Biomimetic hydroxyapatite nanocrystals are an active carrier for Salmonella bacteriophages

Abstract

Andrea Fulgione,1,* Flora Ianniello,1,* Marina Papaianni,1 Felice Contaldi,1 Tiziana Sgamma,2 Cinzia Giannini,3 Stella Pastore,3 Raffaele Velotta,4 Bartolomeo Della Ventura,5 Norberto Roveri,6 Marco Lelli,6 Federico Capuano,7 Rosanna Capparelli1 1Department of Agriculture, University of Naples “Federico II”, Portici, Naples, Italy; 2Biomolecular Technology Group, School of Allied Health Sciences, De Montfort University, Leicester, UK; 3Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, Bari, Italy; 4Department of Physics “Ettore Pancini”, University of Naples “Federico II”, Portici, Naples, Italy; 5Department of Physics, Politecnico di Milano, Milano, Italy; 6Chemical Center Srl, Granarolo dell’Emilia, Bologna, Italy; 7Department of Food Microbiology, Istituto Zooprofilattico Sperimentale del Mezzogiorno, Portici, Naples, Italy *These authors contributed equally to this work Purpose: The use of bacteriophages represents a valid alternative to conventional antimicrobial treatments, overcoming the widespread bacterial antibiotic resistance phenomenon. In this work, we evaluated whether biomimetic hydroxyapatite (HA) nanocrystals are able to enhance some properties of bacteriophages. The final goal of this study was to demonstrate that biomimetic HA nanocrystals can be used for bacteriophage delivery in the context of bacterial infections, and contribute – at the same time – to enhance some of the biological properties of the same bacteriophages such as stability, preservation, antimicrobial activity, and so on. Materials and methods: Phage isolation and characterization were carried out by using Mitomycin C and following double-layer agar technique. The biomimetic HA water suspension was synthesized in order to obtain nanocrystals with plate-like morphology and nanometric dimensions. The interaction of phages with the HA was investigated by dynamic light scattering and Zeta potential analyses. The cytotoxicity and intracellular killing activities of the phage–HA complex were evaluated in human hepatocellular carcinoma HepG2 cells. The bacterial inhibition capacity of the complex was assessed on chicken minced meat samples infected with Salmonella Rissen. Results: Our data highlighted that the biomimetic HA nanocrystal–bacteriophage complex was more stable and more effective than phages alone in all tested experimental conditions. Conclusion: Our results evidenced the important contribution of biomimetic HA nanocrystals: they act as an excellent carrier for bacteriophage delivery and enhance its biological characteristics. This study confirmed the significant role of the mineral HA when it is complexed with biological entities like bacteriophages, as it has been shown for molecules such as lactoferrin. Keywords: biomimetic hydroxyapatite nanocrystals, Salmonella Rissen, bacteriophages, antibiotic resistance

Keywords

• Biomimetic hydroxyapatite nanocrystals
• Salmonella Rissen
• bacteriophages
• antibiotic resistance.