Ultra-low Concentration of Cellulose Nanofibers (CNFs) for Enhanced Nucleation and Yield of ZnO Nanoparticles.

Cellulose nanofibers (CNFs) were used in aqueous synthesis protocols for zinc oxide (ZnO) to affect the formation of the ZnO particles. Different concentrations of CNFs were evaluated in two different synthesis protocols producing distinctly different ZnO morphologies (flowers and sea urchins) as either dominantly oxygen- or zinc-terminated particles. The CNF effects on the ZnO formation were investigated by implementing a heat-treatment method at 400 °C that fully removed the cellulose material without affecting the ZnO particles made in the presence of CNFs. The inorganic phase formations were monitored by extracting samples during the enforced precipitations to observe changes in the ZnO morphologies. A decrease in the size of the ZnO particles could be observed for all synthesis protocols, already occurring at small additions of CNFs. At as low as 0.1 g/L CNFs, the particle size decreased by 50% for the flower-shaped particles and 45% for the sea-urchin-shaped particles. The formation of smaller particles was accompanied by increased yield by 13 and 15% due to the CNFs' ability to enhance the nucleation, resulting in greater mass of ZnO divided among a larger number of particles. The enhanced nucleation could also be verified as useful for preventing secondary morphologies from forming, which grew on the firstly precipitated particles. The suppression of secondary growths' was due to the more rapid inorganic phase formation during the early phases of the reactions and the faster consumption of dissolved salts, leaving smaller amounts of metal salts present at later stages of the reactions. The findings show that using cellulose to guide inorganic nanoparticle growth can be predicted as an emerging field in the preparation of functional inorganic micro/nanoparticles. The observations are highly relevant in any industrial setting for the large-scale and resource-efficient production of ZnO.

Carboxylated Wheat Gluten Proteins: A Green Solution for Production of Sustainable Superabsorbent Materials.

Functionalized wheat gluten (WG) protein particles with the ability to absorb fluids within the superabsorbent range are presented. Ethyleneditetraacetic dianhydride (EDTAD), a nontoxic acylation agent, was used for the functionalization of the WG protein at higher protein content than previously reported and no additional chemical cross-linking. The 150-550 µm protein particles had 50-150 nm nanopores induced by drying. The EDTAD treated WG were able to absorb 22, 5, and 3 times of, respectively, water, saline and blood, per gram of dry material (g/g), corresponding to 1000, 150 and 100% higher values than for the as-received WG powder. The liquid retention capacity after centrifugation revealed that almost 50% of the saline liquid was retained within the protein network, which is similar to that for petroleum-based superabsorbent polymers (SAPs). An advantageous feature of these biobased particulate materials is that the maximum swelling is obtained within the first 10 min of exposure, that is, in contrast to many commercial SAP alternatives. The large swelling in a denaturation agent (6 M urea) solution (about 32 g/g) suggests that the secondary entangled/folded structure of the protein restricts protein network expansion and when disrupted allows the absorption of even higher amounts of liquid. The increased liquid uptake, utilization of inexpensive protein coproducts, easy scalable protocols, and absence of any toxic chemicals make these new WG-based SAP particles an interesting alternative to petroleum-based SAP in, for example, absorbent disposable hygiene products.

Fabrication and Characterisation of Stimuli Responsive Piezoelectric PVDF and Hydroxyapatite-Filled PVDF Fibrous Membranes.

Poly(vinylidene fluoride) has attracted interest from the biomaterials community owing to its stimuli responsive piezoelectric property and promising results for application in the field of tissue engineering. Here, solution blow spinning and electrospinning were employed to fabricate PVDF fibres and the variation in resultant fibre properties assessed. The proportion of piezoelectric ß-phase in the solution blow spun fibres was higher than electrospun fibres. Fibre production rate was circa three times higher for solution blow spinning compared to electrospinning for the conditions explored. However, the solution blow spinning method resulted in higher fibre variability between fabricated batches. Fibrous membranes are capable of generating different cellular response depending on fibre diameter. For this reason, electrospun fibres with micron and sub-micron diameters were fabricated, along with successful inclusion of hydroxyapatite particles to fabricate stimuli responsive bioactive fibres.

Lidocaine-loaded fish scale-nanocellulose biopolymer composite microneedles.

