Browsing by Author "Lehtonen, Janika"

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  • Adsorption and Assembly of Cellulosic and Lignin Colloids at Oil/Water Interfaces
    (2019-01-22) Bai, Long; Greca, Luiz G.; Xiang, Wenchao; Lehtonen, Janika; Huan, Siqi; Nugroho, Robertus Wahyu N.; Tardy, Blaise L.; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The surface chemistry and adsorption behavior of submicrometer cellulosic and lignin particles have drawn wide-ranging interest in the scientific community. Here, we introduce their assembly at fluid/fluid interfaces in Pickering systems and discuss their role in reducing the oil/water interfacial tension, limiting flocculation and coalescence, and endowing given functional properties. We discuss the stabilization of multiphase systems by cellulosic and lignin colloids and the opportunities for their adoption. They can be used alone, as dual components, or in combination with amphiphilic molecules for the design of multiphase systems relevant to household products, paints, coatings, pharmaceutical, foodstuff, and cosmetic formulations. This invited feature article summarizes some of our work and that of colleagues to introduce the readers to this fascinating and topical area.
  • Bacterial nanocellulose enables auxetic supporting implants
    (2022-05-15) Ajdary, Rubina; Abidnejad, Roozbeh; Lehtonen, Janika; Kuula, Jani; Raussi-Lehto, Eija; Kankuri, Esko; Tardy, Blaise; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Owing to its purity and exceptional mechanical performance, bacterial nanocellulose (BNC) is well suited for tissue engineering applications. BNC assembles as a network that features similarities with the extracellular matrix (ECM) while exhibiting excellent integrity in the wet state, suitable for suturing and sterilization. The development of complex 3D forms is shown by taking advantage of the aerobic process involved in the biogenesis of BNC at the air/culture medium interphase. Hence, solid supports are used to guide the formation of BNC biofilms that easily form auxetic structures. Such biomaterials are demonstrated as implantable meshes with prescribed opening size and infill density. The measured mechanical strength is easily adjustable (48–456 MPa tensile strength) while ensuring shape stability (>87% shape retention after 100 burst loading/unloading cycles). We further study the cytotoxicity, monocyte/macrophage pro-inflammatory activation, and phenotype to demonstrate the prospective use of BNC as supportive implants with long-term comfort and minimal biomaterial fatigue.
  • Bakteeriselluloosan ominaisuuksien muokkaus
    (2016-05-08) Utriainen, Katja
     Kemiantekniikan korkeakoulu | Bachelor's thesis
  • Biopohjaiset nahan korvikkeet
    (2021-05-09) Hämäläinen, Petteri
     Kemiantekniikan korkeakoulu | Bachelor's thesis
  • Biosynthetic production of bacterial cellulose-chitosan composite by modifying Hestrin-Schramm broth sugar composition
    (2019-12-17) Laine, Mikko
     Kemian tekniikan korkeakoulu | Master's thesis
    Some microorganisms provide an ecological way to produce pure cellulose without costly, energy-intensive purification steps. However, while bacterial cellulose (BC) holds desirable properties, such as biodegradability and high mechanical strength, human body lacks cellulose-hydrolyzing enzymes, which restricts the use of BC in different biomedical applications. To overcome this limitation, amine-incorporated BC composites, exhibiting chitosan-like properties are introduced. Reactive amine groups incorporated in BC provide an excellent basis for enzyme immobilization and biocompatibility, required for medical applications ranging from drug delivery to artificial skins. In this thesis, BC-chitosan composites are produced biosynthetically by modifying Hestrin-Schramm broth sugar composition. It has been previously shown, that Komagataeibacter xylinus is able to in situ incorporate chitosan and chitin groups from the culture medium to the BC. The results of this study suggest that compared to K. xylinus, K. medellinensis is a more suitable strain for amine-incorporated BC production. The highest chitosan content, 2.3 % (w/w), was achieved with K. medellinensis in HS culture including 2.0 % (w/v) N-acetyl-glucosamine. In addition, amine-incorporated BC was produced with culture including glucose and ammonium chloride, with 0.2 % (w/v) determined as the optimal NH4Cl concentration for BC-composite production. The produced BC composites were analyzed with FTIR, MALDI-TOF, HPAEC-PAD and SEM, with ζ-potential and water holding capacity also determined.
