Cellulose Stearoyl Esters Research Articles

Smart hydrogel structure for microbiome sampling in gastrointestinal tract

Various microbiomes exist in the human body, however, there is an increasing research interest in the microbiomes present in the gastrointestinal (GI) tract and related diseases of the human body. In general, a healthy human body can maintain a certain balance in the microbiome of the GI tract. A condition, wherein the microbiome becomes imbalanced, is called “dysbiosis”, and it can increase the probability of diseases in the body, especially in the GI tract. Therefore, various methods of sampling and analyzing the microbiomes have been proposed to diagnose dysbiosis. However, it is difficult to apply the existing methods to the various environments of the GI tract. To overcome this limitation, we propose a smart hydrogel structure for microbiome sampling in the GI tract. The proposed hydrogel structure comprises a core containing magnetic nanoparticles (MNPs) where microbiome sampling occurs and two protection layers (cellulose stearoyl esters (CSEs) and myristic acid (MA)) that protect the hydrogel structure from the external environment and allow sampling at the desired location. The hydrogel structure can be taken orally owing to its small size; and because it contains MNPs, it is possible to target and sample the microbiome at the desired location and retrieve the hydrogel structure after sampling via external magnetic actuation. The hydrogel structure is heated by an alternating magnetic field (AMF) so that the microbiome sampling can be actively initiated from the outside. The basic performance of the hydrogel structure was analyzed through various characterizations and fundamental tests. Further, the microbiome sampling tests using the hydrogel structure were performed in in-vitro and ex-vivo environments, and its microbiome sampling performances were verified through various analysis methods, such as scanning electron microscope (SEM), confocal, and 16 s rRNA sequencing. Consequently, the proposed hydrogel structure can be applied as a microbiome sampling device for the GI tract, which can be a useful method for diagnosing dysbiosis.

Synthesis of Superhydrophobic Cellulose Stearoyl Ester for Oil/Water Separation.

Developing fluorine-free superhydrophobic and biodegradable materials for oil/water separation has already become an irresistible trend. In this paper, we designed two biopolymer oil/water separation routes based on cellulose stearoyl ester (CSE), which was obtained via the acylation reaction between dissolving pulp and stearoyl chloride homogeneously. The CSE showed a superhydrophobic property, which could selectively adsorb oil from the oil/water mixture. Additionally, the CSE was emulsified with an oxidized starch (OS) solution, and the resulting latex was used to impregnate commercial, filter base paper, finally obtaining a hydrophobic and oleophilic membrane. The SEM revealed the membrane had hierarchical micro/nanostructures, while the water contact angle indicated the low surface energy of the membrane, all of which were attributed to the CSE. The membrane had high strength and long durability due to the addition of OS/CSE, and the separation efficiency was more than 99% even after ten repeated uses.

Improving moisture barrier properties of paper sheets by cellulose stearoyl ester-based coatings

As commonly-used packaging material, paper has very poor moisture barrier properties, which are essential for maintaining physical and mechanical performance of paper as well as the shelf life of the packed goods. Herein, solutions of the synthesized cellulose stearoyl ester (CSE) compound were coated onto the calendered paper sheets by bar coater with the coating grammage ranging from 0.5–23.6 g m−2. When the coating grammage was 5.2 g m−2, the paper surface was totally covered by the CSE film with very low surface roughness (2.327 nm). The resulting CSE-coated papers from this coating grammage showed decreased tensile index and increased elongation at break, indicating the flexibility of the coated papers. Furthermore, the coated paper sheets were hydrophobic and displayed competitive water vapor barrier properties with the barrier ratio up to 90 %. Thereby, the designed CSE-coated paper sheets are promising for moisture barrier packaging application.

