Boronate-immobilized cellulose nanofiber-reinforced cellulose microspheres for pH-dependent adsorption of glycoproteins.

High strength and excellent selectivity are two important aspects of porous cellulose microspheres as adsorbents for protein separation. For this purpose, self-reinforced all-cellulose microspheres (SCMs) with high strength were fabricated using natural cellulose nanofibers (CNFs) as fillers and then immobilized via 3-aminophenylboronic acids as affinity ligands for selective enrichment of glycoproteins. In particular, the inherent stiffness of entrapped CNFs endowed SCMs with more inflexibility, because the stress can be efficiently transferred from the network of SCMs to the stiff CNFs during the separation process. Besides, SCMs, as an all-cellulose material with homogenous surface chemistry and pore structure characteristics, are more suitable as supports for adsorbents. Finally, the SCMs were immobilized with 3-aminophenylboronic acids (BA/EPI-SCMs) and tested their performance in affinity adsorption of glycoproteins. BA/EPI-SCMs showed fast separation, high adsorption amount, and excellent selectivity toward glycoproteins.

Proteinaceous porous nanofiber membrane-type adsorbent derived from amyloid lysozyme protofilaments for highly efficient lead(II) biologic scavenging.

To overcome the technical bottleneck of fine amyloid lysozyme fibrils in environmental engineering, a novel co-operative strategy was identified to fabricate free-standing lysozyme complex nanofibers based membrane-type adsorbent (Lys-CNFs membrane) through a combination of vacuum filtration for lead remediation. The composition of the membrane integrated the linear amyloid protofilaments that were obtained by acid-heating fibrillation and polydopamine that adjusted the fibers' diameters and surface chemistry. As expected, the Lys-CNFs membrane not only showed nanofibrous morphology and layer stacking architecture but presented a hierarchical macro-mesoporous structure along with a high surface area of 220.4 m2/g. Besides, the thermal stability up to 200 â„ƒ and wetting nature of below 2 s endowed its further applicability. Adsorption experiments showed that Lys-CNFs membrane can effectively uptake Pb(II) ions with acceptable selectivity, high adsorption capacity of 270.3 mg/g, rapid equilibrium kinetic within only 10 mins, and good reusability that dropped by 14.9% efficiency even after five cycles, indicating that Lys-CNFs membrane can be as an affordable technology for alleviating the lead pollution issues.

Tentacle-type poly(hydroxamic acid)-modified macroporous cellulose beads: Synthesis, characterization, and application for heavy metal ions adsorption.

Herein, a facile yet efficient template method to fabricate macroporous cellulose beads (MCBs) is reported. In this method, micro-size CaCO3 is utilized to create macroporous structure for fast mass transfer, and tentacle-type poly(hydroxamic acid) as adsorption ligand is immobilized on the MCBs to improve adsorption capacity. The obtained tentacle-type poly(hydroxamic acid)-modified MCMs (TP-CMCBs) show uniform spherical shape (about 80 µm), bimodal pore system (macropores≈3.0 µm; diffusional pores≈14.5 nm), and high specific surface area (52.7 m2/g). The adsorption performance of TP-CMCBs is evaluated by heavy metal ions adsorption. TP-CMCBs exhibit not only high adsorption capacities (342.5, 261.5 and 243.2 mg/g for Cu2+, Mn2+ and Ni2+, respectively.), but also fast adsorption rate (>70% of its equilibrium uptake within 30 min). Additionally, TP-CMCBs have excellent reusability, as evidenced by that the adsorption capacities have no obvious change even after five-time consecutive adsorption-desorption cycles. All results demonstrate that the proposed TP-CMCBs have great potential in removal of heavy metal ions.

Preparation and characterization of highly porous cellulose-agarose composite chromatographic microspheres for enhanced selective separation of histidine-rich proteins.

In this work, the porous cellulose-agarose microspheres with high specific surface area and enhanced mechanical strength are prepared by a novel chemical crosslinking method. The crosslinking reaction homogeneously proceeds between polysaccharides, and the covalent bonding network is generated to replace the inherent hydrogen bonding network of cellulose. The prepared microspheres exhibit low crystallinity of 12.45%, which means high content of amorphous regions. The micro-meso-macroporous structure of microspheres in morphology is conducive to high permeability and adsorption capacity, and the microspheres possess high specific surface area of 183.81 m2/g. The affinity chromatographic microspheres are prepared by immobilizing Cu2+, which exhibits high adsorption capacity of 197.65 mg/g for bovine hemoglobin (BHb), fast adsorption rate wihin 40 minutes, well-selectivity, and excellent recyclability in ten cycles. We expect that this work to provide an outstanding candidate for the high performance of biomacromolecular purification.

Direct preparation of porous cellulose microspheres via a self-growth process on bamboo fibers and their functionalization for specific adsorption of histidine-rich proteins.

The traditional preparation of cellulose microspheres always involves tedious synthetic procedures (e.g., dissolution, emulsification and regeneration) and inevitable organic solvents, which undergoes both high production cost and environmental contamination. To overcome these issues, a feasible and green synthesis strategy is proposed to construct porous cellulose microspheres (PCMs) via one-step spontaneous formation relying on sodium periodate oxidation of pure bamboo fibers. By this strategy, a cluster of robust cellulose microspheres grow up on the surface of bamboo fibers in aqueous phase through amorphous oxidized cellulose self-assembly accumulation and then drop out when their sizes increase to about 15 µm. After being immobilized with Cu(II), the prepared cellulose microspheres serve as metal affinity adsorbent for proteins adsorption, showing high adsorption capacity, good selectivity and excellent reusability for bovine hemoglobin (BHb). Together with green and easy synthesis, the novel cellulose microspheres show a promising alternative to commercially available adsorbent support.

The construction of porous chitosan microspheres with high specific surface area by using agarose as the pore-forming agent and further functionalized application in bioseparation.

Adsorbents with synchronously high protein adsorption performance and a facile synthetic route are highly desired in protein separation. In this study, a facile yet effective strategy to develop porous chitosan microspheres (PCMs) with high specific surface area (SSA) using agarose as the pore-forming agent is reported. Through heat treatment, the agarose chains in the chitosan/agarose composite microspheres (CAM) were removed, leading to the generation of nanopores/nanochannels and the improvement of SSA. The obtained PCMs showed hierarchical porous structure and a maximum SSA of 246.48 m2 g-1. For the application of PCMs as a protein adsorbent, by modification, the resultant immobilized Cu2+ affinity adsorbent (denoted as Cu2+PCM-15) exhibited a high adsorption capacity (301.88 mg g-1), fast adsorption rate (reaching equilibrium in less than 15 min), and excellent adsorption selectivity for BHb. Together with its environmental-friendliness, and abundant biomass chitosan and agarose, the as-prepared affinity adsorbent with high performance has great application potential in the field of bioseparation.