Search

Zirconia is becoming reckoned as a promising solution for different applications, in particular those within the dental implant investigation field. It has been proved to successfully overcome important limitations of the commonly used titanium implants. The adhesion of microorganisms to the implants, in particular of bacteria, may govern the success or the failure of a dental implant, as the accumulation of bacteria on the peri-implant bone may rapidly evolve into periodontitis. However, bacterial adhesion on different zirconia architectures is still considerably unknown. Therefore, the adhesion of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa to zirconia surfaces with different finishings was evaluated and compared to a titanium surface. The adhesion interaction between S. aureus and P. aeruginosa was also evaluated using a co-culture since these bacteria are infamous due to their common presence in chronic wound infections. Results showed that different bacterium species possess different properties which influence their propensity to adhere to different roughness levels and architectures. E. coli revealed a higher propensity to adhere to zirconia channelled surfaces (7.15 × 106 CFU/mL), whereas S. aureus and P. aeruginosa adhered more to the titanium control group (1.07 × 105 CFU/ mL and 8.43 × 106 CFU/mL, respectively). Moreover, the co-culture denoted significant differences on the adhesion behaviour of bacteria. Despite not having shown an especially better behaviour regarding bacterial adhesion, zirconia surfaces with micro-channels are expected to improve the vascularization around the implants and ultimately enhance osseointegration, thus being a promising solution for dental implants., This work was supported by FCT-Portugal through the grant PD/BD/140202/2018, and the projects POCI-01-0145-FEDER-030498, POCI-01-0247-FEDER-017828, UIDB/04436/2020 and UIDP/04436/2020. This work was also funded by FEDER funds through the Operational Competitiveness Program-COMPETE and by National Funds through FCT-under the projects PTDC/CTM-TEX/28295/2017 and UID/CTM/00264/2019.

Surfactants are multipurpose active compounds and are ubiquitously present in detergents. Detergent demand spiked due to the current COVID-19 pandemic, further alerting to the need to replace petrochemical synthetic surfactants with natural and renewable surfactants to mitigate further environmental damage. The neem tree (Azadirachta indica A. Juss) is a fast-growing tree that provides a multitude of commodities, namely neem oil. Neem oil possesses insecticidal and medicinal activity. This work reports the extraction and characterization of a surfactant from neem oil (SNO), displaying a yield of approximately 100%. SNO exhibited suitable detergent characteristics with a high potential to be used as a cleansing agent for textile applications, such as high pH value (10.1), suitable foaming of 1.5 cm and a critical micelle concentration of nearly 0.12 g mL−1. In addition, SNO showed a moderate bactericidal activity against Escherichia coli and bacteriostatic activity against Staphylococcus aureus, both common nosocomial pathogens. Therefore, SNO has a good potential to be used in medical textile applications due to its detergent and bactericidal properties. Finally, an economical overview of the SNO production process was assessed, underscoring its viability., The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Brazilian Coordenacao de Aperfeioamento de Pessoal de Nivel Superior and by the Portuguese Fundacao para Ciencia e a Tecnologia, Fundo Europeu de Desenvolvimento Regional and Programa Operacional Competitividade e Internacionalizacao in the frame of the Portugal 2020 program for the project PLASMAMED PTDC/CTM-TEX/28295/2017.

Nowadays, antimicrobial textiles have been widely applied in several sectors, including hospitals and healthcare centres, food industry, clothing industry and in the domestic environment. Antimicrobial textiles are particularly used in active patches and dressings for wound healing, infection prevention and control (IPC), deodorization and antifungi clothing, among other applications. This chapter reviews the characterization, standard testing methods, as well as existing regulations in Europe and the United States for antimicrobial textiles. Antimicrobial textiles were characterized based on their application area. A summary of the efficacy testing standards on antimicrobial textiles was presented and critically discussed. Safety evaluation, comprising the risk assessment was also introduced. The increasing use of antimicrobial textiles is in need of further development of regulations and international testing standards for safety and efficacy evaluation in vitro including preclinical testing if applicable. Moreover, particular attention was given to the development of durability test standards.

