Biomimetic supramolecular designs for the controlled release of growth factors in bone regeneration

The extracellular matrix (ECM) of tissues is an assembly of insoluble macromolecules that specifically interact with soluble bioactive molecules and regulate their distribution and availability to cells. Recapitulating this ability has been an important target in controlled growth factor delivery strategies for tissue regeneration and requires the design of multifunctional carriers. This review describes the integration of supramolecular interactions on the design of delivery strategies that encompass self-assembling and engineered affinity components to construct advanced biomimetic carriers for growth factor delivery. Several glycan- and peptide-based self-assemblies reported in the literature are highlighted and commented upon. These examples demonstrate how molecular design and chemistry are successfully employed to create versatile multifunctional molecules which self-assemble/disassemble in a precisely predicted manner, thus controlling compartmentalization, transport and delivery. Finally, we discuss whether recent advances in the design and preparation of supramolecular delivery systems have been sufficient to drive real translation towards a clinical impact. 

Desenvolvimento de materiais para isolamento térmico com base em biomimética

Dissertação de mestrado Internacional em Sustentabilidade do Ambiente Construído

Biomimetic superhydrophobic surfaces patterned with wettable spots as implantable chips for in vivo high-content 3D biomaterials response assessment

"Tissue engineering: part A", vol. 21, suppl. 1 (2015)

Closed hybrid hierarchical reservoirs based on the deconstruction of the cellular native microenvironment

The stem cell niche organization and dynamics provide valuable cues for the development of mimetic environments that could have potential to stimulate the regenerative process. We propose the use of biodegradable biomaterials to produce closed miniaturised structures able to encapsulate different cell types or bioactive molecules. In particular, capsules are fabricated using the so-called layer-by-layer technology, where the consecutive (nano-sized) layers are well stabilized by electrostatic interactions or other weak forces. Using alginate-based spherical templates containing cells or other elements (e.g. proteins, magnetic nanoparticles, microparticles) it is possible to produce liquefied capsules that may entrap the entire cargo under mild conditions. The inclusion of liquefied micropcapsules may be used to produce hierarchical compartmentalised systems for the delivery of bioactive agents. The presence of solid microparticles inside such capsules offers adequate surface area for adherent cell attachment increasing the biological performance of these hierarchical systems, while maintain both permeability and injectability. We demonstrated that the encapsulation of distinct cell types (including mesenchymal stem cells and endothelial cells) enhances the osteogenic capability of this system, that could be useful in bone tissue engineering applications.

Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes

Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.

Introducing biomimetic approaches to materials development and product design for engineering students

In this paper, we present a new course entitled “Biomimicry: from life to nanotechnological innovations” at the Mines Nancy Engineering School, Nancy, France, and explain how we developed a specific curriculum covering biomimicry. We discuss strategies that can be followed by teachers to explain selected contents in the multi-disciplinary field of biomimicry and/or bioinspiration to undergraduate students and how practical classroom activities can be conducted as individual or team work. We hope that sharing our experience will help teachers and senior researchers disseminate useful concepts and real examples of biomimetic principles and tools for the development of new materials, new/improved design and fabrication strategies, and innovation methodologies.

New approach on the bioconversion of vineyard pruning waste into surface-active compounds by Lactobacillus paracasei

Strategic funding of UID/BIO/04469/2013 unit and project ref RECI/BBB-EBI/0179/2012 (project number FCOMP-01-0124-FEDER-027462) and Xanel Vecino post-doctoral grant (ref SFRH/BPD/101476/2014) funded by Fundação para a Ciência e a Tecnologia, Portugal

Bacterial cellulose surface modification

The unique properties of bacterial nanocellulose (BNC) provide the basis for a wide range of applications in human and veterinary medicine, odontology, pharmaceuticals, acoustic and filter membranes, biotechnological devices, and in the food and paper industry. In this chapter, an overview of surface modifications of bacterial cellulose is presented. Depending on the envisaged applications, chemical modifications, incorporation of bioactive molecules, modification of the porosity, crystallinity, and biodegradability may be obtained, further enlarging the potential of BNC.

