Surface induced selective delamination of amphiphilic ABA block copolymer thin films

This is the result of an ongoing collaboration with Dr. N. Sommerdijk’s Biomaterials group at the University of Eindhoven (the Netherlands) and illustrates the close collaboration that exists in pursuing the design and application of novel polymeric materials between the two groups. This details work on a physical phenomenon (selective delamination) and key materials (amphiphilic block copolymers) that have subsequently been applied in the design of novel biomaterials. These results have appeared in a larger body of work including Advanced Materials, Angewandtie Chemie International Edition and the Journal of Materials Chemistry

Cellular interaction with novel biomaterials

The objective of this thesis is to report the behaviour of mammalian cells with biocompatible synthetic polymers with potential for applications to the human body. Composite hydrogel materials were tested as possible keratoprosthetic devices. It was found that surface topography is an important consideration, pores, channels and fibres exposed on the surface of the hydrogels tested can have significant effects on the extent of cell adheson and proliferation. It is recommended that the core component is fabricated out of one of the following to provide a non cell adhesive base; A8, A11, A13, A22, A23. The haptic periphery fabricated out of one of the following would provide a cell adhesive composite; A16, A30, A33, A37, A38, A42, A43, A44. The presence of vitronectin in the ocular tissue appears to lead to higher cell adhesion to the posterior surface of a contact lens when compared to the anterior surface. Group IV contact lenses adhere more cells than Group II contact lenses - this may indicate that more protein (including vitronectin) is able to adhere to the contact lens due to the Group IV contact lenses high water content and ionic hydrogel matrix. Artificial lung surfactant analogues were found to be non cytotoxic but also decreased cell proliferation when tested at higher concentrations. Poly(lysine ethyl ester adipamide) [PLETESA] had the most favourable response on cell proliferation and commercial styrene/maleic anhydride (pMA/STY sp2) the most pronounced inhibitory response. The mode of action that decreases cell proliferation appears to be through membrane destabilization. Tissue culture well plates coated with PLETESA allowed cells to adhere in a concentration dependent manner, multilaminar liposomes possibly of PLETESA were observed in solution in PLETESA coated wells. Polyhydroxybutryate (PHB) and polyhydroxyvalerate (PHV) blends that contained hydroxyapatite were found to be the most cell adhesive material of those materials tested. The blends that were most susceptible to degradation adhered the most cells in initial stages of degradation. The initial slight increase in cell adhesion may be due to the increased rugosity of the material. As the degradation continued the number of cells adhering to the samples decreased, this may indicate that the polarity was inhibitory to cell adhesion during the later stages of degradation

Novel biomaterials: plasma-enabled nanostructures and functions

Material processing techniques utilizing low-temperature plasmas as the main process tool feature many unique capabilities for the fabrication of various nanostructured materials. As compared with the neutral-gas based techniques and methods, the plasma-based approaches offer higher levels of energy and flux controllability, often leading to higher quality of the fabricated nanomaterials and sometimes to the synthesis of the hierarchical materials with interesting properties. Among others, nanoscale biomaterials attract significant attention due to their special properties towards the biological materials (proteins, enzymes), living cells and tissues. This review briefly examines various approaches based on the use of low-temperature plasma environments to fabricate nanoscale biomaterials exhibiting high biological activity, biological inertness for drug delivery system, and other features of the biomaterials make them highly attractive. In particular, we briefly discuss the plasma-assisted fabrication of gold and silicon nanoparticles for bio-applications; carbon nanoparticles for bioimaging and cancer therapy; carbon nanotube-based platforms for enzyme production and bacteria growth control, and other applications of low-temperature plasmas in the production of biologically-active materials