  • Effects of Chloride Concentration on the Water Disinfection Performance of Silver Containing Nanocellulose-based Composites
    (2019-12-01) Lehtonen, Janika; Hassinen, Jukka; Honkanen, Riina; Kumar, Avula Anil; Viskari, Heli; Kettunen, Anu; Pahimanolis, Nikolaos; Pradeep, Thalappil; Rojas, Orlando J.; Ikkala, Olli
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The availability of microbially-safe drinking water is a challenge in many developing regions. Due to the well-known antibacterial effect of silver ions, materials used for their controlled release have been widely studied for point-of-use water disinfection. However, even if it is in principle known that chloride anions can suppress the antibacterial efficiency of silver, the majority of previous studies, surprisingly, have not focused on chloride concentrations relevant for freshwaters and thus for practical applications. Here, we prepared low-cost nanocellulose-aluminium oxyhydroxide nanocomposites functionalized with silver nanoparticles. Field samples obtained from Chennai, India were used as a guideline for choosing relevant chloride concentrations for the antibacterial studies, i.e., 10, 90, and 290 ppm. The antibacterial performance of the material against Escherichia coli and Bacillus subtilis was demonstrated and the influence of chloride concentration on the antibacterial effect was studied with E. coli. A 1 h contact time led to bacterial reductions of 5.6 log10, 2.9 log10, and 2.2 log10, respectively. This indicates that an increase of chloride concentration leads to a substantial reduction of antibacterial efficiency, even within chloride concentrations found in freshwaters. This work enables further insights for designing freshwater purification systems that utilize silver-releasing materials.
  • Enzymatic hydrolysis of stilbene glucosides in spruce bark extract
    (2022-08-23) Havaei, Mohammadhossein
     Kemian tekniikan korkeakoulu | Master's thesis
    Spruce inner bark houses a variety of valuable compounds such as stilbenes. Despite this opportunity, this raw material is often incinerated to generate energy or simply landfilled. Stilbenes are polyphenols existing in plants as an extractive with antioxidant and radical scavenging properties that are reported widely in the literature. They are mostly found bonded to a glucose unit which in turn, makes them less bioavailable. In this work, some improvements on the extraction process using spruce bark were investigated and a commercial cellulase enzyme was employed to deglycosylate the stilbene glucosides present in spruce bark extract. The enzyme activity was explored using a Box-Behnken design and optimized via response surface methodology. The possibility of using high performance anion exchange chromatography and gas chromatography methods was investigated for quantification of the results and high performance liquid chromatography was employed for producing the results used in the model. Mass spectroscopy was utilized for the identification of the peaks. In optimized conditions at pH of 5 and 6.28 h, 92.3% of the stilbene species inside the extract solutions were in aglycone form showing great success in the biotransformation. Additionally, 21.4 mg of stilbenes per g of dry wood was extracted as a result of the modifications made in the extraction stage.
  • Filtration properties of bacterial cellulose membranes
    (2015-10-06) Lehtonen, Janika
     Kemian tekniikan korkeakoulu | Master's thesis
    Bacterial cellulose has the same molecular formula as cellulose from plant origin, but it is characterized by several unique properties including high purity, crystallinity and mechanical strength. These properties are dependent on parameters such as the bacterial strain used, the cultivation conditions and post-growth processing. The possibility to achieve bacterial cellulose membranes with different properties by varying these parameters could make bacterial cellulose an interesting material for membrane separation applications. The aim of this study was to evaluate the possibilities of using bacterial cellulose membranes for membrane separation. The properties of unmodified bacterial cellulose membranes were compared to post-modified membranes. The pure water fluxes for the membranes were determined and the rejections of bovine serum albumin and polyethylene glycol, polyethylene oxides and blue dextrans of different molecular weights, for selected membranes, were determined. The morphology of the membranes was visualized by scanning electron microscopy and the surface chemistry was analyzed by x-ray photoelectron spectroscopy. The results from the filtration experiments conducted in this work indicate that bacterial cellulose membranes could have potential for use in membrane separation applications, but significant improvements would have to be made in terms of the pure water fluxes and pore sizes. The pure water flux for an unmodified bacterial cellulose membrane was 10.5 Lm-2h-1 which is significantly lower than for commercial membranes. For separations based on size exclusion, the pore sizes should be decreased if for instance protein separation would be the target. Modifying bacterial cellulose membranes to facilitate affinity separation could be a considerable option for size exclusion based separations.
