AVS 59th Annual International Symposium and Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP10
An Anti-biofilm Formation Design Strategy Based on Fibrous Topographical Cues

Tuesday, October 30, 2012, 6:00 pm, Room Central Hall

Session: Biomaterial Interfaces Poster Session
Presenter: M. Kargar, Virginia Tech
Authors: M. Kargar, Virginia Tech
A.S. Nain, Virginia Tech
B. Behkam, Virginia Tech
Correspondent: Click to Email
Biofilms tend to be significantly less responsive to antimicrobial stressors, compared with planktonic bacteria. Studies on the natural antifouling surfaces have shown that most of them have well organized micro/nanoscale surfaces features. This work aims at improving the current understanding of the effects of well-defined sub-micron surface topographies on microorganism-surface interactions with the ultimate goal of developing a bioinspired antifouling design framework based on topographical cues. To this end, model surfaces with well-defined surface topographies in form of highly aligned polystyrene nano fibers at controlled separation distances ( diameter (Df): 90 nm-900 nm and Separation distance (Sf): 0 nm-5000 nm) were fabricated using our previously developed pseudo-dry spinning method. Pseudomonas aeruginosa strain PAO1 (diameter (Db)≈ 500nm, length (Lb)≈ 1800nm) was then presented on the nanofibrous surfaces in a 2.5-hour static retention assay. Scanning electron microscopy was utilized to quantify linear attachment density (number of bacteria/fiber length) and the degree of alignment between bacteria and fibers for all combination of fiber diameters (Df < Db,Df ≈ Db, Df > Db) and spacing (Sf < Db,Sf ≈ Db, Db < Sf < Lb, Sf > Lb) at single cell level. Our experimental results demonstrate the presence of an optimum antifouling geometrical condition related to the minimum experimental adhesion density. This optimum condition occurs when the fiber diameter is close to the bacteria diameter (Df ≈ Db) and the spacing is less than the bacteria diameter (Sf < Db) ). Comparing to the bare surface this geometrical combination reduces bacterial adhesion by more than 40%. Additionally, the SEM images show that bacteria developed microcolonies (onset of biofilm formation) on the bare samples while the engineered surface inhibited colony formation. Our data reveal strong similarity between thermodynamic underpinnings of bacteria – surface interactions and vesicle– surface interactions. The thermodynamic principles governing the vesicle-rigid surface interactions were used to interpret the experimental data and explain the experimentally observed optimum antifouling topographical condition using an energy-based approach. Furthermore, a systematic design methodology for empirical determination of the optimum antifouling topographical condition for nanofiber textured surfaces is outlined.