Iskanje po katalogu digitalne knjižnice

Opis: Three-dimensional (3D) and porous scaffolds made from nanocellulosic materials hold significant potential in tissue engineering (TE). Here, we present a protocol for fabricating self-standing (nano)cellulose-based 3D scaffolds designed for in vitro testing of cells from skin and cartilage tissues. We describe steps for preparation of nanocellulose ink, scaffold formation using 3D printing, and freeze-drying. We then detail post-processing procedures to enhance mechanical properties, stability, and biocompatibility. This protocol offers researchers a framework for developing versatile and sustainable biomaterials for regenerative medicine.
Ključne besede: tissue engineering, 3D scaffolds, nanocellulosic materials, biocompatibility
Objavljeno v DKUM: 03.11.2025; Ogledov: 0; Prenosov: 4
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Opis: The most frequent neutralisation procedure, applied on chitosan (CS) films includes treatment with NaOH base. Such treatment endows CS films with stability in water, yet, same can significantly decrease the film performance. In the present paper, we investigate Mg(OH)2 nanoparticles as a neutralisation agent for CS solutions followed by casting into films. This is combined and compared with classical casting and film drying from nonneutralized solutions followed by NaOH treatment after film formation. The influence on the properties of resulting films is investigated in detail and large differences are found for structure and barrier properties. The stable, opaque-to-transparent CS films (depending on Mg(OH)2 content and post-treatment) were obtained by facile casting method of neat CS or CS–Mg(OH)2 dispersions, in the complete absence of cross-linkers and plasticizers. FTIR data demonstrate the Mg(OH)2 and NaOH deprotonation effect, and strongly suggest intensive H-bonding interaction between CS and Mg(OH)2. X-ray photoelectron spectroscopy showed differences in the hydroxide content and protonation of CS nitrogen. The reduction of surface roughness and increase of homogeneity, the tensile strength and elongation, as well as thermal stability and excellent oxygen barrier properties were measured for CS enclosing the Mg(OH)2 nanoparticles. Further treatment with 1 M NaOH causes repacking of CS polymer chains, improving the crystallinity and water vapour barrier properties, degrading the mechanical properties by increasing the films brittleness and increasing the char formation due to reduced thermal stability.
Ključne besede: CS films, Mg(OH)2, neutralization, oxygen barrier properties
Objavljeno v DKUM: 14.10.2025; Ogledov: 0; Prenosov: 2
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Opis: Paper artifacts susceptible to acid hydrolysis and mechanical stress require effective conservation methods to ensure their longevity. In this study, a novel approach for the deacidification of acidic paper using calcium carbonate (CaCO3) [1,2]-ethylcellulose nanoparticles (CaCO3-EC NPs) dispersed in a non-aqueous ethyl acetate solution is presented. The dispersions were carefully prepared and applied to model acidic paper samples using a dipcoating method and then analyzed for their effectiveness. Transmission electron microscopy showed the formation of agglomerates containing quadrangular alkaline nanoparticles with diameters of 40 to 100 nm and a total agglomerate size of 250 nm. Hydrodynamic analyzes indicate the presence of a swollen ethyl cellulose coating on these agglomerates, which facilitates their dispersion. The results show the effectiveness of the CaCO3-EC NPs system in neutralizing acidic components (change of paper pH from 4.3 to 7) due to the homogeneous distribution within the paper substrates, effectively arresting the degradation processes. Acid-base titration showed a linear correlation between the concentration of alkaline nanoparticles and the alkaline reserve, emphasizing the role of ethylcellulose in facilitating particle transport within the paper matrix. In addition, ethylcellulose was found to improve the mechanical properties of the treated paper, as demonstrated by the standard mechanical tests. Importantly, the optical properties remained unchanged after treatment, as no adverse changes in color were observed. These results underline the effectiveness of the developed deacidification dispersions for the treatment of acidic paper and potentially other cellulose-based cultural heritage documents prone to acidic degradation. This approach offers promising implications for preserving and restoring valuable historical materials.
Ključne besede: ethylcellulose, calcium carbonate, functional coating, deacidification, strengthening, cultural heritage
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 2
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Ključne besede: superabsorbent hydrogels, pH-responsiveness, hydrogel thin films, quartz crystal microbalance, pH sensor, reversible swelling
Objavljeno v DKUM: 08.01.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (3,69 MB)

Opis: This work explores the modifcation and characterization of chitosan thin flms as a model for functionalized polysaccharide interfaces. The solid–liquid interface of oligo- and polysaccharides is crucial for various biological processes such as cell adhesion and recognition. By covalent surface modifcation of the chitosan via amide formation with diferent small molecules containing carboxylic acids, e.g. specially designed glycoside hydrolase inhibitors, interactions with biomolecules and living cells could potentially be controlled in the future. As a frst step towards this aim, three fuorescent compounds were conjugated onto nanometric chitosan thin flms. The layers were analysed by fuorescence spectroscopy, X-ray photoelectron spectroscopy, time-of-fight secondary ion mass spectrometry, and atomic force microscopy, to proof the covalent attachment of the target molecules. By this analysis, a uniform and chemically stable covalent attachment of the target molecules on the chitosan thin flms could be demonstrated under various conditions. This publication serves as a proof-of-concept-study for further biofunctionalization, pattering, and interaction studies involving polysaccharide interfaces, glycosidase inhibitors, proteins, or living cells.
Ključne besede: carbohydrates, fluorescence spectroscopy, amino acid, chitosan, thin flm modifcation, C-Glycosides
Objavljeno v DKUM: 07.08.2024; Ogledov: 127; Prenosov: 25
Celotno besedilo (2,03 MB)