The mechanism of metal-based antibacterial materials and the progress of food packaging applications: A review

Abstract

Food packages have been detected carrying novel coronavirus in multi-locations since the outbreak of COVID-19, causing major concern in the field of food safety. Metal-based supported materials are widely used for sterilization due to their excellent antibacterial properties as well as low biological resistance. As the principal part of antibacterial materials, the active component, commonly referred to Ag, Cu, Zn, etc., plays the main role in inhibiting and killing pathogenic microorganisms by destroying the structure of cells. As another composition of metal-based antibacterial materials, the carrier could support and disperse the active component, which on one hand, could effectively decrease the usage amount of active component, on the other hand, could be processed into various forms to broaden the application range of antibacterial materials. Different from other metal-based antibacterial reviews, in order to highlight the detailed function of various carriers, we divided the carriers into biocompatible and adsorptable types and discussed their different antibacterial effects. Moreover, a novel substitution antibacterial mechanism was proposed. The coating and shaping techniques of metal-based antibacterial materials as well as their applications in food storage at ambient and low temperatures are also comprehensively summarized. This review aims to provide a theoretical basis and reference for researchers in this field to develop new metal-based antibacterial materials.

Keywords: Antibacterial mechanism; Carrier; Coating method; Food packaging; Metal.

Fig. 1

Antibacterial mechanism of metal based materials (a) Contact antibacterial type; (b) Dissolution antibacterial type; (c) Oxidation antibacterial type; (d) Substitution antibacterial type.

Fig. 2

Simulation of electrostatic interaction of vesicles with positively charged AuNP.

Fig. 3

SEM images of A (the control): the native cells in PBS with shaking for 1 h; B: the cells in PBS in the presence of 0.35 mg/mL TiO₂ solution under natural light with shaking for 1 h; C: the cells in PBS in the presence of 0.35 mg/mL TiO₂ solution under 500W UV light (mainly 365 nm) for 1 h; D: the cells in PBS with 500W UV (mainly 365 nm) light for 1 h.

Fig. 4

Leakage of reducing sugars (bars) and proteins (—●—) for 4 Cronobacter sakazakii strains without (0 mg/L) or with treatment of silver nanoparticles at a final concentration of 200 mg/L: (a) ATCC 29544T; (b) ATCC BAA894; (c) ATCC 29004; (d) ATCC 12868. Error bars represent the SD of data from 3 repetitive experiments.

Fig. 5

Copper damages iron-sulfur-cluster dehydratases. (A) LEM33 (copA cueO cusCFBA) was grown at 37°C in aerobic glucose medium with 1.5 mM alanine (Ala) (squares) or 0.5 mM each of isoleucine (I), leucine (L), and valine (V) (circles), and CuSO₄ was added to 0 M (open symbols) or 10 M (closed symbols). The data are a representative of 3 independent experiments. (B–D) W3110 (WT) and LEM33 (copA cueO cusCFBA) were grown aerobically to an OD₅₀₀ of 0.1, then challenged with 0 M (open bars), 16 M (gray bars), or 80 M CuSO₄ (black bars) for 30 min. (B and C) Cells were grown in glucose/alanine, and IPMI (B) and fumarase (C) activities were measured. (D) Cells were grown aerobically in gluconate medium supplemented with 1.5 mM alanine, and 6-phosphogluconate activity was measured. (B–D) Data are the average of 3 independent experiments, and the error bars represent SD. (B) WT cells exposed to 80 M Cu had IPMI activities below the detection limit (15%).

Fig. 6

YPE-AgNPS and Q-AgNPs induced ROS and superoxide generation. CLSM images (1–14) show the ROS production in P. aeruginosa and MRSA; untreated cells of P.aeruginosa (1), P. aeruginosa + 10 μg/ml YPE-AgNPs (2), P. aeruginosa + 20 μg/ml YPE-AgNPs (3), P. aeruginosa + 50 μg/ml YPE-AgNPs (4), P. aeruginosa + 10 μg/ml Q-AgNPs (5), P. aeruginosa + 20 μg/ml Q-AgNPs (6), P. aeruginosa + 50 μg/ml Q-AgNPs (7), Untreated cells of MRSA (8), MRSA + 10 μg/ml YPE-AgNPs (9), MRSA + 20 μg/ml YPE-AgNPs (10),MRSA + 50 μg/ml YPE-AgNPs (11), MRSA + 10 μg/ml Q-AgNPs (12), MRSA + 20 μg/ml Q-AgNPs (13), and MRSA + 50 μg/ml Q-AgNPs (14). Panel A shows in vitro superoxide anions generation by YPE-AgNPs and Q-AgNPs under light and dark conditions. Panel B represents the percent increase in DCF fluorescence in MRSA, MSSA, E. coli, and P. aeruginosa by Q-AgNPs (line curves) and YPE-AgNPs (histograms).

Fig. 7

Samples inhibition results against Escherichia coli and Staphylococcus aureus.

Fig. 8

Biocompatible carriers loaded with metal antibacterial active components (a) Silver loaded hydroxyapatite; (b) Copper loaded bioactive glass.

Fig. 9

Adsorptable carriers loaded with metal antibacterial active components (a) Silver loaded Linder type A zeolite; (b) Zinc loaded palygorskite clay minerals.

Fig. 10

Silver ion release and MRSA killing test results: (a) Average silver ion release kinetics curves of Ag-zeolites at fast rate (FR, 5.5 mL/min) and slow rate (SR, 0.6 mL/min). Error bars are shown in every 3 min; (b) Pseudo-second order (PSO) linear regression of silver release kinetics data; (c) Assessment of rapid killing ability of Ag-nZeo and Ag-mZeo.

Fig. 11

The mechanism of action for antibacterial superhydrophobic coating.

Fig. 12

Food preservation test: a) open control apple piece and b) apple sample covered with the GD-AS-2 composite film.

Fig. 13

ZnO–Ag antibacterial results: (a) Kinetics of the antibacterial activity NCs BP with 3.0 and 2.0 wt % loading against E. coli and S. aureus; (b) Effect of NCs BP on the survival ratio of E. coli and S.aureus. (zinc oxide: ZnO, silver: Ag, nanocomposites: NCs, biopolymer: BP).

Fig. 14

Toxicity of nanoparticles and factors affecting their migration (a) Effect of pressure on migration of nanoparticles; (b) Effects of pH and temperature on the migration of nanoparticles; (c) Toxicity of nanoparticles to humans.