Paper BI-TuP17
Fabrication of Micro-Templates for the Control of Bacterial Immobilization

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Well-defined micro-patterns of bacteria are significant as a fundamental technique for biosensor arrays utilizing rapid detection of infectious diseases and toxic compounds. Many researchers have studied control methods to fabricate the micro-patterns. However, in these researches, many processes are required for the immobilization and the regioselectivity is not so good. In this study, we aim to fabricate well-defined micro-patterns of bacteria using two types of micro-patterned templates and to elucidate the adhesion behaviors of several bacteria onto the templates from viewpoint of surface topology and chemical properties. Super-hydrophobic/super-hydrophilic and super-hydrophobic/polyethylene glycol (PEG) micro-patterns were fabricated as the templates. In the case of super-hydrophobic/super-hydrophilic patterns, the difference of surface energy in the respective regions differs greatly. The difference could have a great effect on the adhesion of bacterial. In the case of super-hydrophobic/PEG micro-patterns, PEG surface generally avoid the adhesion of bacteria due to volume exclusion effect of PEG based on the structural fluctuation. Super-hydrophobic surface was prepared by microwave plasma enhanced chemical vapor deposition (MPECVD) from trimethylmethoxysilane (TMMOS). Super-hydrophobic/super-hydrophilic micro-patterns were fabricated by irradiating the super-hydrophobic surface with vacuum ultra violet (VUV) light through a stencil mask. In the case of Super-Hydrophobic/PEG micro-patterned surfaces, PEG surfaces were fabricated by reacting COOH groups of methoxypolyethylene glycol propionic acid with NH₂ groups of NH₂-terminated self assembled monolayer in ion-exchanged water. The super-hydrophobic regions were fabricated by MPECVD thorough a stencil mask. Bacteria were cultured on the respective templates in the incubator controlled under the CO₂ concentaration of 5 % at 37 ^oC. After culture, bacteria were observed by phase-contrast microscope. The surfaces were characterized by XPS and FT-IR. As a result, in the case of super-hydrophobic/super-hydrophilic micro-patterns, some bacteria (Escherichia coli, Bacillus subtilis) were adhered to only super-hydrophobic regions. But others bacteria (Pseudomonas stutzeri, Pseudomonas aeruginosa) were not separated well. Their results attribute bacterial charge, cell division rate and adhesion time lag between super-hydrophobic regions and super-hydrophilic regions.