Iskanje po katalogu digitalne knjižnice

Opis: Novel bioactive bacterial nanocellulose (BnC) membranes were developed for effective, non-surgical debridement and infection-prevention in burn wound healing. Membranes were modified in situ with carboxymethyl cellulose (CMC) and ex situ with the proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N). Post-processing into stable cellulose nanocrystal dispersions (ζ = -26 mV), enables assembly of model films for demonstration of high, irreversible bromelain (95 %) and nisin (99.5 %) adsorption. The BnC-CMC and BnC-CMC-N membranes were in vitro cytocompatible for HaCaT cells and induced faster cell proliferation with cell viability exceeding 100 % after 24 h incubation. The innovative aspect of this study lies in the ex vivo evaluation using an advanced human skin explant model with induced burns, providing a realistic, physiologically relevant assessment of membrane performance. Ex vivo experiments indicated the cytocompatibility of the BnC-CMC membrane with no acute toxicity or skin irritation, while nisin presence resulted in moderate irritating effect. Notably, the BnC-CMC-Br membrane showed digestion of intercellular junctions in the epidermis, while not inducing acute toxicity and skin irritation. By leveraging this innovative ex vivo human skin model in novel BnC-based membranes testing, the study provides a crucial translational step, bridging in vitro assessments and clinical applications for burn wound treatment.
Ključne besede: bacterial nanocellulose, Bromelain, Nisin, Carboxymethyl cellulose, antimicrobial function, bioactive, burn wound treatment
Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 5
Celotno besedilo (24,82 MB)
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Opis: Tissue engineering (TE) is an interdisciplinary field that aims towards replacement, healing or reconstruction of damaged tissue and organs. Incurable diseases are currently treated with organ transplantation, that have the disadvantages of insufficient donors, immune response, and organ rejection after transplantation. TE imitate the functions of extracellular matrix (ECM) to develop biocompatible/biodegradable scaffolds with appropriate features which are utilized to provide mechanical support, cellular infiltration, migration, and tissue formation, and to mimic the biochemical and biophysical cues of cells. Several fabrication methods have been introduced to mimic the 3D structure of ECM and 3D printing is one of the additive manufacturing techniques, widely used in TE because of its feasibility to build complex tissue constructs and control over fabrication and cell distribution. The polysaccharide-peptide conjugate has gained enormous interest in recent years owing to its biocompatibility, degradability, flexibility, and structural matching to natural proteoglycans. In this context, we reported here on investigation of biocompatibility with HUVECs, surface modification of 3D printed PCL scaffolds with an amine group and chemically crosslinked oxidized HA-amino acid/peptide conjugates (OHACs) was used to develop a novel biomaterial for use as a tissue engineered vascular graft. Modified polysaccharides were characterized with respect to their chemical structure, charge, UV and fluorescence properties and cytotoxicity. The successful conjugation was demonstrated by XPS, and a decrease in the free amine peaks on the surface was observed after conjugation. In addition, the water contact angle measurements showed improved wetting, an indication that the conjugation to the PCL-A surface was successful. Finally, the biocompatibility of the novel scaffolds was characterized by the MTS and the live- dead assay. In both assays, proliferation of cells was observed after 7 days and cell spreading on the surface was detected by phalloidin staining of actin filaments. In conclusion, it was possible to prepare surface-active scaffolds by combining the advantages of biocompatibility and mechanical strength of polysaccharides and polyesters, respectively.
Ključne besede: 3D tiskanje, karboksimetilceluloza, hialuronska kislina, polikaprolakton, kemija karbodiimida, kemija Shiffove baze, endotelizacija 3D printing, carboxymethyl cellulose, hyaluronic acid, polycaprolactone, carbodiimide chemistry, shiff-base chemistry, endothelialization
Objavljeno v DKUM: 06.10.2023; Ogledov: 522; Prenosov: 56
Celotno besedilo (7,97 MB)

Opis: The aim of the thesis is to investigate the applicability of nanometric amorphous cellulose model films for the immobilization of functional DNA molecules and to apply this knowledge in the field of DNA microarray preparation. To achieve this aim, the whole thesis work is divided into three major parts, namely part I (partly and fully regenerated cellulose film preparation and its characterization), part II (functional polysaccharide conjugates preparation) and part III (DNA microarray preparation from polysaccharide functional conjugates). The first part of the work mainly focuses on the preparation of cellulose model films from spin coated trimethylsilyl cellulose (TMSC) using an in-situ and ex-situ regeneration methods and its characterization. In the in-situ method, the conversion of TMSC to pure cellulose via acid vapor hydrolysis is investigated at the gas-solid interface in real time and at ambient conditions employing quartz crystal microbalance with dissipation (QCM-D). For this purpose, a permanent flow of gaseous HCl is employed which reacts with TMSC coated surface to form pure cellulose. The kinetics behind this reaction is elucidated and reveals first order. Moreover, the influence of the acid concentration on the kinetics and on changes in mass and film thickness of TMSC is studied. In the case of an ex-situ method, partly and fully regenerated cellulose model films are prepared from spin coated TMSC films through acid vapor phase hydrolysis. This is done by exposing the TMSC films placed in a closed container to vapors of HCl. The regeneration is carried out on one hand by exposing the films to different time intervals and on the other hand to different volume of HCl. The changes in surface morphology, structure, surface composition and film thickness in the course of regeneration (i.e. desilylation) is studied by using various surface analytical techniques like atomic force microscopy (AFM), attenuated total reflectance infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and ‘Sarfus’-technique. In order to gain detailed insight into the desilylation reaction of the films the results from ATR-IR, XPS and thickness measurements are compared with data from static contact angle (SCA) and surface free energy (SFE) determination. Besides, to verify the completion of regeneration of cellulose from TMSC the partly and fully regenerated films prepared using ex-situ method are interacted with cellulase enzymes from Trichoderma viride using QCM-D technique. The changes in mass and energy dissipation due to the interaction of the enzymes with the substrates are correlated with the surface wettability and elemental composition of the regenerated films. The enzymatic degradation rate correlated well to the rate of regeneration. It is demonstrated that capillary zone electrophoresis (CZE) can be used to support QCM-D data via the detection of enzyme hydrolysis products in the eluates of the QCM-D cells. It is also shown that a combination of QCM-D together with enzymatic digestion is a reliable method to monitor the time dependent regeneration of TMSC to pure cellulose. Furthermore, the effect of heat treatment on partly and fully regenerated cellulose films prepared using ex-situ method is investigated by exposing the films to elevated temperature (105 °C) for a prolonged time (6 hours). Upon heating, a structural rearrangement in the films from a featureless to a fibrillar-like structure is observed as evidenced by AFM. Several analytical methods, namely GIXRD, ATR-IR, Sarfus, XPS and SCA data are employed to analyze the alteration in the structure, surface composition, film thickness, wettability and SFE of the time dependent regenerated films before and after heat treatment. Results from solvent (D2O/H2O) exchange studies proved that water content and water uptake capacity of heat treated cellulose films are significantly reduced compared to non heated films.Additionally, a new method is developed to structure nanometric cellulose films via vapor phase acid hydrolysis and enzymat
Ključne besede: Cellulose model films, carboxymethyl cellulose, trimethylsilyl cellulose, microarrays, quartz crystal microbalance, carbodiimide coupling, aminofluorescein, DNA
Objavljeno v DKUM: 28.11.2012; Ogledov: 2807; Prenosov: 185
Celotno besedilo (6,46 MB)