Responsive Polyelectrolyte and Nanodiamond Hybrid Materials

In the face of a climate crisis, ways of making materials more durable, lighter, versatile and sustainable is of great interest. Hybrid nanomaterials comprising of two or more interfaces mixed at the nanoscale can improve or extend the properties and applications of conventional materials. An integral component of hybrid nanomaterials are polymers, which themselves are materials with nano-sized dimensions and, depending on their structure, are capable to respond to changes in their environment. In combination with different nanoparticles, new and synergistic properties may emerge for these materials. This thesis examines the synthesis and properties of cationic polyelectrolytes and their hybrid materials made especially with nanodiamonds (ND). Nanodiamonds (ND) are nanomaterials with intriguing mechanical, thermal and chemical properties. Their chemically modifiable surface makes them suitable for varying applications, for example, as fillers and modifying agents in materials, catalysts and platforms in synthesis and carriers and sensors in biomedicine. In the first part of the thesis, routes to mitigate ND aggregation via polyelectrolyte complexation is studied. Different poly(dimethyl aminoethyl methacrylate) (PDMAEMA) polymers were complexed with NDs. Depending on the dispersion conditions the colloidal stability of these particles in water and saline water was improved compared to bare NDs. In the second part, NDs were used as fillers for polyelectrolyte based responsive films. The mechanical properties of the films were improved upon the addition of NDs and the films had stimuli-responsive properties upon change of pH- or temperature. Finally, poly(aminoethyl methacrylate) (PAEMA) polymers were synthesized and modified with guanidine. They were tested for CO2 adsorption and show promising reversible adsorption of CO2.Lisääntyvien ilmastohuolien vuoksi on yhä tärkeämpää tehdä materiaaleista lujempia, kevyempiä ja kestävän kehityksen mukaisia. Hybridimateriaalit joissa on nanomittakaavassa sekoittuneita ainesosia tai rajapintoja, voivat parantaa perinteisten materiaalien ominaisuuksia ja mahdollistaa näille uusia käyttökohteita. Tärkeä hybridimateriaalien luokka ovat polymeerit, jotka voivat toimia matriisina esimerkiksi nanohiukkasten vahvistamissa komposiiteissa tai dispergentteinä nesteissä. Erityisesti niin sanotut ympäristöherkät polymeerit, jotka muuttavat ominaisuuksiaan erilaisten ärsykkeiden myötä yhdistettynä erilaisiin nanopartikkeleihin, voivat saada aikaan uusia ominaisuuksia. Tämä väitöskirjatyö tutkii kationisten polyelektrolyyttien synteesiä, ominaisuuksia ja niiden muodostamia hybridimateriaaleja, jotka sisältävät nanotimantteja. Nanotimantit ovat hienojakoisia timantteja, joilla on hyödyllisiä mekaanisia ja kemiallisia ominaisuuksia. Niitä voidaan käyttää esimerkiksi lämmönjohtavuutta ja lujuutta parantavina täyteaineina, katalyytteinä ja sekä sensoreina biolääketieteessä. Työn ensimmäisessä vaiheessa tutkittiin nanotimanttien vesidispersioiden aggregoitumisen ja saostumisen välttämistä kompleksoimalla niiden pintaan poly(diaminoetyyli metakrylaatti) kopolymeereja. Kompleksoitujen partikkeleiden stabiilisuus parani verrattuna pelkkiin nanotimantteihin, jotka sedimentoituvat helposti. Toisessa vaiheessa nanotimantteja ja niiden komplekseja käytettiin täyteaineina polymeerikalvoissa. Kalvojen mekaaniset ominaisuudet paranivat kompleksoituja nanotimantteja lisätessä. Lisäksi kalvot omasivat ärsykevasteisia ominaisuuksia muuttaen optisia ominaisuuksiaan muutettaessa pH-arvoa tai lämpötilaa. Lopuksi syntetisoitiin poly(aminoetyyli metakrylaattiin) pohjautuvia polymeerejä, joiden odotettiin kykenevän sitomaan ja vapauttamaan hiilidioksidia. Kun polymeerejä edelleen muokattiin guanidiinilla, todettiin näiden johdosten omaavan hyviä hiilidioksidin adsorptio- ja desorptio-ominaisuuksia, joiden myötä niiden voidaan ajatella sopivan esimerkiksi hiilidioksidin kaappaamiseen tai suodatukseen

