Enhancing the multifunctional properties of cellulose fabrics through in situ hydrothermal deposition of TiO2 nanoparticles at low temperature for antibacterial self-cleaning under UV-Vis illumination.

This study aimed to improve the multifunctional properties (including photocatalysis, stability reusability, self-cleaning, antibacterial effects, and thermal radiation shielding) of cellulose fabrics through incorporation of TiO2 nanoparticles. To achieve this, anatase TiO2 nanoparticles were synthesized in situ and deposited onto cotton fabrics through hydrothermal method. The presence of TiO2 nanoparticles in cellulose fabrics greatly enhanced the photocatalytic efficiency and adsorption range and did not damage the fabric fibers. The TiO2-coated cotton exhibited an outstanding photocatalytic efficiency, with dye removal rates of 92.20 % ± 0.015 % and 99.68 % ± 0.002 % under UV-A and visible illumination, respectively. In addition, the material exhibited thermal radiation shielding properties, in which no heat absorption was observed within 60 min at 40 °C-70 °C. To further enhance the hydrophobicity, the TiO2-coated cotton was surface-modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTS). The resulting PFDTS/TiO2-coated cotton was superhydrophobic with a water contact angle of 156.50° ± 0.05° with a sliding angle of 4.33° ± 0.47° and roughness of 67.35 nm. The superhydrophobicity of the PFDTS/TiO2-coated cotton also facilitated self-cleaning through water injection to remove soil impurities. Furthermore, the PFDTS/TiO2-coated cotton exerted antibacterial effects against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria under UV-A or visible illumination. These nanocomposite fabrics with multifunctional properties have potential for industrial, military, and medical applications.

Controllability, antiproliferative activity, Ag+ release, and flow behavior of silver nanoparticles deposited onto cellulose nanocrystals.

Silver nanoparticles (AgNPs)/carboxylated cellulose nanocrystals (Ag-cCNC) from Eucalyptus pulp were prepared using a three-step process. The cCNC were synthesized by oxidation of CNC from Eucalyptus pulp with ammonium persulfate, followed by a hydrothermal reaction to form Ag-cCNC. The Ag-cCNC was then characterized with respect to Ag+ release, flow behavior, and anticancer activity for potential applications in biomedicine and drug delivery. AgNPs with particle sizes in the range of 16.25 ± 7.83 to 21.84 ± 7.21 nm were uniformly embedded on the surface of the cCNC. The Ag-cCNC exhibited a slow and controllable release of Ag+ at a rate of 0.02 % per day for 28 days. Ag+ release was best described by the Korsmeyer-Peppas model based on non-Fickian diffusion. The Ag-cCNC at 200 µg/mL exerted antiproliferative activity in MCF-7 human breast cancer cells with 1.01 % ± 0.35 % cell viability and was non-toxic against normal Vero cells with 90 % viability. In contrast, the chemotherapeutic drug melphalan exhibited cytotoxic effects against both MCF-7 and Vero cells. The Ag-cCNC samples showed shear thinning properties with a pseudoplastic fluid behavior, indicating that Ag-cCNCs are suitable for drug delivery by injection.

Quantifying the origin of released Ag+ ions from nanosilver.

Nanosilver is most attractive for its bactericidal properties in modern textiles, food packaging, and biomedical applications. Concerns, however, about released Ag(+) ions during dispersion of nanosilver in liquids have limited its broad use. Here, nanosilver supported on nanostructured silica is made with closely controlled Ag size both by dry (flame aerosol) and by wet chemistry (impregnation) processes without any surface functionalization that could interfere with its ion release. It is characterized by electron microscopy, atomic absorption spectroscopy, and X-ray diffraction, and its Ag(+) ion release in deionized water is monitored electrochemically. The dispersion method of nanosilver in solutions affects its dissolution rate but not the final Ag(+) ion concentration. By systematically comparing nanosilver size distributions to their equilibrium Ag(+) ion concentrations, it is revealed that the latter correspond precisely to dissolution of one to two surface silver oxide monolayers, depending on particle diameter. When, however, the nanosilver is selectively conditioned by either washing or H(2) reduction, the oxide layers are removed, drastically minimizing Ag(+) ion leaching and its antibacterial activity against E. coli . That way the bactericidal activity of nanosilver is confined to contact with its surface rather than to rampant ions. This leads to silver nanoparticles with antibacterial properties that are essential for medical tools and hospital applications.

Rheology, stability, antioxidant properties, and curcumin release of oil-in-water Pickering emulsions stabilized by rice starch nanoparticles.