A previously developed fiber-based polyester (PES) stent, with mechanical properties comparable to commercial nitinol stents, was coated with metallic silver (Ag0) and silver oxides (AgxO) thin films through direct current (DC) magnetron sputtering. Ag0 and AgxO coatings provide antimicrobial properties to the stents to minimize the occurrence of coronary stent infections. Nevertheless, the stent interacts with the atmosphere and then with the biological fluids and may lead to the generation of silver species with diminished antimicrobial efficiency and/or prone to induce cytotoxicity. Therefore, stent coating nanostructures aged 3 months were thoroughly analyzed by X-ray photoelectron spectroscopy (XPS) and their antimicrobial and cytotoxicity properties were assessed. Aging led to the presence of silver carbonate and bicarbonate as well as chemisorbed oxygen species in Ag0 and AgxO coatings. Bactericidal efficacy was tested against an important nosocomial bacterium, particularly associated to indwelling devices: Staphylococcus epidermidis. Aged Ag0 and AgxO coating presented a Log reduction of 1 and 2 at their surface, respectively. However, aged stents were able to induce a Log reduction of 2 (Ag0) and 4 (AgxO) on the surrounding medium. Only aged AgxO stent was able to provide a mild reduction of the bacterium at its surface and a clear antimicrobial effect (Log reduction &gt, 3) within its vicinity. More importantly, both aged Ag0 and AgxO stents were shown to be compatible with fibroblasts cells indicating that they can be safely used as indwelling devices, despite the aging effect.

The increased resistance of bacteria against conventional pharmaceutical solutions, the antibiotics, has raised serious health concerns. This has stimulated interest in the development of bio-based therapeutics with limited resistance, namely, essential oils (EOs) or antimicrobial peptides (AMPs). This study envisaged the evaluation of the antimicrobial efficacy of selected biomolecules, namely LL37, pexiganan, tea tree oil (TTO), cinnamon leaf oil (CLO) and niaouli oil (NO), against four bacteria commonly associated to nosocomial infections: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. The antibiotic vancomycin and silver nanoparticles (AgNPs) were used as control compounds for comparison purposes. The biomolecules were initially screened for their antibacterial efficacy using the agar-diffusion test, followed by the determination of minimal inhibitory concentrations (MICs), kill-time kinetics and the evaluation of the cell morphology upon 24 h exposure. All agents were effective against the selected bacteria. Interestingly, the AgNPs required a higher concentration (4000‐1250 &micro, g/mL) to induce the same effects as the AMPs (500‐7.8 &micro, g/mL) or EOs (365.2‐19.7 &micro, g/mL). Pexiganan and CLO were the most effective biomolecules, requiring lower concentrations to kill both Gram-positive and Gram-negative bacteria (62.5‐7.8 &micro, g/mL and 39.3‐19.7 &micro, g/mL, respectively), within a short period of time (averaging 2 h 15 min for all bacteria). Most biomolecules apparently disrupted the bacteria membrane stability due to the observed cell morphology deformation and by effecting on the intracellular space. AMPs were observed to induce morphological deformations and cellular content release, while EOs were seen to split and completely envelope bacteria. Data unraveled more of the potential of these new biomolecules as replacements for the conventional antibiotics and allowed us to take a step forward in the understanding of their mechanisms of action against infection-related bacteria.