Microneedle (MN) technology has emerged as an effective drug delivery system, and it has tremendous potential as a patient friendly substitute for conventional methods for transdermal drug delivery (TDD). In this paper, we report on the preparation of lidocaine-loaded biodegradable microneedles, which are manufactured from fish scale-derived collagen. Lidocaine, a common tissue numbing anaesthetic, is loaded in these microneedles with an aim of delivering the drug with controlled skin permeation. Evaluation of lidocaine permeation in porcine skin has been successfully performed using Franz diffusion cell (FDC) which has shown that the drug permeation rate increases from 2.5 to 7.5% w/w after 36 h and pseudo steady state profile is observed from 5.0 to 10.0% w/w lidocaine-loaded microneedle. Swelling experiments have suggested that the microneedles have negligible swellability which implies that the patch would stick to the tissue when inserted. The experiments on MN dissolution have depicted that the lidocaine loaded in the patch is lower than the theoretical loading, which is expected as there can be losses of the drug during initial process manufacture.

Antibacterial properties of tough and strong electrospun PMMA/PEO fiber mats filled with Lanasol--a naturally occurring brominated substance.

A new type of antimicrobial, biocompatible and toughness enhanced ultra-thin fiber mats for biomedical applications is presented. The tough and porous fiber mats were obtained by electrospinning solution-blended poly (methyl methacrylate) (PMMA) and polyethylene oxide (PEO), filled with up to 25 wt % of Lanasol--a naturally occurring brominated cyclic compound that can be extracted from red sea algae. Antibacterial effectiveness was tested following the industrial Standard JIS L 1902 and under agitated medium (ASTM E2149). Even at the lowest concentrations of Lanasol, 4 wt %, a significant bactericidal effect was seen with a 4-log (99.99%) reduction in bacterial viability against S. aureus, which is one of the leading causes of hospital-acquired (nosocomial) infections in the world. The mechanical fiber toughness was insignificantly altered up to the maximum Lanasol concentration tested, and was for all fiber mats orders of magnitudes higher than electrospun fibers based on solely PMMA. This antimicrobial fiber system, relying on a dissolved antimicrobial agent (demonstrated by X-ray diffraction and Infrared (IR)-spectroscopy) rather than a dispersed and "mixed-in" solid antibacterial particle phase, presents a new concept which opens the door to tougher, stronger and more ductile antimicrobial fibers.

Microfibrillated cellulose and borax as mechanical, O2-barrier, and surface-modulating agents of pullulan biocomposite coatings on BOPP.

Multifunctional composite coatings on bi-oriented polypropylene (BOPP) films were obtained using borax and microfibrillated cellulose (MFC) added to the main pullulan coating polymer. Spectroscopy analyses suggested that a first type of interaction occurred via hydrogen bonding between the C6OH group of pullulan and the hydroxyl groups of boric acid, while monodiol and didiol complexation represented a second mechanism. The deposition of the coatings yielded an increase in the elastic modulus of the entire plastic substrate (from ∼2GPa of the neat BOPP to ∼3.1GPa of the P/B+/MFC-coated BOPP). The addition of MFC yielded a decrease of both static and kinetic coefficients of friction of approximately 22% and 25%, respectively, as compared to the neat BOPP. All composite coatings dramatically increased the oxygen barrier performance of BOPP, especially under dry conditions. The deposition of the high hydrophilic coatings allowed to obtain highly wettable surfaces (water contact angle of ∼18°).

Comparison of the properties of cellulose nanocrystals and cellulose nanofibrils isolated from bacteria, tunicate, and wood processed using acid, enzymatic, mechanical, and oxidative methods.

This work describes the measurement and comparison of several important properties of native cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), such as crystallinity, morphology, aspect ratio, and surface chemistry. Measurement of the fundamental properties of seven different CNCs/CNFs, from raw material sources (bacterial, tunicate, and wood) using typical hydrolysis conditions (acid, enzymatic, mechanical, and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation), was accomplished using a variety of measurement methods. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and 13C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy were used to conclude that CNCs, which are rodlike in appearance, have a higher crystallinity than CNFs, which are fibrillar in appearance. CNC aspect ratio distributions were measured and ranged from 148±147 for tunicate-CNCs to 23±12 for wood-CNCs. Hydrophobic interactions, measured using inverse gas chromatography (IGC), were found to be an important contribution to the total surface energy of both types of cellulose. In all cases, a trace amount of naturally occurring fluorescent compounds was observed after hydrolysis. Confocal and Raman microscopy were used to confirm that the fluorescent species were unique for each cellulose source, and demonstrated that such methods can be useful for monitoring purity during CNC/CNF processing. This study reveals the broad, tunable, multidimensional material space in which CNCs and CNFs exist.