According to Food and Agriculture Organization 2015 report, post-harvest agricultural loss accounts for 20-50% annually; on the other hand, reports about preservatives toxicity are also increasing. Hence, preservative release with response to fruit requirement is desired. In this study, acid synthesized in the overripe fruits was envisaged to cleave acid labile hydrazone to release preservative salicylaldehyde from graphene oxide (GO). To maximize loading and to overcome the challenge of GO reduction by hydrazine, two-step activation with ethylenediamine and 4-nitrophenyl chloroformate respectively, are followed. The final composite shows efficient preservative release with the stimuli of the overripe fruit juice and improves the fruit shelf life. The composite shows less toxicity as compared to the free preservative along with the additional scope to reuse. The composite was vacuum-filtered through a 0.4 μm filter paper, to prepare a robust wrapper for the fruit storage.

Cereal grains undergo a huge loss in storage, which is significantly due to microbial contamination; on the other hand, nutrient deficiency also coexists. Grain moisture is key for microbial contamination to occur; hence, we envisage coating the grain with edible hydrophobic moisture barrier "zein". However, the challenge in coating zein is to have control over the zein film thickness. To date, there has been no report of a zein film thickness of less than 50 μm in a nonplanar surface. However, a coating thickness of less than 50 μm has appeared on a planar surface. In the present work, zinc is coordinated with the zein (Zinc@Zein), which unwraps the hydrophobic zein domain and also reduces the viscosity of non-Newtonian zein fluid to form a nanolayer coating. Zinc coordination furnishes an antimicrobial property as well as nutrient supplementation. The nanolayer of Zinc@Zein on Triticum aestivum provides efficient protection from seed-borne pathogen Pseudomonas syringae infection and increases available zinc by 4.5 times in a simulated gastric digestion and Caco 2 cell model study. Approximately ∼2−3 g of zein and 80 mg of zinc will be sufficient for coating 1 kg of grain to enhance mineral availability and antipathogenic effect.

In this study, natural graphite was first converted to collagen-graphene composites and then used as templates for the synthesis of nanoparticles of silver, iron oxide, and hydroxyapatite. X-ray diffraction did not show any diffraction peaks of graphene in the composites after inorganic nucleation, compared to the naked composite which showed (002) and (004) peaks. Scanning electron micrographs showed lateral gluing/docking of these composites, possibly driven by an electrostatic attraction between the positive layers of one stack and negative layers of another, which became distorted after inorganic nucleation. Docking resulted in single layer-like characteristics in certain places, as seen under transmission electron microscopy, but sp 2 /sp 3 ratios from Raman analysis inferred three-layer composite formation. Strain-induced folding of these layers into uniform clusters at the point of critical nucleation, revealed beautiful microstructures under scanning electron microscopy. Lastly, cell viability studies using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays showed the highest cell viability for the collagen-graphene-hydroxyapatite composites. In this manner, this study provided – to the field of nanomedicine – a new process for the synthesis of several nanoparticles (with low toxicity) of high interest for numerous medical applications.

No abstract

No abstract