam. These results can provide a basis for the development of strong all-cellulosic materials for the preparation of non-toxic chemicals in water.

Sex 3D steroid organization.

The clinical treatment of severe bone defects, especially tissue damage caused by vascular and peripheral nerve damage, is still a huge challenge, often leading to bone non-union and other sequelae. Therefore, the scaffold is designed to simulate natural tissue and can be used in next-generation tissue engineering. At the same time, most studies related to bone tissue engineering scaffolds focus on the differentiation of osteoblasts, because promoting new bone growth is the main goal of bone regeneration. Hydroxyapatite (HAp) is an important inorganic component of bone tissue and has been widely used in bone regeneration, drug carrier systems, tumor treatment and cell imaging. Bacterial nanocellulose (BNC), a biodegradable material with hydrophilicity and excellent drug loading and mechanical properties, has been used in wound healing, drug delivery, and reconstruction of biomimetic tissue models in vitro. Considering the remarkable characteristics of BNC and effective osteogenic capacity and strength of HAP, the integration of the two for bone regeneration scaffold is a promising strategy.

Liu Hong from Shandong University successfully constructed a platform for the enhancement of osteogenic/neural differentiation and angiogenesis multi-differentiation to repair and reconstruct the bone of the biomimetic bone tissue on the HApNB-BNC hybrid membrane. After the synthesis of HApNB over 100 μm, the hybrid membrane constructed by assembling HApNB into cellulose hydrogel has significantly improved its mechanical properties, hydrophilicity and drug-carrying performance, which is the application of hybrid membrane in tissue engineering Laid a solid foundation. And animal experiment results show that HApNB-BNC biofilm has excellent repair ability. Interestingly, the platform loaded with growth factors can further improve bone repair and regeneration through the rapid growth of bones, blood vessels and nerves in the body. This platform strategy to enhance differentiation provides a novel and easy-to-operate construction method for bone-like tissue, paving the way for clinical treatment of bone regeneration.



References: Liu, F., Wei, B., Xu, X., Ma, B., Zhang, S., Duan, J., Kong, Y., Yang, H., Sang, Y., Wang, S., Tang, W., Liu, C., Liu, H., Nanocellulose-Reinforced Hydroxyapatite Nanobelt Membrane as a Stem Cell Multi-Lineage Differentiation Platform for Biomimetic Construction of Bioactive 3D Osteoid Tissue In Vitro. Adv. Healthcare Mater. 2020 , 2001851.

8. Saad A. Khan (Journal of Colloid and Interface Science, University of North Carolina, USA): The association structure formed by nanocellulose and nanochitin is pH-responsive and has adjustable rheology

Bio-based nanomaterials are an active and evolving research topic, especially nanocellulose and its similar and complementary properties of nanochitin. The interest in these materials is mainly driven by two factors. First of all, it can increase the use of bio-based components, thereby reducing the negative impact on the environment, such as dependence on disposable plastics, dependence on fossil fuels, and the use of harsh solvents and reagents. Second, this type of material exhibits many advantages due to its tunable surface chemistry and morphology, making them attractive candidates for many different applications. Therefore, they have been used in many fields such as medical applications, water purification, emulsion stabilization, and have achieved great success. Both nanocellulose and nanochitin are bio-based materials with complementary structures and properties. Both show pH-related surface charges with opposite signs. Therefore, it should be possible to manipulate them to form complex structures through ionic bond formation under prescribed pH conditions.

Saad A. Khan of the University of North Carolina in the United States affects its ionization state by mixing nanocellulose and nanochitin after exposure to acidic or neutral conditions. How to monitor the heat of interaction in the process of introducing nanochitosan into nanocellulose by isothermal titration calorimetry. Finally, rheological measurements were used to characterize the strength and gel properties of the resulting structure. It is found that the gel properties obtained in the designed hybrid system directly depend on the charge state of the starting material, which can be determined by pH adjustment. Under different conditions (pH, concentration, ratio of nano-chitin to nano-cellulose) will affect different interactions between particles, including ion attraction, hydrophobic association and physical entanglement. Moreover, the hydrophobic association between the neutralized chitin and nanocellulose strongly helps to increase the elastic modulus value. Ionic complexes provide enhanced stability under wider pH conditions, and the physical entanglement of nanocellulose is an important thickening mechanism in all systems.

References: Facchine EG, Bai L, Rojas OJ and Khan SA. Associative structures formed from cellulose nanofibrils and nanochitins are pH-responsive and exhibit tunable rheology. Journal of Colloid and Interface Science 2021;588:232-241.