A Comparative Study of Self‐Assembled Superstructures from Cellulose Stearoyl Ester and Poly(Vinyl Stearate)

AbstractComb‐like cellulose stearoyl ester (CSE3) and poly(vinyl stearate) (PVS) with distinct skeletons are successfully synthesized. Their self‐assembled superstructures are described and discussed comparatively herein. Differential scanning calorimetry investigation indicates that both comb‐like polymers with various molecular weights show the feasibility to form self‐assembled crystalline structures. The self‐assembled superstructures are obtained from both the evaporation‐induced and temperature‐induced phase separation processes. Due to the interference of different skeletons, self‐assembled superstructures of both comb‐like polymers demonstrate totally different morphologies. CSE3 with semi‐flexible skeleton forms robust petals, which further grows into well‐organized flower‐like particles. In contrast, PVS with more flexible skeleton only form non‐ordered porous structures through stacking of the wrinkled and folded nanofilms.

Differential anti-fungal effects from hydrophobic and superhydrophobic wood based on cellulose and glycerol stearoyl esters

Wood is still a widely used raw material in many fields and is surface-modified for diverse applications. Though a few studies reported the anti-fungal effect derived from enhanced hydrophobicity of wood surface, no report about the influence of superhydrophobic surface upon fungi is known and the comparison of anti-fungal effects between hydrophobicity and superhydrophobicity on wood surface has not been demonstrated. We herein addressed these aspects regarding the anti-fungal properties of both hydrophobic and superhydrophobic wood. Hydrophobic and superhydrophobic beech and pine, representing hard- and softwood were fabricated, using environmentally friendly organic materials (cellulose and glycerol). Cellulose stearoyl ester was used for dip-coating (1st layer) the wood, leading to a hydrophobic surface and glycerol stearoyl ester was used for brush-coating (2nd layer) the wood, leading to a hierarchical superhydrophobic surface. Results showed that hydrophobic and superhydrophobic woods exhibited better anti-fungal properties comparing with non-treated wood. Furthermore, differential anti-fungal effects of hydrophobic and superhydrophobic wood were observed: superhydrophobic wood could thoroughly prevent fungal attachment to treated wood, while fungi could still be found inside hydrophobic wood after anti-fungal test.

How Bound and Free Fatty Acids in Cellulose Films Impact Nonspecific Protein Adsorption.

The effect of fatty acids and fatty acid esters to impair nonspecific protein adsorption on cellulose thin films is investigated. Thin films are prepared by blending trimethylsilyl cellulose solutions with either cellulose stearoyl ester or stearic acid at various ratios. After film formation by spin coating, the trimethylsilyl cellulose fraction of the films is converted to cellulose by exposure to HCl vapors. The morphologies and surface roughness of the blends were examined by atomic force microscopy revealing different feature shapes and sizes depending on the blend ratios. Nonspecific protein adsorption at the example of bovine serum albumin toward the blend thin films was tested by means of surface plasmon resonance spectroscopy in real-time. Incorporation of stearic acid into the cellulose leads to highly protein repellent surfaces regardless of the amount added. The stearic acid acts as a sacrificial compound that builds a complex with bovine serum albumin thereby inhibiting protein adsorption. For the blends where stearoyl ester is added to the cellulose films, the cellulose:cellulose stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific protein adsorption compared to pure cellulose, whereas for the other ratios, adsorption increases. Supplementary results were obtained from atomic force microscopy experiments performed in liquid during exposure to protein solution and surface free energy determinations.

Polymeric Flaky Nanostructures from Cellulose Stearoyl Esters for Functional Surfaces

Herein, the preparation of polymeric flaky nanostructures (PFNS) from cellulose stearoyl esters as a novel platform for functional materials is reported. A temperature‐induced crystallization process using solutions of cellulose stearoyl esters with a degree of substitution of 3 (CSE3) by decreasing the temperature from 55 °C to room temperature at a cooling rate of ≈1 °C min–1 is used. The molecular weights of CSE3, concentrations of polymer solutions, and cooling rates predominantly affect the formation of PFNS via this process. The PFNS are obtained as flakes within microsized flower‐like particles or as organized patterns on diverse substrates (silicon wafers and glass fiber papers). The surface functional groups and surface roughness strongly affect the homogeneity and the amount of PFNS, allowing us to tune the structure of PFNS by varying these parameters. In particular, homogeneous flaky patterns of high amounts are formed on the surfaces containing aliphatic chains. By introducing sufficient amounts of flaky nanostructures on flat wafer surfaces or glass fibers within the glass fiber papers, superhydrophobic surfaces against diverse aqueous liquids and highly viscous glycerol are obtained. Thus, the formation of PFNS exhibits a robust and facile method for the fabrication of functional surfaces on diverse substrates.

