Films of bacterial cellulose (BC) reinforced by natural rubber (NR) with remarkably high mechanical strength were developed by combining the prominent mechanical properties of multilayer BC ...nanofibrous structural networks and the high elastic hydrocarbon polymer of NR. BC pellicle was immersed in a diluted NR latex (NRL) suspension in the presence of ethanol aqueous solution. Effects of NRL concentrations (0.5%-10% dry rubber content, DRC) and immersion temperatures (30-70 °C) on the film characteristics were studied. It was revealed that the combination of nanocellulose fibrous networks and NR polymer provided a synergistic effect on the mechanical properties of NR-BC films. In comparison with BC films, the tensile strength and elongation at break of the NR-BC films were considerably improved ~4-fold. The NR-BC films also exhibited improved water resistance over that of BC films and possessed a high resistance to non-polar solvents such as toluene. NR-BC films were biodegradable and could be degraded completely within 5-6 weeks in soil.
Multifunctional biopolymer composites comprising mechanically-disintegrated bacterial cellulose, alginate, gelatin and curcumin plasticized with glycerol were successfully fabricated through a ...simple, facile, cost-effective mechanical blending and casting method. SEM images indicate a well-distributed structure of the composites. The water contact angles existed in the range of 50-70°. Measured water vapor permeability values were 300-800 g/m
/24 h, which were comparable with those of commercial dressing products. No release of curcumin from the films was observed during the immersion in PBS and artificial saliva, and the fluid uptakes were in the range of 100-700%. Films were stretchable and provided appropriate stiffness and enduring deformation. Hydrated films adhered firmly onto the skin. In vitro mucoadhesion time was found in the range of 0.5-6 h with porcine mucosa as model membrane under artificial saliva medium. The curcumin-loaded films had substantial antibacterial activity against
and
The films showed non-cytotoxicity to human keratinocytes and human gingival fibroblasts but exhibited potent anticancer activity in oral cancer cells. Therefore, these curcumin-loaded films showed their potential for use as leave-on skin applications. These versatile films can be further developed to achieve desirable characteristics for local topical patches for wound care, periodontitis and oral cancer treatment.
•Novel bacterial cellulose–alginate scaffold (N-BCA) was fabricated by freeze drying and crosslinking.•N-BCA displayed open and highly interconnected porous structure.•N-BCA supported attachment and ...proliferation of human fibroblast.
A novel bacterial cellulose–alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca2+. The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90–160μm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering.
Hydrogels from bacterial, algal, and animal cells-bacterial cellulose (BC), alginate, and gelatin, respectively-were combined to fabricate a biocomposite film (BCAGG) via an eco-friendly casting ...technique. In addition, glycerol was added as a plasticizer to improve the elasticity and water absorption capacity of the film. In this study, BC pellicles were simply deconstructed into fibrils suspension and then reconstructed into films with a supplement of alginate, gelatin and glycerol. The physical appearance of fabricated films resembled native BC but possessed improved ductility, enhanced flexibility, higher water uptake ability and better biocompatibility. The film was found to resist tearing under suture pullout strength in a hydrated state. In vitro cytotoxicity tests showed that the film was cytocompatible. A cell study using a human keratinocyte culture demonstrated enhanced cell adhesion, spreading, and proliferation on the BCAGG film compared with BC/alginate film. The BCAGG film therefore has significant potential for use in biomedical applications, particularly in dermal treatment, skin tissue regeneration, and wound healing.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Composite films of bacterial cellulose-silver nanoparticles (BC-Ag) were prepared by different methods of in situ reduction of silver ions, using sodium hydroxide, ascorbic acid, chitosan, and UV ...irradiation. The effects of the reduction methods on their properties were investigated. The chitosan-reduced composite exhibited dispersed silver nanoparticles (AgNPs) within the nanocellulose matrix with the smallest size, while the ascorbic-reduced composite displayed the largest size. The incorporation of AgNPs tended to reduce the crystallinity of the composites, except for the ascorbic-reduced composite, which exhibited an increase in crystallinity. Mechanical testing revealed that the ascorbic-reduced composite had the highest Young's modulus of 8960 MPa, whereas the UV-reduced composite had the highest tensile strength and elongation at break. Thermal analysis of BC-Ag composites indicated similar glass transition temperature and decomposition profiles to BC, with additional weight-loss steps at high temperatures. The sodium hydroxide-reduced composite demonstrated the highest electrical conductivity of 1.1 × 10
S/cm. Water absorption capacity was reduced by the incorporation of AgNPs, except for the chitosan-reduced composite, which showed an enhanced water absorption capacity of 344%. All BC-Ag composites displayed very strong antibacterial activities against
and
These results also highlight the potential uses of BC-Ag composites for various applications.
