Browsing by Subject "nanofibrillar cellulose"
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(2017)In vitro liver cell models are important systems to study for example hepatotoxicity, which is one of the major causes for safety-related failures of drug candidates. 2D cell culture-based tests for compound screening are standard procedures in drug discovery, but reliable data for in vivo studies is hard to obtain because cells in a monolayer are in unnatural microenvironment. In turn, cells in 3D culture systems have more natural interactions with other cells and extracellular matrix, and their responses to drugs resemble more in vivo responses. In drug discovery and development, automation of the cell culture processes and compound screening saves time and costs, and improves the consistency and sterility of the procedures. As 3D cell culture systems are becoming more compatible with automation, they are also more promising to be used in drug discovery and development. The aim of the study was to develop and optimize automated processes for preparing 3D cell cultures into 96-well plates. HepG2, a human liver cancer cell line, cultures in nanofibrillar cellulose were prepared into well plates manually or by using automated liquid handling system. To our knowledge, this was the first time that automated processes for cell seeding into NFC were used to prepare 3D cell cultures. Cell seeding steps that could be automated were identified and optimized based on visual analysis of the wells and viability of the cells after seeding. After optimization, manual and automated processes were compared by studying cell viability, morphology and functionality. Alamar blue assay, Live/Dead assay and fluorescence-activated cell sorting were used to study cell viability, and F-actin staining, differential interference contrast microscopy and light microscopy were used to investigate cell morphology. Cell functionality was analyzed by studying albumin secretion. Cells seeded by using automation secreted normal amounts of liver-specific albumin. Cells maintained viability, morphology and functionality for four days after seeding although the results of viability varied. Alamar blue assays showed decreased development of viability although viability of manually seeded cells increased, but in other experiments the results from cultures seeded manually or by using automation were more similar. For example, lower viscosity of nanofibrillar cellulose and longer waiting time of cells at room temperature before automated processes are possible explanations for differences, as well as the natural variability in cell studies. In the future, automated high-throughput screening of compounds could be performed in 3D cell cultures prepared by using automation. That would save time and costs, and increase the correlation between in vitro and in vivo studies.
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Nanofibrillaarinen selluloosa-hydrogeelilääkeformulaatio ja kirurginen lanka Crohnin taudin hoidossa (2016)Crohn's disease is a type of inflammatory bowel disease. There are no treatment procedures that can cure Crohn's disease, but it is usually controllable with medicinal options. However 70 - 80 % of patients will require surgery and most undergo several during their life, due to weak local potency of drugs and disrupted recovery from surgical treatment. A better method of combined treatment, such as a drug releasing surgical suture, could improve the disease recovery process. One approach would be to coat a surgical suture with nanofibrillar cellulose (NFC) hydrogel containing the active drug ingredient within. NFC is biocompatible, biostable and it can be easily chemically modified. It displays pseudoplastic and thixotropic gel-like behavior in aqueous suspension in addition to high shear thinning properties under low and high shear rates. The shear-thinning behavior is particularly useful in a range of different coating applications. Furthermore, recent studies have shown the potential of NFC in controlled drug release. The aim of this Master's thesis was to investigate the suitability of anionic NFC hydrogel for surgical suture coatings and controlled release applications. The structure of NFC hydrogel was modified with crosslinking cations (Fe3+, Al3+, Ca2+) and alginate. The diffusion studies were performed with two antibiotics, metronidazole and rifaximin together with FITC-dextrans (10 and 250 kDa). The surgical suture was coated with each type of hydrogels (n = 16). Furthermore, the suitability of suture drug formulation for controlled drug release was simulated with STELLA® modeling software. It was shown that the NFC hydrogel structure was stiffened with the use of crosslinking cations; however similar results were not observed with the addition of alginate. Release profiles of model compounds were similar before and after NFC hydrogel crosslinking. At 6 days, 50 - 60 % of 10 kDa dextran (6 µg) was released. For 250 kDa dextran (6 µg) the released amount was 25 - 35 %. During the first 3 days of the diffusion study, all of metronidazole (20 µg) was released. Rifaximin samples were not obtained due to high adsorption to the container surfaces. The release profiles of metronidazole and 10 kDa dextran had linear correlation with square-root diffusion process. 250 kDa dextran followed a near zero-order kinetics after a few hours from the start. The coating was performed successfully with NFC hydrogels except for hydrogels with dextrans or without crosslinking. Metronidazole was predicted to release from the surgical suture almost instantly with STELLA® modeling software. NFC hydrogel shows potential as a matrix for controlled drug release and the coating of surgical sutures. However, the manufacturing method of the NFC hydrogel could be improved with surface modifications of nanofibrils or with the choice of a drug or of its derivatives. With pharmacokinetic simulation models it is possible to predict and estimate different factors which affect drug release from the surgical suture. Furthermore, the simulation models can be used to estimate an effect in the treatment of Crohn's disease.
