Elektrostatisk självorganisation av DNA origami och guldnanopartiklar

Spatially well-ordered structures of gold nanoparticles(AuNPs) and other metal nanoparticles have unique electronic, magnetic and optical properties, and hence there is ever-increasing interest towards these kinds of nanomaterials. DNA and DNA nanostructures have successfully been used to direct the higher-ordered arrangement of AuNPs, but the programmable arrangement of them into larger, well-defined structures is still challenging. The objective of this thesis is to establish a self-assembly method based on electrostatic interactions in which DNA origami nanostructures can be used to guide the higher ordered arrangement of cationic AuNPs in a controlled and programmable manner. The AuNP binding properties of different DNA origami structures was studied with UV/Vis spectroscopy and agarose gel electrophoretic mobility shift assay. DNA origami-AuNP assemblies were formed during dialysis against decreasing ionic strength, and the formed assemblies were characterized using small-angle X-ray scattering, transmission electron microscopy and cryogenic electron tomography. Electrostatic self-assembly of DNA origami 6HB nanostructures and small AuNPs (D_core = 2.5 nm, D_hydrodynamic_diameter = 8.5 nm) yielded highly ordered superlattice structures with a 3D tetragonal lattice structure, whereas other studied combinations of DNA origami structures and AuNPs resulted in amorphous aggregates. These results suggest that both shape and charge complementarity between the building blocks are needed for well-ordered structures to be formed through electrostatic self-assembly. According to the results, electrostatic self-assembly guided by DNA origami structures seems promising for construction of novel, well-ordered structures with unique properties, such as lattice geometry, designed specifically for the chosen application.Guldnanopartiklar och andra metallnanopartiklar organiserade i välordnade strukturer har unika elektroniska, magnetiska och optiska egenskaper och därför finns det ett ständigt växande intresse för dessa typer av nanomaterial. DNA och nanostrukturer av DNA har framgångsrikt använts för att framställa välordnade, förutbestämda tredimensionella guldnanopartikelstrukturer, men det finns fortfarande utmaningar att tackla. Målet med detta diplomarbete är att utveckla en metod för självorganisation baserat på elektrostatiska interaktioner i vilken DNA-origaminanostrukturer på ett programmerbart och kontrollerat sätt kan användas för att styra hurudana strukturer som byggs upp av katjoniska guldnanopartiklar. De olika DNA-origamistrukturernas förmåga att binda guldnanopartiklar studerades med UV/Vis-spektroskopi och agarosgelelektrofores. DNA-origami-guldnanopartikelsystem byggdes upp genom dialys mot stegvis minskade jonkoncentrationer och de uppkomna strukturerna karaktäriserades med lågvinkelspridning, transmissionselektronmikroskopi och kryelektrontomografi. Elektrostatisk självorganisation av DNA-origami 6HB nanostrukturer och små guldnanopartiklar (D_kärna = 2.5 nm, D_hydrodynamisk_diameter = 8.5 nm) gav välordnade tredimensionella tetragonala kristallstrukturer, medan andra undersökta kombinationer av DNA origami strukturer och guldpartiklar endast resulterade i amorfa strukturer. Detta indikerar att de enskilda byggstenarna behöver kompletterande form och laddning för att välordnade strukturer skall kunna byggas upp genom elektrostatik självorganisation. Det förefaller dock finnas goda framtidsutsikter för elektrostatisk självorganisation som en metod att framställa välordnade strukturer med egenskaper, så som typ av kristallstruktur, lämpliga just för det önskade användningsområdet

