Nanoscale geometry determines mechanical biocompatibility of vertically aligned nanofibers

Vertically aligned carbon nanofibers (VACNFs) are promising material candidates for neural biosensors due to their ability to detect neurotransmitters in physiological concentrations. However, the expected high rigidity of CNFs could induce mechanical mismatch with the brain tissue, eliciting formation of a glial scar around the electrode and thus loss of functionality. We have evaluated mechanical biocompatibility of VACNFs by growing nickel-catalyzed carbon nanofibers of different lengths and inter-fiber distances. Long nanofibers with large inter-fiber distance prevented maturation of focal adhesions, thus constraining cells from obtaining a highly spread morphology that is observed when astrocytes are being contacted with stiff materials commonly used in neural implants. A silicon nanopillar array with 500 nm inter-pillar distance was used to reveal that this inhibition of focal adhesion maturation occurs due to the surface nanoscale geometry, more precisely the inter-fiber distance. Live cell atomic force microscopy was used to confirm astrocytes being significantly softer on the long Ni-CNFs compared to other surfaces, including a soft gelatin hydrogel. We also observed hippocampal neurons to mature and form synaptic contacts when being cultured on both long and short carbon nanofibers, without having to use any adhesive proteins or a glial monoculture, indicating high cytocompatibility of the material also with neuronal population. In contrast, neurons cultured on a planar tetrahedral amorphous carbon sample showed immature neurites and indications of early-stage apoptosis. Our results demonstrate that mechanical biocompatibility of biomaterials is greatly affected by their nanoscale surface geometry, which provides means for controlling how the materials and their mechanical properties are perceived by the cells.Peer reviewe

Inorganic particulate matter in the lung tissue of idiopathic pulmonary fibrosis patients reflects population density and fine particle levels

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a dismal prognosis and an unknown etiology. Inorganic dust is a known risk factor, and air pollution seems to affect disease progression. We aimed to investigate inorganic particulate matter in IPF lung tissue samples. Using polarizing light microscopy, we examined coal dust pigment and inorganic particulate matter in 73 lung tissue samples from the FinnishIPF registry. We scored the amount of coal dust pigment and particulate matter from 0 to 5. Using energy dispersive spectrometry with a scanning electron microscope, we conducted an elemental analysis of six IPF lung tissue samples. We compared the results to the registry data, and to the population density and air quality data. To compare categorical data, we used Fisher's exact test; we estimated the survival of the patients with Kaplan-Meier curves. We found inorganic particulate matter in all samples in varying amounts. Samples from the southern regions of Finland, where population density and fine particle levels are high, more often had particulate matter scores from 3 to 5 than samples from the northern regions (31/50, 62.0% vs. 7/23, 30.4%, p = 0.02). The highest particulate matter scores of 4 and 5 (n = 15) associated with a known exposure to inorganic dust (p = 0.004). An association between particulate matter in the lung tissue of IPF patients and exposure to air pollution may exist.Peer reviewe

A bioactive hybrid three-dimensional tissue-engineering construct for cartilage repair

The aim was to develop a hybrid three-dimensional-tissue engineering construct for chondrogenesis. The hypothesis was that they support chondrogenesis. A biodegradable, highly porous polycaprolactone-grate was produced by solid freeform fabrication. The polycaprolactone support was coated with a chitosan/polyethylene oxide nanofibre sheet produced by electrospinning. Transforming growth factor-3-induced chondrogenesis was followed using the following markers: sex determining region Y/-box 9, runt-related transcription factor 2 and collagen II and X in quantitative real-time polymerase chain reaction, histology and immunostaining. A polycaprolactone-grate and an optimized chitosan/polyethylene oxide nanofibre sheet supported cellular aggregation, chondrogenesis and matrix formation. In tissue engineering constructs, the sheets were seeded first with mesenchymal stem cells and then piled up according to the lasagne principle. The advantages of such a construct are (1) the cells do not need to migrate to the tissue engineering construct and therefore pore size and interconnectivity problems are omitted and (2) the cell-tight nanofibre sheet and collagen-fibre network mimic a cell culture platform for mesenchymal stem cells/chondrocytes (preventing escape) and hinders in-growth of fibroblasts and fibrous scarring (preventing capture). This allows time for the slowly progressing, multiphase true cartilage regeneration.Peer reviewe