9. Chang Chunyu of Wuhan University (ACS Nano): Review——The latest development of the controllable arrangement of nanocellulose in polymer matrix

In order to cope with global climate change and plastic pollution, nanocellulose is expected to be used in the manufacture of high-tech materials and products this century due to its carbon dioxide accumulation characteristics. Moreover, various types of sources, such as plants, marine animals (envelopes) and bacteria, can be used to derive different forms of nanometers through various extraction processes (such as acid hydrolysis, mechanical treatment, enzymatic hydrolysis, oxidation methods and ionic liquid treatment). Cellulose. The low density and high elastic modulus of nanocellulose make it an ideal choice for replacing traditional reinforcing agents to prepare strong and lightweight nanocomposites. Nanocellulose has a strong tendency to self-aggregate, and the interface compatibility between its filler and polymer matrix is the main challenge to obtain high-performance nanocomposites.

Chang Chunyu from Wuhan University outlined the latest developments in nanocomposites containing highly ordered nanocellulose, transforming from its favorable structure-property relationship to potential applications. The arrangement of nanocellulose in the polymer matrix determines the overall performance of the nanocomposite. This article reviews three nanocomposites (orientation, spiral and gradient) with controllable nanocellulose arrangement, which provides ideas for the development of a new generation of nanocellulose-based functional composites. Although the preparation methods of highly oriented nanocellulose nanocomposites are diverse (electric field/magnetic field, stretching/shearing force and template), the practical application of these anisotropic materials is still challenging. In addition, integrating the spirally distributed cnc into the polymer matrix enables the nanocomposite to display reversible color changes, which has potential application prospects in humid environments or strain sensors. Finally, the design and preparation of nano-cellulose gradient distribution nanocomposites provide an opportunity for the development of new soft actuators. When nanocellulose is introduced asymmetrically into the environment-responsive polymer matrix, the expansion and swelling of the nanocomposite material can be transformed into various deformations such as stretching/shrinking, bending and rotation under environmental stimuli. Therefore, the author gives three suggestions: 1. Reasonable arrangements for industrial production of nanocellulose with good functions are the key to future development. 2. When considering expanding the scale of production, the cost and quality of nanocellulose are also important factors. 3. The fate and risks of nanocellulose need to be carefully studied in future research.



References: Peng N, Huang D, Gong C, Wang Y, Zhou J and Chang C. Controlled Arrangement of Nanocellulose in Polymeric Matrix: From Reinforcement to Functionality. ACS Nano 2020;14:16169-16179.

10. Stina Grönqvist (ACS Sustainable Chemistry & Engineering), Aalto University, Finland: Enzymatic fibrillation combined with gentle mechanical treatment to produce high solids nanocellulose

People’s interest in bio-based (especially plant-derived) nano-scale materials is increasing, not only because they have the renewable and sustainable characteristics of similar materials that can replace fossils, but also because cellulose nanofibrils have Unique properties, such as biocompatibility and high strength and hygroscopic properties, make it a favorable candidate for use in many technical applications, as well as the basis for advanced materials. Plant-based cellulose materials are an important part of functional materials, and sustainable nanocellulose production strategies have been studied in depth.

Stina Grönqvist of Aalto University in Finland introduced the production of a new type of nanocellulose through the action of enzymes under gentle mechanical agitation. The product of nanocellulose and the corresponding process are called high-concentration enzyme fibrillation of cellulose, or HefCel for short. The friction of fibers with low water content produces shearing force, combined with the continuous action of CBH, through a kind of exfoliation-type reaction to induce surface fibrillation, forming a paste-like fiber network, with a yield of up to 85%. Through high-resolution microscopy imaging, the size and size distribution of fibrils indicate that the HefCel classification belongs to the nanocellulose class of microfibrillated cellulose or cellulose microfibrils (CMFs). And the transverse width of the fibrils is usually between 15 and 20 nm. In general, the method of producing high-solids nanocellulose with lower energy consumption provides new application areas for the sustainable production of nanocellulose, such as textiles, packaging and papermaking.



References: Pere J, Tammelin T, Niemi P, Lille M, Virtanen T, Penttilä PA, et al. Production of High Solid Nanocellulose by Enzyme-Aided Fibrillation Coupled with Mild Mechanical Treatment. ACS Sustainable Chemistry & Engineering 2020;8:18853 -18863.