Moisture-responsive films of cellulose stearoyl esters showing reversible shape transitions.

Moisture-responsive materials are gaining greater interest for their potentially wide applications and the readily access to moisture. In this study, we show the fabrication of moisture-responsive, self-standing films using sustainable cellulose as starting material. Cellulose was modified by stearoyl moieties at first, leading to cellulose stearoyl esters (CSEs) with diverse degrees of substitution (DSs). The films of CSE with a low DS of 0.3 (CSE0.3) exhibited moisture-responsive properties, while CSEs with higher DSs of 1.3 or 3 (CSE1.3 and CSE3) not. The CSE0.3 films could reversibly fold and unfold as rhythmical bending motions within a local moisture gradient due to the ab- and desorption of water molecules at the film surface. By spray-coating CSE3 nanoparticles (NPs) onto CSE0.3 films, moisture-responsive films with non-wetting surface were obtained, which can perform quick reversible bending movements and continuous shape transition on water. Furthermore, bilayer films containing one layer of CSE0.3 at one side and one layer of CSE3 at the other side exhibited combined responsiveness to moisture and temperature. By varying the thickness of CSE0.3 films, the minimal bending extent can be adjusted due to altered mechanical resistances, which allows a bending movement preferentially beginning with the thinner side.

Polymeric Flower-Like Microparticles from Self-Assembled Cellulose Stearoyl Esters.

Flower-like particles (FLPs) with hierarchical surface architectures have recently attracted considerable attention due to their potentially wide application range. Hitherto, nearly all FLPs were fabricated using inorganic compounds, while versatile organic polymers have not received sufficient attention yet. Herein, we show the construction of novel organic, polymeric FLPs with diameters of 2.5-5 μm using cellulose stearoyl esters (CSEs) by means of the crystallization of side chains. CSEs with degrees of substitution of approximately 3 were transformed into FLPs during the gradual precipitation of polymer chains from the mixture of their solutions in dichloromethane (DCM) and a nonsolvent, which is driven by the evaporation of DCM. Ordered petal-like nanostructures were formed on the particle surface through the crystallization of side chains. Finally, partially crystalline FLPs containing lamellar structures were obtained. Moreover, the formation process was strongly affected by the molecular weight of CSE, concentrations of CSE solutions and the volume ratio between DCM and nonsolvents.

Facile formation of stimuli-responsive, fluorescent and magnetic nanoparticles based on cellulose stearoyl ester via nanoprecipitation

In comparison to stimuli-responsive, multi-functional nanoparticles (NPs) from synthetic polymers, such NPs based on sustainable, naturally occurring polysaccharides are still scarce. In the present study, stable stimuli-responsive, fluorescent and magnetic NPs were fabricated using cellulose stearoyl esters (CSEs) consisting of cellulose and stearoyl groups. The multifunctional NPs with the average diameters between 80 and 250 nm were obtained after facile nanoprecipitation using CSE solutions containing Fe3O4-NPs. Using the aqueous solution of fluorescent rhodamine B as precipitant, NPs with rhodamine B on NP surface were obtained. Rhodamine B could be released depending on the temperature. In comparison, stearoylaminoethyl rhodamine B can be encapsulated in CSE-NPs, which renders obtained NPs reversible fluorescence in response to UV illumination and heat treatment.

