Browsing by Subject "hydrogel"

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  • Karppinen, Jutta (Helsingfors universitet, 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.
  • Heilala, Maria (Helsingin yliopisto, 2019)
    Despite the advances in the management of breast cancer, discovery of novel and targeted drugs remains a challenge. It has been suggested that drug failure rates in clinical trials might be diminished by improving the predictive potential of preclinical cancer models. Three-dimensional (3D) scaffold-based cell culture has emerged as an attractive platform for mimicking tissue-like microenvironment, since it is well-known that cells respond to the cues in the extracellular matrix (ECM). The aim of this thesis was to develop fibrin-based hydrogels and evaluate their performance in 3D cell culture of breast cancer cells. The fibrin gel formulation was first optimized by testing the effect of different buffers on gel properties. Structural properties were examined with scanning electron microscopy and mechanical properties measured with oscillatory rheometry. Three different fibrin concentrations of the optimized formulation were then used as scaffolds for DU4475 breast cancer cells. After seven days of culture, the morphology, phenotype and proliferation of the resulting cell structures were assessed by using techniques such as light microscopy, immunofluorescent confocal microscopy and Western blot analysis. The desired properties for 3D cell culture were obtained by preparing fibrin gels at high pH in the absence of calcium. The main finding of the thesis was that fibrin concentration strongly affected the phenotype of DU4475 cells, with cells cultured in the softest gel retaining their original characteristics to the greatest extent. In the future, the developed scaffold could possibly be used in drug discovery and personalized medicine by culturing tumor explants from patients. However, the methods used in the study must be further optimized and the results validated with other breast cancer cell lines and with primary tissues.
  • Shahbazi, Mohammad-Ali; Almeida Ferreira, Monica; Santos, Hélder A. (2019)
    Wound infection is a localized pathological defect in which microorganisms invade skin lesions and decelerate the healing process by triggering inflammation and preventing reepithelization via rapid colonization or biofilm formation [1]. Studies have demonstrated that microorganisms can be seen to accumulate in 6% of acute wounds and over 90% of chronic ones, denoting a therapeutic challenge due to their resistance to conventional antibiotics [2]. This demonstrates that bacterial infections in wounds can become more severe over time and increase healthcare costs when left untreated. To circumvent the above-mentioned challenge, various nanotechnological advancements are under investigation to develop economically viable, multifunctional, potent and ecofriendly therapeutics with novel mechanisms of action as new sources of antibacterial agent [3]. Cutaneous wound healing usually involves topical delivery, which makes nanotherapeutics relatively easy to formulate, generally as wound dressings. Nanomaterials employed for this purpose either exhibit intrinsic properties beneficial for wound treatment and/or can be used as delivery vehicles for therapeutic agents [3]. In this editorial, we aim to provide a balanced discussion on the fundamental aspects of antimicrobial nanodots for wound repair. We focus on the potential of organic and inorganic nanodots/quantum dots (QDs), tiny zero-dimensional particles of small size (usually smaller than 50 nm), for the promotion of wound healing through inhibition of bacterial growth in the skin lesion or overcoming developed antibiotic resistance in the local infections. Current challenges and possible future research directions are also presented.
  • Joraholmen, May Wenche; Johannessen, Mona; Gravningen, Kirsten; Puolakkainen, Mirja; Acharya, Ganesh; Basnet, Purusotam; Skalko-Basnet, Natasa (2020)
    Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infections and causes serious reproductive tract complications among women. The limitations of existing oral antibiotics and treatment of antimicrobial resistance require alternative treatment options. We are proposing, for the first time, the natural polyphenol resveratrol (RES) in an advanced delivery system comprising liposomes incorporated in chitosan hydrogel, for the localized treatment of C. trachomatis infection. Both free RES and RES liposomes-in-hydrogel inhibited the propagation of C. trachomatis in a concentration-dependent manner, assessed by the commonly used in vitro model comprising McCoy cells. However, for lower concentrations, the anti-chlamydial effect of RES was enhanced when incorporated into a liposomes-in-hydrogel delivery system, with inhibition of 78% and 94% for 1.5 and 3 mu g/mL RES, respectively for RES liposomes-in-hydrogel, compared to 43% and 72%, respectively, for free RES. Furthermore, RES liposomes-in-hydrogel exhibited strong anti-inflammatory activity in vitro, in a concentration-dependent inhibition of nitric oxide production in the LPS-induced macrophages (RAW 264.7). The combination of a natural substance exhibiting multi-targeted pharmacological properties, and a delivery system that provides enhanced activity as well as applicability for vaginal administration, could be a promising option for the localized treatment of C. trachomatis infection.
