Browsing by Author "Solin, Katariina"
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Item Adsorption study on the formation of interfacial layers based on birch glucuronoxylans(Elsevier Science Ltd., 2024-09-01) Abik, Felix; Solin, Katariina; Hietala, Sami; Rojas, Orlando J.; Ho, Thao Minh; Mikkonen, Kirsi S.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of HelsinkiGlucuronoxylans (GX), particularly crude fractions obtained by pressurized hot water extraction of birch wood, act as potent emulsifiers and stabilizers against physical separation and lipid oxidation. Herein, we studied the adsorption of GX on hydrophobic interfaces to correlate their multicomponent character towards the formation of interfacial layers in emulsions. Dynamic interfacial tension (DIFT) and quartz crystal microgravimetry with dissipation monitoring (QCM-D) were applied to various GX fractions and the results compared with those from cellulose-based emulsifiers. The roles of residual lignin and polysaccharides are discussed considering the formation of interfacial layers during emulsification. The DIFT of the different GXs reached quasi-equilibrium faster as the lignin concentration increased, implying a correlation between the rate of adsorption and the residual lignin content. The effect of NaCl addition was more pronounced in polysaccharide-rich fractions, indicating that the polysaccharide fraction modulated the effect of ionic strength. QCM-D showed that despite the fast adsorption exhibited by the lignin-rich GX extract in the DIFT curves, the adsorbed materials were lightweight, suggesting that the polysaccharide fraction built the bulk of the interfacial layer. These results provide a foundation towards understanding the role of GX in interfacial stabilization beyond traditional plant-based counterparts.Item Antimicrobial efficacy of solar disinfection in cellulose fiber supported photoactive materials(Elsevier, 2024-03) Langerreiter, Daniel; Solin, Katariina; Jordà-Redondo, Mireia; Bresolí-Obach, Roger; Fliri, Lukas; Nonell, Santi; Kostiainen, Mauri A.; Anaya-Plaza, Eduardo; Department of Bioproducts and Biosystems; Biohybrid Materials; Biopolymer Chemistry and Engineering; Center of Excellence in Life-Inspired Hybrid Materials, LIBER; Ramon Llull University; VTT Technical Research Centre of FinlandAccording to the World Health Organization, antimicrobial resistance is one of the emerging threats to global health. Therefore, the development of new strategies to mitigate resistant bacterial strains is highly desirable. Photodynamic inactivation is a promising approach owing to its effectiveness against a broad range of microorganisms irrespective of their antibiotic resistance profile and its multitarget mechanism that hamper the appearance of acquired resistance. In this work, a self-sterilizing and potentially biodegradable material is developed, providing a green alternative for single-use packaging in the medical, food, and cosmetic industry. We demonstrate two synthetic approaches based on covalent linkage of toluidine blue to tempo-oxidized carbon nanofibers, as well as the supramolecular immobilization based on electrostatic self-assembly. The former shows high activity, reaching inactivation rates of 8 Log10 CFU for S. aureus and E. coli after 15 min under 250 W·m−2 artificial sun irradiation. This simple and facile approach will enable the preparation of composite photoantimicrobial films that are light activated, providing clean and microbiologically safe surfaces, even in challenging situations, such as natural disasters or conflicts, or remote locations with of none or limited access to other forms of energy supply.Item Bicomponent Cellulose Fibrils and Minerals Afford Wicking Channels Stencil-Printed on Paper for Rapid and Reliable Fluidic Platforms(AMERICAN CHEMICAL SOCIETY, 2021-11-12) Solin, Katariina; Borghei, Maryam; Imani, Monireh; Kämäräinen, Tero; Kiri, Kaisa; Mäkelä, Tapio; Khakalo, Alexey; Orelma, Hannes; Gane, Patrick A.C.; Rojas, Orlando J.; School common, CHEM; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Printing Technology; VTT Technical Research Centre of FinlandFlexible and easy-to-use microfluidic systems are suitable options for point-of-care diagnostics. Here, we investigate liquid transport in fluidic channels produced by stencil printing on flexible substrates as a reproducible and scalable option for diagnostics and paper-based sensing. Optimal printability and flow profiles were obtained by combining minerals with cellulose fibrils of two different characteristic dimensions, in the nano- and microscales, forming channels with ideal wettability. Biomolecular ligands were easily added by inkjet printing on the channels, which were tested for the simultaneous detection of glucose and proteins. Accurate determination of clinically relevant concentrations was possible from linear calibration, confirming the potential of the introduced paper-based diagnostics. The results indicate the promise of simple but reliable fluidic channels for drug and chemical analyses, chromatographic separation, and quality control.Item Bioactive nanocellulose films with spatial definition(2018-07-31) Solin, Katariina; Orelma, Hannes; Borghei, Maryam; Kemian tekniikan korkeakoulu; Rojas, OrlandoIn