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
Celotno besedilo (4,46 MB)
Gradivo ima več datotek! Več...

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
Celotno besedilo (2,69 MB)
Gradivo ima več datotek! Več...

Opis: This study enhances the bioactivity of polycaprolactone (PCL) scaffolds for tissue engineering by functionalizing them with oxidized hyaluronic acid glycine-peptide conjugates to improve endothelial cell adhesion and growth. Hyaluronic acid was conjugated with a glycine-peptide to create a bioactive interface on PCL (static water contact angle, SCA(H2O): 98°). The scaffolds were fabricated using a melt extrusion 3D printing technique. The HA-glycine peptide conjugates were oxidized and immobilized on aminolyzed PCL via Schiff-base chemistry, introducing hydrophilicity (SCA(H2O): 21°), multiple functional groups, and a negative zeta potential (-12.04 mV at pH 7.4). A quartz crystal microbalance confirmed chemical conjugation and quantified the mass (8.5-10.3 mg m-2) of oxidized HA-glycine on PCL. The functionalized scaffolds showed enhanced swelling, improved mechanical properties (2-fold increase in strength, from 26 to 51 MPa), and maintained integrity during degradation. In-vitro experiments demonstrated improved endothelial cell adhesion, proliferation and viability, suggesting the potential for vascularized tissue constructs.
Ključne besede: 3D printing, polycaprolactone, hyaluronic acid
Objavljeno v DKUM: 19.03.2025; Ogledov: 0; Prenosov: 3
Celotno besedilo (9,50 MB)
Gradivo ima več datotek! Več...

Opis: The derivatization of the polysaccharide dextran with N-protected amino acids (Boc-L-Phenylalanine, BocGlycine, Boc-L-Cysteine, and Boc-L-Cysteine-S-Trt) and peptides (Boc-L-DiPhenylalanine, Boc DiGlycine, and 2,5-diketopiperazine) as the basis for biomaterial preparation is presented in this Doctoral Dissertation. Such prepared dextran derivatives are intended to mimic the proteoglycan complex (PGs), one of the most important structural and functional biomacromolecules in the extracellular matrix (ECM) of tissue. Nowadays, developments in biomaterials are focusing increasingly on the preparation and use of biomimetic molecular structures to achieve positive results in tissue engineering (TE) and drug delivery. Designing and synthesizing these biomimetic materials, however, requires sophisticated chemical and material preparation methods, knowledge that is, currently, unexplored. In this work, we developed a suitable procedure for dextran derivatization, and investigated the most optimal reaction or deprotection conditions (temperature and time) and isolation/purification methods. The structures of the obtained BocPhe-Dex, BocGly-Dex, BocCys-Dex, and BocSTLC-Dex were analyzed with FTIR, NMR, SEC-MALS, and EA. The results showed that dextran derivatization was successful in all cases except in the case of dextran derivatization with BocCys. Investigation of the effect of the derivatization conditions and purification on the stability, purity, and other important chemical and physical properties of the obtained product, showed that the temperature and time of derivatization do not have a bigger effect on the products' properties, while the purification method, on the other hand, has. Its effect is visible in the product's purity and mass yields of products prepared under the same reaction conditions. Derivatization of dextran with peptides (Boc-L-DiPhenylalanine, BocDiGlycine, and 2,5-diketopiperazine) was performed using the CDI coupling agent or Amberlite-IR 120 as a catalyst. The products were analyzed with FTIR and 1H and 13C NMR. The results showed successful dextran derivatization in the case of BocDiPhenylalanine and BocDiGlycine, while, in the case of 2,5-diketopiperazine, a reaction covalent bond with the dextran was not confirmed. BocPhe-Dex and BocSTLC-Dex were selected as the most optimal amino acid-dextran derivatives for further preparation of 3D formulations in the shape of nanoparticles (NPs). Nanoparticles were prepared with the emulsion/solvent evaporation method from the obtained BocPhe-Dex and BocSTLC-Dex products (prepared in the first stage of this Doctoral Dissertation). SEM analysis showed that the prepared NPs were homogeneous and nicely spherical, with an average dry diameter of 325 ± 118 nm in the case of BocSTLC-Dex, and 1039 ± 382 nm in the case of NPs prepared from BocPhe-Dex. All the prepared NPs retained their proper spherical shape and stability during the acidic treatment, and so confirmed their potential for further functionalization and applications for drug delivery. The BocSTLC-Dex NPs were also evaluated with cell viability tests, which showed that the prepared NPs were not cytotoxic, one of the most important characteristics for the drug delivery applications of NPs. This work serves as a basis for further studies on the derivatization of polysaccharides with amino acids and peptides, and their application in tissue engineering or drug delivery.
Ključne besede: Amino Acid-Dextran derivatives, Peptide-Dextran derivatives, Proteoglycan complex, 3D formulation, Nanoparticles, Drug delivery
Objavljeno v DKUM: 18.10.2024; Ogledov: 0; Prenosov: 47
Celotno besedilo (9,08 MB)

Opis: In this study, we explored the development of cationized 2-hydroxyethyl cellulose (HEC) and succinylated polyallylamine (PAA) in conjunction with polyvinyl alcohol (PVA) for potential applications as antimicrobial wound dressings. Quaternary ammonium compounds are known for their broad-spectrum antimicrobial properties against both Gram-negative and Gram-positive bacteria, but their non-selectivity can lead to high cytotoxicity. To improve the biocompatibility of the cationic materials investigates two distinct approaches. The first approach involves reducing the cationic nature of protonated PAA at a pH below 8.3 through amidation reaction with succinic anhydride. Gradual reduction of the cationic charge is achieved by varying the molar ratios of succinic anhydride during the reaction process. Notably, this reaction can be carried out in an aqueous solution, eliminating potential issues associated with solvent removal. The second part of this thesis focuses on introducing cationic charge by covalently binding naturally occurring quaternary ammonium compounds, such as betaine hydrochloride (BET HCl), choline chloride (ChCl), and carnitine hydrochloride (carnitine). Using 1,1′-carbonyldiimidazole (CDI), we quaternized HEC in anhydrous DMSO, with a detailed investigation of the reaction mechanism by isolating and characterizing intermediate products. This same procedure was applied to form a cationic dimer between BET HCl and ChCl. The chemical structures of the resulting materials were characterized using attenuated total reflectance infrared spectroscopy (ATR-IR) and nuclear magnetic resonance (NMR). The quantification of cationic and total charge was determined through polyelectrolyte and potentiometric titration, respectively. While succinylated PAA exhibited the anticipated biological properties associated with the reduction of cationic characteristics, the same behaviour was not observed for quaternized materials. High cytotoxicity and low antimicrobial properties in the derivatized HEC may be attributed to inadequate purification and the sensitivity of fibroblasts. We produced electrospun non-woven mats incorporating PVA and these derived materials using a single-needle electrospinning machine. The average diameter of the fibres was determined through scanning electron microscopy (SEM) images. Despite the cytotoxicity and the absence of significant antimicrobial properties in these materials, they exhibit potential as effective cationic flocculants for wastewater treatment. Further investigations are pending to address purification issues and make slight adjustments to the procedure to potentially scale up production. These materials still hold promise for applications in both biomedical and environmental chemistry.
Ključne besede: cellulose, quaternary ammonium compounds, antimicrobial, cytotoxicity, electrospinning
Objavljeno v DKUM: 11.07.2024; Ogledov: 127; Prenosov: 59
Celotno besedilo (16,36 MB)