Janus nanoparticles synthesized from hydrophobic carbon dots and carboxymethyl cellulose: Novel antimicrobial additives for fresh food applications

Abstract

The aim of this study was to synthesis Janus nanoparticles (JPs) using beeswax-based hydrophobic carbon dots to form the non-polar face and hydrophilic carboxymethyl cellulose to form the hydrophilic face. Size, morphology, composition, and optical properties of the JPs were characterized. Scanning electron microscopy and light scattering analysis showed these nanoparticles were spheroids with average diameters around 4 nm. A cytotoxicity assay (L929 cells) showed that the hydrophobic carbon dots and JPs exhibited significant toxicity (decrease in cell viability) at 1.5 and 5 mg/mL, respectively. For the hydrophobic carbon dots, the minimum inhibitory concentration was 0.02 mg/mL for Escherichia coli and 0.04 mg/mL for Listeria monocytogenes, whereas for the JPs it was 0.04 mg/mL for both bacteria. Both the hydrophobic carbon dots and JPs also exhibited appreciable antioxidant activity. These particles were then incorporated into minced beef as novel preservatives. At 0.05% concentration, both kinds of nanoparticles caused a significant reduction in chemical and microbial degradation of the meat during storage. The JPs had a greater effect on mesophile (3.3 log10 CFU/g reduction) than on psychrophile (2.8 log10 CFU/g reduction) microbial populations within the meat. The preparation of JPs based on carbon dots, reduced cytotoxicity and improved their antimicrobial properties. JPs developed in this study may be used as novel preservatives with antimicrobial and antioxidant properties in foods.