EFFECT OF TOPOGRAPHICALLY PATTERNED POLY(DIMETHYLSILOXANE) SURFACES ON Pseudomonas aeruginosa ADHESION AND BIOFILM FORMATION

Abstract

Bacterial pathogens, such as Pseudomonas aeruginosa, readily form biofilms on surfaces, limiting the efficacy of antimicrobial and antibiotic treatments. To mitigate biofilm formation, surfaces are often treated with antimicrobial agents, which have limited lifetime and efficacy. Recent studies have shown that well-ordered topographic patterns can limit bacterial attachment to surfaces and limit biofilm formation. In this study, nano and microscale patterned poly(dimethylsiloxane) surfaces were evaluated for their ability to affect adhesion and biofilm formation by Pseudomonas aeruginosa. Feature size and spacing were varied from 500 nm to 2 μm and included repeating arrays of square pillars, holes, lines and biomimetc Sharklet™ patterns. Bacterial surface adhesion and biofilm formation was assessed in microfluidic flow devices and under static conditions. Attachment profiles under static and fluid flow varied within topography types, sizes and spacing. Pillar structures of all sizes yielded lower surface attachment than line-based patterns and arrays of holes. This trend was also observed for biomimetic Sharklet™ patterns, with reduced bacterial attachment to "raised" features as compared to "recessed" features. Notably, none of the topographically patterned surfaces outperformed smooth surfaces (without topography) for resisting cell adhesion. Initial surface attachment patterns were indicative of subsequent biofilm formation and coverage, suggesting a direct role of surface topography in biofilm-based biofouling.

Nano and Microscale Topographies for the Prevention of Bacterial Surface Fouling

“…Many groups have fabricated engineered surface topography, using numerous fabrication techniques (soft lithography and double casting molding techniques, microcontact printing, electron beam lithography, nanoimprint lithography, photolithography, electrodeposition methods, etc.) [37][38][39][40][41][42][43][44][45][46][47] on a wide range of substrates, ranging from various polymeric materials (silicone, polystyrene, polyurethane, and epoxy resins) to metals and metal oxides (silicon, titanium, aluminum, silica, and gold) [21,40,45,[47][48][49][50][51][52][53][54][55]. Furthermore, engineered topography can be considered as part of a multi-faceted strategy to prevent biofouling, and could be combined with other methods such as surface chemical treatments, addition of antibiotics/bacteriostatic agents, etc.…”

“…We have expanded this work to explore cell attachment and subsequent biofilm formation under fluid shear/flow conditions [53]. For this work we examined a novel set of engineered surface topographies, which ranged from 250 nm feature size/spacing, up to 2 μm feature size/spacing.…”

Three-Dimensional Micropatterning Deters Early Bacterial Adherence and Can Eliminate Colonization

“…The screening of the library of patterns revealed a number of potential 3D engineered microsurfaces capable of effectively deterring both bacterial attachment and the early formation of microcolonies against E. coli and K. pneumoniae; for instance, diffused P09 exhibited excellent properties against both bacteria: E. coli (63% and 98% reduction in attached bacteria and microcolonies formed, respectively) and K. pneumoniae (77% and 83% reduction in attached bacteria and microcolonies formed, respectively), being this effectiveness comparable to results reported in the literature for other microbes. 46 Conversely, because of the different colonization strategies followed by P. aeruginosa, 57,58 the effectiveness of the patterns was significantly reduced, with diffused P09 showing only 26% reduction in the formation of microcolonies. Being the most resistant bacteria against antifouling and antiattachment features, the most effective surface (diffused P01, 68% and 66% reduction in attached bacteria and microcolonies formed, respectively) against this bacteria was selected, as it also presented excellent properties against E. coli and K. pneumoniae, 55% and 69% less bacterial cells attached, with 53% and 77% less microcolonies being formed, respectively.…”

Effects of Colloidal Crystals, Antibiotics, and Surface-Bound Antimicrobials on Pseudomonas aeruginosa Surface Density

“…The advantages of this approach compared to antibiotic treatment are that the approach is prophylactic (in contrast to a response to an infection) and does not require systemic treatment of the entire patient (thereby hopefully lessening side-effects). Recent research has included a number of parallel efforts in the development of coatings, including biocides, − anti-attachment chemical groups such as poly­(ethylene oxide) layers, liquid films, mechanical methods, changes in modulus, and topographical treatments. − These methods can be broadly characterized as chemical or physical methods aimed to combat bacterial biofilms. In this work, we seek to evaluate the combination of chemical and physical methods.…”

“…One promising physical approach to preventing biofilms is to modify the topography of a surface. Surface features on the scale of micrometers have been shown to successfully inhibit bacterial adhesion and the progression to biofilms − and alter the relative population density of two bacterial species . Much of this work was inspired by an effort to imitate the features on shark skin, − but there have been subsequent efforts to try to rationalize how surface structures affect microbial attachment to a solid surface.…”