Nanoscale geometry determines mechanical biocompatibility of vertically aligned nanofibers

Vertically aligned carbon nanofibers (VACNFs) are promising material candidates for neural biosensors due to their ability to detect neurotransmitters in physiological concentrations. However, the expected high rigidity of CNFs could induce mechanical mismatch with the brain tissue, eliciting formation of a glial scar around the electrode and thus loss of functionality. We have evaluated mechanical biocompatibility of VACNFs by growing nickel-catalyzed carbon nanofibers of different lengths and inter-fiber distances. Long nanofibers with large inter-fiber distance prevented maturation of focal adhesions, thus constraining cells from obtaining a highly spread morphology that is observed when astrocytes are being contacted with stiff materials commonly used in neural implants. A silicon nanopillar array with 500 nm inter-pillar distance was used to reveal that this inhibition of focal adhesion maturation occurs due to the surface nanoscale geometry, more precisely the inter-fiber distance. Live cell atomic force microscopy was used to confirm astrocytes being significantly softer on the long Ni-CNFs compared to other surfaces, including a soft gelatin hydrogel. We also observed hippocampal neurons to mature and form synaptic contacts when being cultured on both long and short carbon nanofibers, without having to use any adhesive proteins or a glial monoculture, indicating high cytocompatibility of the material also with neuronal population. In contrast, neurons cultured on a planar tetrahedral amorphous carbon sample showed immature neurites and indications of early-stage apoptosis. Our results demonstrate that mechanical biocompatibility of biomaterials is greatly affected by their nanoscale surface geometry, which provides means for controlling how the materials and their mechanical properties are perceived by the cells.</p

Amorphous carbon thin film electrodes with intrinsic Pt-gradient for hydrogen peroxide detection

Nanoscale amorphous carbon thin films with intrinsic Pt gradient show great promise as new electrode materials for electrochemical detection of hydrogen peroxide. Embedding the Pt particles in the carbon matrix during the fabrication process allows tighter integration than, for example, adding them after the fabrication on top of the substrate. Especially, this approach can offer excellent electrochemical properties combined with CMOS compatibility, which is crucial for further device development. Here we provide extensive in depth electrochemical and physicochemical characterization of these novel materials by cyclic voltammetry (CV), chronoamperometry (CA), rotating disk electrode (RDE) experiments, transmission electron microscopy (TEM), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Equipped with these detailed results on these materials we proceed to present some suggestions how the physicochemical properties correlate with the results from electrochemical measurements. (i) It is shown that coarsening of the initially very finely dispersed structure occurs both under electron bombardment during TEM imaging as well as during cyclic voltammetry in H2SO4. (ii) Further, it is shown that OH is adsorbed on small Pt islands much more strongly compared to the bulk Pt, which may heavily influence hydrogen peroxide redox reactions on these Pt-containing amorphous carbon films. (iii) Finally, we proceed to demonstrate that despite these complications, these materials show linear response for hydrogen peroxide reduction in neutral phosphate buffered saline combined with very fast response times.Academy of Finland (E.P. grant #274670, T.L. grants # 285015 and #285526), Biocentrum Helsinki, Finnish Cultural Foundation (N.I. grant #00160331) and Foundation for Aalto University Science and Technology are acknowledged for funding

Effectiveness and economic analysis of the whole cell/recombinant B subunit (WC/rbs) inactivated oral cholera vaccine in the prevention of traveller's diarrhoea

<p>Abstract</p> <p>Background</p> <p>Nowadays there is a debate about the indication of the oral whole-cell/recombinant B-subunit cholera vaccine (WC/rBS) in traveller's diarrhoea. However, a cost-benefit analysis based on real data has not been published.</p> <p>Methods</p> <p>A cost-effectiveness and cost-benefit study of the oral cholera vaccine (WC/rBS), Dukoral^®for the prevention of traveller's diarrhoea (TD) was performed in subjects travelling to cholera risk areas. The effectiveness of WC/rBS vaccine in the prevention of TD was analyzed in 362 travellers attending two International Vaccination Centres in Spain between May and September 2005.</p> <p>Results</p> <p>The overall vaccine efficacy against TD was 42,6%. Direct healthcare-related costs as well as indirect costs (lost vacation days) subsequent to the disease were considered. Preventive vaccination against TD resulted in a mean saving of 79.26 € per traveller.</p> <p>Conclusion</p> <p>According to the cost-benefit analysis performed, the recommendation for WC/rBS vaccination in subjects travelling to zones at risk of TD is beneficial for the traveller, regardless of trip duration and visited continent.</p

