This review highlights the current situation of antimicrobial resistance and the use of magnetic ... more This review highlights the current situation of antimicrobial resistance and the use of magnetic nanoparticles (MNPs) in developing novel routes for fighting infectious diseases. The most important two directions developed recently are: (i) improved delivery of antimicrobial compounds based on a drastic decrease of the minimal inhibition concentration (MIC) of the drug used independently; and (ii) inhibition of microbial attachment and biofilm development on coated medical surfaces. These new directions represent promising alternatives in the development of new strategies to eradicate and prevent microbial infections that involve resistant and biofilm-embedded bacteria. Recent promising applications of MNPs, as the development of delivery nanocarriers and improved nanovehicles for the therapy of different diseases are discussed, together with the mechanisms of microbial inhibition.
This review highlights the current situation of antimicrobial resistance and the use of magnetic ... more This review highlights the current situation of antimicrobial resistance and the use of magnetic nanoparticles (MNPs) in developing novel routes for fighting infectious diseases. The most important two directions developed recently are: (i) improved delivery of antimicrobial compounds based on a drastic decrease of the minimal inhibition concentration (MIC) of the drug used independently; and (ii) inhibition of microbial attachment and biofilm development on coated medical surfaces. These new directions represent promising alternatives in the development of new strategies to eradicate and prevent microbial infections that involve resistant and biofilm-embedded bacteria. Recent promising applications of MNPs, as the development of delivery nanocarriers and improved nanovehicles for the therapy of different diseases are discussed, together with the mechanisms of microbial inhibition.
... close-packed monolayer has been obtained. Acknowledgement. This work was carried out with EPS... more ... close-packed monolayer has been obtained. Acknowledgement. This work was carried out with EPSRC funding (GR/R30501/01) as part of a joint project with Thornton and Schluger (UCL). References. [1] M. Yoshimoto, T. Maeda ...
ABSTRACT Preventing infections is one of the main focuses of wound care. The colonisation of woun... more ABSTRACT Preventing infections is one of the main focuses of wound care. The colonisation of wounds by microorganisms can in fact have negative consequences on the healing process, delaying it. Here, we propose the use of essential oils as natural antimicrobial agents for cellulose-based fibrous dressings. We demonstrate the production of composite electrospun fibres that effectively encapsulate three different types of essential oils (cinnamon, lemongrass and peppermint). The fibrous scaffolds are able to inhibit the growth of Escherichia coli, even when small amounts of essential oils were used. At the same time, they are not cytotoxic, as proved by biocompatibility assays on skin cell models. The created dressings are promising as advanced biomedical devices for topical treatments.
ABSTRACT Flame retardants such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biph... more ABSTRACT Flame retardants such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) have been widely used in numerous applications for the retardation of fires. In this effort the indoor air concentrations of PBDEs and PCBs in European environments, obtained from various research studies, are gathered, analysed and evaluated. Specific microenvironments and materials used in indoor buildings appear to influence the concentration of flame retardants. Even though PBDEs and PCBs in Europe were found at low concentrations, there are some indoor environments presenting elevated levels of halogenated flame retardants (HFRs). Congener PBDE 209 is the most abundant in every studied environment. The extensive use of electrical devices increases the PBDEs concentration. High PBDE and PCB concentrations were found in the UK due to the strict fire regulations in this country. High PCB concentrations in indoor air were detected in buildings reinforced with concrete, as well as in schools, industrial and public buildings and in recycling plants. HFRs have shown that they are linked with various diseases including cancer, immune, neurological, endocrine, and reproductive effects and chlorance. Limitation and/or banning of HFRs is ongoing by many organisations and countries and the need for a universal approach is required. Keywords: halogenated flame retardants, PBDEs, PCBs, emission sources, indoor air concentrations, health effects.
Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium... more Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca 2+ -cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants.
Recombinant proteins represent a new and promising class of polymeric materials in the field of b... more Recombinant proteins represent a new and promising class of polymeric materials in the field of biomaterials research. An important model for biomaterial design is elastin, the protein accounting for the elasticity of several tissues. Human elastin-like polypeptides (HELPs) have been developed as recombinant versions of elastin with the purpose of enhancing some peculiar characteristics of the native protein, like self-assembling. In this paper, we report on a comparative study of rat myoblasts response to coatings based on two different HELP macromolecules, with respect to control cultures on bare cell culture polystyrene and on a standard collagen coating. Cell behavior was analyzed in terms of adhesion, proliferation and differentiation. The collected data strongly suggest the use of HELPs as excellent biomaterials for tissue engineering and regenerative medicine applications.
