Biocomposites Based on Degradable Materials as Biotechnological Dermal Equivalents

Hybrid tissue-engineered biosystems based on biodegradable polymers of microbiological origin – bacterial cellulose (BC) and a copolymer of 3-hydroxybutyric and 4-hydroxybutyric acid P(3HB/4HB) – were constructed using various methods: 1) the dried BC pellicles were soaked with a 2% P(3HB/4HB) solution in chloroform, kept for 24 h, and dried in a dust-free cabinet until the solvent had completely evaporated; 2) nonwoven membranes were placed into the K. xylinus B-12068 culture, and bacterial cellulose synthesized in it grew under static conditions; 3) powdered cellulose (particle size of 120 μm) was added to a 3% P(3HB/4HB) solution in chloroform and mixed ultrasonically to homogeneity; then, the films were produced by the solvent evaporation technique, at polymer to cellulose ratios of 2:1 and 1:1. Investigation of surface properties of the samples showed an increase in surface hydrophilicity of the composites produced by mixing a solution of P(3HB/4HB) with BC at ratios of 2:1 and 1:1 (the contact angle was 43.9±17.55° and 36.1±0.66°) relative to the starting materials. The physical/mechanical properties of the composites based on P(3HB/4HB) and BC were superior to the properties of the neat materials, and they were largely determined by the methods of production of the composite and the properties of the materials used. Based on the study of surface and physical/mechanical properties of the hybrids, films prepared by casting the polymer solution with BC powder (2:1 and 1:1) followed by solvent evaporation were chosen for studying cell adhesion. These scaffolds were loaded with drugs promoting wound healing (actovegin, solcoseryl) and tested in the culture of fibroblasts derived from the adipose tissue MSCs. The MTT assay showed that the most effective hybrid systems were polymer:bacterial cellulose powder (1:1) samples loaded with actovegin or solcoseryl at a concentration of 5%. Those systems produced a stimulating effect on fibroblasts, and, thus, they can be regarded as promising wound dressings to repair skin defect

A Conceptual Framework for Understanding the Biogeochemistry of Dry Riverbeds Through the Lens of Soil Science

Intermittent rivers and ephemeral streams (IRES) encompass fluvial ecosystems that eventually stop flowing and run dry at some point in space and time. During the dry phase, channels of IRES consist mainly of dry riverbeds (DRBs), prevalent yet widely unexplored ecotones between dry and wet phases that can strongly influence the biogeochemistry of fluvial networks. DRBs are often overlooked because they do not strictly belong to either domain of soil or freshwater science. Due to this dual character of DRBs, we suggest that concepts and knowledge from soil science can be used to expand the understanding of IRES biogeochemistry. Based on this idea, we propose that DRBs can be conceptually understood as early stage soils exhibiting many similarities with soils through two main forces: i) time since last sediment transport event, and ii) the development status of stabilizing structures (e.g. soil crusts and/or vascular plants). Our analysis suggests that while DRBs and soils may differ in master physical attributes (e.g. soil horizons vs fluvial sedimentary facies), they become rapidly comparable in terms of microbial communities and biogeochemical processes. We further propose that drivers of DRBs biogeochemistry are similar to those of soils and, hence, concepts and methods used in soil science are transferable to DRBs research. Finally, our paper presents future research directions to advance the knowledge of DRBs and to understand their role in the biogeochemistry of intermittent fluvial networks

Simulating rewetting events in intermittent rivers and ephemeral streams: a global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56‐98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached organic matter. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

Climate change and human pressures are changing the global distribution and the ex‐ tent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (precon‐ ditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experi‐ mentally simulated, under standard laboratory conditions, rewetting of leaves, river‐ bed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative character‐ istics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dis‐ solved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contrib‐ uted most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental vari‐ ables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached sub‐ stances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying event

Materials for Restoration of Bone Tissue

Реконструкция и оптимизация процесса заживления дефектов костной ткани с помощью новых материалов и технологий является актуальной проблемой в медицине. Обусловлено это высоким уровнем травм опорно-двигательного аппарата и распространенностью стоматологических и других социально значимых заболеваний костной ткани, что приводит к катастрофической потери трудоспособности населения и сопровождается огромными материальными затратами. В настоящем обзоре анализируются литературные данные о костно-пластических материалах для реконструктивной хирургии костной ткани от традиционных алло- и ксенотрасплантатов, титановых сплавов, фосфатов кальция, биокерамики до современных материалов на основе биосовместимых и биоразрушаемых полимеров и представлены результаты, полученные коллективом лаборатории биотехнологии новых биоматериалов СФУ.Reconstruction and optimization of the process of healing of bone tissue defects using new materials and technologies is an urgent problem in medicine. This is due to a high level of orthopedic traumas and prevalence of dental and other socially significant diseases of bone tissue, leading to the dramatic incapacitation of population and accompanied by huge financial costs. This review analyzes the published data on osteoplastic materials for bone reconstructive surgery from traditional allo- and xenografts, titanium alloys, calcium phosphates and bioceramics to modern materials based on biocompatible and biodegradable polymers; the results obtained by the SFU Laboratory of New Biomaterials Biotechnology are presente

