Takeshi Serizawa

Adsorbing antibodies of interest onto solid supports displaying corresponding antigens is an efficient strategy for their subsequent purification and detection. We have previously demonstrated the potential of water-dispersible, antibiofouling, and designable cello-oligosaccharide assemblies for antibody detection via enzyme-linked immunosorbent assay (ELISA). However, whether antigen-conjugated cello-oligosaccharide assemblies can detect specific antibodies contained in immune serum remains unexplored. In this study, we demonstrate the utility of oligo(ethylene glycol) (OEG)-conjugated cello-oligosaccharide assemblies for detecting antipoly(ethylene glycol) (PEG) immunoglobulin M (IgM) in serum from immunized animals. Mouse sera containing anti-PEG IgMs, induced by immunogenic polymers, were utilized for evaluation. ELISA results revealed that anti-PEG IgMs in the serum with no heat-inactivation or depletion were successfully detected by cello-oligosaccharide assemblies displaying OEG chains with at least three repeating ethylene glycol units. ELISAs using a series of cello-oligosaccharide assemblies displaying OEG chains indicated that the conjugation rate of OEG chains influences anti-PEG IgM binding. Furthermore, increasing the serum concentration led to enhanced detection efficacy for anti-PEG IgM, likely due to the superior antibiofouling properties of the cello-oligosaccharide assemblies, which minimize nonspecific adsorption of serum proteins. The concentration of the assemblies also significantly influenced the detection efficacy. Additionally, 7 days after a single intravenous injection of OEG-conjugated cello-oligosaccharide assemblies without micrometer-scale aggregates, ELISA signals for IgMs against PEG chains, OEG chains, and cello-oligosaccharide moieties were comparable to those of saline-treated controls. These findings demonstrated that OEG-conjugated cello-oligosaccharide assemblies hold considerable potential for the detection of anti-PEG IgMs in immune serum with no heat-inactivation or depletion.

Artificial nanocelluloses constructed through the self-assembly of low-molecular-weight (LMW) cellulose have emerged as sustainable nanomaterials with tailorable nanomorphologies. Herein, we demonstrate the modulation of LMW cellulose self-assembly using Poloxamer 407 (P407), a poly(ethylene oxide)—poly(propylene oxide)—poly(ethylene oxide) triblock copolymer. LMW cellulose with average degrees of polymerization of approximately 7 and 10 formed nanosheets or nanoribbons in the presence of 15% and 20% (w/v) P407, while their dimensions and aggregation states varied markedly depending on the conditions. In particular, the former LMW cellulose formed nanosheets in intimate contact with one another with poorly defined boundaries at 15% (w/v) P407, while nanosheets with irregular, stepped edges were formed at 20% (w/v) P407. Fourier transform infrared spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses suggested that P407 directly interacted with LMW cellulose and affected its self-assembly. These findings reveal that amphiphilic block copolymers can serve as effective modulators of LMW cellulose self-assembly and expand strategies for controlling the nanomorphologies of artificial nanocelluloses without chemical modification of cellulose molecules.

Stimulus-responsive delivery systems enable precise control over the release of therapeutic and agricultural agents. Among various triggers, cellulase has recently attracted increasing attention because of its unique biological distribution; it is absent in humans but produced by specific micro-organisms and insects. Herein, we report a cellulase-responsive drug delivery carrier based on terminally alkylated cello-oligosaccharide assemblies. Among the assemblies examined, terminally hexylated cello-oligosaccharides with the cellulose I allomorph (CELI-C6) exhibited the highest loading capacity for the hydrophobic antibiotic rifampicin, likely driven by the hydrophobic effect. Upon exposure to cellulase, CELI-C6 underwent rapid degradation, leading to efficient release of rifampicin. This rapid response likely originates from the low degree of polymerization of the constituent cello-oligosaccharide chains, for which only one or a few hydrolytic cleavage events induce solubilization. Notably, rifampicin release was selectively triggered by cellulase containing cellobiohydrolase activity, whereas negligible release was observed with other enzymes. The released rifampicin exhibited potent antibacterial activity against Escherichia coli, whereas loading rifampicin into CELI-C6 effectively suppressed its antibacterial activity in the absence of cellulase. These results demonstrate that CELI-C6 functions as a carrier enabling enzyme-selective, sharp, and rapid release of hydrophobic drugs, offering opportunities for biomedical and agricultural applications.

