Cellulose Hollow Annular Nanoparticles Prepared from High-Intensity Ultrasonic Treatment

Interfacial interactions between spider silk protein and cellulose studied by molecular dynamics simulation

CONTEXT

Due to their excellent biocompatibility and degradability, cellulose/spider silk protein composites hold a significant value in biomedical applications such as tissue engineering, drug delivery, and medical dressings. The interfacial interactions between cellulose and spider silk protein affect the properties of the composite. Therefore, it is important to understand the interfacial interactions between spider silk protein and cellulose to guide the design and optimization of composites. The study of the adsorption of protein on specific surfaces of cellulose crystal can be very complex using experimental methods. Molecular dynamics simulations allow the exploration of various physical and chemical changes at the atomic level of the material and enable an atomic description of the interactions between cellulose crystal planes and spider silk protein. In this study, molecular dynamics simulations were employed to investigate the interfacial interactions between spider silk protein (NTD) and cellulose surfaces. Findings of RMSD, RMSF, and secondary structure showed that the structure of NTD proteins remained unchanged during the adsorption process. Cellulose contact numbers and hydrogen bonding trends on different crystalline surfaces suggest that van der Waals forces and hydrogen bonding interactions drive the binding of proteins to cellulose. These findings reveal the interaction between cellulose and protein at the molecular level and provide theoretical guidance for the design and synthesis of cellulose/spider silk protein composites.

METHODS

MD simulations were all performed using the GROMACS-5.1 software package and run with CHARMM36 carbohydrate force field. Molecular dynamics simulations were performed for 500 ns for the simulated system.

Dissolution behavior of ionic liquids for different ratios of lignin and cellulose in the preparation of nanocellulose/lignin blends

Lignin is regarded as a potential solution for boosting the strength of cellulose-based products. However, the mechanism of co-solubilization for lignin and cellulose has not been investigated. In this study, the effect of lignin content on the interaction between lignin and nanocellulose during lignin/cellulose co-dissolution was examined. The results revealed that lignin binds to nanocellulose throughout the dissolution process to limit the degradation of cellulose and to prepare nanocellulose/lignin composites. Moreover, the S units in lignin were more likely to interact with cellulose during the dissolution process, whereas the G units were more likely to condense. However, when the lignin content exceeded 30 wt%, the excess lignin created a severe condensation reaction, which led to a decrease in the lignin content bound to cellulose, resulting in an unequal dissolution of cellulose. Thus, a small amount of lignin attached to cellulose during the co-dissolution of lignin and cellulose inhibits cellulose degradation and can be utilized to create nanocellulose/lignin to extend the potential applications of nanocellulosic materials.

Micro- and nano-hybrid cellulose fibers prepared by straightforward and high-efficiency hot water soaking-assisted colloid grinding for high-performance cellulose paper

Micro- and nano-hybrid cellulose fiber (MNCF) stands out as a versatile cellulosic nanomaterial with promising applications in various fields owing to its excellent intrinsic nature and outstanding characteristics. However, the inefficiency in preparing MNCF, attributed to a complex multi-step processing, hinders its widespread adoption. In this study, a straightforward and highly efficient method for MNCF preparation was developed via a hot water soaking-assisted colloid grinding strategy. Active water molecules in hot water facilitating stronger transverse shrinkage and longitudinal expansion in fiber crystallized region, and thus improving the fibrillation degree of cellulose fibers. As a result, MNCFs with a mean diameter of 37.5 ± 22.2 nm and high concentration (2 wt%) were successfully achieved though pure mechanical method. The micro and nano-hybrid structure leads to the corresponding resulting cellulose paper with micro- and nano-hybrid structure possesses a compact stacking and fewer defects, leading to extraordinary mechanical properties including tensile strength of 204.5 MPa, Young's modulus of 6.3 GPa and elongation of 10.1 %. This work achieves significant progress towards straightforward and highly efficient production of MNCFs, offering an appreciable prospect for the development of multifunctional MNCF-based materials.

Polysaccharide mediated nanodrug delivery: A review

Polysaccharides have drawn a lot of attention due to their potential as carriers for drugs and other bioactive chemicals. In drug delivery systems, natural macromolecules such as polysaccharides are widely utilized as polymers. This utilization extends to various polysaccharides employed in the development of nanoparticles for medicinal administration, with the goal of enhancing therapeutic efficacy while minimizing side effects. This study not only offers an overview of the existing challenges faced by these materials but also provides detailed information on key polysaccharides expertly engineered into nanoparticles. Noteworthy examples include Bael Fruit Gum, Guar Gum, Pectin, Agar, Cellulose, Alginate, Chitin, and Gum Acacia, each selected for their distinctive properties and strategically integrated into nanoparticles. The exploration of these natural macromolecules illuminates their diverse applications and underscores their potential as effective carriers in drug delivery systems. By delving into the unique attributes of each polysaccharide, this review aims to contribute valuable insights to the ongoing advancements in nanomedicine and pharmaceutical technologies. The overarching objective of this review research is to assess the utilization and comprehension of polysaccharides in nanoapplications, further striving to promote their continued integration in contemporary therapeutics and industrial practices.

