In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.

Applications of nanotechnology in food packaging and food safety: Barrier materials, antimicrobials and sensors

We report a study of self-assembled beta-pleated sheets in B. mori silk fibroin films using thermal analysis and infrared spectroscopy. B. mori silk fibroin may stand as an exemplar of fibrous proteins containing crystalline beta-sheets. Materials were prepared from concentrated solutions (2−5 wt % fibroin in water) and then dried to achieve a less ordered state without beta-sheets. Crystallization of beta-pleated sheets was effected either by heating the films above the glass transition temperature (Tg) and holding isothermally or by exposure to methanol. The fractions of secondary structural components including random coils, alpha-helices, beta-pleated sheets, turns, and side chains were evaluated using Fourier self-deconvolution (FSD) of the infrared absorbance spectra. The silk fibroin films were studied thermally using temperature-modulated differential scanning calorimetry (TMDSC) to obtain the reversing heat capacity. The increment of the reversing heat capacity ΔCp0(Tg) at the glass transition fo...

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Determining Beta Sheet Crystallinity in Fibrous Proteins by Thermal Analysis and Infrared Spectroscopy

Structures, mechanical properties and applications of silk fibroin materials

Recent advances for dyes removal using novel adsorbents: A review

Hyperbranched polymers (HPs) are highly branched three-dimensional (3D) macromolecules. Their globular and dendritic architectures endow them with unique structures and properties such as abundant functional groups, intramolecular cavities, low viscosity, and high solubility. HPs can be facilely synthesized via a one-pot polymerization of traditional small molecular monomers or emerging macromonomers. The great development in synthetic strategies, from click polymerization (i.e., copper-catalyzed azide–alkyne cycloaddition, metal-free azide–alkyne cycloaddition, strain-promoted azide–alkyne cycloaddition, thiol–ene/yne addition, Diels–Alder cycloaddition, Menschutkin reaction, and aza-Michael addition) to recently reported multicomponent reactions, gives rise to diverse HPs with desirable functional/hetero-functional groups and topologies such as segmented or sequential ones. Benefiting from tailorable structures and correspondingly special properties, the achieved HPs have been widely applied in various fields such as light-emitting materials, nanoscience and technology, supramolecular chemistry, biomaterials, hybrid materials and composites, coatings, adhesives, and modifiers. In this review, we mainly focus on the progress in the structural control, synthesis, functionalization, and potential applications of both conventional and segmented HPs reported over the last decade.

Hyperbranched polymers: advances from synthesis to applications

A novel nano-silver colloidal solution was prepared in one step by mixing AgNO3 aqueous solution and an amino-terminated hyperbranched polymer (HBP-NH2) aqueous solution under vigorous stirring at room temperature. All results of Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and UV/Visible Absorption Spectrophotometry indicated that silver nanoparticles had been formed in colloidal solution. Cotton fabric was treated with nano-silver colloid by an impregnation method to provide the cotton fabric with antibacterial properties. The whiteness, silver content, antibacterial activity and washing durability of the silver-treated fabrics were determined. The results indicated that the silver-treated cotton fabric showed 99.01 % bacterial reduction of Staphylococcus aureus and 99.26 % bacterial reduction of Escherichia coli while the silver content on cotton was about 88 mg/kg. The antimicrobial activity of the silver-treated cotton fabric was maintained at over 98.77 % reduction level even after being exposed to 20 consecutive home laundering conditions. In addition, the results of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed that silver nanoparticles have been fixed and well dispersed on cotton fabrics’ surface and the major state of the silver presented on the surface was Ag0.

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Application of silver nanoparticles to cotton fabric as an antibacterial textile finish

Sodium alginate/graphene oxide aerogel with enhanced strength-toughness and its heavy metal adsorption study.

A water-soluble amino-terminated hyperbranched polymer was synthesised from methyl acrylate and diethylene triamine by melt polycondensation. Its molecular weight and possible structure were characterised by gel permeation chromatography, Fourier transform infrared spectrophotometry and nuclear magnetic resonance spectroscopy. The zeta potential of cotton fabrics treated with the aqueous solution of the amino-terminated hyperbranched polymer (6 g dm−3) in the presence of citric acid (2 g dm−3) and sodium hypophosphite (3 g dm−3) of the liquid phase is positive at pHs lower than 7.5. Dyed with reactive dyes, the treated cotton fabric displayed a markedly enhanced colour strength, even when dyeing had been carried out in the absence of the electrolyte. The washing fastness, rubbing fastness and levelling properties of the dyed, treated cotton fabrics were also good compared with that obtained by conventional dyeing. The dyeing behaviour of Reactive Brilliant Yellow A-4GLN on treated cotton fabric was examined and found to follow a Langmuir-type adsorption curve. It is concluded that the amino-terminated hyperbranched polymer can be used as a salt-free auxiliary in reactive dyeing on cotton.

Hong Lin

Papers

Application of silver nanoparticles to cotton fabric as an antibacterial textile finish

Sodium alginate/graphene oxide aerogel with enhanced strength-toughness and its heavy metal adsorption study.

Synthesis of an amino-terminated hyperbranched polymer and its application in reactive dyeing on cotton as a salt-free dyeing auxiliary

Antibacterial cotton fabric grafted with silver nanoparticles and its excellent laundering durability.

HBP-NH2 grafted cotton fiber: Preparation and salt-free dyeing properties