  • Functional Materials from Nanocellulosic Networks and Uses in Water Purification
    (2020) Lehtonen, Janika
     School of Chemical Technology | Doctoral dissertation (article-based)
    Due to their nano-scaled dimensions and mechano-chemical versatility, nanocelluloses have generated interest in the production of various types of bioproducts. However, the full potential of these materials and their applications, which are strongly coupled to their structural features, is yet to be realized. In this thesis, two types of nanocelluloses, cellulose nanofibrils (CNF) and bacterial nanocellulose (BNC), are introduced to achieve different types of porous networks and functional materials. The performance of CNF and CNF-based materials is investigated in applications related to water purification. Composites incorporating cationic CNF and silver nanoparticles are studied for use in drinking water disinfection. Phosphorylated CNF is implemented for the removal of uranium from water via batch adsorption. With BNC, the opportunities provided by biological fabrication of nanofibrous materials are considered in the synthesis of 2D membranes as well as intricate 3D structures. The impact of physico-chemical modifications of the fibrous networks in the BNC membranes are investigated to give insights on their potential use in pressure-driven filtration. To produce 3D structures from BNC, a simple method is developed utilizing hydrophobic particles for stabilization of air-water interfaces. Utilizing this method, capsules were produced and applied as sensors and enzymatic reactors in aqueous media. This thesis provides insights and novel pathways for the production and application of porous nanocellulose-based structures. They are expected to contribute to the development of future functional materials, for instance in the field of water purificaton.
  • Guiding Bacterial Activity for Biofabrication of Complex Materials via Controlled Wetting of Superhydrophobic Surfaces
    (2020-10-27) Greca, Luiz G.; Rafiee, Mahdi; Karakoç, Alp; Lehtonen, Janika; Mattos, Bruno D.; Tardy, Blaise L.; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Superhydrophobic surfaces are promising for preventing fouling and the formation of biofilms, with important implications in the food chain, maritime transport, and health sciences, among others. In this work, we exploit the interplay between wetting principles of superhydrophobic surfaces and microbial fouling for advanced three-dimensional (3D) biofabrication of biofilms. We utilize hydrostatic and capillary pressures to finely control the air-water interface and the aerotaxis-driven biofabrication on superhydrophobic surfaces. Superhydrophobic 3D molds are produced by a simple surface modification that partially embeds hydrophobic particles in silicone rubber. Thereafter, the molds allow the templating of the air-water interface of the culture medium, where the aerobic nanocellulose-producing bacteria (Komagataeibacter medellinensis) are incubated. The biofabricated replicas are hollow and seamless nanofibrous objects with a controlled morphology. Gradients of thickness, topographical feature size, and fiber orientation on the biofilm are obtained by controlling wetting, incubation time, and nutrient availability. Furthermore, we demonstrate that capillary length limitations are overcome by using pressurized closed molds, whereby a persistent air plastron allows the formation of 3D microstructures, regardless of their morphological complexity. We also demonstrate that interfacial biofabrication is maintained for at least 12 days without observable fouling of the mold surface. In summary, we achieve controlled biofouling of the air-water interface as imposed by the experimental framework under controlled wetting. The latter is central to both microorganism-based biofabrication and fouling, which are major factors connecting nanoscience, synthetic biology, and microbiology.
