RESUMO
Since the number of antibiotic-resistant bacterial infections is growing and cases are getting worse every year, the search for new alternative bactericidal wound dressing treatments is becoming crucial. Within this context, the use of polysaccharides from plants and seeds in innovative biopolymer technologies is of key importance. In this work, bio-nano-composite guar gum/polyvinyl alcohol (PVOH) membranes loaded with aluminum-doped zinc oxide nanoparticles were produced via electrospinning. Citric acid was added to the mixture to increase spinnability. However, depending on the pH, zinc oxide nanoparticles are partially dissociated, decreasing their bactericidal efficiency. Thus, a second successful alkaline thermo-chemical regrowth step was added to the process to treat the obtained fibers. This alkaline thermo-chemical treatment reconstituted both the nanoparticles and their bactericidal properties. The Staphylococcus aureus antibacterial assay results show that the membranes obtained after the alkaline thermo-chemical treatment presented a 57% increase in growth inhibition.
RESUMO
Biological scaffolds have become an attractive approach for repairing the infarcted myocardium and have been shown to facilitate constructive remodeling in injured tissues. This study aimed to investigate the possible utilization of bacterial cellulose (BC) membrane patches containing cocultured cells to limit myocardial postinfarction pathology. Myocardial infarction (MI) was induced by ligating the left anterior descending coronary artery in 45 Wistar rats, and patches with or without cells were attached to the hearts. After one week, the animals underwent echocardiography to assess for ejection fraction and left ventricular end-diastolic and end-systolic volumes. Following patch formation, the cocultured cells retained viability of >90% over 14 days in culture. The patch was applied to the myocardial surface of the infarcted area after staying 14 days in culture. Interestingly, the BC membrane without cellular treatment showed higher preservation of cardiac dimensions; however, we did not observe improvement in the left ventricular ejection fraction of this group compared to coculture-treated membranes. Our results demonstrated an important role for BC in supporting cells known to produce cardioprotective soluble factors and may thus provide effective future therapeutic outcomes for patients suffering from ischemic heart disease.
Assuntos
Terapia Baseada em Transplante de Células e Tecidos , Celulose/metabolismo , Infarto do Miocárdio/terapia , Função Ventricular Esquerda/fisiologia , Animais , Terapia Baseada em Transplante de Células e Tecidos/métodos , Coração/fisiopatologia , Miocárdio/metabolismo , Neovascularização Fisiológica , Ratos Wistar , Volume Sistólico/fisiologia , Remodelação Ventricular/fisiologiaRESUMO
PURPOSE: In deep burns, wound contraction and hypertrophic scar formation can generate functional derangement and debilitation of the affected part. In order to improve the quality of healing in deep second-degree burns, we developed a new treatment in a preclinical model using nanostructured membranes seeded with mesenchymal stem cells (MSCs). METHODS: Membranes were obtained by reconstitution of bacterial cellulose (reconstituted membrane [RM]) and produced by a dry-cast process, then RM was incorporated with 10% tamarind xyloglucan plus gellan gum 1:1 and 10% lysozyme (RMGT-LZ) and with 10% gellan gum and 10% lysozyme (RMG-LZ). Membrane hydrophobic/hydrophilic characteristics were investigated by static/dynamic contact-angle measurements. They were cultivated with MSCs, and cell adhesion, proliferation, and migration capacity was analyzed with MTT assays. Morphological and topographic characteristics were analyzed by scanning electron microscopy. MSC patterns in flow cytometry and differentiation into adipocytes and osteocytes were checked. In vivo assays used RMG-LZ and RMGT-LZ (with and without MSCs) in Rattus norvegicus rats submitted to burn protocol, and histological sections and collagen deposits were analyzed and immunocytochemistry assay performed. RESULTS: In vitro results demonstrated carboxyl and amine groups made the membranes moderately hydrophobic and xyloglucan inclusion decreased wettability, favoring MSC adhesion, proliferation, and differentiation. In vivo, we obtained 40% and 60% reduction in acute/chronic inflammatory infiltrates, 96% decrease in injury area, increased vascular proliferation and collagen deposition, and complete epithelialization after 30 days. MSCs were detected in burned tissue, confirming they had homed and proliferated in vivo. CONCLUSION: Nanostructured cellulose-gellan-xyloglucan-lysozyme dressings, especially when seeded with MSCs, improved deep second-degree burn regeneration.