Coulomb drag propulsion experiments of ESTCube-2 and FORESAIL-1

This paper presents two technology experiments – the plasma brake for deorbiting and the electric solar wind sail for interplanetary propulsion – on board the ESTCube-2 and FORESAIL-1 satellites. Since both technologies employ the Coulomb interaction between a charged tether and a plasma flow, they are commonly referred to as Coulomb drag propulsion. The plasma brake operates in the ionosphere, where a negatively charged tether deorbits a satellite. The electric sail operates in the solar wind, where a positively charged tether propels a spacecraft, while an electron emitter removes trapped electrons. Both satellites will be launched in low Earth orbit carrying nearly identical Coulomb drag propulsion experiments, with the main difference being that ESTCube-2 has an electron emitter and it can operate in the positive mode. While solar-wind sailing is not possible in low Earth orbit, ESTCube-2 will space-qualify the components necessary for future electric sail experiments in its authentic environment. The plasma brake can be used on a range of satellite mass classes and orbits. On nanosatellites, the plasma brake is an enabler of deorbiting – a 300-m-long tether fits within half a cubesat unit, and, when charged with -1 kV, can deorbit a 4.5-kg satellite from between a 700- and 500-km altitude in approximately 9–13 months. This paper provides the design and detailed analysis of low-Earth-orbit experiments, as well as the overall mission design of ESTCube-2 and FORESAIL-1.Peer reviewe

Coulomb drag propulsion experiments of ESTCube-2 and FORESAIL-1

This paper presents two technology experiments – the plasma brake for deorbiting and the electric solar wind sail for interplanetary propulsion – on board the ESTCube-2 and FORESAIL-1 satellites. Since both technologies employ the Coulomb interaction between a charged tether and a plasma flow, they are commonly referred to as Coulomb drag propulsion. The plasma brake operates in the ionosphere, where a negatively charged tether deorbits a satellite. The electric sail operates in the solar wind, where a positively charged tether propels a spacecraft, while an electron emitter removes trapped electrons. Both satellites will be launched in low Earth orbit carrying nearly identical Coulomb drag propulsion experiments, with the main difference being that ESTCube-2 has an electron emitter and it can operate in the positive mode. While solar-wind sailing is not possible in low Earth orbit, ESTCube-2 will space-qualify the components necessary for future electric sail experiments in its authentic environment. The plasma brake can be used on a range of satellite mass classes and orbits. On nanosatellites, the plasma brake is an enabler of deorbiting – a 300-m-long tether fits within half a cubesat unit, and, when charged with - 1 kV, can deorbit a 4.5-kg satellite from between a 700- and 500-km altitude in approximately 9–13 months. This paper provides the design and detailed analysis of low-Earth-orbit experiments, as well as the overall mission design of ESTCube-2 and FORESAIL-1.</p