Stable surface modifications of polydimethylsiloxane (PDMS) are of crucial importance for the exp... more Stable surface modifications of polydimethylsiloxane (PDMS) are of crucial importance for the exploitation of the versatile physical properties of silicone in many biological applications. Surface hydrophobic recovery in fact poses severe time limitations to the observation of biological events and, in particular, to cell culturing. A novel method of stable modification of PDMS surface chemistry was therefore elaborated, relying on the use of genipin as a natural low-toxicity cross-linker, and involving free amine moieties. Its effectiveness to long-term cultures was studied by preparation of thin PDMS films with different stiffness. After assessment of surface chemistry and substrate stiffness, H9c2 muscle cells were cultured on the modified films, and differentiating myoblasts were observed for a period of four weeks since differentiation induction. A lower PDMS stiffness increased myotube width and supported a higher actin and myosin colocalization within myotubes, suggesting the achievement of myotube functional maturity. These results provide evidence of the effectiveness of the proposed procedures to PDMS surface chemistry modification. Furthermore, modified PDMS membranes prove to be suitable to several long-term studies of cell behaviour in vitro, including muscle cell contractility investigations.
In the last decade, the importance of topographic properties of extracellular environments has be... more In the last decade, the importance of topographic properties of extracellular environments has been shown to be essential to addressing cell response, especially when replacing damaged tissues with functional constructs obtained in vitro. In the current study, densely packed sub-micron poly (3-hydroxybutyrate) (PHB) fibres were electrospun with random and parallel orientations. PC12 pheochromocytoma cells that mimic central dopaminergic neurons and represent a model for neuronal differentiation were cultured on collagen-coated fibres to evaluate cell response dependence on substrate topography. Cell adhesion, viability and proliferation, as well as dopamine production were evaluated after three days since seeding. Cell differentiation was examined in terms of neurite number, orientation and length 6 days after administration of nerve growth factor (NGF). Results showed that proliferating PC12 cells secreted a higher quantity of dopamine on fibres with respect to control cultures and as a result, a possible use of PHB fibres was considered for cell transplantation in the central nervous system when local production of dopamine is impaired. Differentiated PC12 cells were characterized by highly aligned and longer neurites on parallel PHB fibres with respect to random fibres, thereby demonstrating the suitability of parallel PHB fibres for further studies in peripheral nervous system regeneration. . Immunofluorescent staining of b3-tubulin as an early marker of PC12 differentiation on PHB random (a, b) and parallel fibres (c, d). Low magnification images are on top row whereas high magnification images are on bottom row. Parallel fibre axis is oriented as yellow arrows PC12 neuron-like cell response to electrospun poly(3-hydroxybutyrate) substrates
Introduction: The work presents the development of acellular scaffolds extemporaneously embedded ... more Introduction: The work presents the development of acellular scaffolds extemporaneously embedded with platelet lysate (PL), as an innovative approach in the field of tissue regeneration/reparation. PL embedded scaffolds should have a tridimensional architecture to support cell migration and growth, in order to restore skin integrity. For this reason, chondroitin sulfate (CS) was associated with sodium alginate (SA) to prepare highly porous systems. Methods: The developed scaffolds were characterized for chemical stability to γ-radiation, morphology, hydration and mechanical properties. Moreover, the capability of fibroblasts and endothelial cells to populate the scaffold was evaluated by means of proliferation test 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and confocal laser scanning microscopy study. The scaffolds, not altered by sterilization, were characterized by limited swelling and high flexibility, by foam-like structure with bubbles that formed a high surface area and irregular texture suitable for cell adhesion. Results: Cell growth and scaffold population were evident on the bubble surface, where the cells appeared anchored to the scaffold structure. Conclusion: Scaffold network based on CS and SA demonstrated to be an effective support to enhance and to allow fibroblasts and endothelial cells (human umbilical vein endothelial cells, HUVEC) adhesion and proliferation. In particular, it could be hypothesized that cell adhesion was facilitated by the synergic effect of PL and CS. Although further in vivo evaluation is needed, on the basis of in vitro results, PL embedded scaffolds seem promising systems for skin wound healing.
