Evaluation of lecithin–nisin, chitosan, carvacrol, and lactoferrin–β-cyclodextrin nanoformulations: Antimicrobial potency, biofilm inhibition, virulence gene suppression in food-borne pathogens

Biofilms formed by major foodborne pathogens ( Escherichia coli, Salmonella enteritidis, Listeria monocytogenes, Staphylococcus aureus, and Campylobacter jejuni ) confer high-level tolerance to conventional antimicrobials and promote multidrug resistance. We conducted a direct comparison of four commercial nanoformulations—lecithin–nisin nanoparticles (NPs), chitosan nanoparticles (CSNPs), carvacrol nanoemulsions (NE), and lactoferrin–β-cyclodextrin (LF–βCD) hydrogels—against these pathogens. Particle size and surface charge of each formulation were confirmed by dynamic light scattering. Antimicrobial activity (MIC, sub-MIC, MBC) was determined by broth microdilution. Anti-biofilm efficacy at sub-MIC doses was quantified via crystal violet staining. Lecithin–nisin, which most effectively prevented biofilm formation, was selected for gene expression analysis of csgD, eutE, luxS, icaA , and pnpA using SYBR Green qPCR. Biocompatibility was assessed by MTT assay in L929 fibroblasts following 24 h exposure up to twice the MBC. Four carriers exhibited a consistent two-fold increase from MIC to MBC across pathogens. At sub-MIC concentrations, each formulation reduced biofilm biomass by more than 50%, with lecithin–nisin NPs and carvacrol NE producing the greatest inhibition. Lecithin–nisin treatment downregulated target genes by 1.78-, 1.70-, 1.94-, 2.11-, and 2.34-fold, respectively. Cytotoxicity assays showed ≥98% fibroblast viability at sub-MIC, modest declines at MIC/MBC, and >91% viability even at 2 × MBC. Overall antimicrobial and anti-biofilm potency ranked: lecithin–nisin NPs > carvacrol NE > CSNPs > LF–βCD hydrogels. Nanoencapsulation of diverse antimicrobials enhances bacteriostatic and bactericidal efficacy, impedes biofilm formation, suppresses virulence gene expression, and preserves cell viability, supporting their translational potential for next-generation food safety.