Kuntien yksinäisyystyön mahdollisuudet

Suomalaisista jo noin puolet kokee yksinäisyyttä. Vaikka yksinäisyys on ilmiönä vakava ja sen terveydelliset haittavaikutukset ovat moninaisia, ei siihen olla vielä yhteiskunnan eri tasoilla herätty sen vaatimalla vakavuudella. Yksinäisyys aiheuttaa yksilöille kauaskantoisia inhimillisiä seurauksia. Sen lisäksi sillä on yhteiskunnalle inhimillisten seurausten lisäksi taloudellisia vaikutuksia. Yksinäisyydestä on muodostumassa uhka koko Suomen kansanterveydelle ja sitä kautta kansantaloudelle, mutta sen ratkaisemiseksi on onneksi erilaisia keinoja. Koska paikallisten olosuhteiden huomioiminen yksinäisyystyössä on tärkeää, tulevat kunnat olemaan keskeisessä roolissa, mikäli yksinäisyyttä yhteiskunnassa halutaan torjua ja vähentää. Tässä tutkimuksessa luodaan katsaus kuntien yksinäisyystyöhön tällä hetkellä ja luodaan visiota tulevaisuuteen kunnan yksinäisyystyön mahdollisuuksien osalta. Tavoitteena on ollut selvittää kuntien yksinäisyystyön nykytilaa ja tiedon hyödyntämistä siinä. Tutkimus antaa vastauksia siihen, mitkä ovat kunnan mahdollisuudet ennaltaehkäistä ja vähentää yksinäisyyttä. Sen lisäksi tutkimus kietoo tiedon hyödyntämisen ja tietojohtamisen osaksi kunnan yksinäisyystyötä ja antaa vastauksia myös siihen, hyödyntävätkö kunnat tietoa yksinäisyystyössään. Tutkimuksen tärkein tavoite on ollut etsiä ja löytää konkreettisia työkaluja kunnan yksinäisyystyöhön ja tiedon hyödyntämiseen siinä. Tutkimus tehtiin kvalitatiivisena eli laadullisena tutkimuksena ja siinä toteutettiin kaksi asiantuntijahaastattelua. Aineistona tutkimuksessa käytettiin asiantuntijahaastatteluiden litteroituja aineistoja sekä vastausta valtuustoaloitteeseen, joka koski tahattoman yksinäisyyden torjumista Tampereella. Tutkimus sisälsi aineistolähtöisen sisällönanalyysin, joka tehtiin induktiivisena. Tutkimuksen pohjalta voidaan todeta, että kunnalla on monipuolisesti erilaisia mahdollisuuksia ennaltaehkäistä yksinäisyyden syntymistä sekä vähentää kuntalaisten kokemaa yksinäisyyttä. Kunnan mahdollisuudet yksinäisyystyöhön voidaan jakaa kahdeksaan eri kategoriaan: 1) kodin tuki, 2) varhaiskasvatus ja koulutus, 3) rakentaminen, 4) palvelujärjestelmät, 5) yhteisöllisyyden ja osallisuuden vahvistaminen, 6) rohkeat kokeilut, 7) verkostotoiminta ja 8) tiedon hyödyntäminen. Näiden jokaisen eri kategorian mahdollisuudet ovat laajat ja jokainen kategoria sisältää myös konkreettisia keinoja kunnan yksinäisyystyöhön. Tietoa kunnat eivät vielä hyödynnä riittävästi yksinäisyystyössään, sillä esimerkiksi riittävän konkreettista tietoa ei tähän tarkoitukseen ole saatavilla. Tiedon hyödyntämisen kehittämisessä olisi tärkeää panostaa erityisesti tiedon jakamiseen sekä osaamisen vahvistamiseen. Yhteenvetona voidaan todeta, että yksinäisyyden ennaltaehkäisemiseksi sekä vähentämiseksi on vielä paljon tehtävää. Mahdollisuuksia kuntien yksinäisyystyöhön kuitenkin löytyy, joten edellytykset paremmalle huomiselle, jossa yksinäisyyttä kokee yhä useamman sijasta yhä harvempi, on olemassa. Seuraavaksi kuntien on alettava tekemään määrätietoista ja vaikuttavaa yksinäisyystyötä, niin tulevaisuudessa yhä harvempi kokee yksinäisyyttä

DNA‐Origami‐Templated Growth of Multilamellar Lipid Assemblies

Lipids are important building blocks in cellular compartments, and therefore their self‐assembly into well‐defined hierarchical structures has gained increasing interest. Cationic lipids and unstructured DNA can co‐assemble into highly ordered structures (lipoplexes), but potential applications of lipoplexes are still limited. Using scaffolded DNA origami nanostructures could aid in resolving these drawbacks. Here, we have complexed DNA origami together with a cationic lipid 1,2‐dioleoly‐3‐trimethylammonium‐propane (DOTAP) and studied their self‐assembly driven by electrostatic and hydrophobic interactions. The results suggest that the DNA origami function as templates for the growth of multilamellar lipid structures and that the DNA origami are embedded in the formed lipid matrix. Furthermore, the lipid encapsulation was found to significantly shield the DNA origami against nuclease digestion. The presented complexation strategy is suitable for a wide range of DNA‐based templates and could therefore find uses in construction of cell‐membrane‐associated components.acceptedVersionPeer reviewe

Polymyxin B stabilized DNA micelles for sustained antibacterial and antibiofilm activity against P. aeruginosa

Nucleic acid-based materials showcase an increasing potential for antimicrobial drug delivery. Although numerous reports on drug-loaded DNA nanoparticles outline their pivotal antibacterial activities, their potential as drug delivery systems against bacterial biofilms awaits further studies. Among different oligonucleotide structures, micellar nanocarriers derived from amphiphilic DNA strands are of particular interest due to their spontaneous self-assembly and high biocompatibility. However, their clinical use is hampered by structural instability upon cation depletion. In this work, we used a cationic amphiphilic antibiotic (polymyxin B) to stabilize DNA micelles destined to penetrate P. aeruginosa biofilms and exhibit antibacterial/antibiofilm properties. Our study highlights how the strong affinity of this antibiotic enhances the stability of the micelles and confirms that antibacterial activity of the novel micelles remains intact. Additionally, we show that PMB micelles can penetrate P. aeruginosa biofilms and impact their metabolic activity. Finally, PMB micelles were highly safe and biocompatible, highlighting their possible application against P. aeruginosa biofilmcolonized skin wounds

Effects of COVID-19 Lockdown on Adherence to Individual 2 Home or Gym Based Exercise Training among Women with 3 Post-Menopausal Osteoporosis