  • Impact of incubation conditions and post-treatment on the properties of bacterial cellulose membranes for pressure-driven filtration
    (2021-01-01) Lehtonen, Janika; Chen, Xiao; Beaumont, Marco; Hassinen, Jukka; Orelma, Hannes; Dumée, Ludovic F.; Tardy, Blaise; Rojas Gaona, Orlando
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Bacterial cellulose (BC) has shown potential as a separation material. Herein, the performance of BC in pressure-driven separation is investigated as a function of incubation conditions and post-culture treatment. The pure water flux of never-dried BC (NDBC), was found to be 9 to 16 times higher than that for dried BC (DBC), in a pressure range of 0.25 to 2.5 bar. The difference in pressure response of NDBC and DBC was observed both in cross-flow filtration and capillary flow porometry experiments. DBC and NDBC were permeable to polymers with a hydrodynamic radius of ∼60 nm while protein retention was possible by introducing anionic surface charges on BC. The results of this work are expected to expand the development of BC-based filtration membranes, for instance towards the processing of biological fluids.
  • In situ -talteenotto bioprosesseissa
    (2013-04-30) Lehtonen, Janika
     Kemiantekniikan korkeakoulu | Bachelor's thesis
  • Ligniinin käyttö tekstiileissä funktionaalisten ominaisuuksien parantamiseksi
    (2024-02-28) Brax, Virva
     Kemiantekniikan korkeakoulu | Bachelor's thesis
    Ligniini on kasvien soluseinissä esiintyvä amorfinen biopolymeeri, joka antaa kasveille mekaanista lujuutta ja suojaa patogeenejä vastaan. Ligniinin monimutkainen rakenne, joka koostuu kolmesta päämonomeerista ja useista sidostyypeistä, tekee siitä epäsäännöllisen, ristiin silloittuneen ja haaroittuneen polymeerin. Suurin osa teknisistä ligniineistä, kuten Kraft-ligniini ja lignosulfonaatit, saadaan sellunvalmistuksen sivutuotteina ja niiden ominaisuudet vaihtelevat erotusmenetelmän mukaan. Tekstiiliteollisuudessa ligniiniä voidaan hyödyntää tekstiilien ominaisuuksien parantamiseen. Ligniini voidaan saada osaksi tekstiiliä sekoittamalla se kuitumateriaaliin tai käyttämällä sitä pinnoitteena. Uudet teknologiat ja menetelmät, kuten Ioncell-F, mahdollistavat ligniinipitoisten tekstiilikuitujen valmistuksen. Ligniinistä voidaan jatkojalostaa nanoligniiniä, jota käytetään esimerkiksi biohajoavien komposiittimateriaalien ja funktionaalisten tekstiilipinnoitteiden valmistuksessa. Nanoligniiniä voidaan valmistaa eri menetelmillä, kuten ultraäänikäsittelyllä tai mikrobiaalisilla prosesseilla. Ligniinin lisääminen tekstiileihin voi tehostaa niiden funktionaalisuutta monipuolisesti. Ligniinin rakenteelliset ja kemialliset ominaisuudet tekevät siitä potentiaalisen raaka-aineen tekstiilien toiminnallisuuden kehittämiseen uusiutuvalla ja kestävällä tavalla. Ligniinin sisällyttäminen tekstiiliin voi parantaa tekstiilin UV-suojaa, antibakteriaalisia ominaisuuksia ja palonkestävyyttä. Ligniinipitoisten tekstiilien osoittama UV-suoja perustuu ligniinin rakenteessa esiintyvien funktionaalisten ryhmien ja kromoforien absorboida UV-säteilyä. Antibakteriaalisissa tekstiilisovelluksissa ligniinin polyfenoliset ryhmät vaurioittavat bakteerien soluseiniä, estäen niiden kasvun ja leviämisen tekstiilipinnoilla. Ligniinin aromaattinen rakenne tuottaa hiiltä hajotessaan, mikä parantaa tekstiilien palonkestävyyttä. Ligniinin käyttöä tekstiileissä on tutkittu myös sen antistaattisten ominaisuuksien, värjäysominaisuuksien ja mekaanista kestävyyttä parantavien vaikutusten näkökulmasta.
