Kuvioidut ja bioaktiiviset nanoselluloosafilmit

In 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.Tässä diplomityössä valmistettiin nestevirtauskanavia nanoselluloosa-filmien pinnoille, ja tutkittiin näiden mahdollista käyttöä biosensoreissa. Työn tavoitteena oli valmistaa kanavia muodostamalla filmeille hydrofobisia ja hydrofiilisiä alueita. Lisäksi tavoitteena oli tutkia hIgG-vasta-aineen epäspesifistä adsorptiota CNF-filmeille sekä löytää sopivia adsorptionestoaineita, jotka soveltuvat tälle materiaalille. Adsorptionestoaineina kokeiltiin BSA:ta, fibrinogeenia ja PDMAEMA-blokki-POEGMA -kopolymeerejä. Selluloosan nanofibrillit (cellulose nanofibrils CNF) ovat nanomateriaali, jota valmistetaan puukuiduista mekaanisella käsittelyllä. Tästä materiaalista voidaan valmistaa mekaanisesti vahvoja, läpinäkyviä ja tasaisia filmejä. Tässä työssä valmistettiin CNF-filmeille kanavia käyttäen CLICK-kemian reaktioita sekä polymeerikuviointi-menetelmää käyttäen mustesuihkutulostusta. Valmistettuja pintakanavia tutkittiin SEM- ja AFM-menetelmillä, kontaktikulmamittauksilla sekä virtaustestein. Proteiinien epäspesifistä adsorptiota tutkittiin CNF-mallipinnoilla QCM-D-, SPR- ja AFM-menetelmien avulla. Lisäksi adsorptiota tutkittiin CNF filmeille valmistetuissa kanavissa fluoresoidun vasta-aineen avulla CLSM-menetelmällä. Tutkimukset osoittivat, että mustesuihkutulostettu polystyreeniliuos muodosti parhaiten toimivan nestevirtauskanavan CNF filmin pinnalle. Lisäksi PDMAEMA-blokki-POEGMA -kopolymeeri osoittautui parhaaksi adsorptionestoaineeksi. Se vähensi hIgG:n adsorptiota 95 %. Yhdistämällä pintakanavien valmistusmenetelmä ei-selektiivisen adsorptionestoaineiden kanssa voidaan valmistaa materiaaleja tulevaisuuden biosensoreihin

Nanoselluloosan, veden ja proteiinien vuorovaikutuksien hyödyntäminen sensoreissa

Defence is held on 5.5.2022 12:00 – 15:00 Zoom https://aalto.zoom.us/j/67593740995In 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.Tässä työssä tutkittiin nanoselluloosamateriaalien käyttöä sensoreissa. Työssä keskityttiin sellaisten komponenttien kehittämiseen, joita voitaisiin hyödyntää kosteusantureissa, sekä kemiallisissa että immunologisissa biosensoreissa. Näiden käyttökohteita ovat mm. diagnostiikan sovellukset, painettu elektroniikka ja älypakkaukset. Tässä työssä veden ja proteiinin vuorovaikutuksia selluloosamateriaalien kanssa tutkittiin käyttämällä mikrogravimetriaa, pintaplasmonresonanssia ja konfokaalimikroskopiaa. Kosteuteen reagoivat, elektroaktiiviset komposiittifilmit kehitettiin nanoselluloosasta ja hiilinanoputkista. Veden adsorption aiheuttamat muutokset komposiittifilmien elektroakustisessa admittanssissa ja ominaisvastuksessa osoittivat mahdollisuuden seurata suhteellisen ilmankosteuden muutoksia. Lisäksi lateraalivirtausanalyysiin (LFA) sopivia nestevirtauskanavia valmistettiin joko mustesuihkutulostamalla hydrofobisia kanavien seinämiä nanopaperille tai stensiilitulostamalla nestettä siirtäviä rakenteita hydrofobisille substraateille. Nämä fluidikanavat osoittivat mahdollisuuksia kehittää uusia, sensitiivisiä LFA-laitteita. Painetuilla, huokoisilla, nanoselluloosaa ja mineraaleja hyodyntävillä nestekanavilla osoitettiin kolorimetrisin menetelmin glukoosin, epäspesifisen proteiinin ja antigeenin havaitseminen kliinisesti merkityksellisillä konsentraatioilla. Selluloosa II nanopartikkelien käyttö proteiinien vuorovaikutusten kontrolloinnissa osoitettiin tutkimalla proteiinien adsorptiota nanopartikkeleilla käsitellyille pinnoille. Suurin adsorptio saavutettiin positiivisesti varautuneilla selluloosa II nanopartikkeleilla (NPcat). Lisäksi sekä spesifisiä että epäspesifisiä proteiinien vuorovaikutuksia pystyttiin luomaan eri pinnoilla, mikä viittaa niiden sopivuuteen sensorien bioreagenssien immobilisoivana aineena. Anioniset selluloosa II nanopartikkelit (NPan) osoittautuivat sen sijaan hyviksi pintojen passivoinnissa, mikä osoittaa niiden potentiaalin substraattien blokkausaineena eli epäspesifisten molekyylien vuorovaikutusten estäjänä. Näitä selluloosan nanopartikkeleihin perustuvia proteiineja immobilisoivia ja proteiineja hylkiviä materiaaleja käytettiin SARS-CoV-2-nukleokapsidille suunnatuissa antigeenitesteissä

Immobilized cellulose nanospheres enable rapid antigen detection in lateral flow immunoassays

| openaire: EC/H2020/760876/EU//INNPAPER | openaire: EC/H2020/788489/EU//BioELCell Funding Information: Authors acknowledge funding by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 760876. Also, funding by Academy of Finland's Flagship Programme under Projects Nos. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES) is acknowledged. OJR is grateful for the support received from the ERC Advanced Grant Agreement No. 788489 ("BioElCell") and The Canada Excellence Research Chair Program (CERC-2018-00006), as well as Canada Foundation for Innovation (Project Number 38623). KS acknowledges funding by the Aalto University School of Chemical Engineering doctoral programme. Dr. Dev Sriranganadane is acknowledged for his helpful discussion. Prof. Patrick Gane is acknowledged for his help in the development of the printed fluidic channel. We acknowledge the provision of facilities and technical support by Aalto University at OtaNano—Nanomicroscopy Center (Aalto-NMC). Funding Information: Open Access funding provided by Aalto University. This project was funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 760876. This work was a part of the Academy of Finland's Flagship Programme under Projects Nos. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES). OJR acknowledges support from the ERC Advanced Grant Agreement No. 788489 ("BioElCell") and The Canada Excellence Research Chair Program (CERC-2018-00006), as well as Canada Foundation for Innovation (Project Number 38623). KS acknowledges funding by the Aalto University School of Chemical Engineering doctoral programme. Publisher Copyright: © 2023, The Author(s).Rapid 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.]Peer reviewe

Rheological behavior of high consistency enzymatically fibrillated cellulose suspensions

High-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.]Peer reviewe