Advances in hydrogel research have enabled the design of bulk networks with diverse functionalities; however, precise control of interfacial properties remains a key challenge to expanding their applications, particularly in biointerfaces. Here, we report a simple and versatile surface functionalization strategy based on the self-assembly of terminally modified cello-oligosaccharides. When azido-functionalized cello-oligosaccharides dissolved in 85% phosphoric acid are applied to hydrogel surfaces, mixing with the intrinsic water within the hydrogels induces rapid self-assembly, forming nanostructured granular coatings at the interface. This method is applicable to both chemically and physically cross-linked hydrogels. The resulting azido-functionalized surfaces enable postfunctionalization via click chemistry, allowing biomolecule immobilization. As a proof of concept, antigen-conjugated hydrogels were used for the detection of specific immunoglobulin G, exhibiting selective responses even in serum-containing environments due to the antibiofouling properties of the assemblies. These findings establish terminally modified cello-oligosaccharides as a new class of interfacial modifiers for hydrogels, providing a facile route to biofunctional and antifouling interfaces for sensing and diagnostic applications.

Surface nanostructuring of materials is emerging as an antibiotic-free strategy for infection control. We recently demonstrated the decoration of gauze microfibers with nanospike structures via the self-assembly of low-molecular-weight (LMW) cellulose. The resulting nanospiked gauze exhibited bacterial adhesion-promoting effects when protein was present, which were useful for removing pathogenic bacteria from deep burn wounds with protein-containing exudates. However, these effects depend strongly on the presence and concentration of proteins, representing a challenge for reliable clinical implementation. Herein, we present the use of terminally aminated LMW cellulose as a self-assembling building block for the surface nanostructuring of gauze microfibers to achieve bacterial adhesion-promoting effects across a wide range of protein concentrations. Terminally aminated LMW cellulose formed either nanospike or nanofibrillar-network structures, depending on the solvent and coagulant used during self-assembly. Both the aminated nanospikes and the aminated nanofibrillar networks promoted bacterial adhesion under protein-free conditions, likely through electrostatic attraction between the positively charged nanostructures and negatively charged bacterial cells. Moreover, although the effects of the aminated nanospikes were diminished in the presence of proteins with net negative charges, probably because of protein adsorption, the aminated nanofibrillar networks still displayed bacterial adhesion-promoting effects under the same conditions, likely owing to their characteristic nanostructures.

The continuous increase in global plastic production has intensified concerns regarding the effect of microplastics and nanoplastics on ecosystems and human health. These minute particles are known to act as carriers of toxic compounds. Water-soluble polymers also face potential environmental challenges. Consequently, a precise analysis of these environmental polymers is essential. This review provides a comprehensive overview of the current strategies for environmental polymer analysis. We discuss the advantages, limitations, and recent advancements of prominent analytical methods, including mass spectrometry, infrared spectroscopy, Raman spectroscopy, and fluorescence spectroscopy. Ultimately, this review facilitates the development of more effective and integrated analytical platforms, bridging the gap between current research capabilities and the urgent need for practical and routine environmental assessment methods. This approach will enable a more thorough understanding of the global scope and impact of these concerns.

Terminally alkylated low-molecular-weight cellulose self-assembles on cotton gauze microfibers into nanostructures, and the resulting assemblies promote bacterial adhesion when bearing sufficiently long terminal alkyl chains.

Polysaccharides are valuable building blocks for constructing functional hydrogel materials for diverse applications. Although many polysaccharides with high water solubility require cross-linking to be formulated into hydrogels, physically cross-linking ionic polysaccharides with biocompatible substances under mild aqueous conditions remains a significant challenge. Herein, we report the physical cross-linking of hyaluronic acid with crystalline cello-oligosaccharides via bottom-up coassembly at the molecular level. Neutralization of alkaline mixtures of cello-oligosaccharides and hyaluronate resulted in the facile preparation of translucent hydrogels with equilibrium moduli of 1-10 Pa. Structural analyses suggested that hyaluronate formed the backbone of the gel networks, while crystalline cello-oligosaccharides acted as physical cross-linkers. In vitro cytotoxicity assays demonstrated the excellent cytocompatibility of the coassembled hydrogels. Furthermore, the cationic antibiotic polymyxin B was successfully incorporated into the hydrogels, yielding antibacterial composite hydrogels. This study provides a promising strategy for the development of advanced polysaccharide-based biomaterials through physical cross-linking with crystalline oligosaccharides.