Lämpöherkät oksastettavat mikrogeelipartikkelit

Tässä työssä valmistettiin sarja pinta-funktionalisoitavia ja lämpöherkkiä mikrogeelipartikkeleita lääkeainekuljettajiksi. Partikkelit syntetisoitiin dispersiopolymeroinnilla vinyylikaprolaktaamista (VCL), metakryylihaposta (MAA) ja vinyylibentsyyliatsidista (VBA) käyttäen N, N'-bis(akryyli)kystamiinia silloittajana. Komponentit valittiin niiden funktionaalisuuksien ja bioyhteensopivuuden vuoksi, VBA sisällytettiin partikkeleihin sen liittämisreaktioihin sopivan atsidiryhmän takia. Monomeerisuhteita vaihdeltiin parhaimman lopputuloksen aikaansaamiseksi. Partikkeleiden atsidiryhmien reaktiivisuutta testattiin ATRP menetelmällä valmistetuilla alkyyni-pääteryhmäisillä PDMAEMA-ketjuilla. Ne liitettiin partikkeleihin käyttäen kuparikatalysoitua atsidi-alkyyni sykloadditiota (CuAAC). Partikkelien kemiallista rakennetta selvitettiin NMR- ja IR-analyyseillä. Partikkelien koko mitattiin lämpötilan funktiona dynaamisella valonsironnalla. Oikean reagenssisuhteen ja reaktio-olosuhteiden löydyttyä partikkeleita syntetisoitiin onnistuneesti. Niiden todettiin olevan stabiileja vesiliuoksessa ja niiden todettiin muuttavan kokoaan lämpötilan funktiona. Atsidiryhmien reaktiivisuus todettiin havaitsemalla PDMAEMA IR- ja NMR-spektristä intensiivisen puhdistuksen jälkeen

CO2 Capture and Low-Temperature Release by Poly(aminoethyl methacrylate) and Derivatives

Poly(aminoethyl methacrylate) (PAEMA), poly-(ethylene oxide)-block-(aminoethyl methacrylate) (PEO-PAEMA), and their guanidinylated derivates, poly(guanidine ethyl methacry-late) (PGEMA) and poly(ethylene oxide)-block-(guanidine ethyl methacrylate) (PEO-PGEMA), were prepared to study their capabilities for CO2 adsorption and release. The polymers of different forms or degree of guanidinylation were thoroughly characterized, and their interaction with CO2 was studied by NMR and calorimetry. The extent and kinetics of adsorption and desorption of N-2 and CO2 were investigated by thermogravimetry under controlled gas atmospheres. The materials did not adsorb N-2, whereas CO2 could be reversibly adsorbed at room temperature and released by an elevated temperature. The most promising polymer was PGEMA with a guanidinylation degree of 7% showing a CO2 adsorption capacity of 2.4 mmol/g at room temperature and a desorption temperature of 72 degrees C. The study also revealed relations between the polymer chemical composition and CO2 adsorption and release characteristics that are useful in future formulations for CO2 adsorbent polymer materials.Peer reviewe

Stimuli-Responsive Nanodiamond–Polyelectrolyte Composite Films

Nanodiamonds (NDs) can considerably improve the mechanical and thermal properties of polymeric composites. However, the tendency of NDs to aggregate limits the potential of these non-toxic, mechanically- and chemically-robust nanofillers. In this work, tough, flexible, and stimuli-responsive polyelectrolyte films composed of cross-linked poly(butyl acrylate-co-dimethylaminoethyl methacrylate) (P(BA-co-DMAEMA)) were prepared by photopolymerization. The effects of the added carboxylate-functionalized NDs on their mechanical and stimuli-responsive properties were studied. When the negatively charged NDs were added to the polymerization media directly, the mechanical properties of the films changed only slightly, because of the uneven distribution of the aggregated NDs in the films. In order to disperse and distribute the NDs more evenly, a prepolymerized polycation block copolymer complexing agent was used during the photopolymerization process. This approach improved the mechanical properties of the films and enhanced their thermally-induced, reversible phase-transition behavior