Modification of rice starch nanoparticles (SNP) as an emulsifier in Pickering emulsions is reported in this work. The SNP was prepared by HCl hydrolysis with different resident times and subsequently modified via crosslinking by citric acid using various crosslinking times to improve the hydrophobicity of SNP. The modified SNP was used to prepare sunflower oil-in-water Pickering emulsions loaded with curcumin. The optimal hydrolysis conditions (2.2 M HCl, 6 days) produced SNP with a 21.87 ± 0.69 % yield and 45.56 ± 0.00 % crystallinity. The citric acid-modified SNP with a 6-h crosslinking period (SNP-M-6 h) had a water contact angle of 87.2°. The suitable Pickering emulsion containing 30 wt% curcumin-loaded sunflower oil was stabilized by 3.0 wt% SNP-M-6 h. This Pickering emulsion had shear thinning properties with a pseudoplastic fluid behavior and was characterized by a droplet size of 47.16 ± 4.22 µm with a high degree of stability over five weeks of storage. Furthermore, the curcumin release from the emulsion depended on the pH, and curcumin could maintain its free radical scavenging quality. A very beneficial property of the Pickering emulsion is that it can slowly release curcumin at low pH, but more rapid release at higher pH, making it a potentially excellent candidate for drug delivery through oral intake.

Tailoring the phosphorus release from biochar-based fertilizers: role of magnesium or calcium addition during co-pyrolysis.

The presence of magnesium (Mg) and calcium (Ca) in biochar-based fertilizers is linked to the slow release of phosphorus (P), but these alkali metals have not been systematically compared under identical conditions. In this study, sugarcane filter cake was treated with H3PO4 and MgO or CaO followed by pyrolysis at 600 °C to produce a Mg/P-rich biochar (MgPA-BC) and a Ca/P-rich biochar (CaPA-BC), respectively. The P-loaded biochars were studied by extraction and kinetic release in water over 240 hours to assess the potential P availability. X-ray diffraction and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the pristine and post-kinetics biochars to identify the responsible phases for phosphate release. Additionally, the dissolved P concentrations in the kinetic release experiment were compared to thermodynamic solubility calculations of common Mg and Ca phosphates. Both MgPA-BC and CaPA-BC had P loadings of 73-74 g kg-1 but showed distinctly different release behaviors. Phosphate dissolution from MgPA-BC was gradual and reached 10 g P per kg biochar after 240 hours, with rate-determining phases being Mg2P2O7 (Mg pyrophosphate), MgNH4PO4·6H2O (struvite), and Mg3(PO4)2·22H2O (cattiite). In contrast, CaPA-BC only released 1.2 g P per kg biochar. Phosphate release from CaPA-BC was limited by the low solubility of Ca2P2O7 (Ca pyrophosphate) and (Ca,Mg)3(PO4)2 (whitlockite). Co-pyrolysis with MgO retained P in a more soluble and available form than CaO, making MgO a preferential additive over CaO to immobilize phytoavailable P in biochar-based fertilizers with higher fertilizer effectiveness.

Entrapment of nano-ZnO into alginate/polyvinyl alcohol beads with different crosslinking ions for fertilizer applications.

Zinc oxide nanoparticles (nano-ZnO) are attractive as fertilizer materials but high concentrations may negatively affect the environment. To reduce their dispersion in the environment we entrapped nano-ZnO in biodegradable polymer beads consisting of alginate and polyvinyl alcohol (PVA). The alginate/PVA/ZnO beads were prepared via ionotropic gelation using two different crosslinking ions (Ca2+ and Zn2+), and the effect of alginate crosslinking ion and PVA content on bead structure, water absorption, water retention and zinc release was investigated. The pure CaAlg and ZnAlg beads demonstrated a poor water absorption and retention, which were strongly enhanced by the incorporation of PVA into the beads. The continuous Zn release was measured in a sand column, and it was found that the Zn-crosslinked beads rapidly released high concentrations of Zn followed by a more gradual Zn release, whereas Ca alginates showed only a gradual Zn release. The Zn dissolution kinetics could be tuned by the crosslinking ion composition. The prepared nano-ZnO-containing alginate/PVA beads may be attractive for Zn fertilizer applications under water-limited conditions.

Synthesis of nanocomposite hydrogel based carboxymethyl starch/polyvinyl alcohol/nanosilver for biomedical materials.