this thesis, fluidic channels were prepared on films made from cellulose nanofibers (CNF) and their potential use in biosensor applications was studied. The main goal was to develop hydrophilic-hydrophobic patterns to controllably produce CNF substrates for microfluidic applications. The work included a detailed investigation, to prevent non-specific adsorption of a type of human serum protein, hIgG, on CNF. A suitable antifouling agent for the CNF films was tested. CNF is a cellulosic material that has at least one dimension in the nanometer range and it is mainly produced mechanically from wood fibers. It can be used to make strong, translucent and smooth films. Two different approaches were tested to prepare 2D-channels on the CNF films: photolithography and inkjet printing of hydrophobic materials. The photolithographic method utilized simultaneously thiol-ene and thiol-yne click chemistries. In the inkjet studies, it was observed that polystyrene dissolved in p-xylene worked successfully. The prepared microfluidic CNF materials were characterized with SEM, AFM, contact angle measurements and liquid flow tests. Additionally, the non-specific protein adsorption was studied by using model CNF films with QCM-D, SPR and AFM techniques. Furthermore, the adsorption of fluorescent hIgG was performed on real CNF films and channels with CLSM method. The molecules used for protein blocking included BSA, fibrinogen and PDMAEMA-block-POEGMA copolymers. The results indicated that the best fluid flow was obtained by inkjet printing channels with polystyrene edges on CNF films. In addition, the PDMAEMA-block-POEGMA copolymer was the best antifouling agent for CNF and it reduced the hIgG adsorption up to 95 %. The successful blocking of the channels point out that these systems could be developed further and possibly be used in future biosensing applications.Item Cross-linked and surface-modified cellulose acetate as a cover layer for paper-based electrochromic devices(AMERICAN CHEMICAL SOCIETY, 2021-05-14) Kaschuk, Joice Jaqueline; Borghei, Maryam; Solin, Katariina; Tripathi, Anurodh; Khakalo, Alexey; Leite, Fábio A. S.; Branco, Aida; Amores de Sousa, Miriam C.; Frollini, Elisabete; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Ynvisible GmbH; Ynvisible SA; Universidade de São Paulo; VTT Technical Research Centre of FinlandWe studied the surface and microstructure of cellulose acetate (CA) films to tailor their barrier and mechanical properties for application in electrochromic devices (ECDs). Cross-linking of CA was carried out with pyromellitic dianhydride to enhance the properties relative to unmodified CA: solvent resistance (by 43% in acetone and 37% in DMSO), strength (by 91% for tensile at break), and barrier (by 65% to oxygen and 92% to water vapor). Surface modification via tetraethyl orthosilicate and octyltrichlorosilane endowed the films with hydrophobicity, stiffness, and further enhanced solvent resistance. A detailed comparison of structural, chemical, surface, and thermal properties was performed by using X-ray diffraction, dynamic mechanical analyses, Fourier-transform infrared spectroscopy, and atomic force microscopy. Coplanar ECDs were synthesized by incorporating a hydrogel electrolyte comprising TEMPO-oxidized cellulose nanofibrils and an ionic liquid. When applied as the top layer in the ECDs, cross-linked and hydrophobized CA films extended the functionality of the assembled displays. The results indicate excellent prospects for CA films in achieving environmental-friendly ECDs that can replace poly(ethylene terephthalate)-based counterparts.Item Electrically Conductive Thin Films Based on Nanofibrillated Cellulose : Interactions with Water and Applications in Humidity Sensing(AMERICAN CHEMICAL SOCIETY, 2020-08-12) Solin, Katariina; Borghei, Maryam; Sel, Ozlem; Orelma, Hannes; Johansson, Leena Sisko; Perrot, Hubert; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Sorbonne University; VTT Technical Research Centre of FinlandTEMPO-oxidized cellulose nanofibrils (TOCNF) and oxidized carbon nanotubes (CNT) were used as humidity-responsive films and evaluated using electroacoustic admittance (quartz crystal microbalance with impedance monitoring, QCM-I) and electrical resistivity. Water uptake and swelling phenomena were investigated in a range of relative humidity (% RH) between 30 and 60% and temperatures between 25 and 50 °C. The presence of CNT endowed fibril networks with high water accessibility, enabling fast and sensitive response to changes in humidity, with mass gains of up to 20%. The TOCNF-based sensors became viscoelastic upon water uptake, as quantified by the Martin-Granstaff model. Sensing elements were supported on glass and paper substrates and confirmed a wide window of operation in terms of cyclic % RH, bending, adhesion, and durability. The electrical resistance of the supported films increased by ∼15% with changes in % RH from 20 to 60%. The proposed system offers a great potential to monitor changes in smart packaging.Item Immobilized cellulose nanospheres enable rapid antigen detection in lateral flow immunoassays(SPRINGER, 2023-03) Solin, Katariina; Beaumont, Marco; Borghei, Maryam; Orelma, Hannes; Mertens, Pascal; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Coris