Nano cells from fruit bunch residue: Nestling nanotechnology within the circular oil palm milling residue management.

Nano-structured materials gain a vast market acceptance mainly due to their overarching endurance. Nanofibrillar cellulose (NFC) is one example of an augmenting agent unviable for production by small and medium enterprises (SMEs) due to the underlying process complexity. This study aims to characterise the NFC-alternative cells denoted as TRX-cellsⓇ, which is a mix of cellulose and non-cellulose components, ruling out its status as 'cellulose nanofibers, CNF'. The aim to test-fit the TRX-cells® production process into the circularity model was executed by deliberating on the usability of the byproduct. In doing so, fibrous oil palm empty fruit bunch (EFB) was treated with dioxydanyl radicals (DIOR) and homogenised. The rapid EFB-DIOR reaction at 70°C targeting dearomatisation reaction in a 10%-solid open system was performed before refining the DIOR-treated EFB to micro-scale fibres. Subjecting the micro-fibres to 17 kWh/mt PFI-milling yielded 85-95% of nano-scale fibrous mass. Relative to the stiff micro-fibres, the nano-scale cells web exhibit 34-41% softness enhancement judged from the web tear resistance profile associated with inter-fibre space reduction. Advanced chromatographic evidence for 27% xylan amongst TRX-cells®' total aldo-sugars was one form of the non-cellulose nano-component. High-resolution Transmission Electron Microscopy hyphenated to Energy Dispersive Analysis of X-ray (HRTEM-EDX) elemental mapping showed a 0.4 atomic percentage of nano-biominerals, confirming the presence of the redistributed dearomatised cells adjacent to cellulose held in the web of the hemicellulose. Shearing at the dearomatised inter-cell wall layers by PFI mill peeled 5 nm-100 nm thickness laminae. The smorgasbord of cellulose and non-celluloses resulted in crystallinity comparable to softwood NFC of approximately 60%, with unique preservation and precision-printing enabling properties. Given the non-recyclability of the DIOR-treated EFB microfibres, nestling the rapid waste transformation process into the circularity model shed light on circular bio-nanotechnology to the spectrum of opportunity for zero-waste, reduced emission and net zero carbon practices on top of an added value from waste transformation to a product.

Subcutaneous tissue reaction to a novel nano zinc oxide eugenol dental cement.

BACKGROUND: Zinc oxide eugenol (ZOE) cement is a popular dental material due mainly to its analgesic, antibacterial and anti-inflammatory effects. The formulation of ZOE cement from nano particle-sized zinc oxide (ZnO) has the potential to increase these properties as well as reduce its adverse effects to the surrounding tissues. OBJECTIVE: This study evaluated the subcutaneous tissue response towards nano ZOE cements (ZOE-A and ZOE-B) in comparison to conventional ZOE (ZOE-K). METHODS: Test materials were implanted into 15 New Zealand white rabbits. Tissue samples were obtained after 7, 14, and 30 days (n = 5 per period) for histopathological evaluation of inflammatory cell infiltrate, fibrous tissue condensation, and abscess formation. RESULTS: ZOE-A showed the lowest score for the variable macrophage and lymphocyte at day 7. Both ZOE-A and ZOE-B presented lower fibrous tissue condensation and abscess formation compared to conventional ZOE-K. By day 30, ZOE-A exhibited less lymphocytic and neutrophilic infiltrate compared to the other materials, while ZOE-B had the lowest score for macrophages. ZOE-K exerted higher inflammatory cell response at almost all of the experimental periods. All of the materials resulted in thin fiber condensation after 30 days. CONCLUSIONS: Rabbit tissue implanted with ZOE-A and ZOE-B showed better response compared to ZOE-K.

An investigation of the morphological, thermal, mechanical, and barrier properties of an active packaging containing micro- and nano-sized ZnO particles.

Biodegradable films are extremely important for food packaging applications since they minimize environmental effects. However, their application areas are limited due to insufficient characteristics required for particular applications. The objective of the present research was to improve the properties of sago-based biodegradable films embedded with nano- and micro-ZnO (zinc oxide). Nano and micro-ZnO were incorporated in the films at different percentages (1%, 3%, and 5%) in that the films were formed using the solvent casting method. The physicochemical, barrier, thermal, optical, morphology, and mechanical properties of sago-based films were investigated. Adding 5% of micro- and nano-ZnO significantly improved film thickness (0.162 and 0.150 mm, respectively) and WVP (4.40 and 5.64 (kg/s)/(m.Pa), respectively) while the optical properties and thermal stability exhibited superior performance. Micro-ZnO particles improved the mechanical properties of sago-based biodegradable films with the tensile strength reaching 6.173 MPa. Moreover, sago-based nano-ZnO films showed excellent UV-shielding performance and relatively good visible-light transmittance. This study suggested that sago biodegradable film incorporated with micro-ZnO could be an excellent alternative to petroleum-based plastic packaging.

