Bacterial cellulose-hydroxyapatite nanocomposites for bone regeneration

The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA) nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl2 followed by Na2HPO4. BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40-50 of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA), similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration. © 2011 S. Saska et al.

Reduction of bacterial adhesion to biocompatible polymer surfaces via plasma processing

Plasma processing of the surfaces of biomaterials is interesting because it enables modification of the characteristics of a surface without affecting bulk properties. In addition, the results are strongly influenced by the conditions of the treatment. Therefore, by adjusting the plasma parameters it is possible to tailor the surface properties to best fulfill the requirements of a given application. In this work, polyurethane substrates have been subjected to sulfur hexafluoride glow discharge plasmas. The influences of different SF 6 plasma exposure times and pressures on the adhesion of Staphylococcus aureus and Pseudomonas aeruginosa to the polymer have been investigated. The wettability and surface free energy have been evaluated via contact angle measurements. At low pressure (6.7 Pa) the contact angle decreases with increasing exposure time in the 180 s to 540 s interval, but at higher pressure (13.3 Pa) it increases as a function of the same variable. Bacterial adhesion has been quantified from in vitro experiments by determining the growth of colonies on Petri dishes treated with agar nutrient. It has been observed that the surface properties play an important role in microbe adhesion. For instance, the density of adhered P. aeruginosa decreased as the surface contact angle increased. S. aureus preferred to adhere to hydrophobic surfaces. © 2011 by Begell House, Inc.

Preparation and characterization of the bacterial cellulose/polyurethane nanocomposites

New nanocomposites based on bacterial cellulose nanofibers (BCN) and polyurethane (PU) prepolymer were prepared and characterized by SEM, FT-IR, XRD, and TG/DTG analyses. An improvement of the interface reaction between the BCN and the PU prepolymer was obtained by a solvent exchange process. FT-IR results showed the main urethane band at 2,270 cm-1 to PU prepolymer; however, in nanocomposites new bands appear as disubstituted urea at 1,650 and 1,550 cm-1. In addition, the observed decrease in the intensity of the hydroxyl band (3,500 cm-1) suggests an interaction between BCN hydroxyls and NCO-free groups. The nanocomposites presented a non-crystalline character, significant thermal stability (up to 230 °C) and low water absorption when compared to pristine BCN. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Bacterial nanocellulose for medical implants

Bacterial cellulose (BC) has established to be a remarkably versatile biomaterial and can be used in wide variety of applied scientific endeavours, especially for medical devices. In fact, biomedical devices recently have gained a significant amount of attention because of an increased interest in tissue-engineered products for both wound care and the regeneration of damaged or diseased organs. Due to its unique nanostructure and properties, microbial cellulose is a natural candidate for numerous medical and tissue-engineered applications. Hydrophilic bacterial cellulose fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. The microbial cellulose fiber has a high degree of crystallinity. Using direct nanomechanical measurement, determined that these fibers are very strong and when used in combination with other biocompatible materials, produce nanocomposites particularly suitable for use in human and veterinary medicine. Moreover, the nanostructure and morphological similarities with collagen make BC attractive for cell immobilization and cell support. The architecture of BC materials can be engineered over length scales ranging from nano to macro by controlling the biofabrication process. The chapter describes the fundamentals, purification and morphological investigation of bacterial cellulose. This chapter deals with the modification of microbial cellulose and how to increase the compatibility between cellulosic surfaces and a variety of plastic materials. Furthermore, provides deep knowledge of fascinating current and future applications of bacterial cellulose and their nanocomposites especially in the medical field, materials with properties closely mimic that of biological organs and tissues were described. © Springer-Verlag Berlin Heidelberg 2013.

Do Atopobium vaginae, Megasphaera sp. and Leptotrichia sp. change the local innate immune response and sialidase activity in bacterial vaginosis?

Objectives: To investigate if the participation of Atopobium vaginae, Megasphaera sp. and Leptotrichia sp. in the bacterial community of bacterial vaginosis (BV) is associated with distinct patterns of this condition. Methods: In this cross-sectional controlled study, 205 women with BV and 205 women with normal flora were included. Vaginal rinsing samples were obtained for measuring the levels of pro-inflammatory cytokines and bacterial sialidases. Real-time PCR was used to quantify the BV-associated bacteria and to estimate the total bacterial load using the 16S rRNA. Principal component analysis (PCA) using the measured parameters was performed to compare the BV samples with lower and higher loads of the species of interest. Results: Higher bacterial load (p<0.001), levels of interleukin 1-β (p<0.001) and sialidase activity (p<0.001) were associated with BV. Women with BV and higher relative loads of A vaginae, Megasphaera sp. and Leptotrichia sp. presented increased sialidase activity, but unchanged cytokine levels. PCA analysis did not indicate a different pattern of BV according to the loads of A vaginae, Megasphaera sp. and Leptotrichia sp. Conclusions: Greater participation of A vaginae, Megasphaera sp. and Leptotrichia sp. in vaginal bacterial community did not indicate a less severe form of BV; moreover, it was associated with increased sialidase activity.