Rheology of cellulose nanocrystal and nanofibril suspensions

Nanocellulose is a sustainable nanomaterial and a versatile green platform that has attracted increasing attention. Although the wide applications of its aqueous suspensions are closely related to rheology, comprehensive studies of their rheological behavior, especially the yielding behavior, are still limited. Herein, to investigate the relationship between structure and rheological properties, the viscoelasticity, thixotropy and yielding behavior of two commonly used nanocelluloses, rod-shaped cellulose nanocrystals (CNCs) and filamentous cellulose nanofibrils (CNFs), were systematically investigated. The viscosity, viscoelasticity and thixotropic behavior of the suspensions were analyzed by steady-state shear, frequency sweep, creep-recovery, hysteresis loop, and three-interval thixotropic recovery tests. The yielding behaviors were evaluated through creep, steady-state shear, step shear rate, stress ramps, amplitude sweep, and large amplitude oscillatory shear tests. The rheological properties of the two typical suspensions showed a strong dependence on concentration and time. However, compared to CNC suspensions, CNF suspensions exhibited stronger thixotropy and higher yield stress due to the higher aspect ratio of CNF and the stronger structural skeleton of the suspensions as supported by Simha's equation and micromorphology analysis. This work provides a theoretical rheology basis for the practical applications of nanocellulose suspensions in various fields.

High-yield and scalable cellulose nanomesh preparation via dilute acid vapor and enzymatic hydrolysis-mediated nanofabrication

Nanocellulose has received considerable attention in diverse research fields owing to its unique nanostructure-mediated physicochemical properties. However, classical acid hydrolysis usually destroys the microstructural integrity of cellulose, leading to the violent dissociation of cellulose into low-dimensional nanofibers and limiting the formation of intact structures with high specific surface areas. Herein, we have optimized the methodology of dilute acid vapor hydrolysis combined with the enzymatic hydrolysis (DAVE) method and investigated the pore formation mechanism of cellulose nanomesh (CNM). Benefiting from the selective nano-engraving effect of hydrochloric acid vapor on the amorphous region of cellulose followed by widening of the three-dimensional nanopores using enzymatic hydrolysis, confirmed by topographic, spectroscopic, and crystallographic tests, the as-prepared CNM, significantly different from the existing nanocellulose, exhibited improved specific surface area (98.37 m2/g), high yield (88.5 %), high crystallinity (73.4 %), and excellent thermal stability (375.4 °C). The proposed DAVE approach may open a new avenue for nanocellulose manufacturing.

Extracting dialdehyde cellulose nanocrystals using choline chloride/urea-based deep eutectic solvents: A comparative study in NaIO4 pre-oxidation and synchronous oxidation

Dialdehyde cellulose nanocrystals (DCNC) are defined as C2 and C3 aldehyde nanocellulose, which can be used as raw materials for nanocellulose derivatization, owing to the high activity of aldehyde groups. Herein, a comparative study in NaIO4 pre-oxidation and synchronous oxidation is investigated for DCNC extraction via choline chloride (ChCl)/urea-based deep eutectic solvent (DES). Ring-liked DCNC with an average particle size of 118 ± 11 nm, a yield of 49.25 %, an aldehyde group content of 6.29 mmol/g, a crystallinity of 69 %, and rod-liked DCNC with an average particle size of 109 ± 9 nm, a yield of 39.40 %, an aldehyde group content of 3.14 mmol/g, a crystallinity of 75 % can be extracted via optimized DES treatment combined with pre-oxidation and synchronous oxidation, respectively. In addition, the average particle size, size distribution, and aldehyde group content of DCNC were involved. TEM, FTIR, XRD, and TGA results reveal the variation of microstructure, chemical structure, crystalline structure, and thermostability of two kinds of DCNC during extraction even though the obtained DCNC exhibiting different micromorphology, pre-oxidation, or synchronous oxidation during ChCl/urea-based DES treatment can be considered as an efficient approach for DCNC extraction.

How to Develop Drug Delivery System Based on Carbohydrate Nanoparticles Targeted to Brain Tumors

Brain tumors are the most difficult to treat, not only because of the variety of their forms and the small number of effective chemotherapeutic agents capable of suppressing tumor cells, but also limited by poor drug transport across the blood-brain barrier (BBB). Nanoparticles are promising drug delivery solutions promoted by the expansion of nanotechnology, emerging in the creation and practical use of materials in the range from 1 to 500 nm. Carbohydrate-based nanoparticles is a unique platform for active molecular transport and targeted drug delivery, providing biocompatibility, biodegradability, and a reduction in toxic side effects. However, the design and fabrication of biopolymer colloidal nanomaterials have been and remain highly challenging to date. Our review is devoted to the description of carbohydrate nanoparticle synthesis and modification, with a brief overview of the biological and promising clinical outcomes. We also expect this manuscript to highlight the great potential of carbohydrate nanocarriers for drug delivery and targeted treatment of gliomas of various grades and glioblastomas, as the most aggressive of brain tumors.

Homogeneous activation induced by bacterial cellulose nanofibers to construct interconnected microporous carbons for enhanced capacitive storage

Porous carbons have been widely applied for capacitive energy storage, yet usually suffer from insufficient rate performance because of the sluggish ion transport kinetics in deep and multi-branched pores. Herein, we fabricated an interconnected microporous capacitive carbon (IMCC) by growing D (+)-glucosamine on bacterial cellulose (BC) nanofibers scaffold, followed by carbonization and activation. The BC nanofibers acted as a sacrificial template during pre-carbonization, facilitating the subsequent KOH permeation and homogeneous activation. By taking advantage of the interconnected microporous structure, the IMCC delivers a high capacitance of 302 F g^-1 at 1 A g^-1 and an excellent rate capability of 165 F g^-1 at 100 A g^-1 for aqueous supercapacitor, demonstrating its fast ion transport capability. Impressively, it also shows a superior gravimetric capacity of 177 mAh g^-1 at 0.5 A g^-1 and remains a high value of 72 mAh g^-1 at 20 A g^-1 as a cathode material for Zn-ion hybrid capacitor. This facile and cost-effective design strategy exhibits a great potential to construct carbohydrates-derived interconnected microporous carbon materials for high-rate energy storage.