On the Infectivity of Bacteriophages in Polyelectrolyte Multilayer Films: Inhibition or Preservation of Their Bacteriolytic Activity?

Abstract

Antibiotic resistance in bacterial cells has motivated the scientific community to design new and efficient (bio)materials with targeted bacteriostatic and/or bactericide properties. In this work, a series of polyelectrolyte multilayer films differing in terms of polycation-polyanion combinations are constructed according to the layer-by-layer deposition method. Their capacities to host T4 and φx174 phage particles and maintain their infectivity and bacteriolytic activity are thoroughly examined. It is found that the macroscopic physicochemical properties of the films, which includes film thickness, swelling ratio, or mechanical stiffness (as derived by atomic force microscopy and spectroscopy measurements), do not predominantly control the selectivity of the films for hosting infective phages. Instead, it is evidenced that the intimate electrostatic interactions locally operational between the loaded phages and the polycationic and polyanionic PEM components may lead to phage activity reduction and preservation/enhancement, respectively. It is argued that the underlying mechanism involves the screening of the phage capsid receptors (operational in cell recognition/infection processes) because of the formation of either polymer-phage hetero-assemblies or polymer coating surrounding the bioactive phage surface.

Impacts of Mechanical Stiffness of Bacteriophage-Loaded Hydrogels on Their Antibacterial Activity

“…Effective loading of phages within hydrogels has been already described in our previous work. 31 The presence of phages inside hydrogels volume is clearly confirmed by fluorescence-based observations using CLSM (as illustrated by Figure S4). We emphasize that no phages were located/observed at the extreme surface, as judged by SEM micrographs reported in Figure S5.…”

“…Subsequently, phages were loaded in the polyelectrolyte multilayers (PEM in short) via passive diffusion process as described elsewhere. 31 Procedures for the production and purification of the here-adopted T4 and φX174 bacteriophages are detailed in the next section. The above protocol was adopted for the construction and phages-filling of (PDADMAC-PAA), (PLL-HA), (PAH-PGA) and…”

“…21,30 We recently evidenced that some hydrogels consisting of polyelectrolyte multilayers can host phages whose infectivity and virulence towards bacteria remain preserved. 31 However, there remains a lot to be done for optimizing the performance of hydrogels and polymeric films to host phages 32,33 and for formulating antibacterial gels or biocoatings operational against specific target bacteria. Such devices truly constitute a breakthrough in biomaterials science and biotechnology, especially in the fields of implants and artificial joints as they may serve as sterile growth scaffold for human tissue.…”

“…[37][38][39][40] Despite of all these efforts, most of these processes still lead to a serious loss of-and/or reduction in-the bacteriolytic activity of bacteriophages once the latter are incorporated into the hosting organic matrix. 31,40 To solve this issue and to propose operational bacteriophages-loaded hydrogels with full preservation of the native phages activity, the way physicochemical properties defining the hydrogel matrix affect the infectivity potential of the loaded phages should be addressed.…”

Electrophoresis of composite soft particles with differentiated core and shell permeabilities to ions and fluid flow

“…on microorganisms, nanoparticles or colloids, are interpreted on the basis of analytical equations derived by Ohshima valid for specific ranges of particle size, Debye layer thickness and shell Brinkman length. It is believed that the analytical mobility expressions developed here, valid over a larger range of conditions and applicable to a wider spectrum of core-shell particle types, will pave the way for a refined evaluation of the electro-hydrodynamic properties of colloids whose composition often involves complex mixtures of biotic and abiotic materials with diversified (bio)polymers-based surface functionalization, as required in drug delivery [74], environmental [75] and other biomedical applications [76][77]. Future developments of this work involve the derivation of electrophoretic mobility of the composite core-shell particles examined here albeit with full account of electric double layer relaxation and polarization at the Poisson-Nernst-Planck level, which requires numerical analysis of the relevant governing electro-hydrodynamic equations.…”