Differentiation of Mscs into Osteoblasts on a Porous 3D -Carrier of Poly-3-Hydroxybutyrate

В настоящей статье разработаны и исследованы экспериментальные пористые 3D-носители из разрушаемого природного полимера 3-гидроксимасляной кислоты [П(3ГБ)], предназначенные для восстановления дефектов костной ткани. Способность разработанных 3D-носителей поддерживать адгезию, пролиферацию и направленную дифференцировку клеток в остеобластическом направлении исследована в культуре мультипотентных мезенхимальных стволовых клеток (ММСК), выделенных из костного мозга и жировой ткани. Дифференцировка ММСК в остеобласты подтверждена измерением активности щелочной фосфатазы, экспрессии генов к маркеру костного белка BGP (глутаминовый протеин, участвующий в процессах минерализации), измерением внеклеточных преципитатов солей кальция и фосфораThe study describes preparation and testing of porous 3D implants of natural degradable polymer of 3-hydroxybutyric acid [P(3HB)] for regeneration of bone tissue defects. The ability of the 3D carriers to favor attachment and facilitate proliferation and directed differentiation into osteoblasts of mesenchymal stem cells (MSCs) was studied in the culture of MSCs isolated from bone marrow and adipose tissue. MSC differentiation into osteoblasts was confirmed by measurements of the activity of alkaline phosphatase, gene expression of the marker of bone protein BGP (glutamic protein participating in mineralization) and measurements of intracellular precipitates of calcium and phosphorus salt

Способ получения и характеристики композитов бактериальной целлюлозы и наночастиц серебра

Bacterial cellulose (BC) is widely used in medicine as a dressing material due to its good biological properties – high biocompatibility, low adhesion and the ability to absorb wound exudate. The BC does not have antimicrobial activity itself, which limits the use of products in infected wounds, and also treatment of wounds in hospitals. A method for producing a two-component composite material based on bacterial cellulose (BC) synthesized in culture of Komagataeibacter xylinus B-12068 with silver nanoparticles [BC/AgNps], by hydrothermal synthesis of AgNO3 in the layer of BC at different temperatures and concentrations of AgNO3, is proposed. The antibacterial activity of BC/AgNps samples against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Staphylococcus aureus has been confirmed in vitro with the disc diffusion method. It is shown, that the antibacterial activity of samples is mostly expressed in cultures of P. aeruginosa and S. aureusБактериальная целлюлоза (БЦ) широко используется в медицине в качестве перевязочного материала благодаря своим биологическим свойствам – высокой бисовместимости, низкой адгезионности и способности поглощать раневой экссудат. Собственно БЦ не обладает антимикробной активностью, что ограничивает использование изделий при инфицированных ранах, а также при лечении ран в стационарах. Предложен вариант способа получения двухкомпонентного композитного материала на основе бактериальной целлюлозы (БЦ), синтезированной культурой Komagataeibacter xylinus В-12068, с наночастицами серебра [БЦ/AgNps] путем гидротермального синтеза AgNО3 в толще пласта при различных температурных режимах и концентрациях AgNО3. С использованием дискодиффузионного метода подтверждена антибактериальная активность образцов БЦ/AgNps в отношении Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae и Staphylococcus aureus. Показано, что антибактериальная активность образцов композита наиболее выражена по отношению P. aeruginosa и S. aureu

Biocomposites Based on Degradable Materials as Biotechnological Dermal Equivalents