Polyelectrolyte stabilized nanodiamond dispersions

Colloidal stability of negatively charged nanodiamonds (ND) has been realized with the help of double hydrophilic block copolymers poly(ethylene oxide)-block-poly(dimethylaminoethyl methacrylate)-dodecyl (PEO-bPDMAEMA-C12). The polymers were synthesized through RAFT polymerization of DMAEMA with a PEO macromonomer carrying trithiocarbonate and dodecyl end-groups. The NDs and the polymers were complexed by mixing them in different ratios. In addition to the amount of polymers, the effect of the detailed structure of the polymer was of interest and thus, also polymers with different lengths of the PEO-block were synthesized, as well as a block copolymer without the dodecyl end-group. The composition of the polymer, as well as the complexation conditions were varied to find the route to stable nanoparticles. The optimized complexation method gave colloidally stable ND particles with positively charged PDMAEMA coronas. The colloids were stable at room temperature and also in saline solutions up to 0.154 M NaCl.Peer reviewe

Cationic polymers for DNA origami coating - examining their binding efficiency and tuning the enzymatic reaction rates

DNA origamis are fully tailored, programmable, biocompatible and readily functionalizable nanostructures that provide an excellent foundation for the development of sophisticated drug-delivery systems. However, the DNA origami objects suffer from certain drawbacks such as low cell-transfection rates and low stability. A great deal of studies on polymer-based transfection agents, mainly focusing on polyplex formation and toxicity, exists. In this study, the electrostatic binding between a brick-like DNA origami and cationic block-copolymers was explored. The effect of the polymer structure on the binding was investigated and the toxicity of the polymer-origami complexes evaluated. The study shows that all of the analyzed polymers had a suitable binding efficiency irrespective of the block structure. It was also observed that the toxicity of polymer-origami complexes was insignificant at the biologically relevant concentration levels. Besides brick-like DNA origamis, tubular origami carriers equipped with enzymes were also coated with the polymers. By adjusting the amount of cationic polymers that cover the DNA structures, we showed that it is possible to control the enzyme kinetics of the complexes. This work gives a starting point for further development of biocompatible and effective polycation-based block copolymers that can be used in coating different DNA origami nanostructures for various bioapplications.Peer reviewe

Seurantakäsikirja Suomen merenhoitosuunnitelman seurantaohjelmaan vuosille 2020–2026

Tämä merenhoidon seurantakäsikirja käsittää merenhoitosuunnitelman seurantaohjelman kuvauksen kokonaisuudessaan. Se päivittää vuoden 2014–2020 seurantaohjelman ja sitä sovelletaan vuoden 2020 heinäkuusta vuoden 2026 heinäkuuhun. Seurantaohjelma on osa merenhoidon suunnittelua, jota tehdään vesienhoidon ja merenhoidon järjestämisestä annetun lain (272/2011) ja merenhoidon järjestämisestä annetun valtioneuvoston asetuksen (980/2011) toteuttamiseksi. Tämä laki ja asetus on annettu meristrategiadirektiivin (Euroopan parlamentin ja neuvoston direktiivi 2008/56/EY yhteisön meriympäristöpolitiikan puitteista) kansallista toimeenpanoa varten. Suomessa meristrategiadirektiivin mukaista meristrategiaa kutsutaan merenhoitosuunnitelmaksi. Suomen seurantaohjelma koostuu 13:sta ohjelmasta, joiden alla on yhteensä 44 alaohjelmaa. Tähän päivitettyyn seurantaohjelmaan lisättiin kuusi uutta alaohjelmaa ja useita alaohjelmia muokattiin joko muuttuneiden vaatimusten, kehittyneempien menetelmien tai muuttuneen toimintaympäristön takia. Merenhoidon uusia vaatimuksia ovat meristrategiadirektiivin liitteen 3 päivitys (EU/2017/845), Euroopan komission päätös EU/2017/848 merivesien hyvän ekologisen tilan vertailuperusteista ja menetelmästandardeista sekä seurantaa ja arviointia varten tarkoitetut täsmennykset standardoiduista menetelmistä. Seurantakäsikirja koostuu kolmesta osasta: seurantaohjelman tausta, varsinainen seurantaohjelma, ja kolmas osa, joka käsittelee seurannan kehitystarpeita, kustannuksia ja riittävyyttä. Seurantaohjelma kattaa ekosysteemilähestymistavan mukaisesti erilaisia muuttujia, jotka kuvaavat toisaalta veden ominaisuuksia ja laatua ja toisaalta ekosysteemin osia ja niiden tilaa sekä niihin kohdistuvia ihmisestä johtuvia paineita. Seurannan alaohjelmissa on kuvattu mitattavat meriympäristön ominaisuudet tai paineet, niiden seurantatiheys, indikaattorit, joihin seurantatietoa käytetään, seurannalla kootun tiedon hallinta ja yhteydet meristrategiadirektiivin hyvän tilan laadullisiin kuvaajiin ja kriteereihin

