Antimicrobial Properties of Palladium and Platinum Nanoparticles: A New Tool for Combating Food-Borne Pathogens

Abstract

Although some metallic nanoparticles (NPs) are commonly used in the food processing plants as nanomaterials for food packaging, or as coatings on the food handling equipment, little is known about antimicrobial properties of palladium (PdNPs) and platinum (PtNPs) nanoparticles and their potential use in the food industry. In this study, common food-borne pathogens Salmonella enterica Infantis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus were tested. Both NPs reduced viable cells with the log10 CFU reduction of 0.3–2.4 (PdNPs) and 0.8–2.0 (PtNPs), average inhibitory rates of 55.2–99% for PdNPs and of 83.8–99% for PtNPs. However, both NPs seemed to be less effective for biofilm formation and its reduction. The most effective concentrations were evaluated to be 22.25–44.5 mg/L for PdNPs and 50.5–101 mg/L for PtNPs. Furthermore, the interactions of tested NPs with bacterial cell were visualized by transmission electron microscopy (TEM). TEM visualization confirmed that NPs entered bacteria and caused direct damage of the cell walls, which resulted in bacterial disruption. The in vitro cytotoxicity of individual NPs was determined in primary human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs). Due to their antimicrobial properties on bacterial cells and no acute cytotoxicity, both types of NPs could potentially fight food-borne pathogens.

Evaluation of the Antimicrobial Efficacy of N-Acetyl-l-Cysteine, Rhamnolipids, and Usnic Acid—Novel Approaches to Fight Food-Borne Pathogens

“…Isolates were refreshed from a deep-frozen aliquot by inoculating one loopful on the non-selective Tryptic Soy Agar (TSA) purchased from the VWR (Radnor, PA, USA). Starting inoculum was prepared according to Chlumsky et al [ 38 ]. Briefly, a single colony from an agar plate was inoculated into 2 mL of BHI and incubated at 37 °C overnight.…”

“…The determination of MICs was performed according to Chlumsky et al [ 38 ]. Briefly, 96-well flat-bottomed microtiter plates were inoculated with 75 µL (for biofilm formation) or 100 µL (for preformed biofilm) of bacterial suspension (A 625nm 0.08 to 0.1) in technical triplicates and were then carefully mixed with the dilution series of the test substances (24 h cultivation at 25 °C for S. Infantis, 37 °C for other strains) or were directly cultivated to preform biofilms (18 h).…”

“…All inhibitions were calculated using the formula of Chlumsky et al [ 38 ] below (Equation (1)): where is the absorbance of bacterial suspension/biofilm itself, and is the absorbance of the bacterial suspension/biofilm with the added natural substance (NAC, RLs, and UA).…”

Antimicrobial Nanomaterials for Food Packaging

“…PdNP concentrations of 22.25–44.5 mg/L and PtNP concentrations of 50.5–101 mg/L were found to be the most effective in reducing biofilm formation. The IC 50 values of PdNPs (>4.45 mg/L) and PtNPs (>10.1 mg/L) were determined in human epithelial kidney cells, human dermal fibroblasts, human keratinocytes, primary human coronary artery endothelial cells and primary human renal tubular epithelial cells using in vitro cytotoxicity studies [ 58 ].…”

Green Synthesis of Platinum Nanoparticles for Biomedical Applications

“…PtNPs showed cytotoxicity against normal cells, changing the morphology and density of cells, causing chromosome condensation, blocking cell proliferation and inducing apoptosis [ 196 ]. However, the acute cytotoxicity absence of PtNPs in vitro for human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs) was observed [ 197 ]. PtNPs described above were produced by physical and chemical methods; however, a toxic effect was not shown for “green synthesis”.…”