Development of a water-in-oil-in-water multiple emulsion system integrating biomimetic aqueous-core lipid nanodroplets for protein entity stabilization. Part I: experimental factorial design

Lipid nanoballoons integrating multiple emulsions of the type water-in-oil-in-water enclose, at least in theory, a biomimetic aqueous-core suitable for housing hydrophilic biomolecules such as proteins, peptides and bacteriophage particles. The research effort entertained in this paper reports a full statistical 23x31 factorial design study (three variables at two levels and one variable at three levels) to optimize biomimetic aqueous-core lipid nanoballoons for housing hydrophilic protein entities. The concentrations of protein, lipophilic and hydrophilic emulsifiers, and homogenization speed were set as the four independent variables, whereas the mean particle hydrodynamic size (HS), zeta potential (ZP) and polydispersity index (PI) were set as the dependent variables. The V23x31 factorial design constructed led to optimization of the higher (+1) and lower (-1) levels, with triplicate testing for the central (0) level, thus producing thirty three experiments and leading to selection of the optimized processing parameters as 0.015% (w/w) protein entity, 0.75% (w/w) lipophilic emulsifier (soybean lecithin) and 0.50% (w/w) hydrophilic emulsifier (poloxamer 188). In the present research effort, statistical optimization and production of protein derivatives encompassing full stabilization of their three-dimensional structure, has been attempted via housing said molecular entities within biomimetic aqueous-core lipid nanoballoons integrating a multiple (W/O/W) emulsion.

Experimental procedures for the identification of material properties of intervertebal disc - a contribution for the development of biomimetic substitutes for the nucleus pulposus

Tese de Doutoramento em Engenharia Mecânica.

Surface phenomena and hydrodynamic effects on the deposition of Pseudomonas fluorescens

Biofilm adhesion to metals (copper, aluminium and brass) was studied at two different velocities and pH values of 7 and 9. Both bacteria and metals showed negative surface charges at those values of pH, which tends to slow down adhesion. Film densities increased with the fluid velocity and were also affected by the pH and by the growth rate of the bacteria. Long duration tests based on heat transfer measurements were run at five different fluid velocities and at pH = 7, showing in general an asymptotic behaviour and a control of deposition by adhesion and growth phenomena.

Optimisation of a surface mount technology process using a SnAgCu lead-free alloy

The impending introduction of lead-free solder in the manufacture of electrical and electronic products has presented the electronics industry with many challenges. European manufacturers must transfer from a tin-lead process to a lead-free process by July 2006 as a result of the publication of two directives from the European Parliament. Tin-lead solders have been used for mechanical and electrical connections on printed circuit boards for over fifty years and considerable process knowledge has been accumulated. Extensive literature reviews were conducted on the topic and as a result it was found there are many implications to be considered with the introduction of lead-free solder. One particular question that requires answering is; can lead-free solder be used in existing manufacturing processes? The purpose of this research is to conduct a comparative study of a tin-lead solder and a lead-free solder in two key surface mount technology (SMT) processes. The two SMT processes in question were the stencil printing process and the reflow soldering process. Unreplicated fractional factorial experimental designs were used to carry out the studies. The quality of paste deposition in terms of height and volume were the characteristics of interest in the stencil printing process. The quality of solder joints produced in the reflow soldering experiment was assessed using x-ray and cross sectional analysis. This provided qualitative data that was then uniquely scored and weighted using a method developed during the research. Nested experimental design techniques were then used to analyse the resulting quantitative data. Predictive models were developed that allowed for the optimisation of both processes. Results from both experiments show that solder joints of comparable quality to those produced using tin-lead solder can be produced using lead-free solder in current SMT processes.

Changeability of Surface Ozone Concentration in Tbilisi in 1984-2010

მოყვანილია ქალაქ თბილისში 1984-დან 2010 წლებში მიწისპირა ოზონის კონცენტრაციის საშუალო ნახევარწლიური და წლიური მონაცემების დეტალური სტატისტიკური ანალიზის შედეგები.

Connection Between Surface Ozone Concentration and Visibility in Tbilisi

წარმოდგენილია მიწისპირა ოზონის საშუალოწლიური მონაცემების და სხვადასხვა ბალიანობის ხილვადობის სიშორის მქონე დღეების რიცხვს შორის კორელაციური და რეგრესიული კავშირის გამოკვლევის შედეგები 9, 12 და 15 საათზე დაკვირვებებისათვის.

Forearm surface EMG signals recognition and muscoloskeletal system dynamics identification using intelligent computational methods

Biosignals processing, Biological Nonlinear and time-varying systems identification, Electomyograph signals recognition, Pattern classification, Fuzzy logic and neural networks methods