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Cellulose nitrate (CN) is used in numerous industrial materials, such as propellants, lacquers, and plastics, exploiting its highly flammable, hydrophobic, and plastic characters. The downsizing of cellulose nitrate fibers may enhance their properties. Although a direct nitration of cellulose nanofiber (CNF) is a prospective method for preparing nanosized CN materials, it is difficult because of the susceptibility of CNF to acids. In the previous study, we prepared nitrated cellulose nanofibers (NCNFs) using never-dried CNFs and relatively dilute H2SO4, obtaining a high yield and degree of substitution. In this study, we describe a novel highly surface-selective nitration method using dried CNFs. To prevent the acid hydrolysis of the CNFs, mildly acidic conditions (acetic acid/acetic anhydride/HNO3) were used instead of the conventional mixed-acid systems. Solid- and gel-state NMR studies revealed that the original crystalline structure of the produced NCNF core was retained, even after nitration, whereas the cellulose molecules on the NCNF surface were completely converted to cellulose pernitrates. The NCNFs exhibited morphologies comprising thin nanofiber diameters of approximately 10–50 nm with high specific surface areas of approximately 260 m2 g–1. Thus, unique core–shell NCNFs were prepared, potentially leading to the development of CNF derivatives with novel applications and functions.

Organic pigments are prone to aggregate, resulting in decreasing of their properties. Therefore, pigment dispersants are demanded to have both high adsorption capacity and aggregation inhibiting property for pigment particles. In the present study, the suitability of cellulose nanofibers (CNFs) as a dispersant for quinacridone, a common red–violet organic pigment, was investigated. Quinacridone particles were well adsorbed on the CNFs. Scanning electron microscopy images of the quinacridone–CNF mixtures showed that the quinacridone primary particles were stacked along the cellulose fibers, and the aggregations were inhibited. In addition, the size of the quinacridone particles had an effect on their color. The interactions of quinacridone and cellulose were investigated by Fourier transform infrared (FTIR) and solution-state nuclear magnetic resonance (NMR) spectroscopies. FTIR spectra of the quinacridone–CNF mixtures indicated the intermolecular interactions between quinacridone and cellulose. Because quinacridone and CNFs were insoluble in the NMR solvents, gel-state NMR spectroscopy, which has been used for the whole plant cell wall analysis, was conducted on them. Consequently, whole signals arising from quinacridone and cellulose were enabled to be assigned, and the coupling constant of quinacridone has reported for the first time. The nuclear Overhauser effect spectroscopy (NOESY)-NMR spectrum of the quinacridone–CNF mixture revealed both NH group and aromatic moiety of quinacridone were interacted with glucose unit. The former was considered to be related to hydrogen bonding, and the latter to CH–π interactions. These specific interactions might contribute to achieve the high adsorption capacity of CNFs for quinacridone.Graphic abstract

Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca8Na1.07H6.33(PO4)4.44(SiO4)1.32(SH-malate)2.40·nH2O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials.

Background Data in East Asian patients and in other epithelial skin cancers, including extramammary Paget’s disease (EMPD) and adnexal carcinomas, are scarce. Therefore, we conducted a phase II trial of nivolumab in Japanese patients with advanced non-melanoma skin cancers (NMSCs). Patients and methods This multicentre, open-label, single-arm phase II study enrolled adults (≥ 20 years) with histologically confirmed unresectable or recurrent epithelial cutaneous malignancies, Eastern Cooperative Oncology Group performance status 0–1, and at least one measurable lesion (RECIST v1.1). Nivolumab 480 mg was administered intravenously every 4 weeks for up to 26 cycles. The primary endpoint was overall response rate (ORR), assessed by blinded independent central review (BICR; RECIST v1.1). Secondary endpoints included progression-free survival, overall survival, and safety. Results Thirty-one patients were enrolled (20 cSCC, 4 EMPD, 2 BCC, 5 other NMSCs); median age was 73 years (range 58–86), and 71% were male. ORR by BICR was 22.6% (7/31), and the disease control rate was 54.8% (17/31). Responses were durable, with a median duration of 21.3 months. In the cSCC cohort, median tumour mutational burden (TMB) was 9.0 mut/Mb, lower than in Western series; among three patients with TMB ≥ 30 mut/Mb, two achieved objective responses. Common adverse events included pyrexia, hypothyroidism, adrenal insufficiency, and pruritus. Conclusions Nivolumab showed durable antitumour activity with manageable toxicity in Japanese patients with advanced NMSCs, including rare non-cSCC. The lower ORR compared with Western trials may reflect intrinsic biological differences and support biomarker-driven, region-specific immunotherapy. Clinical trial registration jRCT2031190048; registered 2 July 2019.