Reversibly Crystalline Nanoparticles from Cellulose Alkyl Esters via Nanoprecipitation

Nanoparticles (NPs) from biopolymers, in particular polysaccharides, attract much attention but they are rarely systematically investigated in comparison to NPs from synthetic polymers. In this report, stable aqueous suspensions of NPs from cellulose alkyl esters with different alkyl chain lengths (cellulose stearoyl, lauroyl, and caproyl ester) and degrees of substitution (DS) are fabricated via nanoprecipitation. Their properties are investigated in terms of the average size, surface charge and polarity, temperature-responsive crystalline structure, and dry-state morphology, in relationship with the chemical compositions of cellulose esters. Generally, the average diameters of NPs increase with higher DS and longer alkyl chains length, but the surface hydrophobicity decreases with longer alkyl chain length. The presence of the crystallizable stearoyl groups along polymeric backbones renders polymeric NPs with reversibly temperature-responsive property. The NPs from cellulose stearoyl esters (CSE) with stearoyl groups of high contents (DS of 1.3 and 3) and poly(vinyl stearate) can be altered between more crystalline, solid nanospheres, and amorphous, liquid nanodroplets without the loss of their stability by changing the temperature. In comparison, NPs from CSE with a low DS of 0.3, cellulose lauroyl and caproyl ester contain only slightly ordered structure.

Thermo-responsive superhydrophobic paper using nanostructured cellulose stearoyl ester

Hydrophilic paper was rendered with hydrophobic and superhydrophobic property after the treatment with solutions and nanoparticles of cellulose stearoyl ester (CSE), respectively. Cellulose stearoyl ester with a degree of substitution of 2.99 was synthesized from cellulose using stearoyl chloride. By dip-coating paper in CSE solution of at least 3 mg/ml in toluene, paper became hydrophobic with stable water contact angles of more than 120°. After further spray-coating using CSE nanoparticles that were prepared from CSE solution via nanoprecipitation, paper surface became superhydrophobic with water contact angles of larger than 150°. These superhydrophobic surfaces also exhibited self-cleaning character. Furthermore, the superhydrophobic paper surfaces showed a temperature-responsive character and could be turned hydrophobic after a heat-treatment at 70 °C for 5 min.

Formation of nanostructured cellulose stearoyl esters via nanoprecipitation

Nanoparticles (NPs) from derivatives of native polysaccharides have not been as intensively studied yet as those from synthetic polymers. In this report, NPs in aqueous suspensions were fabricated using cellulose stearoyl esters (CSEs) with different molecular weights via nanoprecipitation using dropping and dialysis techniques. The average diameters of NPs depended strongly on the concentrations of CSE solutions, molecular weights of CSE and also the nanoprecipitation technique. Both nanoprecipitation techniques are based on different mechanisms and NPs from dialysis are generally larger than NPs from dropping. The mechanism for dropping nanoprecipitation was further analyzed based on the properties of NPs which contain crystallized stearoyl groups in CSE chains. The average diameters of freshly-prepared CSE nanoparticles decreased with rising temperature, which is accompanied by the release of THF from the interior of NPs. The intensity of the size reduction of up to 35% depended on the one hand on the concentration of CSE solutions, and on the other hand on the molecular weights of CSEs. Finally, it was shown that these NPs can be used for the fabrication of temperature-responsive superhydrophobic surfaces.

Superhydrophobic surfaces fabricated from nano- and microstructured cellulose stearoyl esters

Robust, superhydrophobic and self-cleaning films were fabricated using nano- or microstructured cellulose fatty acid esters, which were prepared via nanoprecipitation. The superhydrophobic films could be coated on diverse surfaces with non-uniform shapes by distinct coating techniques.

Highly water repellent aerogels based on cellulose stearoyl esters

Herein we combine in a novel way the physical effect of porous structure of a cellulosic aerogel with the chemical effect of long alkyl tails by a well known homogeneous green esterification method, to achieve purely bio-based and highly water repellent cellulosic materials. As an alternative for a traditional fluoro derivatized hydrophobization, here long fatty acid tails are utilized to lower the surface energy. To minimize the process emission, ionic liquid (IL) 1-allyl-3-methylimidazolium chloride is used for the esterification, due to its non-volatility and recyclability. We have shown here that low degree of substitution (DS) of the fatty acid cellulose material enables the spontaneous formation of aerogels. Additionally, the very low content of the long stearoyl tails combined with the porous aerogel structure resulted in significant increase in hydrophobicity from an aqueous contact angle of 0° up to 124°. We foresee that this approach can allow sustainable and completely bio-based coatings and insulators paving the way for a new green application potential for cellulose based materials.