Chitosan nanocomposite films based on Ag-NP and Au-NP biosynthesis by Bacillus Subtilis as packaging materials

Investigation of morphology, mechanical, thermal and flame retardant properties of an EVA/EPDM blend by combination of organoclay with Na+-tripolyphosphate

Schematic representation the methodology of the EVA/EPDM/MMT nanocomposites preparation, characterization and applications.

Comparative study of preparation, characterization and anticandidal activities of a chitosan silver nanocomposite (CAgNC) compared with low molecular weight chitosan (LMW-chitosan)

A chitosan-silver nanocomposite (CAgNC) was synthesized in a green manner using low molecular weight chitosan (LMW-chitosan) and silver nitrate without applying external chemical reducing agents.

The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and P_hag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag₂O, indicating that Ag-NP toxicity is likely mediated by released Ag⁺ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag₂O. These findings provide conclusive evidence for the role of Ag⁺ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation.

Evaluation of bionanocomposites as packaging material on properties of soft white cheese during storage period

Novel bionanocomposites based on chitosan/poly(vinyl alcohol)/titanium nanoparticles (CS/PVA/TiO2 nanocomposite) were prepared and used as packaging materials for soft white cheese. The prepared bionanocomposites were characterized using XRD, SEM, TEM and FT-IR. The CS/PVA/TiO2 bionanocomposites exhibited good mechanical properties. Furthermore, the obtained bionanocomposites exhibited superior antibacterial activity against gram positive (Staphylococcus aureus), gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria and fungi (Candidia albicans). The soft white cheese was manufactured and packaged within the CS/PVA/TiO2 nanocomposite films and stored at 7 °C for 30 days. The color, rheological and chemical properties of cheese were evaluated, also the influence of CS/PVA/TiO2 bionanocomposites on microbiological analysis of soft white cheese was assessed, the results indicated that the total bacterial counts, mold & yeast and coliform decreased with the increasing storage period and disappeared at the end of storage period compared with control. Consequently, CS/PVA/TiO2 bionanocomposite can be used in food packaging applications.

Synthesis and anti-fungal effect of silver nanoparticles-chitosan composite particles

Silver nanoparticles have been used in various fields, and several synthesis processes have been developed. The stability and dispersion of the synthesized nanoparticles is vital. The present article describes a novel approach for one-step synthesis of silver nanoparticles-embedded chitosan particles. The proposed approach was applied to simultaneously obtain and stabilize silver nanoparticles in a chitosan polymer matrix in-situ. The diameter of the synthesized chitosan composite particles ranged from 1.7 mm to 2.5 mm, and the embedded silver nanoparticles were measured to be 15 ± 3.3 nm. Further, the analyses of ultraviolet-visible spectroscopy, energy dispersive spectroscopy, and X-ray diffraction were employed to characterize the prepared composites. The results show that the silver nanoparticles were distributed over the surface and interior of the chitosan spheres. The fabricated spheres had macroporous property, and could be used for many applications such as fungicidal agents in the future.

Effect of reactive organoclay on physicochemical properties of vegetable oil-based waterborne polyurethane nanocomposites

The environmentally friendly vegetable oil-based waterborne polyurethane–organoclay nanocomposites have been successfully synthesized from castor oil polyols, isophorone diisocyanate and dimethylolpropionic acid.