In Vitro Antimicrobial Activity of Embothrium coccineum Used as Traditional Medicine in Patagonia against Multiresistant Bacteria.

Embothrium coccineum J.R. Forst. & G. Forst is an evergreen tree that has been used as a folk remedy for the treatment of neuralgia, tooth pains, wound healing, and glandular conditions, as well as an antiseptic agent against bacterial infection. The antibacterial activities of sequential extracts (hexane, dichloromethane, ethyl acetate, and ethanol) from the leaves of E. coccineum were evaluated by means of the micro-dilution assay against six (Escherichia coli; Klebsiella pneumoniae; Proteus mirabilis; Pseudomonas aeruginosa; Staphylococcus aureus and Streptococcus pyogenes) multiresistant bacteria strains. Ethyl acetate extract showed the best spectra of antibacterial activity against all tested bacteria, and was analyzed by gas chromatography-mass spectrometry (GC-MS) for its composition. The results of the present work provide useful baseline information for the potential development and use of nanoparticles and/or nanofibers doped with extracts of E. coccineum in the fight against multiresistant bacteria, which would allow the validation of the traditional use of E. coccineum by native peoples of Patagonia as an antimicrobial agent in the biomedical Field.

Design of a biodegradable UV-irradiated gelatin-chitosan/nanocomposed membrane with osteogenic ability for application in bone regeneration.

Guided bone regeneration membranes are used in oral surgery to protect the site of a lesion exposed to connective tissue invasion which, in turn, prevents new bone formation. Although non-degradable and degradable materials have been applied in clinical treatments, biodegradable membranes have the advantage that they do not require a secondary surgical procedure to be removed. However, they have a very low mechanical strength. As biodegradable membranes, biomaterials based on gelatin-chitosan have gained importance in clinical applications due to their unique properties. Gelatin contains RGD-like sequences, promoting cell adhesion/migration, and it can be blended with chitosan, which allows the immobilization of nanoparticles. In this work, we designed a new gelatin-chitosan polymeric membrane which contains hydroxyapatite and titania nanoparticles as two very well-documented osteoconductive materials. UV radiation was used as a non-toxic cross-linking agent to improve the thermophysical/mechanical characteristics and to control the biodegradability of the nanocomposed membrane. The microstructure, thermophysical and mechanical properties of the UV-irradiated material were studied by scanning electron microscopy, differential scanning calorimetry and Young's modulus, respectively. The in vitro biocompatibility of the new nanocomposite was evaluated by cell adhesion and proliferation assays. The osteoconductive ability was determined by an alkaline phosphatase production assay using mouse embryonic fibroblast (MEF) cells. The results show a homogeneous material with an appropriate distribution of nanoparticles. Cross-linking by UV radiation improved the mechanical and biological performance of the membrane. The presence of two osteoconductive nanoparticles, such as titania and hydroxyapatite, increased the osteogenic potential of the gelatin-based material in vitro, which confers a biological function, in addition to functioning as a physical barrier. The material obtained herein represents a good alternative to current guided bone regeneration membranes, with high potential for use in oral/orthopaedic applications in patients.

Cold-adaptation of a methacrylamide gelatin towards the expansion of the biomaterial toolbox for specialized functionalities in tissue engineering.

Tissue regeneration is witnessing a significant surge in advanced medicine. It requires the interaction of scaffolds with different cell types for efficient tissue formation post-implantation. The presence of tissue subtypes in more complex organs demands the co-existence of different biomaterials showing different hydrolysis rate for specialized cell-dependent remodeling. To expand the available toolbox of biomaterials with sufficient mechanical strength and variable rate of enzymatic degradation, a cold-adapted methacrylamide gelatin was developed from salmon skin. Compared with mammalian methacrylamide gelatin (GelMA), hydrogels derived from salmon GelMA displayed similar mechanical properties than the former. Nevertheless, salmon gelatin and salmon GelMA-derived hydrogels presented characteristics common of cold-adaptation, such as reduced activation energy for collagenase, increased enzymatic hydrolysis turnover of hydrogels, increased interconnected polypeptides molecular mobility and lower physical gelation capability. These properties resulted in increased cell-remodeling rate in vitro and in vivo, proving the potential and biological tolerance of this mechanically adequate cold-adapted biomaterial as alternative scaffold subtypes with improved cell invasion and tissue fusion capacity.

The application of polymerized lipid vesicles as colorimetric biosensors for real-time detection of pathogens in drinking water

The inadequate treatments given to the served waste water which are disposal to the rivers and sea coast are the major sources of faecal Microorganisms and enteric bacterial pathogens. They are among the most serious effects of water pollution bringing risks on public health. None of the current methods for detection of pathogens offer real-time on site solutions, are capable of delivering a simple visual detection signal, or can be easily instrumented as an indicator of the presence of a pathogen in water. The use of lipid vesicles incorporating Polydiacetylenes (PDAs) for the development of biosensors for “real-time” detection of pathogens has become an alternative, due to its potential for simple colorimetric response against harmful environmental effectors. However, its actual application in the field has been complicated because lipid vesicles are unable to respond specifically to environmental changes. In this paper, we report several experimental trials leading to improved response in the detection of flagellated pathogens in drinking water. Chromatic biomimetic membranes of TRCDA/DMPC and TRCDA/DMPC/Tryptophan were used in agar and liquid media, which were challenged with different amounts of Escherichia coli and Salmonella typhimurium. In addition, the effect of some divalent cations on the interaction with vesicles TRCDA/DMPC was investigated. The results indicated an improvement in the response times, both visually and quantitatively, through the use of TRIS-EDTA and proper growing conditions for E. coli and Salmonella. With the application of both conditions, it was possible by incubation at 35ºC to promote bacterial growth, therefore avoiding a dramatic effect on the colour change over control samples which may invalidate the test. Our experiments indicated that the minimum bacterial concentration necessary to produce the transition from blue to red on the vesicles as biosensor approaches 10(8) CFU/ml within 4 hrs...