Hybrid Carbon Nanostructures for Direct Neuronal Interfacing

We have developed a concept of hybrid carbon nanomaterials, where different allotropes of carbon are integrated into a structure. In order to facilitate the long-term measurements in vivo, the cellular response at the bioelectric interface should be optimized. Indeed, failure of implant integration has been proposed to be the main reason for sensor failure in vivo. Most strategies to enhance electrode integration into target tissue exploit a protective layer or barrier on an electrode substrate. For the detection of neurotransmitters, this is not as suitable strategy, because (1) such films give rise to an increased background electrode capacitance and impedance, and (2) act as a diffusion barrier and as a result, a decreased amount of the analyte reaches the electrode surface and the kinetics is compromised. Here we demonstrate that we can regulate the cellular response just with the electrode material. Specifically, we will show that it is possible to combine the properties of different carbon allotropes toobtain hybrid materials with enhanced neural response. We will present three examples of the approach: (i) functionalized nanodiamonds on tetrahedral amorphous carbon (ta-C), (ii) multi-walled carbon nanotubes grown directly on top of to-C, and (iii) carbon nanofibres synthesized on top of ta-C thin films. We demonstrate that hybrid structures may promote neural integration as, for example, hydrogen-terminated nanodiamonds enhance neural cell viability and while not increasing glial cell viability. Moreover, carbon nanofibers show prominence for tuning the cellular response as their dimension match biologically relevant cues. We show that nanofiber dimensions significantly alter glial and neural cell adhesion as well as their morphology. The properties of the hybrid structures can be tailored, both geometrically and chemically, with high definition. Consequently, these materials possess exceptionally high potential to achieve optimal host response just with the electrode material.Peer reviewe

Environmental communication and brand awareness : case study Metso Corporation

Globaalit kestävän kehityksen haasteet luovat mahdollisuuksia niille yrityksille, joilla on tarjottavana ratkaisuja näihin haasteisiin. Brändi, joka on tunnettu kestävien teknologisten ratkaisujen tarjoaja, houkuttaa asiakkaita, sijoittajia sekä tulevaisuuden osaajia. Kirjallisuuden mukaan vahva brändi on yksi tärkeimmistä kilpailutekijöistä globaaleilla markkinoilla toimiville yrityksille. Viestinnällä on tärkeä rooli brändin rakentamisessa ja johtamisessa, ja siksi sen kehittäminen on oleellinen osa yrityksen brändityötä. Tutkimuksen tavoitteena oli selvittää case yrityksen (Metso Oyj) ympäristöviestinnän nykytilaa, jotta sitä voisi kehittää tulevaisuudessa entistä paremmin tukemaan Metson tavoitetilaa olla tunnettu kestävien ratkaisujen toimittaja. Teoreettisessa osassa käsiteltiin brändi – ja viestintäteoriaa, ympäristöviestintää käsitteenä sekä viestinnän roolia brändin rakentamisessa ja johtamisessa. Empiirisessä osassa haastateltiin Metson arvoketjun toimijoita (alihankkija, metsolaiset, asiakas ja asiakkaan asiakas). Vastaukset analysoitiin teemoitettuina kokonaisuuksina. Tutkimuksessa selvitettiin Metson brändin tunnettuutta ja ympäristöviestintää tutkimushetkellä sekä ympäristöviestinnän mahdollisuuksia ja haasteita yleisesti. Nykytila-arviota käytetään taustamateriaalina viestinnän kehitystyössä. Tulokset erosivat arvoketjun eri osissa: kokemus case-yrityksen yrityskuvasta ja viestinnästä vaihteli, riippuen siitä oliko haastateltava metsolainen vai yrityksen ulkopuolelta. Tutkimuksen löydös on tarve kehittää ympäristöviestintää. Case-yrityksessä on ratkaisuja asiakkaiden ympäristöhaasteiden ratkaisemiseksi, on viestinnällinen haaste saattaa se kohderyhmien tietoon.Global sustainability challenges create opportunities for companies providing solutions to these challenges. According literature a strong sustainable brand is attractive for customers, shareholders and future talents. A strong brand is a major competitive advantage for companies in global markets. In brand management communication has a vital role, and therefore developing communication is important in creating and managing brand value. The aim of this study was to find out the current status of the case company’s (Metso Corporation) environmental communication in order to develop it to strengthen company’s image as a sustainable solutions provider. In the theoretical part, the concepts of a brand, communication and environmental communication were studied, as well as the role of a communication in brand building and management. The empirical part of the study consists of interviews in across the case company’s value chain (subcontractor, Metso employees, customers and customer’s customers). Answers were gathered and analyzed under themed entities. Current state of brand awareness and environmental communication were studied, as well as opportunities and challenges of environmental communication in general. Current state analysis gave background information for future development. Results varied depending on the actor of the value chain: case company was seen differently among employees than outside of the company. Final conclusion was that there is a need to develop the environmental communication. Case company has environmental solutions for customer’s needs and a great story to tell, it is just about to communicate it to the target audience