Bacteria are simple organisms with a remarkable capacity for survival by adapting to different environments, which is a result of their long evolutionary history. Taking into consideration these adapting mechanisms, this work now investigates the effect of electrically active microenvironments on bacteria and on how this stimulation may trigger bacteria growth inhibition or proliferation. Electrical microenvironments are generated via stimulation of a piezoelectric polymer with a mechanical cue, thus developing an electrical response and a variation on the surface charge of the polymeric material. Specifically, Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli were grown overnight under static and dynamic conditions on piezoelectric poly(vinylidene) fluoride (PVDF) films to further study bacteria behavior under: (i) the effect of the material surface charge in static conditions, (ii) the mechanical effect, and (iii) the piezoelectric effect, the last two performed under dynamic conditions. Bacteria viability in planktonic and biofilm forms was measured, and the microorganism morphology was characterized. Whereas E. coli responds little to any of the stimuli application, S. epidermidis growth can be regulated through the material surface charge and by the applied frequency. Positively charged PVDF induces bacterial growth inhibition in planktonic and adhered cells in static conditions, whereas antifouling properties are obtained when a mechanical or piezoelectric effect at 4 Hz stimuli is applied. By increasing the stimuli to 40 Hz, however, the adhesion of bacteria is promoted. In conclusion, the behavior of certain bacteria species is tailored through the application of piezoelectric materials, which provide sufficient mechanoelectrical stimuli for growth or inhibition of bacteria, allowing for the design of suitable anti- and promicrobial strategies. Such strategies are only found in studies related to mammalian cells, whereas in bacterial cells this type of stimuli are still unknown. Thus, this work provides one of the first insights on the effect of piezoelectric stimuli on bacterial cells., FCT(Fundação para a Ciência e Tecnologia) and by ERDF through COMPETE2020 Programa Operacional Competitividade e Internacionalização (POCI) in the framework of the Strategic Programs UID/FIS/04650/2019 as well as under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 Programa Operacional Regional do Norte. The work was also supported by FCT through project LungChek ENMed/0049/2016. M.M.F. and C.R. thank FCT for the grant SFRH/BPD/121464/2016 and SFRH/BPD/ 90870/2012, respectively. Finally, the authors acknowledge funding by the Spanish Ministry of Economy and Com- petitiveness (MINECO) through the project MAT2016- 76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry and Education Departments under the ELKARTEK and PIBA (PIBA-2018-06) programs, respectively, info:eu-repo/semantics/publishedVersion

Bacterial cellulose (BC) films from two distinct sources (obtained by static culture with Gluconacetobacter xylinus ATCC 53582 (BC1) and from a commercial source (BC2)) were modified by bovine lactoferrin (bLF) adsorption. The functionalized films (BC+bLF) were assessed as edible antimicrobial packaging, for use in direct contact with highly perishable foods, specifically fresh sausage as a model of meat products. BC+bLF films and sausage casings were characterized regarding their water vapour permeability (WVP), mechanical properties, and bactericidal efficiency against two food pathogens, Escherichia coli and Staphylococcus aureus. Considering their edibility, an in vitro gastrointestinal tract model was used to study the changes occurring in the BC films during passage through the gastrointestinal tract. Moreover, the cytotoxicity of the BC films against 3T3 mouse embryo fibroblasts was evaluated. BC1 and BC2 showed equivalent density, WVP and maximum tensile strength. The percentage of bactericidal efficiency of BC1 and BC2 with adsorbed bLF (BC1+bLF and BC2+bLF, respectively) in the standalone films and in inoculated fresh sausages, was similar against E. coli (mean reduction 69 % in the films per se versus 94 % in the sausages) and S. aureus (mean reduction 97 % in the films per se versus 36 % in the case sausages). Moreover, the BC1+bLF and BC2+bLF films significantly hindered the specific growth rate of both bacteria. Finally, no relevant cytotoxicity against 3T3 fibroblasts was found for the films before and after the simulated digestion. BC films with adsorbed bLF may constitute an approach in the development of bio-based edible antimicrobial packaging systems., The authors would like to acknowledge Portuguese Foundation for Science and Technology (Fundação para a Ciência e Tecnologia) for the research grants: Jorge Padrão SFRH/BD/64901/2009, Sara Gonçalves SFRH/BD/63578/2009, João Pedro Silva SFRH/BPD/ 64958/2009, Ana Cristina Pinheiro SFRH/BPD/101181/2014. V. Sencadas thanks support from the COST Action MP1206: “Electrospun nano-fibres for bio inspired composite materials and innovative industrial applications” and MP1301: “New Generation Biomimetic and Customized Implants for Bone Engineering”. The authors would also like to thank the co-funded by the Programa Operacional Regional do Norte (ON.2 e O Novo Norte), QREN, FEDER Projects “BioHealth e Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124- FEDER-000027; “BioInd e Biotechnology and Bioengineering for improved Industrial and Agro-Food processes”, REF. NORTE-07- 0124-FEDER-000028; Strategic Project PEST-C/FIS/UI607/2014; Matepro eOptimizing Materials and Processes”, ref. NORTE-07- 0124-FEDER-000037; Strategic Project PEst-OE/EQB/LA0023/2013 and project ref. RECI/BBB-EBI/0179/2012 (project number FCOMP- 01-0124-FEDER-027462). Finally, the authors thank the Fundação para a Ciência e Tecnologia for the strategic funding from the UID/ BIO/04469/2013 unit.