Sialidase activity in aerobic vaginitis is equal to levels during bacterial vaginosis

Objective: To evaluate levels of proinflammatory cytokines and sialidase activity in aerobic vaginitis (AV) in relation to normal vaginal flora and bacterial vaginosis (BV). Study design: In this cross-sectional study, a total of 682 consecutive non-pregnant women attending the gynecology service were assessed and 408 women were included. Vaginal rinsing samples were collected from 223 women with microscopic finding of BV (n = 98), aerobic vaginitis (n = 25) and normal flora (n = 100). Samples were tested for interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and sialidase activity. Results: Compared to women with normal flora, vaginal levels of IL-1β were highly increased in both BV and AV (p < 0.0001). Significantly higher vaginal IL-6 was detected in AV (p < 0.0001) but not in BV, in relation to normal flora. Women with AV also presented increased IL-8 levels (p < 0.001), while those with BV presented levels similar to normal flora. Sialidase was increased in BV and AV compared with the normal group (p < 0.0001) but no difference in sialidase activity was observed between BV and AV. Conclusion: A more intense inflammatory host response occurs for AV than for BV when compared with normal flora. Furthermore, the increased sialidase activity in AV and BV indicates that both abnormal vaginal flora types can be harmful to the maintenance of a healthy vaginal environment. © 2012 Elsevier B.V.

Qualitative analysis of preputial and vaginal bacterial microbiota in owl monkeys (Aotus azarai infulatus) raised in captivity

Background: The aim of this study was to identify the aerobic bacteria of the preputial and vaginal microbiota in owl monkeys that have been raised in captivity and to evaluate the antimicrobial susceptibility of these bacteria by gender and social organization. Methods: Thirty clinically healthy Aotus azarai infulatus were used. A total of 134 samples were collected, 60 from the preputial mucosa and 74 from the vaginal mucosa. An automated system of bacterial identification was used. Results and Conclusions: Staphylococcus intermedius and Proteus mirabilis were the microorganisms that were most frequently identified according to gender and social organization. The antimicrobial susceptibility of the isolated gram-positive bacteria was similar in both sexes. However, the gram-negative strains had some differences. The aerobic bacterial population of the vaginal and preputial microbiota is similar in owl monkeys, and there are no differences in the number and bacterial species according to sex and social organization. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Optically transparent membrane based on bacterial cellulose/ polycaprolactone

Optically transparent membranes from bacterial cellulose (BC)/polycaprolactone (PCL) have been prepared by impregnation of PCL acetone solution into dried BC membranes. UV-Vis measurements showed an increase on transparency in BC/PCL membrane when compared with pristine BC. The good transparency of the BC/PCL can be related to the presence of BC nanofibers associated with deposit of PCL nano-sized spherulites which are smaller than the wavelength of visible light and practically free of light scattering. XRD results show that cellulose type I structure is preserved inside the BC/PCL membrane, while the mechanical properties suggested indicated that PCL acts as a plasticizer for the BC membrane. The novel BC/PCL membrane could be used for preparation of fully biocompatible flexible display and biodegradable food packaging.

Simple green approach to reinforce natural rubber with bacterial cellulose nanofibers

Natural rubber (NR) is a renewable polymer with a wide range of applications, which is constantly tailored, further increasing its utilizations. The tensile strength is one of its most important properties susceptible of being enhanced by the simple incorporation of nanofibers. The preparation and characterization of natural-rubber based nanocomposites reinforced with bacterial cellulose (BC) and bacterial cellulose coated with polystyrene (BCPS), yielded high performance materials. The nanocomposites were prepared by a simple and green process, and characterized by tensile tests, dynamical mechanical analysis (DMA), scanning electron microscopy (SEM), and swelling experiments. The effect of the nanofiber content on morphology, static, and dynamic mechanical properties was also investigated. The results showed an increase in the mechanical properties, such as Young's modulus and tensile strength, even with modest nanofiber loadings. © 2013 American Chemical Society.

ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer

In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures. © 2013 The Royal Society of Chemistry.

Flexible magnetic membranes based on bacterial cellulose and its evaluation as electromagnetic interference shielding material

Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe 3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10 ± 1 to 13 ± 1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g- 1 and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials. © 2013 Elsevier B.V.

Induction of suppressiveness to Fusarium wilt of chrysanthemum with composted sewage sludge

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bacterial cellulose/triethanolamine based ion-conducting membranes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modular Hyperthermostable Bacterial Endo-beta-1, 4-Mannanase: Molecular Shape, Flexibility and Temperature-Dependent Conformational Changes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bacterial Pathogens Related to Chronic Suppurative Otitis Media in Individuals With Cleft Palate: Bacteriological Culture and Polymerase Chain Reaction

Objective: To characterize the microbial etiology of chronic suppurative otitis media comparing the methods of classical bacteriological culture and polymerase chain reaction.Design/Setting/Patients: Bacteriological analysis by classical culture and by molecular polymerase chain reaction of 35 effusion otitis samples from patients with cleft lip and palate attending the Hospital for Rehabilitation of Craniofacial Anomalies of the University of Sao Paulo, Bauru, Brazil.Interventions: Collection of clinical samples of otitis by effusion through the external auditory tube.Main Outcome Measure: Otolaryngologic diagnosis of chronic suppurative otitis media.Results: Positive cultures were obtained from 83% of patients. Among the 31 bacterial lineages the following were isolated. In order of decreasing frequency: Pseudomonas aeruginosa (54.9%), Staphylococcus aureus (25.9%), and Enterococcus faecalis (19.2%). No anaerobes were isolated by culture. The polymerase chain reaction was positive for one or more bacteria investigated in 97.1% of samples. Anaerobe lineages were detected by the polymerase chain reaction method, such as Fusobacterium nucleatum, Bacteroides fragilis, and Peptostreptococcus anaerobius.Conclusions: Patients with cleft lip and palate with chronic suppurative otitis media presented high frequency of bacterial infection in the middle ear. The classical bacteriological culture did not detect strict anaerobes, whose presence was identified by the polymerase chain reaction method.