Treatment of infections using wound dressing integrated with multiple functions such as antibacterial activity, non-toxicity, and good mechanical properties has attracted much attention. In this study, carboxymethyl starch/polyvinyl alcohol/citric acid (CMS/PVA/CA) hydrogels containing silver nanoparticles (AgNPs) were prepared. The CMS, PVA and CA were used as polymer matrix and bio-based reducing agents for green synthesis of AgNPs. Silver nitrate (AgNO3) concentrations of 50, 100, and 150 mM were used to obtain nanocomposite hydrogels containing different AgNPs concentrations (AgNPs-50, AgNPs-100 and AgNPs-150, respectively). The minimum inhibitory concentration against E. coli and S. aureus was observed in CMS/PVA/CA hydrogels containing AgNPs-50. Uniform dispersion of AgNPs-100 in the hydrogel provided the highest storage modulus at 56.4 kPa. AgNPs-loaded hydrogels showed low toxicity to human fibroblast cells indicating good biocompatibility. Incorporation of AgNPs demonstrated an enhancement in antibacterial properties and overall mechanical properties, which makes these nanocomposite hydrogels attractive as novel wound dressing materials.

Structure, dissolution, and plant uptake of ferrous/zinc phosphates.

Development of slow release fertilizers by tuning dissolution kinetics can reduce the environmental impact of (micro) nutrients added to crops. Mixed metal compounds may have different dissolution kinetics and plant uptake than single metal compounds. In this study, mixed Fe(II)/Zn(II) phosphates (0-100 at% Zn) were prepared by aqueous precipitation and their structural characteristics and dissolution kinetics in a sand column were measured as model for divalent metal and phosphate release in soil. Three minerals were identified, namely vivianite (Fe3(PO4)2·8H2O) at 0-20 at% Zn, phosphophyllite (Zn2Fe(PO4)2·4H2O) at 20-79 at% Zn, and hopeite (Zn3(PO4)2·4H2O) at 79-100 at% Zn. The Fe-rich materials had high SSA of 42-64 m2 g-1, which decreased to ≤4 m2 g-1 for ≥79 at% Zn. The Fe K-edge and Zn K-edge XANES spectroscopy measurements show that the samples had comparable local structure and contained 13-72% of Fe as Fe(III) due to partial oxidation. In the sand column, Zn(II) and Fe(II) phosphates dissolved near-congruently at steady state (>7 h), whereas mixed Fe(II)/Zn(II) phosphates showed preferential release of Zn over P and Fe, likely due to reprecipitation of Fe. Pot experiments demonstrate that Zn from Fe(II)/Zn(II) phosphates is absorbed by bird's eye chili plants (C. annuum), in agreement with the preferential dissolution of Zn(II). These results may provide insight into the dissolution of other divalent metals, which not only aids in the growth of plants and resulting foodstuff but ultimately leads to reductions in environmental contamination.

Lignin materials for adsorption: Current trend, perspectives and opportunities.

Lignin is a highly aromatic low value biomass residue, which can be utilized for chemicals, fuels and materials production. In recent years significant attention has focused on adsorbent materials from lignin. However, only 5% of available lignin is exploited worldwide, thus significant opportunities still exist for materials development. This review summarizes recent research advances in lignin-based adsorbents, with a particular emphasis on lignin, its modification and carbon materials derived from this abundant feedstock. Lignin derived activated carbons have been utilized for air pollutant adsorption (e.g. CO2, SO2 and H2S), while modified lignin materials have been developed for the removal of organic dyes and organics (like methylene blue, Procion Blue MX-R and phenols), heavy metals (such as Cu, Zn, Pb and Cd), or recovery of noble metals (e.g., Pd, Au and Pt). Future perspectives highlight how green chemistry approaches for developing lignin adsorbents can generate added value processes.

Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe color changes than FeSO(4) when added to difficult-to-fortify foods.

Iron from nanocompounds containing iron and zinc is highly bioavailable in rats without tissue accumulation.

Effective iron fortification of foods is difficult, because water-soluble compounds that are well absorbed, such as ferrous sulphate (FeSO(4)), often cause unacceptable changes in the colour or taste of foods. Poorly water-soluble compounds, on the other hand, cause fewer sensory changes, but are not well absorbed. Here, we show that poorly water-soluble nanosized Fe and Fe/Zn compounds (specific surface area approximately 190 m(2) g(-1)) made by scalable flame aerosol technology have in vivo iron bioavailability in rats comparable to FeSO(4) and cause less colour change in reactive food matrices than conventional iron fortificants. The addition of Zn to FePO(4) and Mg to Fe/Zn oxide increases Fe absorption from the compounds, and doping with Mg also improves their colour. After feeding rats with nanostructured iron-containing compounds, no stainable Fe was detected in their gut wall, gut-associated lymphatics or other tissues, suggesting no adverse effects. Nanosizing of poorly water-soluble Fe compounds sharply increases their absorption and nutritional value.