The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strong... more The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strongly limited by their high solubility in aqueous environments and by the difficulty to adjust their degradation dynamics. Here, an alternative strategy to enhance the stability and to control the degradability of alginate nanofibers is described by treating them with trifluoroacetic acid for specific time intervals. It is demonstrated that by increasing the duration of the acid treatment procedure, lower degradation rate of the resulting fibers in buffer solutions can be achieved. Furthermore, the produced mats are free from cytotoxic compounds and highly biocompatible. The properties conferred to the alginate nanofibrous mats by the proposed method are extremely attractive in the production of innovative biomedical devices.
The present study reports a simple method to control the mechanical and surface properties of cel... more The present study reports a simple method to control the mechanical and surface properties of cellulose fiber networks and to protect them from humidity, without altering their initial morphology. This is achieved by dip coating the fiber networks in solutions containing different amounts of ethyl cyanoacrylate monomer (ECA). Under ambient humidity and due to the presence of the -OH groups of the cellulose, the ECA polymerizes around each individual cellulosic fiber forming a thin poly(ethyl cyanoacrylate) (PECA) shell. PECA was found to interact with the cellulose surface via hydrogen bonding as evidenced by Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. The detailed surface characterization reveals that only 3.5 wt% of ECA in solution is sufficient to form compact PECA cladding around every cellulose fiber. After the proposed treatment the cellulose sheets become hydrophobic, well protected from the environmental humidity and with increased Young's modulus.
We present natural polymeric composite films made of essential oils (EOs) dispersed in sodium alg... more We present natural polymeric composite films made of essential oils (EOs) dispersed in sodium alginate (NaAlg) matrix, with remarkable anti-microbial and anti-fungal properties. Namely, elicriso italic, chamomile blue, cinnamon, lavender, tea tree, peppermint, eucalyptus, lemongrass and lemon oils were encapsulated in the films as potential active substances. Glycerol was used to induce plasticity and surfactants were added to improve the dispersion of EOs in the NaAlg matrix. The topography, chemical composition, mechanical properties, and humidity resistance of the films are presented analytically. Antimicrobial tests were conducted on films containing different percentages of EOs against Escherichia coli bacteria and Candida albicans fungi, and the films were characterized as effective or not. Such diverse types of essential oil-fortified alginate films can find many applications mainly as disposable wound dressings but also in food packaging, medical device protection and disinfection, and indoor air quality improvement materials, to name a few.
The adsorption of a range of organic molecules from toluene onto the oxidized surface of magnetro... more The adsorption of a range of organic molecules from toluene onto the oxidized surface of magnetronsputtered aluminium metal is studied using sessile drop water contact angle measurements. Molecules with different head group functionalities and various chain lengths are considered, including alkyl carboxylic acids, alkyl phosphonic acids, alkyl amines, alkyl trimethoxysilanes, alkyl trichlorosilanes and epoxy alkanes. Alkyl phosphonic and carboxylic acids are identified as readily forming the most wellpacked monolayers on the aluminium surface, whereas the others adsorb less well and the chlorosilanes polymerize as a result of combination with moisture to form a thick deposit. The high-adsorption-density monolayers of alkyl phosphonic and carboxylic acids were studied using polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and x-ray photoelectron spectroscopy (XPS): PM-IRRAS reveals relatively poorer ordering of the C 10 alkyl carboxylic acid monolayer compared with that formed from the phosphonic acid, and XPS data suggest that this is likely to relate to a lower ability to displace preadsorbed volatile organic compounds.
This review highlights the current situation of antimicrobial resistance and the use of magnetic ... more This review highlights the current situation of antimicrobial resistance and the use of magnetic nanoparticles (MNPs) in developing novel routes for fighting infectious diseases. The most important two directions developed recently are: (i) improved delivery of antimicrobial compounds based on a drastic decrease of the minimal inhibition concentration (MIC) of the drug used independently; and (ii) inhibition of microbial attachment and biofilm development on coated medical surfaces. These new directions represent promising alternatives in the development of new strategies to eradicate and prevent microbial infections that involve resistant and biofilm-embedded bacteria. Recent promising applications of MNPs, as the development of delivery nanocarriers and improved nanovehicles for the therapy of different diseases are discussed, together with the mechanisms of microbial inhibition.