Quinacridone, a π-conjugated planar molecule, and common red pigment in industrial and painting applications, easily aggregates to form large clusters of pigment particles, resulting in a reduction in color strength. Cotton-derived cellulose nanofiber (NF), which almost consists of cellulose without hemicellulose and lignin, has been found to adsorb quinacridone on the surface, which inhibits pigment aggregation. The aggregation inhibition property of cellulose NF was induced by the strong intermolecular interactions between cellulose and quinacridone. In this study, the properties of lignocellulosic fibers for suppressing the aggregation of quinacridone pigments were investigated to reveal the influence of hemicellulose and lignin on the intermolecular interactions between quinacridone and fibers. Two lignocellulosic fibers with different degrees of fibrillation were used as dispersants of the pigment. In the scanning electron microscopy (SEM) images of the quinacridone–lignocellulose mixture, quinacridone particles were observed along the lignocellulose fiber, indicating that the quinacridone particles were well-adsorbed on the fiber surface. Consequently, the color of the aqueous suspension of quinacridone–lignocellulose mixture became increasingly vivid as the weight ratio of the lignocellulose fibers increased and as the fiber was fibrillated. The nuclear Overhauser effect spectroscopy (NOESY)–nuclear magnetic resonance (NMR) spectrum for quinacridone–lignocellulose suspension in d -dimethyl sulfoxide showed several NOE cross-peaks between quinacridone and cellulose/hemicellulose, whereas no cross-peaks between quinacridone and lignin were observed. It can be concluded that cellulose and hemicellulose promote the adsorption of quinacridone on the fiber surface, whereas lignin does not interact with quinacridone, even though both are aromatic molecules. This suggests that the intermolecular interactions based on hydrogen bonding and CH–π attraction are more dominant than the π–π attraction between quinacridone and lignocellulosic fibers.

The acetylation behavior of xylan and cellulose in kraft pulp (KP) was investigated. Heteronuclear single quantum coherence-nuclear magnetic resonance (HSQC-NMR) spectroscopy was used to identify the positions at which the hydroxyl groups of polysaccharides were acetylated. X-ray diffraction analysis was used to determine the acetylation of cellulose in the crystal region. It was found that only xylan was obviously acetylated in the initial stages of the reaction. In the next stage of the acetylation, however, both the xylan and surface of the cellulose crystals reacted. Then, acetylation of the inner crystal region of the cellulose started before the completion of the xylan modification. To improve the reactivity of xylan in KP, the effect of drying or the dehydration of never-dried KP prior to acetylation was also investigated. The use of supercritical CO 2 (scCO 2 ) drying produced a KP with a higher specific surface area. This caused the xylan to exhibit a higher reactivity than that resulting from freeze drying and vacuum drying after solvent exchange. Furthermore, never-dry dehydration pretreatment produced xylan with the highest reactivity. This suggests that the cellulose–cellulose and/or cellulose–hemicellulose adhesion in the cell wall that arises as a result of drying reduces the reactivity of the xylan.

