High-strength and low-crystallinity cellulose/agarose composite microspheres: Fabrication, characterization and protein adsorption

Rational design of agarose/dextran composite microspheres with tunable core-shell microstructures for chromatographic application

A new type of core-shell microsphere was prepared by a pre-crosslinking method, consisting of cross-linked agarose microspheres as the core and agarose-dextran as the shell. After optimizing the preparation process, the microspheres with a uniform particle size were obtained and characterized using cryo-scanning electron microscopy to determine their surface and cross-sectional morphology. Results from flow rate-pressure and chromatographic performance tests showed that the core-shell agarose microspheres were supported by the core microspheres and composed of composite polysaccharides, forming an interpenetrating polymer network structure as a hard shell. The core-shell agarose microspheres showed a 300.5 % increase in linear flow rate compared to composite polysaccharide microspheres prepared from shell materials and a 141.5 % increase compared to 6 % agarose microspheres. Additionally, the large pore structure of the shell combined with the fine pore structure of the core improved the material separation efficiency in the range of 0.1-2000 kDa. These findings suggest that core-shell natural polysaccharide microspheres have great potential as a separation chromatographic medium.

pH-Responsive Cellulose/Silk/Fe3O4 Hydrogel Microbeads Designed for Biomedical Applications

In this study, cellulose/Fe3O4 hydrogel microbeads were prepared through the sol-gel transition of a solvent-in-oil emulsion using various cellulose-dissolving solvents and soybean oil without surfactants. Particularly, 40% tetrabutylammonium hydroxide (TBAH) and 40% tetrabutylphosphonium hydroxide (TBPH) dissolved cellulose at room temperature and effectively dispersed Fe3O4, forming cellulose/Fe3O4 microbeads with an average diameter of ~15 µm. Additionally, these solvents co-dissolved cellulose and silk, allowing for the manufacture of cellulose/silk/Fe3O4 hydrogel microbeads with altered surface characteristics. Owing to the negatively charged surface characteristics, the adsorption capacity of the cellulose/silk/Fe3O4 microbeads for the cationic dye crystal violet was >10 times higher than that of the cellulose/Fe3O4 microbeads. When prepared with TBAH, the initial adsorption rate of bovine serum albumin (BSA) on the cellulose/silk/Fe3O4 microbeads was 18.1 times higher than that on the cellulose/Fe3O4 microbeads. When preparing TBPH, the equilibrium adsorption capacity of the cellulose/silk/Fe3O4 microbeads for BSA (1.6 g/g) was 8.5 times higher than that of the cellulose/Fe3O4 microbeads. The pH-dependent BSA release from the cellulose/silk/Fe3O4 microbeads prepared with TBPH revealed 6.1-fold slower initial desorption rates and 5.2-fold lower desorption amounts at pH 2.2 than those at pH 7.4. Cytotoxicity tests on the cellulose and cellulose/silk composites regenerated with TBAH and TBPH yielded nontoxic results. Therefore, cellulose/silk/Fe3O4 microbeads are considered suitable pH-responsive supports for orally administered protein pharmaceuticals.

Progress of ligand-modified agarose microspheres for protein isolation and purification

Proteins are the material basis of life and the primary carriers of life activities, containing various impurities that must be removed before use. To keep pace with the increasing complexity of protein samples, it is essential to constantly work on developing new purification technologies for downstream processes. While traditional downstream purification methods rely heavily on protein A affinity chromatography, there is still a lot of interest in finding safer and more cost-effective alternatives to protein A. Many non-affinity ligands and technologies have also been developed in biological purification recently. Here, the current status of biotechnology and the progress of protein separation technology from 2018 to 2023 are reviewed from the aspects of new preparation methods and new composite materials of commonly used separation media. The research status of new ligands with different mechanisms of action was reviewed, including the expanded application of affinity ligands, the development prospect of biotechnology such as polymer grafting, continuous column technology, and its new applications.

Three-dimensional porous wood monolithic columns for efficient purification of spike glycoprotein of SARS-CoV-2

Considerable research has been devoted to finding a cost-effective chromatographic matrix with efficient adsorption and high throughput. Wood exhibits complex micro-network structures that make it a powerful contender for a novel environment-friendly chromatographic matrix material. We demonstrate a novel strategy to manufacture a wood monolithic column, which chemically modified the wood and imported diethyl aminoethyl, diethylamine, and amino groups. This wood monolithic column can maintain fully monolithic column performances and highly selective to spike glycoprotein of SARS-CoV-2 by ion exchange force. The wood monolithic column was evaluated by static adsorption, dynamic adsorption, and frontal analysis. The results showed that the static adsorption capacity of the wood monolithic column with 2-diethylaminoethylchloride hydrochloride for bovine serum albumin was 14.72 mg/g, and the adsorption process was chemisorption. In addition, it retained 80 % adsorption capacity after 110 repeated adsorption-elution cycles.