The SARS‐CoV‐2 virus outbreak revealed that these nano‐pathogens have the ability to rapidly change lives. Undoubtedly, SARS‐CoV‐2 as well as other viruses can cause important global impacts, affecting public health, as well as, socioeconomic development. But viruses are not only a public health concern, they are also a problem in agriculture. The current treatments are often ineffective, are prone to develop resistance, or cause considerable adverse side effects. The use of nanotechnology has played an important role to combat viral diseases. In this review three main aspects are in focus: first, the potential use of nanoparticles as carriers for drug delivery. Second, its use for treatments of some human viral diseases, and third, its application as antivirals in plants. With these three themes, the aim is to give to readers an overview of the progress in this promising area of biotechnology during the 2017–2020 period, and to provide a glance at how tangible is the effectiveness of nanotechnology against viruses. Future prospects are also discussed. It is hoped that this review can be a contribution to general knowledge for both specialized and non‐specialized readers, allowing a better knowledge of this interesting topic., Viruses can cause important global impacts, affecting public health, and agriculture. The use of nanotechnology for viral disease treatments has played an important role. This technnology has been used in drug delivery, treatments of some human viral diseases, and as antivirals in plants. An overview of the progress during the 2017–2020 period is presented.

The feasibility of bacterial cellulose (BC) as a novel substrate for retinal pigment epithelium (RPE) culture was evaluated. Thin (41.6 ± 2.2 m of average thickness) and heatdried BC substrates were surface modified via acetylation and polysaccharide adsorption, using chitosan and carboxymethyl cellulose. All substrates were characterized according to their surface chemistry, wettability, energy, topography and also regarding their permeability, dimensional stability, mechanical properties and endotoxin content. Then, their ability to promote RPE cell adhesion and proliferation in vitro was assessed. All surface-modified BC substrates presented similar permeation coefficients with solutes of up to 300 kDa. Acetylation of BC decreased its swelling and the amount of endotoxins. Surface modification of BC greatly enhanced the adhesion and proliferation of RPE cells. All samples showed similar stress-strain behavior; BC and acetylated BC showed the highest elastic modulus, but the latter exhibited a slightly smaller tensile strength and elongation at break as compared to pristine BC. Although similar proliferation rates were observed among the modified substrates, the acetylated ones showed higher initial cell adhesion. This difference may be mainly due to the moderately hydrophilic surface obtained after acetylation., The authors acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for the financial support provided by the Research Grants SERH/BD/63578/2009, SFRH/BD/64901/2009, SFRH/BPD/64958/2009, and SFRH/BPD/63148/2009 for S.G., J.P., J.P.S., and V.S., respectively. The authors also acknowledge the Projects PEst-OE/EQB/LA0004/2013, PEst-OE/EQB/LA0023/2013, PTDC/BBB-BQB/2450/2012, and RECI/BBB-EBI/0179/2012 (Number: FCOMP-01-0124-FEDER-027462), cofunded by QREN, FEDER.

