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This manuscript describes the fabrication of bacterial surface arrays by using photolithographic techniques having in addition some particularly interesting features. The methodology employed is based on the crosslinking and degradation processes occurring in polystyrene upon exposure to UV light. As a result of both processes, this approach produced different patterns depending not only on the mask but also depending on the experimental conditions employed. Patterns with nanoscale resolution were formed without the requirement of expensive fine focalization settings. More interestingly, the feasibility of this strategy to incorporate functional groups to modulate the affinity between the bacteria and the surface is demonstrated. In particular, hydrophilic segments, i.e. poly(acrylic acid) that favor the bacterial immobilization were introduced. The strategy employed allowed not only the incorporation of functional groups but also permits to fine tune the amount of hydrophilic functional groups. This unique feature has been used to determine the role of the surface hydrophilicity on the adhesion of Staphylococcus aureus (S. aureus) onto the different surface patterns. Finally, those surfaces in which both the photodegradation and photocrosslinking occurred produced thin patterns largely below the micrometer that have been employed to prepare arrays of isolated S. aureus bacteria. The formation of bacterial arrays of S. aureus on the single-cell level has been a challenge since they exhibit a large tendency to grow in clusters. This technology has a great potential for the isolation of single bacteria for diagnosis, and the study of bacteria populations at the single cell level.

Abstract:The generation of nano-microstructured surfaces is a current challenge in polymer science. The fabrication of such surfaces has been accomplished mainly following two different alternatives i.e., by adapting techniques, such as molding (embossing) or nano/microimprinting, or by developing novel techniques including laser ablation, soft lithography or laser scanning. Surface instabilities have been recently highlighted as a promising alternative to induce surface features. In particular, wrinkles have been extensively explored for this purpose. Herein, we describe the preparation of wrinkled interfaces by confining a photosensitive monomeric mixture composed of monofunctional monomer and a crosslinking agent within a substrate and a cover. The wrinkle characteristics can be controlled by the monomer mixture and the experimental conditions employed for the photopolymerization. More interestingly, incorporation within the material of a functional copolymer allowed us to vary the surface chemical composition while maintaining the surface structure. For that purpose we incorporated either a fluorinated copolymer that enhanced the surface hydrophobicity of the wrinkled interface or an acrylic acid containing copolymer OPEN ACCESSPolymers 2014, 6 2846 that increased the hydrophilicity of the wrinkled surface. Finally, the role of the hydrophobicity on the bacterial surface adhesion will be tested by using Staphylococcus aureus.