This review highlights the current situation of antimicrobial resistance and the use of magnetic ... more This review highlights the current situation of antimicrobial resistance and the use of magnetic nanoparticles (MNPs) in developing novel routes for fighting infectious diseases. The most important two directions developed recently are: (i) improved delivery of antimicrobial compounds based on a drastic decrease of the minimal inhibition concentration (MIC) of the drug used independently; and (ii) inhibition of microbial attachment and biofilm development on coated medical surfaces. These new directions represent promising alternatives in the development of new strategies to eradicate and prevent microbial infections that involve resistant and biofilm-embedded bacteria. Recent promising applications of MNPs, as the development of delivery nanocarriers and improved nanovehicles for the therapy of different diseases are discussed, together with the mechanisms of microbial inhibition.
... close-packed monolayer has been obtained. Acknowledgement. This work was carried out with EPS... more ... close-packed monolayer has been obtained. Acknowledgement. This work was carried out with EPSRC funding (GR/R30501/01) as part of a joint project with Thornton and Schluger (UCL). References. [1] M. Yoshimoto, T. Maeda ...
ABSTRACT Preventing infections is one of the main focuses of wound care. The colonisation of woun... more ABSTRACT Preventing infections is one of the main focuses of wound care. The colonisation of wounds by microorganisms can in fact have negative consequences on the healing process, delaying it. Here, we propose the use of essential oils as natural antimicrobial agents for cellulose-based fibrous dressings. We demonstrate the production of composite electrospun fibres that effectively encapsulate three different types of essential oils (cinnamon, lemongrass and peppermint). The fibrous scaffolds are able to inhibit the growth of Escherichia coli, even when small amounts of essential oils were used. At the same time, they are not cytotoxic, as proved by biocompatibility assays on skin cell models. The created dressings are promising as advanced biomedical devices for topical treatments.
ABSTRACT Flame retardants such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biph... more ABSTRACT Flame retardants such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) have been widely used in numerous applications for the retardation of fires. In this effort the indoor air concentrations of PBDEs and PCBs in European environments, obtained from various research studies, are gathered, analysed and evaluated. Specific microenvironments and materials used in indoor buildings appear to influence the concentration of flame retardants. Even though PBDEs and PCBs in Europe were found at low concentrations, there are some indoor environments presenting elevated levels of halogenated flame retardants (HFRs). Congener PBDE 209 is the most abundant in every studied environment. The extensive use of electrical devices increases the PBDEs concentration. High PBDE and PCB concentrations were found in the UK due to the strict fire regulations in this country. High PCB concentrations in indoor air were detected in buildings reinforced with concrete, as well as in schools, industrial and public buildings and in recycling plants. HFRs have shown that they are linked with various diseases including cancer, immune, neurological, endocrine, and reproductive effects and chlorance. Limitation and/or banning of HFRs is ongoing by many organisations and countries and the need for a universal approach is required. Keywords: halogenated flame retardants, PBDEs, PCBs, emission sources, indoor air concentrations, health effects.
Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium... more Biodegradable polymeric materials based on blending aqueous dispersions of natural polymer sodium alginate (NaAlg) and povidone iodine (PVPI) complex, which allow controlled antiseptic release, are presented. The developed materials are either free standing NaAlg films or Ca 2+ -cross-linked alginate beads, which properly combined with PVPI demonstrate antibacterial and antifungal activity, suitable for therapeutic applications, such as wound dressing. Glycerol was used as the plasticizing agent. Film morphology was studied by optical and atomic force microscopy. It was found that PVPI complex forms well dispersed circular micro-domains within the NaAlg matrix. The beads were fabricated by drop-wise immersion of NaAlg/PVPI/glycerol solutions into aqueous calcium chloride solutions to form calcium alginate beads encapsulating PVPI solution (CaAlg/PVPI). Controlled release of PVPI was possible when the composite films and beads were brought into direct contact with water or with moist media. Bactericidal and fungicidal properties of the materials were tested against Escherichia coli bacteria and Candida albicans fungi. The results indicated very efficient antibacterial and antifungal activity within 48 h. Controlled release of PVPI into open wounds is highly desired in clinical applications to avoid toxic doses of iodine absorption by the wound. A wide variety of applications are envisioned such as external and internal wound dressings with controlled antiseptic release, hygienic and protective packaging films for medical devices, and polymer beads as water disinfectants.