11. Hong Feng of Donghua University (Biomacromolecules): Improve the performance of bacterial nanocellulose catheters by introducing silk fibroin nanoparticles and heparin for small-caliber blood vessel transplantation applications

According to the annual report of the World Health Organization, cardiovascular disease (CVD) is still the main cause of human death. Revascularization occupies an important position in the clinical operation of CVD, especially for arterial and venous diseases, such as severe trauma, congenital malformations, vascular tumors and vascular occlusion secondary to stent implantation. Vascular grafts used for vascular reconstruction can be classified into biological vascular grafts or synthetic material grafts. Tubular bacterial nanocellulose (BNC) has been proven to be used for small-caliber blood vessel transplantation due to its unique characteristics (such as extracellular matrix-like 3D nanofibril network structure, high purity and water retention, good plasticity and uniqueness) Of promising natural biological materials. Silk fibroin (SF) is a natural fibrin that can be extracted from silkworm cocoons and spider silk. Due to its considerable biocompatibility and biodegradability, it has been widely used as a biological material. Heparin has been widely used as an anticoagulant in clinical practice, and surface modification with EDC/NHS cross-linked heparin can significantly improve the blood compatibility of vascular grafts for a long time.

Hong Feng of Donghua University made two types of small-caliber vascular grafts (BNC-SFNP and BNC) by attaching SF nanoparticles (SFNP) and heparin-embedded SFNP (SF-HepNP) emulsion to the BNC wall from the inside. -SF-HepNP). The results showed that heparinized BNC-Hep and BNC-SFNP-Hep catheters improved the anticoagulant performance. While BNC-SFNP-Hep promotes the proliferation of human umbilical vein endothelial cells, it also controls the excessive proliferation of human arterial smooth muscle cells and assists in rapid Endothelialization improves lumen patency. Four weeks after subcutaneous implantation, no obvious inflammation and material degradation were seen, and autologous tissues were seen around the catheter, and cells infiltrated to the edges of all samples. The BNC-SFNP catheter infiltrated the deepest, providing a suitable angiogenesis microenvironment for small-caliber blood vessels. BNC-Hep and BNC-SFNP-Hep have fewer inflammatory cells around the duct. Therefore, the anticoagulant properties of BNC-SFNP-Hep catheter and its stimulation of endothelialization suggest that it has great potential as a small-caliber artificial blood vessel in clinical applications.



References: Bao L, Hong FF, Li G, Hu G and Chen L. Improved Performance of Bacterial Nanocellulose Conduits by the Introduction of Silk Fibroin Nanoparticles and Heparin for Small-Caliber Vascular Graft Applications. Biomacromolecules 2020.

12. Anand Bala Subramaniam (ACS Applied Materials & Interfaces), University of California, USA: Using nano-cellulose paper to promote the convenient and high-yield assembly of giant monolayer vesicles

Giant single-membrane vesicles (GUVs) are single-wall enclosed phospholipid bilayer membranes with a diameter greater than 1 μm. GUV is similar to the smallest biological cell. This similarity makes GUV help to improve the understanding of membrane organization, cytoskeletal mechanics, reproduction, division, transportation, and electrical signaling. In addition, bottom-up synthetic biology, artificial tissue engineering, and drug delivery innovations have opened up new avenues for the use of GUV in biomimetic applications.

Anand Bala Subramani, University of California am proposed to use nano cellulose paper composed of entangled cylindrical nanofibers to promote the ease and high yield of assembly of GUVs. Compared with the existing surface-assisted assembly technology, the use of nano-cellulose paper can reduce the cost by 100,000 times while increasing the output. Quantitative measurements of yield and size distribution using a large data set confocal microscope clarified the mechanism of assembly. At the same time, a BNM model of thermodynamic germination and merging is proposed, which provides a unified explanation for the difference in yield and size of GUVs obtained from different geometric and chemical surfaces. The BNM model balances the elasticity, adhesion and edge energy of the part where the surface adhesion film is transformed into the surface adhesion bulb, and takes into account the change of free energy caused by bud. This model shows that the formation of GUVs is spontaneous on the hydrophilic surface of entangled columnar nanofibers of similar size to nanocellulose fibers. This work advances the understanding of the effect of surface properties on polystyrene assembly. It also solves the actual obstacles that currently hinder the use of GUVs as drug delivery vehicles, synthetic cell manufacturing, and large-scale assembly of artificial tissues.



Reference: Pazzi J and Subramaniam AB. Nanoscale Curvature Promotes High Yield Spontaneous Formation of Cell-Mimetic Giant Vesicles on Nanocellulose Paper. ACS Applied Materials & Interfaces 2020;12:56549-56561.

