Soft, adhesive (+) alpha tocopherol phosphate planar bilayers that control oral biofilm growth through a substantive antimicrobial effect

Robert A Harper,Mais M Saleh,Guy Carpenter,Vincenzo Abbate,Gordon Proctor,Richard D Harvey,Robert J Gambogi,Anthony Geonnotti,Robert Hider,Stuart A Jones

doi:10.1016/j.nano.2017.12.024

Abstract

‘Soft’ nanomaterials have the potential to produce substantive antibiofilm effects. The aim of this study was to understand the oral antimicrobial activity of soft nanomaterials generated from alpha-tocopherol (α-T) and alpha-tocopherol phosphate (α-TP). (+) α-TP formed planar bilayer islands (175 ± 21 nm, −14.9 ± 3.5 mV) in a Trizma® buffer, whereas (+) α-T formed spherical liposomes (563 ± 1 nm, −10.5 ± 0.2 mV). The (+) α-TP bilayers displayed superior Streptococcus oralis biofilm growth retardation, a more substantive action, generated a superior adsorption to hydroxyapatite and showed an enhanced inhibition of multi-species bacterial saliva biofilm growth (38 ± 7μm vs 58 ± 18 μm, P ˂ 0.05) compared to (+) α-T. Atomic force microscopy data indicated that the ability of the ‘soft’ α-TP nanomaterials to transition into planar bilayer structures upon contact with interfaces facilitated their adhesive properties and substantive antimicrobial effects.

Highlights

The ability of synthetic nanomaterials to impair bacterial adhesion, dismantle biofilms and kill microorganisms has been established using solid nanosized particles.[1,2,3,4] there is a lack of information about how ‘soft’ nanomaterials, e.g. liposomes, act as antimicrobial agents.[5]
The aim of this study was to understand the antimicrobial activity of soft nanomaterials generated from alpha-tocopherol (α-T) and alpha-tocopheryl phosphate (α-TP). α-T shows some surface activity in aqueous solvents where it forms liposomes, but when phosphorylated to produce alpha-tocopheryl phosphate (α-TP) the phosphate of α-TP will be charged, which enables it to bind charged surfaces, e.g., teeth.[9]
The structure of (+) α-TP (obtained with a 27% yield and 99% purity, see supplementary materials, Figure S1) was confirmed by the presence of a single phosphorus nuclear magnetic resonance (NMR) peak at −1.27 ppm (See supplementary materials, Figure S2, A), 29 carbon NMR peaks and the aromatic methyl group chemical shifts of (+) α-T and (+) α-TP, which indicated that the conversion from (+) α-T to (+) α-TP was successful

Summary

Introduction

The ability of synthetic nanomaterials to impair bacterial adhesion, dismantle biofilms and kill microorganisms has been established using solid nanosized particles.[1,2,3,4] there is a lack of information about how ‘soft’ nanomaterials, e.g. liposomes, act as antimicrobial agents.[5] Soft nanomaterials can elicit antimicrobial effects, in a similar manner to solid nanomaterials, through physical surface interactions with microorganisms, but in addition, soft nanomaterials can

Objectives

Methods

Results