Chitosan Cross‐Linked Graphene Oxide Nanocomposite Films with Antimicrobial Activity for Application in Food Industry

Abstract

The present study investigates the synthesis of graphene oxide‐chitosan (CS‐GO) nanocomposite films and their potential application in food packaging. Nanocomposite films were synthesized by cross‐linking graphene oxide with chitosan at high temperatures (120°C). The gel content assay showed an increasing in the % Gel of the nanocomposite film with the introduction of GO, from 64% to almost 89%, which could be related to the cross‐linking reaction between GO epoxy groups and chitosan amine and hydroxyl groups. Mechanical strength, thermal stability, infrared analysis and antimicrobial properties were also investigated. The tensile strength at break increased from 22.7 ± 1.2 to 6471.6 ± 1775.5 MPa when 0.1 wt% of GO was added. Thermal studies showed an increasing in the endothermal peak values with the increasing in GO content, which is also related to the increasing in the cross‐linking degree of the films and water interaction. Finally, the nanocomposites films were evaluated for antimicrobial properties, using E. coli K‐12 MG 1655 (Gram‐negative) and B. subtillis 102 (Gram‐positive). CS‐GO 0.6 wt% films presented the best microbial inactivation against E. coli and B. subtillis, with 22.83% and 54.93% inactivation, respectively. On the other hand, chitosan film (CS) control did not show any antimicrobial property. Therefore, cross‐linking of GO with chitosan improved significantly mechanical and antimicrobial properties of the films. These enhancements in the properties of the films made them suitable for application in food packaging.

Chitosan Nanocomposite Coatings for Food, Paints, and Water Treatment Applications

“…Carbon-based nanomaterials, such as CNT, graphene, and graphene oxide have been well-studied. Incorporation of graphene oxide into chitosan improves the mechanical properties of chitosan in addition to enhancing its antimicrobial and pollutant removal abilities [88,89]. Chitosan being a biocompatible polymer has been applied to improve the solubility of CNT and reduce its toxicity to facilitate practical applications (Table 1) [90].…”

Nanostructured Antimicrobials in Food Packaging—Recent Advances

“…Graphene oxide (GO) results from graphene functionalization with oxygen‐containing groups, while reduced GO (rGO) is synthesized by reducing their oxygen‐containing groups . Figure presents the schematic structures of graphene, GO, and rGO.…”

“…Besides antimicrobial properties, GBM may impart materials with enhanced barrier properties due to their tortuosity effect, which was further increased by cross‐linking GO with boric acid . Moreover, GBM may enhance polymer tensile properties and UV light absorption . Finally, smart functions may be also explored, since GBM may act as sensors for humidity, hydrogen peroxide, organophosphorate pesticides, and nitrate .…”

“…[67] Some interesting properties of graphene are its high electron mobility, excellent tensile properties, and thermal conductivity, making it highly promising for several applications, although its cost is still high. [68] Graphene oxide (GO) results from graphene functionalization with oxygen-containing groups, [69] while reduced GO (rGO) is synthesized by reducing their oxygen-containing groups. [70] Figure 2 presents the schematic structures of graphene, GO, and rGO.…”

“…Pristine graphene is poorly dispersible in water due to the low occurrence of hydrophilic groups, while GO and rGO present some amphiphilicity due to their functional groups, [71] which enhances their dispersibility into different matrices. [69] Graphene-based materials (GBMs) are effective against bacteria, [72] mainly G(+) bacteria, [73] effect which has been reported to arise from i) cell membrane damage upon contact with sharp edges, ii) oxidative stress through superoxide anion-independent oxidation (or ROS), and/or iii) phospholipid extraction from cell membrane. [71,74] GBM has been also combined or functionalized with other antimicrobials, enhancing their activities.…”