BioConcept SPRL; University of Natural Resources and Life Sciences, Vienna; VTT Technical Research Centre of FinlandRapid diagnostic systems are essential in controlling the spread of viral pathogens and efficient patient management. The available technologies for low-cost viral antigen testing have several limitations, including a lack of accuracy and sensitivity. Here, we introduce a platform based on cellulose II nanoparticles (oppositely charged NPan and NPcat) for effective control of surface protein interactions, leading to rapid and sensitive antigen tests. Passivation against non-specific adsorption and augmented immobilization of sensing antibodies is achieved by adjusting the electrostatic charge of the nanoparticles. The interactions affecting the performance of the system are investigated by microgravimetry and confocal imaging. As a proof-of-concept test, SARS-CoV-2 nucleocapsid sensing was carried out by using saliva-wicking by channels that were stencil-printed on paper. We conclude that inkjet-printed NPcat elicits strong optical signals, visible after a few minutes, opening the opportunity for cost-effective and rapid diagnostic. Graphical abstract: [Figure not available: see fulltext.]Item Interfacial Membranization of Regenerated Cellulose Nanoparticles and a Protein Renders Stable Water-in-Water Emulsion(Wiley-VCH Verlag, 2024-07-16) Zhu, Ya; Beaumont, Marco; Solin, Katariina; Spiliopoulos, Panagiotis; Zhao, Bin; Tao, Han; Kontturi, Eero; Bai, Long; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Materials Chemistry of Cellulose; Bio-based Colloids and MaterialsPickering water-in-water (W/W) emulsions stabilized by biobased colloids are pertinent to engineering biomaterials with hierarchical and confined architectures. In this study, stable W/W emulsions are developed through membranization utilizing biopolymer structures formed by the adsorption of cellulose II nanospheres and a globular protein, bovine serum albumin (BSA), at droplet surfaces. The produced cellulose II nanospheres (NPcat, 63 nm diameter) bearing a soft and highly accessible shell, endow rapid and significant binding (16 mg cm−2) with BSA. NPcat and BSA formed complexes that spontaneously stabilized liquid droplets, resulting in stable W/W emulsions. It is proposed that such a system is a versatile all-aqueous platform for encapsulation, (bio)catalysis, delivery, and synthetic cell mimetics.Item Nanocellulose and Nanochitin Cryogels Improve the Efficiency of Dye Solar Cells(AMER CHEMICAL SOC, 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.; Department of Applied Physics; Department of Bioproducts and Biosystems; New Energy Technologies; Bio-based Colloids and MaterialsBiobased 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.Item Nanocellulose Interactions with Protein and Water in Advanced Sensing Systems(Aalto University, 2022) Solin, Katariina; Borghei, Maryam, Dr., Aalto University, Finland; Orelma, Hannes, Dr., VTT Technical Research Centre of Finland, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, FinlandIn this work, cellulosic nanomaterials were investigated for application as fluidic and sensing platforms. These platforms were used for humidity measurement, biosensors, and immunoassays, which are relevant to the areas of diagnostics, printed electronics, and smart packaging. A systematic investigation was carried out to study the interactions between water and protein molecules with cellulosic materials, which was facilitated by advanced techniques such as quartz microgravimetry, surface plasmon resonance, and confocal microscopy. Humidity responsive and electroactive composite films were developed using hybrid materials composed of nanocellulose and carbon nanotubes. The changes in relative humidity of air were monitored by measuring the shift in electroacoustic admittance and electrical resistivity of composite films upon water uptake. Other systems that incorporated mineral particles and nano-and microcellulose were used for lateral flow assays (LFA) based on fluidic wicking. For this purpose, inkjet printing was used to produce hydrophobic channel sidewalls on nanopaper. Alternatively, stencil printing of the fluid-wicking element was applied on hydrophobic supports. These wicking systems showed the potential as new types of LFA devices with excellent sensitivity. Glucose, non-specific protein, and antigen detection were demonstrated by colorimetric sensing at clinically relevant concentrations. A new type of cellulose nanomaterial, cellulose II nanoparticles, was introduced as a substrate for controlled protein adsorption. The interactions and protein accessibility to surfaces treated with such cellulose II nanoparticles, which formed a hydrogel film, were investigated in detail. Cationic cellulose II nanoparticles (NPcat) showed one of the highest levels of accessibility recorded, following both specific and non-specific protein interactions, and suggested NPcat suitability as a new immobilizing agent for biomolecular sensing. Oppositely charged anionic cellulose II nanoparticles (NPan) were used for surface passivation and indicated a great potential as a blocking agent that can be deposited on substrates to minimize non-specific molecular