This work studied the physical immobilization of a commercial laccase on bacterial nanocellulose (BNC) aiming to identify the laccase antibacterial properties suitable for wound dressings. Physico-chemical analysis demonstrates that the BNC structure is manly formed by pure crystalline I cellulose. The pH optimum and activation energy of free laccase depends on the substrate employed corresponding to pH 6, 7, 3 and 57, 22, 48 kJ mol1 for 2,6-dimethylphenol (DMP), catechol and 2,2 -azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), respectively. The Michaelis-Menten constant (Km) value for the immobilized laccase (0.77 mM) was found to be almost double of that of the free enzyme (0.42 mM). However, the specific activities of immobilized and free laccase are similar suggesting that the cage-like structure of BNC allows entrapped laccase to maintain some flexibility and favour substrate accessibility. The results clearly show the antimicrobial effect of laccase in Gram-positive (92%) and Gram-negative (26%) bacteria and cytotoxicity acceptable for wound dressing applications., Andrea Zille (C2011-UMINHO-2C2T-01) acknowledges FCT funding from Programa Compromisso para a Ciência 2008, Portugal, FEDER funding on the Programa Operacional Factores de Competitividade - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136 and UID/CTM/00264. Jorge Padrão and João P. Silva acknowledge Portuguese Foundation for Science and Technology (FCT) grants SFRH/BD/64901/2009 and SFRH/BPD/64958/2009 respectively. The authors Jorge Padrão, JoãoP. Silva and Fernando Dourado would like to thank the FCT StrategicProject PEst-OE/EQB/LA0023/2013, also to the Project “BioHealth −Biotechnology and Bioengineering approaches to improve healthquality”, Ref. NORTE-07-0124-FEDER-000027, co-funded by thePrograma Operacional Regional do Norte (ON.2-O Novo Norte),QREN, FEDER, and finnally to RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462).

This work evaluated the effect of acetylated bacterial cellulose (ABC) substrates coated with urinary bladder matrix (UBM) on the behavior of Retinal Pigment Epithelium (RPE), as assessed by cell adhesion, proliferation and development of cell polarity exhibiting transepithelial resistance and polygonal shaped-cells with microvilli. Acetylation of bacterial cellulose (BC) generated a moderate hydrophobic surface (around 65°) while the adsorption of UBM onto these acetylated substrates did not affect significantly the surface hydrophobicity. The ABS substrates coated with UBM enabled the development of a cell phenotype closer to that of native RPE cells. These cells were able to express proteins essential for their cytoskeletal organization and metabolic function (ZO-1 and RPE65), while showing a polygonal shaped morphology with microvilli and a monolayer configuration. The coated ABC substrates were also characterized, exhibiting low swelling effect (between 1.52.0 swelling/mm3), high mechanical strength (2048 MPa) and non-pyrogenicity (2.12 EU/L). Therefore, the ABC substrates coated with UBM exhibit interesting features as potential cell carriers in RPE transplantation that ought to be further explored., The authors would also like to acknowledge José Ramalho for kindly supplying the RPE65 primary antibody. The authors acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for the financial support provided through the doctoral and posdoctoral grants SFRH/BD/63578/2009, SFRH/BD/64901/2009, SFRH/BPD/64958/2009 and SFRH/BPD/63148/2009 for Sara Gonc¸ alves, Jorge Padrão, João Pedro Silva, and Vitor Sencadas, respectively. The authors also acknowledge the projects PEst-OE/EQB/LA0004/2013, PEst-OE/EQB/LA0023/2013, PEST-C/FIS/UI607/2014, PTDC/BBB-BQB/2450/2012 and PTDC/SAU-ORG/118694/2010, co-funded by QREN, FEDER. Finally, the authors thank the FCT strategic project UID/BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124- FEDER-027462) and the project “BioInd—Biotechnology and Bioengineering for improved Industrial and Agro-Food processes”, REF. NORTE-07-0124-FEDER-000028 co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER.

Genetic engineering was used to produce an elastin-like polymer (ELP) with precise amino acid composition, sequence and length, resulting in the absolute control of MW and stereochemistry. A synthetic monomer DNA sequence encoding for (VPAVG)20, was used to build a library of concatemer genes with precise control on sequence and size. The higher molecular weight polymer with 220 repeats of VPAVG was biologically produced in Escherichia coli and purified by hot and cold centrifugation cycles, based on the reversible inverse temperature transition property of ELPs. The use of low cost carbon sources like lactose and glycerol for bacteria cells culture media was explored using Central Composite Design approach allowing optimization of fermentation conditions. Due to its self-assembling behaviour near 33 oC stable spherical microparticles with a size ~ 1μm were obtained, redissolving when a strong undercooling is achieved. The polymer produced showed hysteresis behaviour with thermal absorbing/releasing components depending on the salt concentration of the polymer solution., This work was supported by the ElastM Project, POCI/CTM/57177/2004 from Fundação para a Ciência e Tecnologia (Portugal) and FEDER, “Junta de Castilla y Leon” (VA087A06, VA016B08 and VA030A08), MEC (MAT2007-66275-C02-01 and NAN2004-08538), and by the Marie Curie RTN Biopolysurf (MRTN-CN-2004-005516). Raul Machado received a PhD grant: SFRH/BD/36754/2007 from Fundação para a Ciência e Tecnologia (Portugal). The authors would like to thank Magda Graça (CBMA) for all the technical support in sequencing, Lígia Rodrigues for the CCD enlightenment and Dan W. Urry for the stimulating discussions and encouragement to pursue the studies on protein-based polymers.