Surface morphological and mechanical properties of zinc oxide eugenol using different types of ZnO nanopowder.

Zinc oxide eugenol (ZOE) cements are generally made up of 80%-90% ZnO powder while the remaining content consists of eugenol bonding resin. ZnO structure plays a major role in the morphology and mechanical properties of ZOE. In this study, we investigated the effects of different particle sizes/shapes of ZnO particles on the surface and mechanical properties of ZOE. Three samples were prepared namely ZnO-Ax, ZnO-B and ZnO-K. The crystallite sizes calculated from XRD were 37.76 nm (ZnO-Ax), 39.46 nm (ZnO-B) and 42.20 nm (ZnO-K) while the average particle sizes obtained by DLS were 21.11nm (ZnO-Ax), 56.73 nm (ZnO-B) and 2012 nm (ZnO-K). Results revealed that the compressive strengths of ZOE-Ax and ZOE-B were improved by 87.92% and 57.16%, respectively, relative to that of commercial ZOE-K. Vickers hardness test demonstrated that the hardness of ZOE-Ax and ZOE-B also increased by 74.9% and 31.1%, respectively. The ZnO-Ax nanostructure possessed a small average particle size (21.11 nm), a homogeneous size distribution (DLS) and an oxygen-rich surface (from EDS and elemental mapping). Meanwhile, ZnO-B exhibited a slightly larger average particle size of 56.73 nm compared with that of other samples. Sample ZnO-Ax demonstrated the highest compressive strength which was attributed to its large particle surface area (21.11 nm particle size) that provided a large contact area and greater interfacial (or interlock) bonding capability if compared to that of ZnO-K sample (2012 nm particle size).

Application of antimicrobial active packaging film made of semolina flour, nano zinc oxide and nano-kaolin to maintain the quality of low-moisture mozzarella cheese during low-temperature storage.

BACKGROUND: Active food packaging films with improved properties and strong antimicrobial activity were prepared by blending mixed nanomaterials with different ratio [1:4 (40 mg:160 mg), 3:2 (120 mg: 80 mg), 0:5 (0 mg: 200 mg) and 5:0 (200 mg:0 mg)] of ZnO and kaolin with semolina using a solvent casting method and used for the packaging of low moisture mozzarella cheese to test the effect of packaging on the quality change of the cheese for long-term (up to 72 days) refrigerated storage. RESULTS: Compared with the neat semolina film, mechanical strength (TS) of the nanocomposite films increased significantly (increase in 21-65%) and water vapor barrier (WVP) and O2 gas barrier (OP) properties decreased significantly (decrease in 43-50% and 60-65%, respectively) depending on the blending ratio of ZnO and kaolin nanoclay. The nanocomposite films also exhibited strong antimicrobial activity against bacteria (E. coli and S. aureus), yeast (C. albicans), and mold (A. niger). The nanocomposite packaging films were effectively prevented the growth of microorganisms (coliforms, total microbial, and fungi) of the cheese during storage at low-temperature and showed microbial growth of less than 2.5 log CFU/g after 72 days of storage compared to the control group, and the quality of the packaged cheese was still acceptable. CONCLUSION: The semolina-based nanocomposite films, especially Sem/Z3 K2 film, were effective for packaging of low moisture mozzarella cheese to maintain the physicochemical properties (pH, moisture, and fat content) and quality (color, taste, texture, and overall acceptability) of the cheese as well as preventing microbial growth (coliforms, total microbial, and fungi). © 2018 Society of Chemical Industry.

In-vitro efficacy of different morphology zinc oxide nanopowders on Streptococcus sobrinus and Streptococcus mutans.

ZnO with two different morphologies were used to study the inhibition of Streptococcus sobrinus and Streptococcus mutans which are closely associated with tooth cavity. Rod-like shaped ZnO-A and plate-like shaped ZnO-B were produced using a zinc boiling furnace. The nanopowders were characterized using energy filtered transmission electron microscopy (EFTEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, Raman spectroscopy and dynamic light scattering (DLS) to confirm the properties of the ZnO polycrystalline wurtzite structures. XRD results show that the calculated crystallite sizes of ZnO-A and ZnO-B were 36.6 and 39.4nm, respectively, whereas DLS revealed particle size distributions of 21.82nm (ZnO-A) and 52.21nm (ZnO-B). PL spectra showed ion vacancy defects related to green and red luminescence for both ZnO particles. These defects evolved during the generation of reactive oxygen species which contributed to the antibacterial activity. Antibacterial activity was investigated using microdilution technique towards S. sobrinus and S. mutans at different nanopowder concentrations. Results showed that ZnO-A exhibited higher inhibition on both bacteria compared with ZnO-B. Moreover, S. mutans was more sensitive compared with S. sobrinus because of its higher inhibition rate.

Fabrication and characterization of novel semolina-based antimicrobial films derived from the combination of ZnO nanorods and nanokaolin.