The influences of two structural modifications on the photocurrent generation performance of the Langmuir–Blodgett (LB) film of the 6- O -phthalocyaninyl cellulose derivative were investigated. These structural modifications were the substituent groups at the O -2 and O -3 positions, and the central metal of the phthalocyanine moiety. Specifically, 6- O -Zn/phthalocyaninyl- ( 8a ) and Pd/phthalocyaninyl ( 8b ) -2,3-di- O -myristoylcelluloses were prepared instead of 6- O -Zn/phthalocyaninyl-2,3-di- O -myristylcellulose ( 2 ). The LB monolayer film of compound 8a on an indium thin oxide electrode showed higher photocurrent generation performance than that of compound 2 . This suggested that myristoyl groups (C-14 acyl groups) were more beneficial to photocurrent generation than myristyl groups (C-14 alkyl groups), as the substituent at the O -2 and O -3 positions. The LB monolayer film of compound 8b showed photocurrent generation from 500 to 700 nm, although a blue-shift in the Q-band maximum was observed. The photocurrent generation performance of compound 8b was significantly higher than that of compound 8a . This indicated that Pd was more beneficial to photocurrent generation than Zn. The film of compound 8b prepared by the horizontal lifting method showed better photocurrent generation performance than that prepared by the vertical dipping method. Consequently, compound 8b is a complementary material to the porphyrin-appended cellulose derivative ( 1 ) for photocurrent generation system.

The 6- O -phthalocyanine cellulose derivative, 2,3-di- O -myristyl-6- O -[ p -(9(10),16(17),23(24)-tri- tert -butyl-2-zinc(II)phthalocyaninyl-benzoyl)cellulose ( 8e ) was synthesized in a high yield with the degree of substitution of 0.33 for the phthalocyaninyl group (DS phthalocyanine ) via the esterification of 2,3-di- O -myristyl cellulose ( 1 ) with the mono -substituted phthalocyanine derivative ([9(10),16(17),23(24)-tri- tert -butyl-2-[4-(carboxy)phenoxy]phthalocyaninato]zinc(II), 7 ). A chloroform solution of compound 8e was more stable under illumination than that of low molecular weight phthalocyanine, [2(3),9(10),16(17),23(24)-tetrakis( tert -butyl)phthalocyaninato]zinc(II). Langmuir–Blodgett (LB) monolayer films of compound 8e were prepared on a variety of different substrates using the vertical dipping method with an annealing time of 5 min. An LB monolayer film of compound 8e on an indium tin oxide (ITO) electrode exhibited a photocurrent generation performance in the range of 600–700 nm. The photocurrent density of the film composed of 8e at 680 nm was better than that of 2,3-di- O -myristyl-6- O -(zinc(II) phthalocyaninyl) cellulose ( 3 ) which was the corresponding phthalocyanine-containing cellulose synthesized through a phthalocyanine-ring forming reaction on the cellulose backbone according to an existing procedure.

6- O -[Acetylacetonato-bis(2,2′-bipyridine)ruthenium(II)]-2,3-di- O -myristyl cellulose ( 3 ) was prepared from 2,3-di- O -myristyl cellulose ( 1 ) by two reaction steps in 37.7 % total yield. The LB monolayer film of compound 3 was successfully deposited onto an indium tin oxide electrode by a vertical dipping method and showed photocurrent generation performance in the range of 400–600 nm. Compound 3 was expected as a complementary material of porphyrin-bound cellulose derivative for biomaterial-based solar cells.

Esterification of wood with maleic anhydride assists its mechanical fibrillation to realize ultrathin lignocellulose nanofibers (LCNFs) with thicknesses of 3 nm. We investigated the effects of the moisture content of raw wood and the esterification reaction time on the properties of the LCNFs. Increasing the moisture content of raw wood decreases both the amount of maleic acid ester and the lignin content in esterified wood. Moisture is required not only for a high degree of esterification but also for the removal of lignin to prepare ultrathin LCNFs suitable for mechanical fibrillation. 2D HSQC-NMR analysis reveals that cellulose, hemicellulose, and lignin are esterified. The maleic acid ester introduced on the LCNF surface tends to be hydrolyzed, resulting in the detachment of the maleic acid ester. Ester hydrolysis, which is facilitated under alkaline and high temperature conditions, converts the LCNF suspension into a gel. Finally, the stability against ultra violet (UV) light irradiation is examined. Since lignin absorbs UV light, the reduction in the viscosity of the LCNF suspension is lower than that of the pure cellulose nanofiber suspension. These results should contribute to the effective utilization of wood, which is the most abundant biomass.