Highly Efficient Antibacterial Surfaces Based on Bacterial/Cell Size Selective Microporous Supports

Abstract

We report on the fabrication of efficient antibacterial substrates selective for bacteria, i.e., noncytotoxic against mammalian cells. The strategy proposed is based on the different size of bacteria (1-4 μm) in comparison with mammalian cells (above 20 μm) that permit the bacteria to enter in contact with the inner part of micrometer-sized pores where the antimicrobial functionality are placed. On the contrary, mammalian cells, larger in terms of size, remain at the top surface, thus reducing adverse cytotoxic effects and improving the biocompatibility of the substrates. For this purpose, we fabricated well-ordered functional microporous substrates (3-5 μm) using the breath figures approach that enabled the selective functionalization of the pore cavity, whereas the rest of the surface remained unaffected. Microporous surfaces were prepared from polymer blends comprising a homopolymer (i.e., polystyrene) and a block copolymer (either polystyrene-b-poly(dimethylaminoethyl methacrylate) (PDMAEMA) or a quaternized polystyrene-b-poly(dimethylaminoethyl methacrylate)). As a result, porous surfaces with a narrow size distribution and a clear enrichment of the PDMAEMA or the quaternized PDMAEMA block inside the pores were obtained that, in the case of the quaternized PDMAEMA, provided an excellent antimicrobial activity to the films.

Antimicrobial Porous Surfaces Prepared by Breath Figures Approach

“…Previous works indicate that, in general, copolymers with large hydrophilic blocks produce poorly ordered structures because the interfacial tension tends to decrease and, consequently, the coalescence of the water droplets increases [29,37,39]. However, in this case, relatively ordered porous arrays are obtained for all the blends, using both types of antimicrobial copolymers with large cationic segments as additives.…”

“…Due to the formation mechanism of the breath figures, the hydrophilic polymers tend to migrate towards the condensed water droplets, which imply their localization at the surface, on the wall of the pores [26,27,28]. In this context, cationic antimicrobial polymers based on quaternary ammonium groups have been incorporated into breath figures films by using blends [29]. However, only systems based on copolymers with low positive charge density have been prepared due to the difficulty to dissolve them in organic solvents [29,30].…”

“…In this context, cationic antimicrobial polymers based on quaternary ammonium groups have been incorporated into breath figures films by using blends [29]. However, only systems based on copolymers with low positive charge density have been prepared due to the difficulty to dissolve them in organic solvents [29,30]. In this work, we prepared porous films by a breath figures approach functionalized with high charge density by the incorporation of antimicrobial cationic polymers bearing two quaternary ammonium groups per monomeric unit.…”

Porous Microstructured Surfaces with pH‐Triggered Antibacterial Properties

“…Porous films functionalized with the antimicrobial copolymer PS 54 ‐ b ‐PTTBM 23 were prepared by the breath figures approach using chloroform as the solvent. In previous works, cationic copolymers with permanent positive charges, such as polymers with quaternary ammonium groups, have been employed to incorporate antimicrobial properties into breath figure films . However, polar solvents such as THF, which produce poorly ordered structures, and/or polymers with low charge density are required in most cases in order to solubilize the cationic polymers.…”

“…In previous works, cationic copolymers with permanent positive charges, such as polymers with quaternary ammonium groups, have been employed to incorporate antimicrobial properties into breath figure films. [39,40] However, polar solvents such as THF, which produce poorly ordered structures, and/or polymers with low charge density are required in most cases in order to solubilize the cationic polymers. In the current work, we prepared films from a neutrally charged polymer, PS 54 -b-PTTBM 23 ; thus, typical organic solvents used in the breath figures approach can be employed.…”