This study aimed to provide novel biopolymer-based antimicrobial films as food packaging that may assist in reducing environmental pollution caused by the accumulation of synthetic food packaging. The blend of ZnO nanorods (ZnO-nr) and nanokaolin in different ratios (1:4, 2:3, 3:2 and 4:1) was incorporated into semolina, and nanocomposite films were prepared using solvent casting. The resulting films were characterized through field-emission scanning electron microscopy and X-ray diffraction. The mechanical, optical, physical, and antimicrobial properties of the films were also analyzed. The water vapor permeability of the films decreased with increasing ZnO-nr percentage, but their tensile strength and modulus of elasticity increased with increasing nanokaolin percentage. The UV transmittance of the semolina films were greatly influenced by an increase in the amount of ZnO-nr. The addition of ZnO-nr: nanokaolin at all ratios (except 1:4) into semolina reduced UV transmission to almost 0%. Furthermore, the ZnO-nr/nanokaolin/semolina films exhibited a strong antimicrobial activity against Staphylococcus aureus. These properties suggest that the combination of ZnO-nr and nanokaolin are potential fillers in semolina-based films to be used as active packaging for food and pharmaceuticals.

Preparation and characterization of bionanocomposite films reinforced with nano kaolin.

Effects of nano-kaolin incorporation into semolina films on the physical, mechanical, thermal, barrier and antimicrobial properties of the resulting bio-nanocomposite films were investigated. The properties included crystal structure (by X-ray diffraction), mechanical resistance, color, Fourier transform infrared spectra, decomposition temperature, water-vapor permeability (WVP), oxygen permeability (OP), and antimicrobial activity against Staphylococcus aureus and Escherichia coli. Kaolin was incorporated into biofilms at various amounts (1, 2, 3, 4, and 5 %, w/w total solid). All films were plasticized with 50 % (w/w total solid) combination of sorbitol/glycerol at 3:1 ratio. The incorporation of nanokaolin into semolina films decreased OP and WVP. The moisture content and water solubility of the films were found to decrease by nanokaolin reinforcement, and mechanical properties of films were improved by increasing nanokaolin concentration. Tensile strength and Young's modulus increased from 3.41 to 5.44 MPa and from 63.12 to 136.18, respectively, and elongation-at-break decreased. The films did not exhibit UV absorption. In conclusion, nanokaolin incorporation enhanced the barrier and mechanical properties of semolina films, indicating the potential application of these bio-nanocomposites in food-product packaging.

High-performance dye-sensitized solar cells based on morphology-controllable synthesis of ZnO-ZnS heterostructure nanocone photoanodes.

High-density and well-aligned ZnO-ZnS core-shell nanocone arrays were synthesized on fluorine-doped tin oxide glass substrate using a facile and cost-effective two-step approach. In this synthetic process, the ZnO nanocones act as the template and provide Zn2+ ions for the ZnS shell formation. The photoluminescence spectrum indicates remarkably enhanced luminescence intensity and a small redshift in the UV region, which can be associated with the strain caused by the lattice mismatch between ZnO and ZnS. The obtained diffuse reflectance spectra show that the nanocone-based heterostructure reduces the light reflection in a broad spectral range and is much more effective than the bare ZnO nanocone and nanorod structures. Dye-sensitized solar cells based on the heterostructure ZnO-ZnS nanocones are assembled, and high conversion efficiency (η) of approximately 4.07% is obtained. The η improvement can be attributed primarily to the morphology effect of ZnO nanocones on light-trapping and effectively passivating the interface surface recombination sites of ZnO nanocones by coating with a ZnS shell layer.

Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism.

Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH- (hydroxyl radicals), and O2 -2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

Physical properties of fish gelatin-based bio-nanocomposite films incorporated with ZnO nanorods.

Well-dispersed fish gelatin-based nanocomposites were prepared by adding ZnO nanorods (NRs) as fillers to aqueous gelatin. The effects of ZnO NR fillers on the mechanical, optical, and electrical properties of fish gelatin bio-nanocomposite films were investigated. Results showed an increase in Young's modulus and tensile strength of 42% and 25% for nanocomposites incorporated with 5% ZnO NRs, respectively, compared with unfilled gelatin-based films. UV transmission decreased to zero with the addition of a small amount of ZnO NRs in the biopolymer matrix. X-ray diffraction showed an increase in the intensity of the crystal facets of (10i1) and (0002) with the addition of ZnO NRs in the biocomposite matrix. The surface topography of the fish gelatin films indicated an increase in surface roughness with increasing ZnO NR concentrations. The conductivity of the films also significantly increased with the addition of ZnO NRs. These results indicated that bio-nanocomposites based on ZnO NRs had great potentials for applications in packaging technology, food preservation, and UV-shielding systems.

Fabrication of an electrically-resistive, varistor-polymer composite.

This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10-50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages.