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Natural food antimicrobials are bioactive compounds that inhibit the growth of microorganisms involved in food spoilage or food-borne illness. However, stability issues result in degradation and loss of antimicrobial activity. Nanoencapsulation allows protection of antimicrobial food agents from unfavorable environmental conditions and incompatibilities. Encapsulation of food antimicrobials control delivery increasing the concentration of the antimicrobials in specific areas and the improvement of passive cellular absorption mechanisms resulted in higher antimicrobial activity. This paper reviews the present state of the art of the nanostructures used as food antimicrobial carriers including nanoemulsions, nanoliposomes, nanoparticles, and nanofibers.

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Most of antimicrobial peptides interact with food components decreasing their activity, which limit their successful incorporation into packaging material, functional foods and edible films. The aim of this work was to develop a nisin carrier. Nanofibers of amaranth protein and pullulan (50:50) loaded with nisin were obtained by electrospinning. The nanofibers morphology was determined by scanning electron microscopy and fluorescent microscopy. The molecular interactions were characterized by infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The nisin loading efficiency as well as the antimicrobial activity against Leuconostoc mesenteroides were evaluated. The micrographs of the obtained materials exhibited smooth and continuous fibers with no defects characterized by diameters between 124 and 173 nm. The FTIR analysis showed intermolecular interactions mainly by hydrogen bonding. The electrospinning process improved the thermal properties of the polymeric mixture displacing the Tm peak to higher temperatures and increasing crystallinity. The antimicrobial activity of nisin in broth and agar against L. mesenteroides was maintained after incorporation into fibers. The results presented an outlook for the potential use of protein amaranth nanofibers when incorporating antimicrobials as a food preservation strategy.

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Gold nanoparticles (AuNPs) are promising nanomaterials exhibiting anti-cancer effects. Green AuNPs synthesis using plant extracts can be used to achieve stable and beneficial nanoparticles due to their content of bioactive compounds. This research aimed to synthesize and evaluate the antiproliferative and caspase-3 activity induction of green AuNPs synthesized with common mullein (V. thapsus) flowers (AuNPsME) and castor bean (R. communis) leaves (AuNPsCE) ethanolic extracts in human HT29 and SW480 colorectal cancer cells. Their effect was compared with chemically synthesized AuNPs (AuNPsCS). The extracts mainly contained p-coumaric acid (71.88–79.93 µg/g), ferulic acid (19.07–310.71 µg/g), and rutin (8.14–13.31 µg/g). The obtained nanoparticles presented typical FT-IR bands confirming the inclusion of polyphenols from V. thapsus and R. communis and spherical/quasi-spherical morphologies with diameters in the 20.06–37.14 nm range. The nanoparticles (20–200 µg/mL) showed antiproliferative effects in both cell lines, with AuNPsCE being the most potent (IC50 HT29: 110.10 and IC50SW480: 64.57 µg/mL). The AuNPsCS showed the lowest intracellular reactive oxygen species (ROS) generation in SW480 cells. All treatments induced caspase 3/7 activity to a similar or greater extent than 30 mM H2O2-treated cells. Results indicated the suitability of V. thapsus and R. communis extracts to synthesize AuNPs, displaying a stronger antiproliferative effect than AuNPsCS.

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