interactions. Both cellulose nanospheres, NPcat and NPan were deployed in protein-accessible and protein-repellent materials, respectively, and facilitated the design of a rapid antigen sensing system for SARS-CoV-2 nucleocapsid.Item Nanotärkkelyksen valmistus, ominaisuudet ja sovelluskohteet(2015-12-07) Solin, Katariina; Kuusisto, Jonna; Kemiantekniikan korkeakoulu; Hiltunen, EeroItem Rheological behavior of high consistency enzymatically fibrillated cellulose suspensions(SPRINGER, 2021-03) Jaiswal, Aayush Kumar; Kumar, Vinay; Khakalo, Alexey; Lahtinen, Panu; Solin, Katariina; Pere, Jaakko; Toivakka, Martti; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; VTT Technical Research Centre of Finland; Åbo Akademi UniversityHigh-consistency processing of fibrillated cellulose materials is attractive for commercial applications due to potential for lowered production costs, energy savings and easier logistics. The current work investigated structure–property relationships of fibrillated cellulose suspensions produced at 20% consistency using VTT HefCel (High-consistency enzymatic fibrillation of cellulose) technology. Morphological examination of the fibrillated materials revealed that enzymatic action on the cellulose substrates was not a direct function of enzyme dosage but rather was dependent on the raw material composition. Furthermore, shear viscosity of the HefCel suspensions was found to decrease with increasing enzyme dosage while the water retention increased. The shear viscosity followed power law relationship with the power law index varying in the range 0.11–0.73. The shear-thinning behavior decreased with increasing consistency. Moreover, suspension viscosity (μ) was found to be highly dependent on the consistency (c) as μ ∼ c m, with m ranging from 2.75 to 4.31 for different samples. Yield stress (τy) of the HefCel suspensions was measured at 7 and 10% consistencies. The performance of the fibrillated cellulose grades in a typical application was demonstrated by casting films, which were characterized for their mechanical properties. Graphic abstract: [Figure not available: see fulltext.]Item Self-Assembly of Soft Cellulose Nanospheres into Colloidal Gel Layers with Enhanced Protein Adsorption Capability for Next-Generation Immunoassays(WILEY-V C H VERLAG GMBH, 2020-12-17) Solin, Katariina; Beaumont, Marco; Rosenfeldt, Sabine; Orelma, Hannes; Borghei, Maryam; Bacher, Markus; Opietnik, Martina; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; University of Bayreuth; University of Natural Resources and Life Sciences, Vienna; Lenzing AG; VTT Technical Research Centre of FinlandSoft cationic core/shell cellulose nanospheres can deform and interpenetrate allowing their self-assembly into densely packed colloidal nanogel layers. Taking advantage of their water-swelling capacity and molecular accessibility, the nanogels are proposed as a new and promising type of coating material to immobilize bioactive molecules on thin films and paper. The specific and nonspecific interactions between the cellulosic nanogel and human immunoglobulin G as well as bovine serum albumin (BSA) are investigated. Confocal microscopy, electroacoustic microgravimetry, and surface plasmon resonance are used to access information about the adsorption behavior and viscoelastic properties of self-assembled nanogels. A significant BSA adsorption capacity on nanogel layers (17 mg m−2) is measured, 300% higher compared to typical polymer coatings. This high protein affinity further confirms the promise of the introduced colloidal gel layer, in increasing sensitivity and advancing a new generation of substrates for a variety of applications, including immunoassays, as demonstrated in this work.Item Two-Dimensional Antifouling Fluidic Channels on Nanopapers for Biosensing(AMER CHEMICAL SOC, 2019-02-11) Solin, Katariina; Orelma, Hannes; Borghei, Maryam; Vuoriluoto, Maija; Koivunen, Risto; Rojas, Orlando J.; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Printing TechnologyTwo-dimensional (hydrophilic) channels were patterned on films prepared from cellulose nanofibrils (CNF) using photolithography and inkjet printing. Such processes included UV-activated thiol-yne click coupling and inkjet-printed designs with polystyrene. The microfluidic channels were characterized (SEM, wetting, and fluid flow) and applied as platforms for biosensing. Compared to results from the click method, a better feature fidelity and flow properties were achieved with the simpler inkjet-printed channels. Human immunoglobulin G (hIgG) was used as target protein after surface modification with either bovine serum albumin (BSA), fibrinogen, or block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) (PDMAEMA-block-POEGMA copolymers). Surface plasmon resonance (SPR) and AFM imaging were used to determine their antifouling effect to prevent nonspecific hIgG binding. Confocal laser scanning microscopy revealed diffusion and adsorption traces in the channels. The results confirm an effective surface passivation of the microfluidic channels (95% reduction of hIgG adsorption and binding). The inexpensive and disposable systems proposed here allow designs with space-resolved blocking efficiency that offer a great potential in biosensing.
