Physico-Chemical Characterization and Antimicrobial Properties of Hybrid Film Based on Saponite and Phloxine B

Abstract

This research was aimed at the preparation of a hybrid film based on a layered silicate saponite (Sap) with the immobilized photosensitizer phloxine B (PhB). Sap was selected because of its high cation exchange capacity, ability to exfoliate into nanolayers, and to modify different surfaces. The X-ray diffraction of the films confirmed the intercalation of both the surfactant and PhB molecules in the Sap film. The photosensitizer retained its photoactivity in the hybrid films, as shown by fluorescence spectra measurements. The water contact angles and the measurement of surface free energy demonstrated the hydrophilic nature of the hybrid films. Antimicrobial effectiveness, assessed by the photodynamic inactivation on hybrid films, was tested against a standard strain and against methicillin-resistant bacteria of Staphylococcus aureus (MRSA). One group of samples was irradiated (green LED light; 2.5 h) and compared to nonirradiated ones. S. aureus strains manifested a reduction in growth from 1-log10 to over 3-log10 compared to the control samples with Sap only, and defects in S. aureus cells were proven by scanning electron microscopy. The results proved the optimal photo-physical properties and anti-MRSA potential of this newly designed hybrid system that reflects recent progress in the modification of surfaces for various medical applications.

Surface Characterization and Anti-Biofilm Effectiveness of Hybrid Films of Polyurethane Functionalized with Saponite and Phloxine B

“…It seems the presence of small amounts of PhB cations in complex PhB/PUC membranes did not affect the spacing significantly. This trend is similar to the results observed for PhB-functionalized organoclays published recently [22]. OC films used for the preparation of the PUC membranes were also measured (Section S4, Figure S3).…”

“…PhB is a member of halogenated xanthene dyes with photoactive properties and a high antimicrobial potential. It has been proved to be effective against Gram-positive bacteria, including MRSA strains [22,[28][29][30]. Sap is a layered silicate with a negative layer charge and does not significantly adsorb PhB molecules without an appropriate modification [22][23][24].…”

“…It has been proved to be effective against Gram-positive bacteria, including MRSA strains [22,[28][29][30]. Sap is a layered silicate with a negative layer charge and does not significantly adsorb PhB molecules without an appropriate modification [22][23][24]. Therefore, Sap particles had to be modified by ODTMA cations to activate the surface for PhB adsorption and in the same way to get a compatible material for the nanocomposite with PU.…”

“…The material was based on two antimicrobial components: a cationic surfactant (octadecyltrimethylammonium, ODTMA) used to modify the Sap particles and necessary to achieve compatibility with the polymer and the photosensitizer phloxine B (PhB). The properties of the precursor in the form of OC films with adsorbed PhB molecules have been tested in a recent study [22] and the effect and photoactivity of PhB as a part of other similar materials were confirmed in other works [23,24]. It is not expected that photooxidation of the surface by the photosensitizer should significantly alter the structure and antimicrobial properties of the composites.…”

“…Results are expressed as average values with standard deviations. More details about the method have been published elsewhere [22].…”