Fast and facile preparation of composite films containing natural rubber and Eucalyptus cellulose microfiber was achieved by the addition of carboxyl methyl cellulose to yield advantage properties ...such as chemical resistance, biodegradability and excellent tensile strength. It was found that carboxyl methyl cellulose can be employed as pre-agglomeration stabilizer to obtain high dispersion of hydrophilic cellulose fibers in hydrophobic natural rubber latex. The incorporation of cellulose fibers into the natural rubber matrix significantly improved the crystallinity of the composite films. At the highest loading content of cellulose at 50% w/w, the uptake toluene of the film was reduced to only 5%, whereas its tensile strength was increased to 100 times higher than the neat rubber film. Thermal stability was decreased slightly, depending on cellulose fiber loading content, but the glass transition temperature remained constant at about − 64 °C. According to the hydrophilic nature of cellulose, the water absorption capacity and water vapor transmission of the composite films were enhanced. In addition, it was shown that the biodegradability was considerably improved; the composite films degraded sufficiently in soil within 2 weeks.
Green natural rubber (NR) composites reinforced with black rice husk ash (BRHA)/white rice husk ash (WRHA), using alginate as a thickening and dispersing agent and crosslinking by CaCl
, was ...developed to improve mechanical, chemical and dielectric properties of NR-based films by using a latex aqueous microdispersion process. A maximum of 100 per hundred rubbers (phr) of rice husk ashes (RHAs) could be integrated in NR matrix without phase separation. Mechanical properties of the composite films were considerably enhanced, compared to the neat NR film. The composite films reinforced with WRHA demonstrated relatively better mechanical properties than those reinforced with BRHA, whereas the composites filled with BRHA demonstrated higher elongation at break. The crosslinking by CaCl
improved the film tensile strength but lowered the film elasticity. The reinforcement strongly improved chemical resistance of the composite films in toluene. The films are biodegradable in soil, with weight loss of 7.6-18.3% of the initial dry weight after 3 months. Dielectric constant and dielectric loss factors of the composite films were enhanced with RHAs loading. According to the obtained properties, the composites offer potential for further development as stretchable conductive substrate or semiconducting polymer films for electronic applications.
The porous carbon (bacterial cellulose (BC)-activated carbon (AC)(BA)) prepared via two-step activation of bacterial nanocellulose by treatments with potassium hydroxide (KOH) and then phosphoric ...acid (H
PO
) solutions showed superior adsorption properties and effective performance as catalyst support. BC-AC(BA) had an open and interconnected multi-porous structure, consisting of micropores (0.23 cm
/g), mesopores (0.26 cm
/g), and macropores (4.40 cm
/g). The BET surface area and porosity were 833 m
/g and 91.2%, respectively. The methylene blue adsorption test demonstrated that BC-AC(BA) was superior in its mass transfer rate and adsorption capacities. Moreover, BC-AC(BA) modified by H
PO
treatment showed a significant enhancement of catalytic performance for dehydration of ethanol. At the reaction temperature of 250-400 °C, 30P/BC-AC(BA) gave ethanol conversion at 88.4-100%, with ethylene selectivity of 82.6-100%, whereas, high selectivity for diethyl ether (DEE) at 75.2%, at ethanol conversion of 60.1%, was obtained at the reaction temperature of 200 °C.
Green composite films of natural rubber/bacterial cellulose composites (NRBC) were prepared via a latex aqueous microdispersion process. The acid modified natural rubber/bacterial cellulose ...composites (ANRBC), in which lactic acid was used, showed significant improvement in mechanical properties, melting temperature, and high resistance to polar and non-polar solvents. The ANRBC films exhibited improved water resistance over that of BC and NRBC films, and possessed a higher resistance to non-polar solvents, such as toluene, than NR and NRBC films. The modification had a slight effect on the degradability of the composite films in soil. The NRBC and ANRBC films were biodegradable; the NRBC80 and ANRBC80 films were degraded completely within 3 months in soil. NRBC and ANRBC showed no antibacterial activity against Escherichia coli and Staphylococcus aureus and did not show cytotoxic effects on the HEK293 and HaCaT cell lines.
Green natural rubber (NR) composites reinforced with synthetic graphite platelets, using alginate as a thickening and dispersing agent, were successfully developed to improve mechanical properties, ...chemical resistance, and electrical conductivity. The fabrication was performed using a latex aqueous microdispersion process. The research demonstrated the effective incorporation of graphite platelets into the NR matrix up to 60 parts per hundred rubbers (phr) without causing agglomeration or phase separation. Graphite incorporation significantly improved the mechanical strength of the composite films. NR with 60 phr of graphite exhibited the highest Young's modulus of 12.3 MPa, roughly 100 times that of the neat NR film. The reinforcement also strongly improved the hydrophilicity of the composite films, resulting in a higher initial water absorption rate compared to the neat NR film. Moreover, the incorporation of graphite significantly improved the chemical resistance of the composite films against nonpolar solvents, such as toluene. The composite films exhibited biodegradability at about 21% to 30% after 90 days in soil. The electrical conductivity of the composite films was considerably enhanced up to 2.18 × 10
S/cm at a graphite loading of 60 phr. According to the improved properties, the developed composites have potential applications in electronic substrates.
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