Preparation of multi-functional cellulose containing huge conjugated system and its UV-protective and antibacterial property

Green Solvent Processed Cellulose/Graphene Oxide Nanocomposite Films with Superior Mechanical, Thermal, and Ultraviolet Shielding Properties

This study reports for the first time a green process to fabricate Lyocell fiber and graphene oxide (GO) based novel cellulose/graphene oxide nanocomposite (CGN) flexible films for ultraviolet (UV) shielding applications. A polyethelene glycol (PEG) mediated solvent system was utilized to make CGN films via solution casting route. To improve the dispersion of GO sheets in a cellulosic matrix, a reactive interface was formed in between cellulose and oxygenic functionalized groups of GO sheets via cross-linking them with epichlorohydrin (ECH). The addition of GO sheets in cellulose matrix leads to the synergistic changes, which were observed in the structure and surface morphology of CGN nanocomposite films. Enhanced dispersion of GO sheets in CGN films was observed in morphological investigations which is attributed to the adequate cellulose-GO interaction by hydrogen bonding and led to significant enhancement in the mechanical and thermal properties. The tensile strength and Young's modulus of CGN films with 2 wt % GO loading (CGN2) increased to 89 MPa and 4.3 GPa from 55.6 MPa and 2.1 GPa, respectively, as compared to the neat cellulosic film. Additionally, the CGN films exhibited remarkable UV shielding capability which increased with GO loading in a cellulose matrix. The CGN2 film (2 wt % GO loading) possessed outstanding absorbance in the wavelength range of 280 to 400 nm and showed almost complete shielding (∼99%) of UV rays in both the UV-B and the UV-A regions. Moreover, the ultraviolet protection factor of the CGN2 film demonstrated more than 80-fold increase compared to that of the neat cellulose film. The obtained CGN nanocomposite film has a high potential for applications in the field of UV protection.

Homogeneous grafting of cellulose with polycaprolactone using quaternary ammonium salt systems and its application for ultraviolet-shielding composite films

Microcrystalline cellulose grafted polycaprolactone (MCC-g-PCL) was successfully synthesized by ring-opening copolymerization catalyzed by 4-dimethylaminopyridine in a dual tetrabutylammonium acetate/dimethyl sulfoxide solvent system. A novel ultraviolet-shielding film based on MCC-g-PCL was prepared by introducing graphene oxide (GO). The results obtained showed that the introduction of GO not only obviously influenced the inherent structure of the MCC-g-PCL but remarkably changed the surface morphology of the composite film. Moreover, the GO/MCC-g-PCL composite showed a significant improvement in tensile strength, from 2.63 to 4.55 MPa, as well as elongation-at-break, from 6.4% to 15.5%, compared with the pure MCC-g-PCL film, owing to the strong hydrogen-bonding interaction that physically crosslinked GO with MCC-g-PCL. Importantly, GO/MCC-g-PCL composite films offered an effective high-energy light-shielding capacity; in particular MCC-g-PCL film containing 1.0 wt% GO possessed good absorbance between 200 nm and 300 nm. This study provides a framework for developing cellulose-based ultraviolet-shielding polymers and better understanding the ultraviolet-shielding mechanism.

Microcrystalline cellulose graft polycaprolactone (MCC-g-PCL) was successfully synthesized by ring-opening copolymerization catalyzed by 4-dimethylaminopyridine in a dual tetrabutylammonium acetate/dimethyl sulfoxide solvent system.

Drug release and antioxidant/antibacterial activities of silymarin-zein nanoparticle/bacterial cellulose nanofiber composite films

Bacterial cellulose (BC) is a biopolymer composed of nanofibers which has excellent film-forming ability. However, BC do not have antibacterial or antioxidant activity, thus limiting the applicability of BC for food and biomedical applications. In this study, flavonoid silymarin (SMN) and zein were assembled into spherical SMN-Zein nanoparticles that could be effectively adsorbed onto BC nanofibers. SMN-Zein nanoparticles greatly changed the wettability and swelling property of BC films due to the formation of nanoparticles/nanofibers nanocomposites. SMN-Zein nanoparticles enhanced the release of sparingly soluble silymarin from the nanocomposite films. The active films showed more effective antioxidant and antibacterial activities as compared with pure BC films and thus were able to protect salmon muscle from deterioration and lipid oxidation. These findings suggest that the nanoparticle/nanofiber composites may offer a suitable platform for modification of BC films with improved drug release properties and biological activities.

