Superior performance of macroporous over gel type polystyrene as a support for the development of photo-bactericidal materials

Abstract

a Hexanuclear molybdenum cluster [Mo6I8Ac6] 2-(1) has been ionically bound onto macroporous (Pmp) and gel-type (Pgel) resins and their performance as materials for the photodynamic inactivation of microorganism have been studied. It has been found that 1@Pmp in combination with light is able to reduce 99.999999% the population of Gram-positive Staphylococcus aureus whereas the activity of 1@Pgel is limited to a 99.99% reduction at the same light dose. The same trend is observed with Gram-negative Pseudomonas aeruginosa. A comprehensive study of both materials has been performed using confocal laser scanning microscopy, thermogravimetric analysis, nitrogen porosimetry, steady state and time resolved fluorometries and diffuse reflectance spectroscopy. The photochemical generation of singlet oxygen ( 1 O2) has been assessed using 9,10-dimethylanthracene as a trap for this reactive oxygen species. It can be concluded that the nature of the polymeric support is of paramount importance for the development of surfaces with bactericidal properties.

Octahedral molybdenum cluster as a photoactive antimicrobial additive to a fluoroplastic

“…Highly photoluminescent complexes of the general formula [{Mo6I8}L6] 2-, where L is an electron-withdrawing ligand, in particular perfluorinated carboxylic acid and organic sulfonate, demonstrate the ability to efficiently generate singlet oxygen upon excitation with UV or blue light [8][9][10][11], and thus they are good candidates as photosensitisers for materials with photoinduced antibacterial activity. In a proof-of-concept studies it was demonstrated A c c e p t e d m a n u s c r i p t that compounds based on {Mo6I8} 4+ had antibacterial activity against S. aureus [12,13] and E. faecalis [14], while in our recent study, silica nanoparticles doped with molybdenum clusters demonstrated pronounced photodynamic activity against larynx carcinoma (Hep2) cells [15].…”

Molybdenum Iodides – from Obscurity to Bright Luminescence

“…Macroporous material is more efficient than gel type polystyrene with the same chemical composition: in the first case, only 1 ppm of the initial population survives the irradiation; in the latter case the survival rate is four orders of magnitude higher – 0.01 %. These materials can be used as support for the development of photo‐antibacterial materials , …”

A cost-effective combination of Rose Bengal and off-the-shelf cationic polystyrene for the photodynamic inactivation of Pseudomonas aeruginosa

“…1 log10 CFU/mL. [22] Probably, a combination of factors would explain the performance of RB@Pmp towards P. aeruginosa here reported: the appropriate distribution of ammonium groups on the polymer, the right nanostructure of the surface, the ability of the surface to bind (and sequester) the bacteria, the high yield of 1 O2 generated by RB at the employed concentration and maybe the manufacturing process (and even commercial batch) of the resin. Since those factors are not optimized yet, it is expected that a deeper knowledge of these materials will lead to an improved balance between them and hence it will allow obtaining polymeric materials with even a better performance.…”

“…[20] In previous reports we used this ion exchange strategy to explore the possibilities of molybdenum-based photosensitizers bound to cationic polymers. [21,22] We found that both supports, Pmp and Pgel, are appropriate for the development of photobactericidal materials, against planktonic cultures of S. aureus and P. aeruginosa, with a better performance of the Pmp resin over the Pgel one. In order to expand the range of useful photosensitizers employing this strategy, we decided to use RB, providing its dianionic nature, and considering that it is one of the most studied photo-antimicrobials so far, that it is safe for human use and also that its cost is very low, which could be a practical advantage for future application in real medical contexts.…”