"Available online 6 May 2016", An effective tissue engineering approach requires adjustment according to the target tissue to be engineered. The possibility of obtaining a protein-based formulation for the development of multivalent tunable scaffolds that can be adapted for several types of cells and tissues is explored in this work. The incremental substitution of bovine serum albumin (BSA) by human serum albumin (HSA), changing the scaffolds hydrophilic/hydrophobic ratio, on a previously optimized scaffold formulation resulted in a set of uniform porous scaffolds with different physical properties and associated cell proliferation profile along time. There was a general trend towards an increase in hydrophilicity, swelling degree and in vitro degradation of the scaffolds with increasing replacement of BSA by HAS. The set of BSA/HSA scaffolds presented distinct values for the storage (elastic) modulus and loss factor which were similar to those described for different native tissues such as bone, cartilage, muscle, skin and neural tissue. The preferential adhesion and proliferation of skin fibroblasts on the BSA25%HSA75% and HSA100% scaffolds, as predicted by their viscoelastic properties, demonstrate that the BSA/HSA scaffold formulation is promising for the development of scaffolds that can be tuned according to the tissue to be repaired and restored., This work was supported by FCT I.P through the strategic funding UID/BIO/04469/2013 and the strategic funding UID/BIA/04050/2013. Artur Ribeiro thanks FCT for the SFRHBPD983882013 grant.

Fiber meshes of poly(hydroxybutyrate) (PHB) and poly(hydroxybutyrate)/poly(ethylene oxide) (PHB/PEO) with different concentrations of chlorhexidine (CHX) were prepared by electrospinning for assessment as a polymer based drug delivery system. The electrospun fibers were characterized at morphological, molecular and mechanical levels. The bactericidal potential of PHB and PHB/PEO electrospun fibers, with and without CHX, was investigated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by disk diffusion susceptibility tests. Electrospun fibers containing CHX exhibited bactericidal activity. PHB/PEO-1%CHX displayed higher CHX release levels and equivalent antibacterial activity when compared to PHB/PEO with 5 and 10 wt% CHX. Bactericidal performance of samples with 1 wt% CHX was assessed by Colony Forming Units (CFU), where reductions of 100% and 99.69% against E. coli and S. aureus were achieved, respectively., This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and PEST-C/QUI/UIO686/2011. The authors also thank funding from Matepro - Optimizing Materials and Processes", ref. NORTE-07-0124-FEDER-000037", co-funded by the "Programa Operacional Regional do Norte" (ON.2 - O Novo Norte), under the "Quadro de Referencia Estrategico Nacional" (QREN), through the "Fundo Europeu de Desenvolvimento Regional" (FEDER). D.M.C, JP and VS thanks the FCT for the, SFRH/BD/82411/2011, SFRH/BD/64901/2009 and SFRH/BPD/63148/2009 grants respectively. The authors also thank support from the COST Action MP1003, 2010 'European Scientific Network for Artificial Muscles' and to the COST Action MP1206 'Electrospun Nano-fibres for Bio inspired Composite Materials and Innovative Industrial Applications'. The authors also thank prof. Jose Luis Gomez Ribelles from the Unversidad Politecnica de Valencia, Spain, for interesting discussions on these issues.