Assuntos
Bandagens , Queimaduras/terapia , Celulose/química , Glucanos/química , Células-Tronco Mesenquimais/citologia , Muramidase/química , Nanoestruturas/química , Polissacarídeos Bacterianos/química , Xilanos/química , Animais , Vasos Sanguíneos/patologia , Queimaduras/patologia , Adesão Celular , Diferenciação Celular , Proliferação de Células , Celulose/ultraestrutura , Colágeno/metabolismo , Inflamação/patologia , Masculino , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/ultraestrutura , Nanoestruturas/ultraestrutura , Ratos Wistar , CicatrizaçãoRESUMO
Hyaluronic acid (HA) and galactomannans (such as guar gum - GG and locust bean gum - LBG) are biomacromolecules with various applications due to their physicochemical characteristics in solution, especially their ability to form films or hydrogels in some conditions. Some of these applications are possible because they are nontoxic and biocompatible. Mixtures of HA and GG or LBG, at pH 7.4, were prepared at 25 g·L-1 of HA:LBG or HA:GG with percentages of 50:50, 60:40, 70:30 and 80:20 (w/w) and evaluated by rheology and NMR experiments regarding the interactions. The best synergism observed was between HA:LBG, most pronounced at 50% (w/w), where the dynamic modulus values G' and Gâ³ indicated the formation of physical gels with viscoelastic behavior close to that of HA. 2D NOESY spectra revealed hydrogen interconnectivity of H-1 glucuronic acid units of HA with H-5 mannose units of the main galactomannan chains. This synergism, besides producing a hydrogel with interesting properties, also can decrease the cost by partially replacing HA in many applications, such as in nutraceutical foods, support for tissue engineering and cosmetics.
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Ácido Hialurônico/química , Mananas/química , Galactanos/química , Galactose/análogos & derivados , Gomas Vegetais/químicaRESUMO
The influence of Na2SO4 as a kosmotropic salt on the thermogelation of xyloglucan (XG) solutions was measured by rheology. The gelation occurred at lower temperatures and shorter times when the salt concentration was increased above 0.5â¯mol.L-1. For Na2SO4 concentrations equal to 1â¯mol.L-1, a not thermoreversible elastic hydrogel was obtained. Salts containing various types of anions were used, and it was observed that SO42-, HPO42- and H2PO4- promoted the formation of a gelled network. The gel structure was observed using confocal laser scanning microscopy and scanning electron microscopy. In XG containing SO42 at 1â¯mol.L-1aggregates and gels were formed by interconnected sub-micrometer XG particles. Increasing the concentration of SO42- led to conformation changes in the XG, from a twisted/helical to an extended/flat conformation, as observed using circular dichroism. The naturally occurring hydrophobic sequences promoted an economically feasible XG gelling that may produce thermo and kosmo-sensitive hydrogels.
RESUMO
The mechanical pretreatments intensities on characteristics of cellulose nanocrystals (CNC) prior to acid hydrolysis was evaluated. The cellulose was submitted to mechanical pretreatment as: magnetic stirring (CNCst), blending (CNCbl) or grinding by 20 (CNC20x) and 40 (CNC40x) passages in a super mass colloid mill. Then, all samples were submitted to H2SO4 hydrolysis and the CNC were evaluated by total mass yield (TMY%), rheological behavior, size distribution for width/length (WD), crystallinity index (CI%), OSO3- substitution degree (SD) and zeta potential (ζ). After hydrolysis samples exhibited the same SD (190⯱â¯5â¯mMol·kg-1), ζ (-55⯱â¯3â¯mV) and CI% (65⯱â¯2), differing only in TMY% and WD. The CNCst showed TMY% of 85%, WD of 8⯱â¯5â¯nm and 100-800â¯nm, with presence of cellulose nanofibers (CNF), suggesting incomplete hydrolysis. The CNCbl and CNC20x revealed TMY% of 65⯱â¯1, but differed in WD of 8⯱â¯5â¯nm and 300⯱â¯200â¯nm and 8⯱â¯5â¯nm and 200⯱â¯170â¯nm, respectively. The results showed that the grinding mechanical pretreatment is mandatory for CNF isolation, but not for CNC. Stability profile after the hydrolytic procedure, CI%, morphology and similar character generated CNC with adequate features and good yield, by simple mechanical stirring or blending, reducing the production's cost and allowing industrial-scale production.