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Hybrid tissue-engineered biosystems based on biodegradable polymers of microbiological origin – bacterial cellulose (BC) and a copolymer of 3-hydroxybutyric and 4-hydroxybutyric acid P(3HB/4HB) – were constructed using various methods: 1) the dried BC pellicles were soaked with a 2% P(3HB/4HB) solution in chloroform, kept for 24 h, and dried in a dust-free cabinet until the solvent had completely evaporated; 2) nonwoven membranes were placed into the K. xylinus B-12068 culture, and bacterial cellulose synthesized in it grew under static conditions; 3) powdered cellulose (particle size of 120 μm) was added to a 3% P(3HB/4HB) solution in chloroform and mixed ultrasonically to homogeneity; then, the films were produced by the solvent evaporation technique, at polymer to cellulose ratios of 2:1 and 1:1. Investigation of surface properties of the samples showed an increase in surface hydrophilicity of the composites produced by mixing a solution of P(3HB/4HB) with BC at ratios of 2:1 and 1:1 (the contact angle was 43.9±17.55° and 36.1±0.66°) relative to the starting materials. The physical/mechanical properties of the composites based on P(3HB/4HB) and BC were superior to the properties of the neat materials, and they were largely determined by the methods of production of the composite and the properties of the materials used. Based on the study of surface and physical/mechanical properties of the hybrids, films prepared by casting the polymer solution with BC powder (2:1 and 1:1) followed by solvent evaporation were chosen for studying cell adhesion. These scaffolds were loaded with drugs promoting wound healing (actovegin, solcoseryl) and tested in the culture of fibroblasts derived from the adipose tissue MSCs. The MTT assay showed that the most effective hybrid systems were polymer:bacterial cellulose powder (1:1) samples loaded with actovegin or solcoseryl at a concentration of 5%. Those systems produced a stimulating effect on fibroblasts, and, thus, they can be regarded as promising wound dressings to repair skin defects

Global Water Transfer Megaprojects: A Potential Solution for the Water-Food-Energy Nexus?

Globally, freshwater is unevenly distributed, both in space and time. Climate change, land use alteration, and increasing human exploitation will further increase the pressure on water as a resource for human welfare and on inland water ecosystems. Water transfer megaprojects (WTMP) are defined here as large-scale engineering interventions to divert water within and between river basins that meet one of the following criteria: construction costs >US 1 billion, distance of transfer >190 km, or volume of water transferred exceeds 0.23 km3 per year. WTMP represent an engineered solution to cope with water scarcity. These projects are most commonly associated with large-scale agricultural and energy development schemes, and many of them serve multiple purposes. Despite numerous case studies that focus on the social, economic, and environmental impacts of individual water transfer megaprojects, a global inventory of existing, planned and proposed projects is lacking. We carried out the first comprehensive global inventory of WTMP that are planned, proposed or under construction. We collected key information (e.g., location, distance, volume, costs, purpose) on 34 existing and 76 future (planned, proposed or under construction) WTMP. If realized, the total volume of water transferred by future projects will reach 1,910 km3 per year with a total transfer distance of more than twice the length of the Earth's equator. The largest future WTMP are located in North America, Asia, and Africa and the predicted total investment will exceed 2.7 trillion US. Among future projects, 42 are for agricultural development, 13 for hydropower development and 10 combine both purposes. Future megaprojects are also planned to support mining, ecosystem restoration and navigation. Our results underscore the extent to which humans have and are planning to re-engineer the global hydrological network and flows through WTMP, creating a network of “artificial rivers.” They emphasize the need to ensure the inclusion of these projects in global and basin hydrological models, and to develop internationally agreed criteria to assess the ecological, social and economic impacts of WTMP

GLOBAL WATER TRANSFER MEGAPROJECTS: A SOLUTION FOR THE WATER-FOOD-ENERGY NEXUS?

Globally, freshwater is unevenly distributed, both in space and time. Climate change, land use alteration, and increasing human exploitation will further increase the pressure on water as a resource for human welfare and on inland water ecosystems. Water transfer megaprojects (WTMP), i.e. large-scale engineering interventions to divert water within and between catchments, represent an approach in coping with increasing water scarcity. These projects are most commonly associated with large-scale agricultural and energy development schemes, and many of them serve multiple purposes. Despite numerous case studies that focus on the social, economic and environmental impacts of individual projects, a global inventory of existing and planned WTMP is lacking. We carried out the first comprehensive global inventory of WTMP that are either planned or under construction. We collected key information (e.g. location, distance, volume, costs, purpose) on 33 existing and 76 future (planned or under construction) WTMP. If realized, the future projects will transfer a total volume of 1,923 km3 per year across a total distance exceeding more than twice the length of Earth’s equator. The largest WTMP planned or under construction are located in North America, Asia and Africa. The predicted total investments in these WTMP will exceed 2.6 trillion US$. Among future projects, 43 will serve purposes of agriculture development, 14 transfer water for hydropower development and 10 combine both purposes. Our results show that WTMP will create artificial connections between river basins, alter the global hydrological cycle, and change the natural functions and services freshwaters provide for humans and nature. The results also emphasize the need to include these projects in global hydrological models, in strategies related to the water-energy-food nexus, and in developing internationally agreed criteria to assess the ecological, social and economic consequences these projects may cause