Development of preservative-free nanoparticles-based emulsions: Effects of NP surface properties and sterilization process.
Model emulsions were developed with or without commercial titanium dioxide nanoparticles (NP) carrying various surface treatments in order to get close physicochemical properties whatever the NP surface polarity (hydrophilic and hydrophobic). Rheology and texturometry highlighted that the macroscopic properties of the three formulated emulsions were similar. However, characterizations by optical microscopy, static light scattering and zetametry showed that their microstructures reflected the diversity of the incorporated NP surface properties. In order to use these model emulsions as tools for biological evaluations of the NP in use, they had to show the lowest initial microbiological charge and, specifically for the NP-free emulsion, the lowest bactericidal effect. Hence, formulae were developed preservative-free and a thermal sterilization step was conducted. Efficiency of the sterilization and its impact on the emulsion integrity were monitored. Results highlighted the effect of the NP surface properties: only the control emulsion and the emulsion containing hydrophilic NP fulfilled both requirements. To ensure the usability of these model emulsions as tools to evaluate the 'NP effect' on representative bacteria of the skin microflora (S. aureus and P. fluorescens), impact on the bacterial growth was measured on voluntary inoculated formulae.
Normandie Univ, ULH, CNRS, URCOM, 76600 Le Havre, France; Laboratoire de Microbiologie Signaux et Microenvironnement EA 4312, Université de Rouen, 55 rue saint Germain 27000 Evreux, France.
Laura
L
Rowenczyk
Normandie Univ, ULH, CNRS, URCOM, 76600 Le Havre, France. Electronic address: celine.picard@univ-lehavre.fr.
Céline
C
Picard
Laboratoire de Microbiologie Signaux et Microenvironnement EA 4312, Université de Rouen, 55 rue saint Germain 27000 Evreux, France.
Cécile
C
Duclairoir-Poc
Normandie Univ, ULH, CNRS, URCOM, 76600 Le Havre, France.
Nicolas
N
Hucher
Laboratoire de Microbiologie Signaux et Microenvironnement EA 4312, Université de Rouen, 55 rue saint Germain 27000 Evreux, France.
Nicole
N
Orange
Laboratoire de Microbiologie Signaux et Microenvironnement EA 4312, Université de Rouen, 55 rue saint Germain 27000 Evreux, France.
Marc
M
Feuilloley
Normandie Univ, ULH, CNRS, URCOM, 76600 Le Havre, France.
Michel
M
Grisel
D004655:Emulsions; D006801:Humans; D053758:Nanoparticles / Q000008:administration & dosage / Q000737:chemistry*; D010316:Particle Size; D011310:Preservatives, Pharmaceutical; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013242:Sterilization / Q000379:methods*; D013499:Surface Properties
D004655:Emulsions; D011310:Preservatives, Pharmaceutical
Emulsion formulation; Microbiological assays; Particle size measurement; Rheology; Sterilization; Texturometry; TiO(2) NP