Artificial chaperones based on thermoresponsive polymers recognize the unfolded state of the protein

Stabilization of the enzymes under stress conditions is of special interest for modern biochemistry, bioengineering, as well as for formulation and target delivery of protein-based drugs. Aiming to achieve an efficient stabilization at elevated temperature with no influence on the enzyme under normal conditions, we studied chaperone-like activity of thermoresponsive polymers based on poly(dimethylaminoethyl methacrylate) (PDMAEMA) toward two different proteins, glyceraldehyde-3-phosphate dehydrogenase and chicken egg lysozyme. The polymers has been shown to do not interact with the folded protein at room temperature but form a complex upon heating to either protein unfolding or polymer phase transition temperature. A PDMAEMA-PEO block copolymer with a dodecyl end-group (d-PDMAEMA-PEO) as well as PDMAEMA-PEO without the dodecyl groups protected the denatured protein against aggregation in contrast to PDMAEMA homopolymer. No effect of the polymers on the enzymatic activity of the client protein was observed at room temperature. The polymers also partially protected the enzyme against inactivation at high temperature. The results provide a platform for creation of artificial chaperones with unfolded protein recognition which is a major feature of natural chaperones. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe

Mechanistic insights into carbamate formation from CO2 and amines : the role of guanidine-CO2 adducts

Capture of CO2 by amines is an attractive synthetic strategy for the formation of carbamates. Such reactions can be mediated by superbases, such as 1,1,3,3-tetramethylguanidine (TMG), with previous implications that zwitterionic superbase-CO2 adducts are able to actively transfer the carboxylate group to various substrates. Here we report a detailed investigation of zwitterionic TMG-CO2, including isolation, NMR behavior, reactivity, and mechanistic consequences in carboxylation of aniline-derivatives. Our computational and experimental mechanistic analysis shows that the reversible TMG-CO2 zwitterion is not a direct carboxylation agent. Instead, CO2 dissociates from TMG-CO2 before a concerted carboxylation occurs, where the role of the TMG is to deprotonate the amine as it is attacking a free CO2. This insight is significant, as it opens a rational way to design new synthesis strategies. As shown here, nucleophiles otherwise inert towards CO2 can be carboxylated, even without a CO2 atmosphere, using TMG-CO2 as a stoichiometric source of CO2. We also show that natural abundance N-15 NMR is sensitive for zwitterion formation, complementing variable-temperature NMR studies.Peer reviewe

UV-Triggered On-Demand Temperature-Responsive Reversible and Irreversible Gelation of Cellulose Nanocrystals

We show ionically cross-linked, temperature-responsive reversible or irreversible hydrogels of anionic cellulose nanocrystals (CNCs) and methacrylate terpolymers by mixing them homogeneously in the initially charge-neutral state of the polymer, which was subsequently switched to be cationic by cleaving side groups by UV irradiation. The polymer is a random terpolymer poly(di(ethylene glycol) methyl ether methacrylate)-rnd-poly(oligo(ethylene glycol) methyl ether methacrylate)-rnd-poly(2-((2-nitrobenzyl)oxycarbonyl)aminoethyl methacrylate), that is, PDEGMA-rnd-POEGMA-rnd-PNBOCAEMA. The PDEGMA and POEGMA repeating units lead to a lower critical solution temperature (LCST) behavior. Initially, homogeneous aqueous mixtures are obtained with CNCs, and no gelation is observed even upon heating to 60 °C. However, upon UV irradiation, the NBOCAEMAs are transformed to cationic 2-aminoethyl methacrylate (AEMA) groups, as 2-nitrobenzaldehyde moieties are cleaved. The resulting mixtures of anionic CNC and cationic PDEGMA-rnd-POEGMA-rnd-PAEMA show gelation for sufficiently high polymer fractions upon heating to 60 °C due to the interplay of ionic interactions and LCST. For short heating times, the gelation is thermoreversible, whereas for long enough heating times, irreversible gels can be obtained, indicating importance of kinetic aspects. The ionic nature of the cross-linking is directly shown by adding NaCl, which leads to gel melting. In conclusion, the optical triggering of the polymer ionic interactions in combination with its LCST phase behavior allows a new way for ionic nanocellulose hydrogel assemblies.Peer reviewe