Recombinant proteins represent a new and promising class of polymeric materials in the field of b... more Recombinant proteins represent a new and promising class of polymeric materials in the field of biomaterials research. An important model for biomaterial design is elastin, the protein accounting for the elasticity of several tissues. Human elastin-like polypeptides (HELPs) have been developed as recombinant versions of elastin with the purpose of enhancing some peculiar characteristics of the native protein, like self-assembling. In this paper, we report on a comparative study of rat myoblasts response to coatings based on two different HELP macromolecules, with respect to control cultures on bare cell culture polystyrene and on a standard collagen coating. Cell behavior was analyzed in terms of adhesion, proliferation and differentiation. The collected data strongly suggest the use of HELPs as excellent biomaterials for tissue engineering and regenerative medicine applications.
Stable surface modifications of polydimethylsiloxane (PDMS) are of crucial importance for the exp... more Stable surface modifications of polydimethylsiloxane (PDMS) are of crucial importance for the exploitation of the versatile physical properties of silicone in many biological applications. Surface hydrophobic recovery in fact poses severe time limitations to the observation of biological events and, in particular, to cell culturing. A novel method of stable modification of PDMS surface chemistry was therefore elaborated, relying on the use of genipin as a natural low-toxicity cross-linker, and involving free amine moieties. Its effectiveness to long-term cultures was studied by preparation of thin PDMS films with different stiffness. After assessment of surface chemistry and substrate stiffness, H9c2 muscle cells were cultured on the modified films, and differentiating myoblasts were observed for a period of four weeks since differentiation induction. A lower PDMS stiffness increased myotube width and supported a higher actin and myosin colocalization within myotubes, suggesting the achievement of myotube functional maturity. These results provide evidence of the effectiveness of the proposed procedures to PDMS surface chemistry modification. Furthermore, modified PDMS membranes prove to be suitable to several long-term studies of cell behaviour in vitro, including muscle cell contractility investigations.
In the last decade, the importance of topographic properties of extracellular environments has be... more In the last decade, the importance of topographic properties of extracellular environments has been shown to be essential to addressing cell response, especially when replacing damaged tissues with functional constructs obtained in vitro. In the current study, densely packed sub-micron poly (3-hydroxybutyrate) (PHB) fibres were electrospun with random and parallel orientations. PC12 pheochromocytoma cells that mimic central dopaminergic neurons and represent a model for neuronal differentiation were cultured on collagen-coated fibres to evaluate cell response dependence on substrate topography. Cell adhesion, viability and proliferation, as well as dopamine production were evaluated after three days since seeding. Cell differentiation was examined in terms of neurite number, orientation and length 6 days after administration of nerve growth factor (NGF). Results showed that proliferating PC12 cells secreted a higher quantity of dopamine on fibres with respect to control cultures and as a result, a possible use of PHB fibres was considered for cell transplantation in the central nervous system when local production of dopamine is impaired. Differentiated PC12 cells were characterized by highly aligned and longer neurites on parallel PHB fibres with respect to random fibres, thereby demonstrating the suitability of parallel PHB fibres for further studies in peripheral nervous system regeneration. . Immunofluorescent staining of b3-tubulin as an early marker of PC12 differentiation on PHB random (a, b) and parallel fibres (c, d). Low magnification images are on top row whereas high magnification images are on bottom row. Parallel fibre axis is oriented as yellow arrows PC12 neuron-like cell response to electrospun poly(3-hydroxybutyrate) substrates
Introduction: The work presents the development of acellular scaffolds extemporaneously embedded ... more Introduction: The work presents the development of acellular scaffolds extemporaneously embedded with platelet lysate (PL), as an innovative approach in the field of tissue regeneration/reparation. PL embedded scaffolds should have a tridimensional architecture to support cell migration and growth, in order to restore skin integrity. For this reason, chondroitin sulfate (CS) was associated with sodium alginate (SA) to prepare highly porous systems. Methods: The developed scaffolds were characterized for chemical stability to γ-radiation, morphology, hydration and mechanical properties. Moreover, the capability of fibroblasts and endothelial cells to populate the scaffold was evaluated by means of proliferation test 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and confocal laser scanning microscopy study. The scaffolds, not altered by sterilization, were characterized by limited swelling and high flexibility, by foam-like structure with bubbles that formed a high surface area and irregular texture suitable for cell adhesion. Results: Cell growth and scaffold population were evident on the bubble surface, where the cells appeared anchored to the scaffold structure. Conclusion: Scaffold network based on CS and SA demonstrated to be an effective support to enhance and to allow fibroblasts and endothelial cells (human umbilical vein endothelial cells, HUVEC) adhesion and proliferation. In particular, it could be hypothesized that cell adhesion was facilitated by the synergic effect of PL and CS. Although further in vivo evaluation is needed, on the basis of in vitro results, PL embedded scaffolds seem promising systems for skin wound healing.