Development of bacterial cellulose based slow-release active films by incorporation of Scrophularia striata Boiss. extract

Novel bacterial cellulose (BC) based monolayer and multilayer films, incorporating 5wt.% Scrophularia striata Boiss. extract (SE) were obtained. The effect of lamination and β-cyclodextrin (β-CD) inclusion complexation of SE on morphological, physical, antioxidant and release properties of films were investigated. FT-IR results reflected that some new interactions have occurred between BC and β-CD. The XRD analyses showed a decrease in diffraction intensities of BC by addition of free SE. SEM results indicated that the intrinsic compactness of the BC film was preserved by addition of SE/β-CD complex. Lamination and SE/β-CD addition enhanced the mechanical properties. SE loaded films exhibited a good antioxidant activity. Release studies indicated that the release rate and diffusion coefficient (D) of SE in 95% ethanol simulant were significantly decreased by lamination and complexation of SE with β-CD. Results suggest that SE loaded BC films may be used as controlled release antioxidant food active packaging.

Adsorption and photocatalyst assisted dye removal and bactericidal performance of ZnO/chitosan coating layer

Pure chitosan and its zinc oxide composite coatings were applied on microfibriller cellulose mat (MCM) to prepare chitosan coated microfibriller cellulose (Chi-MCM) and zinc oxide/chitosan coated microfibriller cellulose (ZnO/Chi-MCM), respectively. X-ray diffraction (XRD), and scanning electron microscopy (SEM), were used to characterize the samples in this study. SEM images showed that dense chitosan solutions (3 and 5wt%) made a thick layer over MCM while diluted solution (1wt%) resulted in wrapping of the chitosan over the individual microfibers and avoided the thick layer formation. Removal of an azo dye methyl orange (MO) from aqueous solution using adsorption and combined adsorption with photodegradation activity of the Chi-MCM and ZnO/Chi-MCM were evaluated, respectively. Compared in the absence of UV light, ZnO/Chi-MCM showed faster and higher degree of dye removal by photocatalytic dissociation and adsorption under ultraviolet irradiation. Various parameters including pH of MO solution and its initial concentration were tested for the removal of MO dye. ZnO/Chi-MCM showed maximum adsorption capacity of 42.8mg/g. Antibacterial activities were also evaluated where ZnO/Chi-MCM displayed a remarkable performance inhibiting the Escherichia coli growth.

In Vitro Studies of Bacterial Cellulose and Magnetic Nanoparticles Smart Nanocomposites for Efficient Chronic Wounds Healing

The quality of life of patients with chronic wounds can be extremely poor and, therefore, over the past decades, great efforts have been made to develop efficient strategies to improve the healing process and the social impact associated with these conditions. Cell based therapy, as a modern tissue engineering strategy, involves the design of 3D cell-scaffold bioconstructs obtained by preseeding drug loaded scaffolds with undifferentiated cells in order to achieve in situ functional de novo tissue. This paper reports on the development of bionanocomposites based on bacterial cellulose and magnetic nanoparticles (magnetite) for efficient chronic wounds healing. Composites were obtained directly in the cellulose bacterial culture medium by dispersing various amounts of magnetite nanoparticles during the biosynthesis process. After purification and drying, the membranes were characterized by Raman spectroscopy and X-ray diffraction to reveal the presence of magnetite within the bacterial cellulose matrix. Morphological investigation was employed through SEM and TEM analyses on bionanocomposites. The biocompatibility of these innovative materials was studied in relation to human adipose derived stem cells in terms of cellular morphology, viability, and proliferation as well as scaffolds cytotoxic potential.