  • Lignin Nano- and Microparticles as Template for Nanostructured Materials: Formation of Hollow Metal-Phenolic Capsules
    (2018) Tardy, Blaise; Richardson, Joseph J.; Guo, Junling; Lehtonen, Janika; Ago, Mariko; Rojas Gaona, Orlando
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Hollow polymeric, submicrometer-scaled capsules show promise in applications ranging from water remediation to drug delivery, and the preferred method for their synthesis includes templating from sacrificial particles. Such particles are typically non-renewable and the process of selective dissolution used to produce the capsules often requires harsh and/or toxic solvents. Thus, there is a critical need to develop inexpensive, sustainable templates that can be dismantled under mild conditions. Lignins have recently been introduced as renewable precursors for the synthesis of solid particles and can favorably substitute solid particles based on petrochemical (such as latex) or mineral (such as silica) precursors. Conveniently, widely available by-product streams of biomass processing can be used for the supramolecular assembly required for lignin particle formation. Herein, we introduce two common lignin sources (kraft and alkali lignins) as renewable and easily degradable particulate templates for the preparation of hollow polymeric capsules. The polymeric nanocoating, or wall of the capsules, was synthesized from renewable tannins, which self-assemble around the lignin particle template in the presence of metal ions, thereby coordinating into metal-phenolic networks (MPNs). The lignin template particles were easily degraded with aqueous or organic solvents under ambient conditions. Thus, the nanocoating assembly and template disassembly processes can be considered to be fully “green”. Finally, the synthesized hollow capsules were successfully utilized for water clean-up through the degradation of an organic dye, exemplifying a cost-effective and facile route for using environmentally friendly nanomaterials for environmental remediation.
  • Multiwalled Carbon Nanotubes/Nanofibrillar Cellulose/Nafion Composite-Modified Tetrahedral Amorphous Carbon Electrodes for Selective Dopamine Detection
    (2019-01-01) Durairaj, Vasuki; Wester, Niklas; Etula, Jarkko; Laurila, Tomi; Lehtonen, Janika; Rojas, Orlando J.; Pahimanolis, Nikolaos; Koskinen, Jari
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We introduce a composite membrane comprised of multiwalled carbon nanotubes (MWCNTs) dispersed in a matrix of sulfated nanofibrillar cellulose (SNFC) and Nafion. The high negative charge densities of the SNFC and Nafion ionomers enhance the cationic selectivity of the composite. The composite is characterized by scanning electron (SEM) and transmission electron (TEM) microscopies as well as Fourier transform infrared (FTIR) and Raman spectroscopies. Tetrahedral amorphous carbon (ta-C) electrodes modified with the composite are investigated as potential dopamine (DA) electrochemical sensors. The composite-modified electrodes show significant selectivity and sensitivity toward DA in the presence of ascorbic acid (AA) and uric acid (UA) in physiologically relevant concentrations. A linear dopamine detection range of 0.05-100 μM with detection limits of 65 nM in PBS and 107 nM in interferent solution was determined using 100 mV/s cyclic voltammetry (CV) measurements. These results highlight the potential of the composite membrane for in vivo detection of neurotransmitters.
  • Nanocellulose and Nanochitin Cryogels Improve the Efficiency of Dye Solar Cells
    (2019-06-17) Poskela, Aapo; Miettunen, Kati; Borghei, Maryam; Vapaavuori, Jaana; Greca, Luiz G.; Lehtonen, Janika; Solin, Katariina; Ago, Mariko; Lund, Peter D.; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Biobased cryogel membranes were applied as electrolyte holders in dye solar cells (DSC) while facilitating carrier transport during operation. They also improved device performance and stability. For this purpose, cellulose nanofibers (CNF), TEMPO-oxidized CNF (TOCNF), bacterial cellulose (BC), and chitin nanofibers (ChNF) were investigated. The proposed materials and protocols for incorporating the electrolyte, via simple casting, avoided the typical problems associated with injection of the electrolyte through filling holes, a major difficulty especially in manufacturing large area cells. Owing to the fact that cryogel membranes did not require any orifice for injection, they were effective in minimizing leakage and in retaining liquid electrolyte. The results indicated the reduction of performance losses compared to conventional electrolyte filling, likely due to the better spatial distribution of electrolyte. DSCs based on BC cryogels had an initially higher performance and similar stability compared to those of the reference cells. When compared to reference cells, CNF and ChNF cryogels produced higher initial performance, but they underwent a faster degradation. The difference in stability was attributed to the effect of residual components, including lignin in CNF and proteins in ChNF, as demonstrated in bleaching experiments. TOCNF indicated a relatively poor performance, most likely because of residual aldehydes. Overall, we offer a comprehensive evaluation based on current-voltage (IV) profiles under simulated sunlight, incident photon-to-charge carrier efficiency (IPCE), electrochemical impedance spectroscopy (EIS), and color image processing, together with accelerated DSC stability tests, to unveil the effects of new membrane-based assembly. Our results give guidelines for future developments related in particular to the effects of the tested biomaterials on device stability.