Adherence is important for an exercise program’s efficacy. This study aims at investigating whether the COVID-19 lockdown had different consequences on the adherence to an exercise program specifically designed for women with postmenopausal osteoporosis when administered as individual home training (IHT) or gym group training (GGT). At the start of the lockdown, which imposed the temporary closure of any gym activities, GGT participants were invited to continue to exercise at home. IHT participants continued to exercise at home as usual. Adherence was recorded via logs and measured as the percentage of exercise sessions actually performed out of the total number of scheduled sessions in three 1-month periods: one before (PRE) and two after (M1 and M2) the beginning of lockdown. Before lockdown, IHT (66.8% ± 26.6) and GGT (76.3% ± 26.6) adherence were similar. During lockdown, IHT participation increased (M1: 81.5% ± 31.0; M2: 88.0% ± 28.3), while that of GGT showed no statistical differences (M1: 79.4% ± 34.2; M2: 80.6% ± 36.4). Exercise protocols based on supervised gym practice must consider the possibility of disruptive events, which could cause a sudden interruption of gym activity and include educational initiatives to instruct participants to exercise effectively and safely without a trainer’s direct supervision

Effect of Exercise Training on Bone Mineral Density in Post-menopausal Women : A Systematic Review and Meta-Analysis of Intervention Studies

Osteoporosis is a major health problem in post-menopausal women (PMW). Exercise training is considered a cost-effective strategy to prevent osteoporosis in middle aged-older people. The purpose of this study is to summarize the effect of exercise on BMD among PMW. A comprehensive search of electronic databases was conducted through PubMed, Scopus, Web of Science, Cochrane, Science Direct, Eric, ProQuest, and Primo. BMD changes (standardized mean differences: SMD) of the lumbar spine (LS) femoral neck (FN) and/or total hip were considered as outcome measures. After subgroup categorization, statistical methods were used to combine data and compare subgroups. Seventy-five studies were included. The pooled number of participants was 5,300 (intervention group:n= 2,901, control group:n= 2,399). The pooled estimate of random effect analysis was SMD = 0.37, 95%-CI: 0.25-0.50, SMD = 0.33, 95%-CI: 0.23-0.43, and SMD = 0.40, 95%-CI: 0.28-0.51 for LS, FN, and total Hip-BMD, respectively. In the present meta-analysis, there was a significant (p<0.001), but rather low effect (SMD = 0.33-0.40) of exercise on BMD at LS and proximal femur. A large variation among the single study findings was observed, with highly effective studies but also studies that trigger significant negative results. These findings can be largely attributed to differences among the exercise protocols of the studies. Findings suggest that the true effect of exercise on BMD is diluted by a considerable amount of studies with inadequate exercise protocols.Peer reviewe

DNA Origami as a Tool for Assembling Functional Biohybrid Nanomaterials

Recent advances in nanotechnology have given us a versatile toolbox of nanoscale objects with different functionalities. However, approaches for constructing stimuli-responsive and highly ordered macroscopic materials from these nanometer-sized components are still needed. The DNA origami technique enables the fabrication of custom-designed, well-defined, and highly addressable DNA-based structures and could therefore aid in the development of more advanced nanomaterials. In this doctoral thesis, the use of DNA origami in bottom-up nanofabrication was explored with the aim to construct functional biohybrid nanomaterials with high structural order. In publications I and II, the co-assembly of (negatively charged) DNA origami and cationic lipids was studied. The results demonstrated that DNA origami may serve as templates and nucleation sites for the formation of ordered lipid assemblies. The formed lipid matrix encapsulated the DNA origami, which also enhanced the DNA origami stability against endonuclease digestion. Moreover, the encapsulated DNA origami could be released from the lipid assemblies on demand by addition of competitive polyanions (publication I) or by illumination with long-wavelength UV light (publication II). In publication III, for one, highly ordered gold nanoparticle (AuNP) superlattices were assembled by employing electrostatic interactions between the cationic AuNPs and DNA origami. The ionic strength of the solution was used to control the assembly, and well-defined three-dimensional tetragonal superlattices were formed by gradually decreasing the salt concentration. Finally, in publication IV, pH-responsive and dynamically reconfigurable DNA-origami based lattices were constructed. Two pH-sensitive latches relying on Hoogsteen-type triplex formation were incorporated into the arms of the lattice-forming DNA origami unit, and thus the unit and the whole lattice could switch between an open and a closed state depending on the pH of the surrounding solution. The work shows that the library of stimuli-responsive elements initially developed for small DNA-based devices could be used to induce dynamicity also in considerably larger, hierarchical DNA origami lattices. In conclusion, the results demonstrate that DNA origami could function as a versatile self-assembling building block for advanced nanomaterials. The thesis highlights the potential of using DNA origami to fabricate highly ordered nanomaterials by electrostatic self-assembly and contributes to a broader understanding of such assemblies in bottom-up nanofabrication. In addition, the developed methods could aid in the engineering of more sophisticated stimuli-responsive hierarchical nanomaterials