Plasma-inspired biomaterials

The first questions which arise when one looks at the title of this special issue are what are plasma-inspired biomaterials, and what is this Special Issue of Journal of Physics D: Applied Physics (JPhysD) all about? Peculiar as it may seem, from a philosophical point of view 'inspiration' is something that influences by idea or is a good idea that connects two at first glance opposite things—plasma and biomaterials. On the one hand, plasma as a discharge state of the gas is considered nowadays as a cutting edge tool which can manipulate objects at the atomic or molecular scale (figure 1). On the other hand, biomaterials are substances that are engineered to possess certain properties which can control the interactions with components of living systems, inducing favourable response from the biological entities, and as such can direct the course of a therapy or diagnostic procedure [1]. In this respect, plasmas can be used to initiating even more favourable or selective responses, making the biomaterials even more suitable for their interaction biological entitiesPeer ReviewedPostprint (author's final draft

Novel biomaterials for innovative therapies in the severe wounds treatment

Treatment of non-healing wounds represents hitherto a severe dilemma for the healthcare worldwide because of wound failure to recover. The physiological wound healing is in fact a critical process requiring lack of both bacterial contamination and persistent inflammatory events in the damaged site. Despite a broad range of both antimicrobial and anti-inflammatory agents is commercially available, a successful tackling of bacterial infections and chronic inflammation is particularly challenging due to the increase of microbial resistance and remarkable side effects caused by an abuse of drugs. To this end, the development of innovative biomaterials used in combination with alternative agents is very challenging. The goals for the present thesis were to fabricate and characterize in terms of physical, chemical and biological properties, nanoengineered biomaterials to be used in the treatment of severe wounds. The potential use of two polysaccharides, namely chitosan and hyaluronan, and of their derivatives has been investigated. In the Chapter I is described an innovative method for the production of tridimensional hydrogels based on chitosan and on the cross-linker tripolyphosphate (TPP). The possibility to obtain hydrogels with chitosans with different acetylation degree (Fa) and molecular weight (Mw) was tackled. Resulting hydrogels were studied in terms of mechanical properties. Finally, soft-pliable and biocompatible membranes were obtained by freeze-drying. Further analyses are accounted in the Chapter II aiming at deeply investigating on hydrogel-forming process. More in detail, the different affinity of cross-linkers TPP and pyrophosphate (PPi) towards chitosan was explored in diluted solutions. The mechanical behavior of resulting hydrogels was further investigated whereas the polymer distribution within matrices has been assessed by both qualitative and quantitative methods. In the Chapter III the preparation of soft pliable chitosan-based membranes prepared from hydrogels containing antimicrobial silver nanoparticles (AgNPs) stabilized by a lactose-modified chitosan (chitlac) is tackled. A thorough investigation on bactericidal properties of the material revealed the synergistic activity of chitosan and AgNPs to reduce the growth of different bacteria strains and to break apart mature biofilms. Finally, biocompatibility assays on keratinocytes and fibroblasts did not prove any harmful effect on mammalian cells. The anti-inflammatory behavior of the short chain fatty acid butyrate is discussed in the first part of Chapter IV. Such feature was proved to be time- and dose-dependent. To extend on time and to modulate the biological activity of butyrate, chitosan/hyaluronan-based nanoparticles (complexes) were developed. These carriers showed the ability to encapsulate butyrate as payload, an intrinsic scavenging activity, the ability to quickly interact with neutrophils, muco-adhesive properties and lack of cytotoxicity. In the Chapter V it has been reported the biological investigation of a complex between hyaluronan-lipoate and silver ions (named SHLS12). Biological studies showed the ability of SHLS12 to exert a straightforward bactericidal activity against different bacterial strains grown both in sessile and planktonic state. The lack of toxicity was proved towards mammalian cells. By considering its ability to preserve antibacterial properties when exposed to serum proteins, this complex may be considered as a promising biomaterial for the treatment of non-healing wounds

