# Development of poly-D-mannose-stabilized silver nanoparticles exhibiting antibacterial and antibiofilm properties

## TL;DR

This paper describes the creation of silver nanoparticles stabilized with poly-D-mannose, which show antibacterial and antibiofilm properties useful for food safety.

## Contribution

The novel use of poly-D-mannose as a stabilizer for silver nanoparticles, avoiding hazardous chemicals and showing antimicrobial efficacy.

## Key findings

- PM-AgNPs effectively inhibit foodborne pathogens like Pseudomonas aeruginosa and Escherichia coli.
- PM-AgNPs show strong antibiofilm activity against Staphylococcus aureus and Salmonella Typhimurium.
- PM-AgNPs have a zeta potential of −24.7 mV and particle sizes between 2 and 18 nm.

## Abstract

In this study, previously synthesized poly-D-mannose (PM) served as the stabilizing agent for the production of silver nanoparticles (designated PM-AgNPs), which were subsequently assessed for their antibacterial and antibiofilm capabilities against foodborne pathogens. The PM-AgNPs were successfully synthesized, exhibiting a distinct surface plasmon resonance absorption peak at 400 nm. Fourier transform infrared analysis revealed the stabilization mechanism of silver nanoparticles by PM, involving the formation of O–H⋯Ag hydrogen bonds and C–O⋯Ag coordination bonds. Both transmission electron microscopy and dynamic light scattering measurements confirmed the spherical morphology of PM-AgNPs, with particle sizes ranging from 2 to 18 nm and a zeta potential of −24.7 mV. Furthermore, energy-dispersive X-ray spectroscopy analysis disclosed the elemental composition of PM-AgNPs to be C:O:Ag in a ratio of 39.32:37.93:22.75. To evaluate the antibacterial and antibiofilm efficacy of PM-AgNPs against selected pathogenic bacteria and their biofilms, the broth microdilution method and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide staining assay were employed, respectively. The inhibitory effect of PM-AgNPs on five pathogenic bacteria was found to be in the following order: Pseudomonas aeruginosa > Escherichia coli O157:H7 > Salmonella Typhimurium > Staphylococcus aureus > Bacillus cereus, with corresponding minimum inhibitory concentrations of 23.8 µg/mL, 95 µg/mL, 190 µg/mL, 380 µg/mL, and 380 µg/mL, respectively. The efficacy of PM-AgNPs in suppressing the biofilms of the five aforementioned pathogenic bacteria showed a ranking of S. aureus > S. Typhimurium > E. coli O157:H7 > B. cereus > P. aeruginosa. In summary, PM-AgNPs exhibit promising potential as an antibacterial agent in the food industry.

The control of foodborne pathogens, including Escherichia coli O157:H7, Staphylococcus aureus, Salmonella Typhimurium, Pseudomonas aeruginosa, and Bacillus cereus, represents a critical challenge in food safety, necessitating the development of novel antimicrobial agents with both efficacy and safety. In this study, hyperbranched poly-D-mannose was employed as a stabilizer to successfully synthesize silver nanoparticles with exceptional stability and dispersibility. The prepared PM-AgNPs demonstrated remarkable bactericidal and anti-biofilm activities while circumventing the use of potentially hazardous chemical stabilizers commonly employed in conventional nanoparticle synthesis. This advancement provides an innovative solution for pathogenic microorganism control during food processing and storage, offering a combination of high antimicrobial efficacy and biosafety. The excellent biocompatibility and controlled release characteristics of this system make it particularly suitable for preservation applications in high-risk food products such as meat and dairy items, thereby significantly contributing to the enhancement of food safety standards.