The thermal and hydrolytic degradation of electrospun gelatin membranes cross-linked with glutaraldehyde in vapor phase has been studied. In vitro degradation of gelatin membranes was evaluated in phosphate buffer saline solution at 37 ºC. After 15 days under these conditions, a weight loss of 68 % was observed, attributed to solvation and depolymerization of the main polymeric chains. Thermal degradation kinetics of the gelatin raw material and as-spun electrospun membranes showed that the electrospinning processing conditions do not influence polymer degradation. However, for cross-linked samples a decrease in the activation energy was observed, associated with the effect of glutaraldehyde cross-linking reaction in the inter- and intra-molecular hydrogen bonds of the protein. It is also shown that the electrospinning process does not affect the formation of the helical structure of gelatin chains., This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and by projects project references NANO/NMed-SD/0156/2007 and PTDC/CTM-NAN/112574/2009. The authors also thank support from the COST Action MP1003, 2010 ‘European Scientific Network for Artificial Muscles’. DMC, JP and VS would like to acknowledge the FCT for the SFRH/BD/ 82411/2011, SFRH/BD/64901/2009 and SFRH/BD/64901/2009 grants respectively.

Protein-based polymers are present in a wide variety of organisms fulfilling structural and mechanical roles. Advances in protein engineering and recombinant DNA technology allow the design and production of recombinant protein-based polymers (rPBPs) with an absolute control of its composition. Although the application of recombinant proteins as biomaterials is still an emerging technology, the possibilities are limitless and far superior to natural or synthetic materials, as the complexity of the structural design can be fully customized. In this work, we report the electrospinning of two new genetically engineered silk-elastin-like proteins (SELPs) consisting of alternate silk- and elastin-like blocks. Electrospinning was performed with formic acid and aqueous solutions at different concentrations without addition of further agents. The size and morphology of the electrospun structures was characterized by scanning electron microscopy showing its dependence on the concentration and solvent used. Treatment with methanol-saturated air was employed to stabilize the structure and promote water insolubility through a time-dependent conversion of random coils into β-sheets (FTIR). The resultant methanol-treated electrospun mats were characterized for swelling degree (570–720%), water vapour transmission rate (1083 g/m2/day) and mechanical properties (modulus of elasticity ∼126 MPa). Furthermore, the methanol-treated SELP fibre mats showed no cytotoxicity and were able to support adhesion and proliferation of normal human skin fibroblasts. Adhesion was characterized by a filopodia-mediated mechanism. These results demonstrate that SELP fibre mats can provide promising solutions for the development of novel biomaterials suitable for tissue engineering applications., This work was financially supported by the European Commission via the 7th Framework Programme project EcoPlast (FP7-NMP-2009-SME-3, collaborative project number 246176), by Portuguese funding from FEDER through POFC-COMPETE and PEst project C/BIA/UI4050/2011 (Portugal), PEST-C/FIS/UI607/2011 and PEST-C/QUI/UIO686/2011. By MICINN (MAT 2009-14195-C03-03, IT2009-0089, ACI2009-0890, MAT201015310 and MAT2010-15982), the JCyL (VA034A09, VA030A08 and VA049A11-2) and CIBER-BBN. EC (Spain). The authors also thank funding from Matepro-Optimizing Materials and Processes", ref. NORTE-07-0124-FEDER-000037", co-funded by the 'Programa Operacional Regional do Norte' (ON.2-O Novo Norte), under the 'Quadro de Referencia Estrategico Nacional' (QREN), through the 'Fundo Europeu de Desenvolvimento Regional' (FEDER). RM, AC, CMC and VS acknowledge FCT for SFRH-BPD/86470/2012, SFRH/BD/75882/2011, SFRH/BD/68499/2010 and SFRH/BPD/63148/2009 grants, respectively., info:eu-repo/semantics/publishedVersion

A laccase from Ascomycetemyceliophthora thermophila was used to assist the binding of chitosan and catechin onto a previous enzymatically oxidized linen surface. The process consists of the pre-treatment of the linen with laccase followed by the application of chitosan in a first step and catechin plus laccase in a second step. The results presented here support the conclusion that laccase is able to oxidize phenols naturally existing in flax fibres, and that the o-quinones formed promote the attachment of chitosan or/and catechin. The pre-treatment of linen with laccase is therefore the key factor for the success of catechin and chitosan grafting. A multifunctional linen product with both antioxidant and antibacterial properties was obtained with an acceptable level of durability in terms of end user requirements., Carla Silva would like to acknowledge the Portuguese Fundacao para a Ciencia e a Tecnologia (FCT) for funding under the scholarship SFRH/BPD/46515/2008.