DESIGN, DEVELOPMENT AND CHARACTERIZATION OF NOVEL BIOMATERIALS FOR PERIODONTAL TISSUE ENGINEERING

Periodontium is a complex system of different tissues, such as connective tissue, cartilage and bone, which work together to sustain the tooth. Gingivitis and periodontitis are devastating diseases that could affect the structure and function of the periodontal tissue. When the gingivitis are not treated and controlled with a correct oral hygiene, they could evolve in periodontitis, which could seriously damage the tissue surrounding the tooth and lead tooth loss. The main objective of periodontal tissue engineering is to regenerate the tooth’s supporting tissues. Periodontal tissue regeneration involves formation of new connective tissue (cementum and periodontal ligament) and new alveolar bone. The restoration of tooth by using a titanium dental implant is nowadays a quite common procedure. However, the positive fate of a surgical procedure that involves an insertion of titanium screw depends on the quality and quantity of alveolar bone which is present in the extraction site. The main objective of this doctoral thesis is to develop a set of novel biomaterials, designed to improve periodontal bone regeneration in patients and to control or prevent the bacterial infection in the wound site, via a sustained in situ drug release. Three different materials have been developed and characterized: 1. Three-dimensional porous scaffold coated with a polyelectrolyte complex for periprosthetic infection prevention 2. Bioceramic-reinforced hydrogel for alveolar bone regeneration 3. Antiadhesive guided tissue regeneration membrane The results demonstrated that they could be used in periodontal tissue engineering with predictable and excellent outcomes. With this set of biomaterials it is possible to control or prevent possible bacterial growth, achieve the correct alveolar bone quantity and quality and guide the tissue regeneratio

De Novo Design of Bioactive Protein-Resembling Nanospheres via Dendrimer-Templated Peptide Amphiphile Assembly

Self-assembling peptide amphiphiles (PAs) have been extensively used in the development of novel biomaterials. Because of their propensity to form cylindrical micelles, their use is limited in applications where small spherical micelles are desired. Here we present a platform method for controlling the self-assembly of biofunctional PAs into spherical 50 nm particles using dendrimers as shape-directing scaffolds. This templating approach results in biocompatible, stable protein-like assemblies displaying peptides with native secondary structure and biofunctionality

Maximum Valency Lattice Gas Models

We study lattice gas models with the imposition of a constraint on the maximum number of bonds (nearest neighbor interactions) that particles can participate in. The critical parameters, as well as the coexistence region are studied using the mean field approximation and the Bethe-Peierls approximation. We find that the reduction of the number of interactions suppresses the temperature-density region where the liquid and gas phases coexist. We confirm these results from simulations using the histogram reweighting method employing grand Canonical Monte Carlo simulations

Nanopartículas Poliméricas en Dermocosmética

Indexación: Web of Science; Scielo.Recent advances in the fields of biomaterials and nanotechnology have allowed the development of advanced nanoparticles for biomedical applications. Despite a vast number of nanostructures such as liposomes, solid­lipid nanocapsules, polymeric and hybrid lipid­polymer nanoparticles have been studied as carriers for drug delivery for different pathologies with remarkable promising results; the use of polymeric nanoparticles in dermocosmetic still has not been widely explored. The evolution of cosmetic into the care skin and dermatology represents novel technological challenges. Also, the increasing knowledge about normal skin physiology and advances in nanotechnology provide an attractive environment for the creation of innovative dermocosmetic formulations. In this work, we discuss the state of the art of polymeric nanoparticles formulated for dermocosmetics, its mechanisms of action, and diffusion into the skin.Los recientes avances en el campo de los biomateriales y la nanotecnología han permitido el desarrollo de nanopartículas avanzadas para aplicaciones biomédicas. A pesar de que un gran número de nanoestructuras tales como liposomas, nanocápsulas lípido-sólidas, nanopartículas poliméricas y lípido-polímero híbridas han sido estudiadas como vehículos para la administración de fármacos en diferentes patologías con notables resultados prometedores, el uso de nanopartículas poliméricas en dermocosmética todavía no ha sido ampliamente explorado. La evolución de la cosmética en el cuidado de la piel y la dermatología nos enfrentan a nuevos retos tecnológicos. Además, el aumento de los conocimientos sobre la fisiología de la piel normal y los avances en la nanotecnología proporcionan un entorno atractivo para la creación de formulaciones dermocosméticas innovadoras. En este trabajo se discute el estado del arte de las nanopartículas poliméricas desarrolladas para dermocosmética, sus mecanismos de acción y la difusión en la piel.http://ref.scielo.org/b68hz