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Celulose/química , Celulose/isolamento & purificação , Nanopartículas/química , Ácidos Sulfúricos/química , Celulose/análise , Fracionamento Químico/métodos , Hidrólise , Microscopia de Força Atômica , Nanopartículas/análise , Análise Espectral , ViscosidadeRESUMO
The biotechnological evolution towards the development of antigens to detect leprosy has been progressing. However, the identification of leprosy in paucibacillary patients, based solely on the antigen-antibody interaction still remains a challenge. The complexity of clinical manifestations requires innovative approaches to improve the sensitivity of assays to detect leprosy before the onset of symptoms, thus avoiding disabilities and contributing, indirectly, to reduce transmission. In this study, the strategies employed for early leprosy diagnosis were: i. using a phage-displayed mimotope (APDDPAWQNIFNLRR) which mimics an immunodominant sequence (PPNDPAWQRNDPILQ) of an antigen of Mycobacterium leprae known as Ag85B; ii. engineering the mimotope by adding a C-terminal flexible spacer (SGSG-C); iii. conjugating the mimotope to a carrier protein to provide better exposure to antibodies; iv. amplifying the signal using biotin-streptavidin detection system in an ELISA; and v. coating the optimized mimotope on a quartz crystal microbalance (QCM) sensor for label-free biosensing. The ELISA sensitivity increased up to 91.7% irrespective of the immunological profile of the 132 patients assayed. By using comparative modeling, the M. tuberculosis Ag85B was employed as a template to ascertain which features make the mimotope a good antigen in terms of its specificity. For the first time, a sensitive QCM-based immunosensor to detect anti M. leprae antibodies in human serum was used. M. leprae antibodies could also be detected in the sera of paucibacillary patients; thus, the use of a mimotope-derived synthetic peptide as bait for antibodies in a novel analytical label-free immunoassay for leprosy diagnosis exhibits great potential.
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Técnicas Biossensoriais , Imunoensaio , Hanseníase/diagnóstico , Mycobacterium leprae/isolamento & purificação , Técnicas de Microbalança de Cristal de Quartzo , Adulto , Animais , Biomarcadores/análise , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Sodium alginate (Alg) reacted with antibiotic gentamicin sulfate (GS) in an aqueous-phase condition mediated by carbodiimide chemistry, in the molar ratios Alg: GS of (1:0.5), (1:1) and (1:2). The Alg-GS conjugated derivatives were characterized by elemental analysis for nitrogen content, Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analyses (TGA) and water sorption measurements. XPS and FTIR-ATR analyses clearly indicated that GS molecules covalently attached to the backbone of the alginate chains by amide bond formation. The highest amount of GS bound to Alg (43.5⯱â¯0.4â¯wt%) and the highest swelling ratio (4962⯱â¯661%) were observed for the Alg-GS (1:2) sample. Bioluminescence assays with Pseudomonas aeruginosa PAO1/lecA:lux and colony forming counting of Staphylococcus aureus and Escherichia coli upon contact with all Alg-GS conjugates revealed microbicidal activity; however, Alg-GS (1:2) was the most efficient, due to the highest GS content.
Assuntos
Alginatos/química , Anti-Infecciosos/química , Gentamicinas/química , Hidrogéis/química , Carbodi-Imidas/química , Quitosana/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Pseudomonas aeruginosa/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos , TermogravimetriaRESUMO
Gelation kinetics of aqueous solutions of xyloglucan (XG) extracted from H. courbaril seeds were investigated, in-situ, during enzymatic removal of galactose units by oscillatory shear rheological measurements, at different XG and enzyme (ß-galactosidase) concentrations. Increasing the enzyme concentration (Cenz) led to an increase of the gelation rate. Master curves of the evolution of the storage shear modulus at different Cenz could be formed by time-Cenz superposition showing that Cenz influenced the kinetics, but not the gelation process and the final gel stiffness. The behaviour of gels formed by XG with different molar mass (Mw), prepared by endoglucanase hydrolysis, was evaluated as a function of the temperature. It was found that cooling led to a decrease of the crosslink density causing a decrease of the gel stiffness. The decrease of the crosslink density was sufficient to depercolate the network formed by relatively small XG with Mw=105gmol-1, but gels formed by XG with Mw≥8×105gmol-1 persisted down to 10°C. It is shown that the melting temperature and the gel stiffness at high temperatures can be controlled independently by varying the molar mass and the concentration of XG chains.
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Bacterial cellulose (BC) derived materials represents major advances to the current regenerative and diagnostic medicine. BC is a highly pure, biocompatible and versatile material that can be utilized in several applications - individually or in the combination with different components (e.g. biopolymers and nanoparticles) - to provide structural organization and flexible matrixes to distinct finalities. The wide application and importance of BC is described by its common utilization as skin repair treatments in cases of burns, wounds and ulcers. BC membranes accelerate the process of epithelialization and avoid infections. Furthermore, BC biocomposites exhibit the potential to regulate cell adhesion, an important characteristic to scaffolds and grafts; ultra-thin films of BC might be also utilized in the development of diagnostic sensors for its capability in immobilizing several antigens. Therefore, the growing interest in BC derived materials establishes it as a great promise to enhance the quality and functionalities of the current generation of biomedical materials.