Structural and adhesion properties of surfaces functionalized with polyelectrolytes and polystyrene particles

Surfaces functionalized with polystyrene particles and polyelectrolytes were used to investigate the morphological and adhesion properties of composite substrates. Atomic force microscopy (AFM) studies showed that surfaces with non-homogeneous topography have non-homogeneous adhesion properties. In addition, the homogeneity of the adhesion properties is dependent upon the chemical species used to functionalize the surface. Force volume (FV) imaging was utilized to map the adhesion of the fabricated substrates with high-resolution. The FV studies revealed that the hydrophobicity of the surface is not uniform despite the fact that the surface was functionalized with the same polyelectrolyte. The analysis methodology we report here opens the possibility to design better surfaces for future tissue engineering applications.     

Direct patterning of silanized-biomolecules on semiconductor surfaces

A novel approach to pattern silanized-biomolecules directly onto glass (SiO(x)) substrates via Dip-Pen nanolithography (DPN) and microcontact printing (μCP) is presented. Subsequent hybridization reactions of DPN patterned silanized-DNA with its complementary strands provide "proof-of-concept" that the patterned oligonucleotides maintain their biological activities. The fabrication strategy does not require premodification of substrates and offers a cheap and robust way to immobilize molecules on electronically important semiconductor surfaces.     

Attachment of motile bacterial cells to prealigned holed microarrays

Construction of biomotors is an exciting area of scientific research that holds great promise for the development of new technologies with broad potential applications in areas such as the energy industry and medicine. Herein, we demonstrate the fabrication of prealigned microarrays of motile Escherichia coli bacterial cells on SiOx substrates. To prepare these arrays, holed surfaces with a gold layer on the bottom of the holes were utilized. The attachment of bacteria to the holes was achieved via nonspecific interactions using poly-l-lysine hydrobromide (PLL). Our data suggest that a single motile bacterial cell can be selectively attached to an individual hole on a surface and bacterial cell binding can be controlled by altering the pH, with the greatest occupancy occurring at pH 7.8. Cells attached to hole arrays remained motile for at least 4 h. These data indicate that holed surface structures provide a promising footprint for the attachment of motile bacterial cells to form high-density site-specific functional bacterial microarrays.