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(2016)Nanofibrillar cellulose (NFC) can form hydrogels with high water content (> 98 %). It has been studied for drug release, and it has been used as a cell culture matrix, due to its similar structure to extracellular matrix (ECM). In addition it has been found that they has no cytotoxicity. Iontophoresis is the application of an electric current over a defined area for the purpose of enhancing permeation across a membrane for ionized drug species. The aim in the experimental work in this Master's thesis is twofold. First, to find out the suitable drug loading concentrations into NFC hydrogels, which can provide a good release profile, a release study with two model drugs, propranolol and ketoprofen, loaded into three types of NFC hydrogels at three different concentrations, was carried out for this purpose. Second, to see if NFC hydrogels are applicable as a drug reservoir in iontophoretic transdermal drug delivery applications, an iontophoresis study was carried out using porcine ear skin model in vitro for human skin with propranolol loaded into NFC hydrogel of type A. In addition, Stella models were used as an aid to find suitable ways to predict the release and permeation behaviour of models drugs in the abovementioned context. The UPLC results from the release study show for both model drugs, the wt. % released had linear correlation with squareroot of time. At 6 hours, more than 70 wt. % propranolol was released from hydrogel reservoir. For ketoprofen, the release varied between 30 - 87 wt. %, where higher initial loading concentrations produced a decrease in the wt. % released from hydrogel. The iontophoresis study did not show a significant difference between the tested current densities (0.50 mA/cm2; 0.25 mA/cm2) produced on the wt. % of drug released. Simulation models could be run with the mathematical equations for diffusion controlled drug release. In conclusion, the NFC hydrogels show potential as drug reservoir for drug release. Additional experimental data using other types of drug reservoirs should be obtained for a better understanding of the suitability of NFC hydrogels as a drug reservoir in iontophoretic transdermal drug delivery.
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(2013)Cellulose has already been used as an industrial raw material for over a century. However, during recent years the nanostructural features of the naturally occurring biopolymer have been fully investigated and characterized through different processing methods as nanofibrillar cellulose (NFC). This has led to a rapid development of novel cellulose based nanoscale materials and advancements in the field of composite materials. NFC offers interesting specific properties that differ from many other natural and synthetic polymers, such as self-renewable raw materials, semi-crystalline morphology, broad chemical modification capacity, biocompatibility and biodegradability. Biocompatibility and the biomimetic aspects of NFC have enabled the fabrication of nanoporous membranes and scaffolds that can function as medical devices (e.g. tissue engineering, wound healing, novel active implants). In this study, the properties of plant-derived NFC, as potential injectable drug releasing hydrogel "implants" were investigated. Three different sized candidate molecules were selected (123I-NaI, 123I-β-CIT and 99mTc-HSA, from small to large respectively) and investigated with the use of a small animal SPECT/CT molecular imaging device. Study compounds were mixed with the NFC biomaterial and injected into the pelvic region of mice. Drug release was observed for a period of 24 hours and the results were compared to saline/study compound control injections. In addition, 99mTc labeled NFC hydrogels were prepared for dual label tracing to observe the hydrogel positioning during the SPECT/CT acquisitions. For the smaller compounds (123I-NaI, 123I-β-CIT), no differences were found in the drug release or absorption in between the NFC biomaterial and saline injections. However, a clear difference was found with the large compound (99mTc-HSA). In the NFC hydrogel, the rate of release was slower and the distribution of 99mTc-HSA was more concentrated around the area of injection. In addition, the NFC hydrogel did not migrate from, or disintegrate, at the site of injection, suggesting a robust enough structural integrity to withstand normal movement and activity. In conclusion, the labeling of NFC was found to be a reliable and simple method. NFC hydrogels have the potential use as drug releasing medical devices with larger compounds. NFC matrix did not have any controlled release effect on the studied small molecules. Therefore further studies are required for more specific conclusions.
Now showing items 1-4 of 4