Extraction, Modification and Biomedical Application of Agarose Hydrogels: A Review

Numerous compounds present in the ocean are contributing to the development of the biomedical field. Agarose, a polysaccharide derived from marine red algae, plays a vital role in biomedical applications because of its reversible temperature-sensitive gelling behavior, excellent mechanical properties, and high biological activity. Natural agarose hydrogel has a single structural composition that prevents it from adapting to complex biological environments. Therefore, agarose can be developed into different forms through physical, biological, and chemical modifications, enabling it to perform optimally in different environments. Agarose biomaterials are being increasingly used for isolation, purification, drug delivery, and tissue engineering, but most are still far from clinical approval. This review classifies and discusses the preparation, modification, and biomedical applications of agarose, focusing on its applications in isolation and purification, wound dressings, drug delivery, tissue engineering, and 3D printing. In addition, it attempts to address the opportunities and challenges associated with the future development of agarose-based biomaterials in the biomedical field. It should help to rationalize the selection of the most suitable functionalized agarose hydrogels for specific applications in the biomedical industry.

Preparation of macroporous rigid agarose microspheres by pre-crosslinking with cyclic anhydride

In this study, a new method for preparing macroporous rigid agarose microspheres was developed by one-step pre-crosslinking method with cyclic anhydride. Three different cyclic anhydrides, namely, maleic anhydride, succinic anhydride, and glutaric anhydride, were used to pre-crosslink agarose. The reaction temperature and the amount of cyclic anhydride in the pre-crosslinking process were optimized to endow agarose with stronger cross-linking. Under the optimal cross-linking condition, macroporous rigid agarose microspheres with homogeneous particle size were successfully obtained by adjusting emulsification method. Cryo-scanning electron microscopy was used to characterize the morphology of cross-linked agarose gel and microspheres. The addition of cyclic anhydride increased the gel aperture of cross-linked agarose microspheres, thereby making the macropores in the microspheres more dense and enhancing the mass transfer in the particles. Under low pressure, the cross-linked agarose microsphere column can effectively separate model proteins at linear flow rates three times higher than the agarose microsphere column. These results indicate that the developed agarose microspheres are a promising high-speed chromatographic medium.

Multifunctional Cellulose and Cellulose-Based (Nano) Composite Adsorbents

In recent years, faced with the improvement of environmental quality problems, cellulose and cellulose-based (nano) composites have attracted great attention as adsorbents. In this review article, we first report the recent progress of modification and functionalization of cellulose adsorbents. In addition, the adsorbents produced by the modification and functionalization of carboxymehyl cellulose are also introduced. Moreover, the cellulose-based (nano) composites as adsorbents are reviewed in detail. Finally, the development prospect of cellulose and cellulose-based (nano) composites is studied in the field of the environment. In this review article, a critical comment is given based on our knowledge. It is believed that these biomass adsorbents will play an increasingly important role in the field of the environment.

Probing Effect of Papirindustriens Forskningsinstitut (PFI) Refining on Aggregation Structure of Cellulose: Crystal Packing and Hydrogen-Bonding Network

Supramolecular structure is the critical factor that affects the properties of cellulosic fibers. This article studied the action of Papirindustriens forskningsinstitut (PFI) refining on the molecular aggregation and hydrogen bonding network, and tried to explore the relationship between the crystal packing and hydrogen-bonding network in cellulosic fibers. The results showed that the polymorph, H-bonding distance, and H-bonding energy of various H-bonds remained almost unchanged, while the crystalline index, crystallite size, and content of various H-bonds changed with refining. Therein, the content of the inter-molecular O(6)H⋯O(3') H-bonds was significantly correlated with the crystalline index that was obtained in intensities of the XRD peaks. The Pearson correlation coefficient between them was 0.888 (p < 0.05) for softwood fibers and 0.889 (p < 0.05) for hardwood fibers, respectively. It can be concluded that the variations of accessibility, swelling, and fibrillation were closely related to the supramolecular structure and the intermolecular H-bonds play an important role in the crystal packing of cellulose.