13. Wu Defeng, Yangzhou University (Carbohydrate Polymers): Adjust the shape and viscoelasticity of Piemulsion by adjusting the flexibility of the fiber

As people pay more and more attention to environmental issues, biomass materials as a substitute for traditional materials or synthetic materials have received extensive attention in many fields. Nano cellulose has become the most representative material due to its abundant renewable resources and excellent mechanical properties. Therefore, this type of material has attracted widespread attention in the field of green composite materials and functional materials. Another potential application is the preparation of Pickering emulsions, because nanocellulose can meet the requirements of sustainable and environmentally friendly particle emulsifiers. The more attractive aspect of these nanocelluloses is their anisotropic fiber structure, which helps stabilize the oil/water (O/W) interface at very low loading levels. In addition, their surface properties can be easily adjusted by chemical modification, which provides more possibilities for adjusting the morphology and final properties of emulsions. Therefore, so far, a large number of studies have been conducted around the preparation and application of nanocellulose stable emulsions.

Wu Defeng of Yangzhou University prepared an oil-in-water Piezoe emulsion with three types of nanocellulose (BC), cellulose nanofiber (CNF) and cellulose nanocrystal (CNC) as raw materials, and discussed the flexibility of the fiber The effect of sex on the emulsification effect. In the aqueous suspension, the shortest CNC is rigid, while the longest BC is completely flexible, which results in a large difference between the dilution to half-diluted concentration and the rheological leachate. Therefore, these cellulose nanofibers play different roles in the emulsification process. Flexible BC has almost no emulsification ability, while semi-flexible CNF and rigid CNC can be used to stabilize emulsions. For a CNF-stable system, the consumption effect is dominant and easily leads to the formation of droplet clusters. For a CNF-stable system, the repulsive force is more important. Dynamic rheology further reveals visible evidence of long-term structural relaxation of droplets. This work puts forward some interesting points, which can adjust the morphology and viscoelasticity of Pis emulsion by adjusting the flexibility of the fiber.

References: Lu Y, Li J, Ge L, Xie W and Wu D. Pickering emulsion stabilized with fibrous nanocelluloses: Insight into fiber flexibility-emulsifying capacity relations. Carbohydrate Polymers 2021;255:117483.

14. Gil Garnier (Biomacromolecules), Monash University, Australia: Cationic cross-linked nano-cellulose matrix for the growth and recovery of intestinal organoids

Hydrogel is a porous three-dimensional structure that can hold a large amount of water and has certain mechanical integrity. Such soft materials rely on physically or chemically cross-linked fiber networks, which can respond to temperature changes, pH and radiation. The colloidal stability of the hydrogel depends on the entangled network of nanocellulose, which can be further modified by covalent or ionic crosslinking. Additives (such as amino acids and sugars) can also be dissolved in these hydrogels to design their biochemical properties to achieve specific levels of osmolality and ionic strength. Because of its great tunability and its biocompatibility, plant-based nanocellulose hydrogels are ideal for biomedical applications. Functionalized nanocellulose hydrogels are used for the growth of intestinal organoids. However, the stiffness of these gels is directly proportional to the solid content, and the effects of various crosslinking agents and their concentrations have not been evaluated. Finally, even in the short term, the restoration and passage of spheres and organoids grown in a cellulose matrix has not been thoroughly investigated.

Gil Garnier of Monash University in Australia studies cationic crosslinking to control the mechanical properties of nanocellulose hydrogels to promote the growth and recovery of intestinal organoids. A hypothesis is proposed that highly carboxylated cellulose nanofibers can form a functionalized matrix to provide ideal biochemical and physical properties for organoid growth. And evaluated its influence on the formation of hydrogel and organoids. The mechanical properties of the TPON hydrogel cross-linked with Ca2 + and Mg2 + were characterized from the perspective of rheology. The organoids were cultured in these cellulose substrates for 4 days, and then recovered for passage and RNA extraction. The cell clusters recovered from the magnesium cross-linked hydrogel can pass through, and the extracted RNA is intact. Cationic crosslinked nanocellulose hydrogels are expected to become an alternative plant-based matrix for 3D cell culture systems.



Reference: Curvello R and Garnier G. Cationic Cross-Linked Nanocellulose-Based Matrices for the Growth and Recovery of Intestinal Organoids. Biomacromolecules 2020.

This article was contributed by Chun Guo.

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