  • Srbova, Linda (Helsingin yliopisto, 2020)
    In this work, a series of biocompatible nanocomposite hydrogels was prepared by UV-initiated polymerization based on 2-hydroxyethyl methacrylate (HEMA), using ethylene glycol dimethacrylate (EGDMA) as a crosslinker and 2-hydroxymethyl-2-methylpropiophenone as a photoinitiatior, containing liquid crystals of cellulose nanocrystals (CNCs) doped with magnetic nanoparticles. The formation of liquid crystals was achieved thanks to the intrinsic property of CNCs to self-assemble above a critical aqueous concentration. By varying the preparation conditions, allowing different times for phase-separation between the nanoparticles and CNCs and exposing the polymerization mixture to small magnetic field, films with different size and orientation of CNC liquid crystal domains were synthesized. Subsequently, the hydrogel films were studied by dynamic mechanical analysis (DMA) to evaluate the effect of these parameters on the mechanical properties, specifically the Young’s modulus and the ultimate strength. Also, the microstructure of the films was studied via polarized optical microscopy (POM) and scanning electron microscopy (SEM). The water uptake capacity was also analyzed. The results indicate that the presence of cellulose nanocrystals modulates the architecture of the prepared hydrogels. Cholesteric microdomains were embedded in PHEMA matrix and their uniaxial alignment was achieved upon exposure to small static magnetic field, already after several hours. Moreover, structural gradient in the distribution of the liquid crystalline microdomains, in dependence on their size, was obtained within the material. This originated from the direct proportionality between the size and the density of liquid crystals. Finally, it was shown that cellulose nanocrystals act as reinforcing structures of the hydrogels, when the degree of their self-assembly is sufficient, and therefore the resulting hydrogel exhibits both higher resistance to elastic deformation and also higher ultimate strength. Finally, we showed that mechanical performance of these nanocomposites can be enhanced by systematic orientation of the liquid crystalline domains.
  • Kunnari, Mikko (Helsingfors universitet, 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.
  • Alakalhunmaa, Suvi (Helsingfors universitet, 2014)
    Aerogels are lightweight, porous and dry foams that are produced from gels by replacing the liquid phase by air. When produced from polysaccharide-based hydrogels, potential applications for aerogels could be found as bio-based packaging materials. The literature review focused on the production of polysaccharide-based hydrogels and their chemical crosslinking, as well as the production of aerogels and their properties. In the experimental study the possibilities for utilization of spruce galactoglucomannan (GGM), an abundant but largely unexploited raw material, as aerogel matrix was explored. Nanofibrillated cellulose (NFC) was used as reinforcement and the polysaccharides were crosslinked with ammonium zirconium carbonate (AZC). Hydrogels were prepared from GGM-NFC-suspensions and heat treatment was performed in order to induce crosslinking reaction. Prepared hydrogels were frozen in a bath of carbon dioxide ice and ethanol and subsequently freeze-dried into cubic aerogels. The aim was to investigate the effect of polysaccharide proportions and AZC content on the strength of hydrogels and on the mechanical properties and moisture sensitivity of aerogels. The formation of crosslinks was observed indirectly from the values of storage and loss moduli by dynamic rheological measurement. The strength of hydrogels was highly dependent on the AZC and NFC content. In contrast, the compressive modulus of aerogels instead was affected only by NFC content at relative humidity (RH) of 50% and 23 °C. Hydrogel strength could not be used for prediction of aerogel strength under these ambient conditions. AZC and NFC mainly decreased the sensitivity of aerogels towards moisture by decreasing the water absorption and its plasticizing effect on aerogels. The effect of crosslinking on mechanical and physical properties of aerogels appeared clearly at RH over 50%. GGM was shown to be a suitable aero-gel raw material when combined with NFC. The role of NFC in enhancing the aerogel’s me-chanical properties was significant. The mechanical properties of uncrosslinked aerogels, how-ever, weakened in a humid environment. In particular, AZC is needed to protect aerogels from the plastizicing effect of water. Properties of crosslinked aerogels in a humid environment would be an interesting subject of further studies.
  • Laurén, Patrick (Helsingfors universitet, 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.