  • Nanocellulose composites for degradation of organic contaminants
    (2018-10-02) Eklund, Amanda
     Kemian tekniikan korkeakoulu | Master's thesis
    The growing water pollution has increased the need for efficient and inexpensive water purification methods. In addition to contaminant adsorption, photodegradation of organic contaminants catalysed by semiconductors, such as titanium dioxide (TiO2), has been widely investigated. To reduce the amount of residual catalyst nanoparticles in the purified water, composite structures are often utilised. Nanofibrillated cellulose (NFC), also called cellulose nanofibers (CNF), is a feasible support material to bind the catalyst nanoparticles owing to its large specific surface area and thus adsorption capacity, good mechanical properties and tuneable surface chemistry. In this work, TiO2-NFC nanocomposites were prepared in situ by low temperature sol-gel synthesis, and based on commercial constituents. The resulting composites were characterised using X-ray diffraction, scanning electron microscopy, tensile testing, and nitrogen adsorption to determine the surface area. The surface charges were also measured. Photodegradation of the contaminants was investigated using two model contaminants, cationic methylene blue and anionic methyl orange. The adsorption and photodegradation efficiencies of the composites were tuned by changing the ratio of TiO2 and NFC, as well as using NFCs with different charges. The contaminant adsorption was promoted on composites with an opposite charge compared to that of the contaminant. However, degradation efficiency was also improved, especially at high dye concentrations, when using composites with a similar charge to that of the contaminant. The photoactivity of the anatase crystal form of TiO2 was also extended from UV- to visible light region using calcination of the composites. The best dye removal was achieved at calcination temperature of 350°C. The results show the potential of composites produced economically with green technology processes to be used in efficient photodegradation of organic contaminants in water.
  • Phosphorylated cellulose nanofibers exhibit exceptional capacity for uranium capture
    (2020-12) Lehtonen, Janika; Hassinen, Jukka; Kumar, Avula Anil; Johansson, Leena Sisko; Mäenpää, Roni; Pahimanolis, Nikolaos; Pradeep, Thalappil; Ikkala, Olli; Rojas, Orlando J.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We investigate the adsorption of hexavalent uranium, U(VI), on phosphorylated cellulose nanofibers (PHO-CNF) and compare the results with those for native and TEMPO-oxidized nanocelluloses. Batch adsorption experiments in aqueous media show that PHO-CNF is highly efficient in removing U(VI) in the pH range between 3 and 6. Gelling of nanofiber hydrogels is observed at U(VI) concentration of 500 mg/L. Structural changes in the nanofiber network (scanning and transmission electron microscopies) and the surface chemical composition (X-ray photoelectron spectroscopy) gave insights on the mechanism of adsorption. The results from batch adsorption experiments are fitted to Langmuir, Freundlich, and Sips isotherm models, which indicate a maximum adsorption capacity of 1550 mg/g, the highest value reported so far for any bioadsorbent. Compared to other metals (Zn, Mn, and Cu) and typical ions present in natural aqueous matrices the phosphorylated nanofibers are shown to be remarkably selective to U(VI). The results suggest a solution for the capture of uranium, which is of interest given its health and toxic impacts when present in aqueous matrices.
  • Raskasmetallien poisto jätevedestä nanoselluloosan avulla
    (2017-05-07) Knuutila, Lotta
     Kemiantekniikan korkeakoulu | Bachelor's thesis
  • Sustainable Plant-based Solid Fragrances
    (2021-12-31) Nurmela, Elias
     Kemiantekniikan korkeakoulu | Bachelor's thesis