The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strong... more The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strongly limited by their high solubility in aqueous environments and by the difficulty to adjust their degradation dynamics. Here, an alternative strategy to enhance the stability and to control the degradability of alginate nanofibers is described by treating them with trifluoroacetic acid for specific time intervals. It is demonstrated that by increasing the duration of the acid treatment procedure, lower degradation rate of the resulting fibers in buffer solutions can be achieved. Furthermore, the produced mats are free from cytotoxic compounds and highly biocompatible. The properties conferred to the alginate nanofibrous mats by the proposed method are extremely attractive in the production of innovative biomedical devices.
The present study reports a simple method to control the mechanical and surface properties of cel... more The present study reports a simple method to control the mechanical and surface properties of cellulose fiber networks and to protect them from humidity, without altering their initial morphology. This is achieved by dip coating the fiber networks in solutions containing different amounts of ethyl cyanoacrylate monomer (ECA). Under ambient humidity and due to the presence of the -OH groups of the cellulose, the ECA polymerizes around each individual cellulosic fiber forming a thin poly(ethyl cyanoacrylate) (PECA) shell. PECA was found to interact with the cellulose surface via hydrogen bonding as evidenced by Fourier transform infrared spectroscopy and thermogravimetric analysis measurements. The detailed surface characterization reveals that only 3.5 wt% of ECA in solution is sufficient to form compact PECA cladding around every cellulose fiber. After the proposed treatment the cellulose sheets become hydrophobic, well protected from the environmental humidity and with increased Young's modulus.
We present natural polymeric composite films made of essential oils (EOs) dispersed in sodium alg... more We present natural polymeric composite films made of essential oils (EOs) dispersed in sodium alginate (NaAlg) matrix, with remarkable anti-microbial and anti-fungal properties. Namely, elicriso italic, chamomile blue, cinnamon, lavender, tea tree, peppermint, eucalyptus, lemongrass and lemon oils were encapsulated in the films as potential active substances. Glycerol was used to induce plasticity and surfactants were added to improve the dispersion of EOs in the NaAlg matrix. The topography, chemical composition, mechanical properties, and humidity resistance of the films are presented analytically. Antimicrobial tests were conducted on films containing different percentages of EOs against Escherichia coli bacteria and Candida albicans fungi, and the films were characterized as effective or not. Such diverse types of essential oil-fortified alginate films can find many applications mainly as disposable wound dressings but also in food packaging, medical device protection and disinfection, and indoor air quality improvement materials, to name a few.
The adsorption of a range of organic molecules from toluene onto the oxidized surface of magnetro... more The adsorption of a range of organic molecules from toluene onto the oxidized surface of magnetronsputtered aluminium metal is studied using sessile drop water contact angle measurements. Molecules with different head group functionalities and various chain lengths are considered, including alkyl carboxylic acids, alkyl phosphonic acids, alkyl amines, alkyl trimethoxysilanes, alkyl trichlorosilanes and epoxy alkanes. Alkyl phosphonic and carboxylic acids are identified as readily forming the most wellpacked monolayers on the aluminium surface, whereas the others adsorb less well and the chlorosilanes polymerize as a result of combination with moisture to form a thick deposit. The high-adsorption-density monolayers of alkyl phosphonic and carboxylic acids were studied using polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and x-ray photoelectron spectroscopy (XPS): PM-IRRAS reveals relatively poorer ordering of the C 10 alkyl carboxylic acid monolayer compared with that formed from the phosphonic acid, and XPS data suggest that this is likely to relate to a lower ability to displace preadsorbed volatile organic compounds.
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Papers by Ioannis Liakos