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Using the soft lithographic technique, microcontact printing, we demonstrate an example of how a biocompatible polymer can be easily patterned upon another polymer substrate, creating a surface with two spatially different properties. A poly(dimethylsiloxane) mold allowed the patterning of a negative replica of an E-PROM microchip, forming a spatially defined pattern with a period of approximately 1 μm. The amphiphilic biocompatible polymer, poly(lactic acid)−poly(ethylene glycol) (PLA−PEG), was used as the “ink” in order to block off areas of a hydrophobic, polystyrene (PS) substrate. This created a surface with two properties: 2−3 μm strips of PLA−PEG polymer, which resists protein adsorption, divided by micrometer strips of PS. The ability of the patterning technique to provide a true heterogeneous surface was analyzed using atomic force microscopy, while fluorescence microscopy provided a high-contrast method by which to trace the position of specific molecules. We believe this technique to be an ele...

A scanning probe microscope employing a shear force feedback mechanism as used in most near-field scanning optical microscopes has been utilized to provide phase images of a patterned protein boundary. The microscope employed a dithering fiber optic tip and tuning fork method of tip-sample distance control. The effect of tip vibration amplitude upon the phase contrast is investigated, and possible contrast mechanisms are discussed.

We have used albumin-modified atomic force microscope (AFM) tips to probe interactions with a range of hydrophilic polymer brush surfaces and protein. Copolymers of poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) (PEO−PPO−PEO) (Pluronics) adsorbed onto polymer interfaces have been shown in previous studies to modify adsorption properties of blood components [using surface plasmon resonance (SPR) and AFM]. Here we have employed protein-coated AFM probes to study a series of PEO−PPO−PEO-coated interfaces prepared with a range of PEO and PPO molecular weights. Subsequent force−distance experiments have shown a good correlation between the forces of adhesion of an albumin-functionalized AFM probe with the various PEO−PPO−PEO surfaces and the adsorption trends of albumin onto these polymeric surfaces observed with SPR. The data suggest that the size of the hydrophobic PPO segment of the Pluronic is a major determinant of the polymer protein resistance properties. In addition, as the PEO layer d...

The effect of power ultrasound in the modification of voltammetric processes is investigated and the role of surface activation by means of electrode erosion/roughening characterized. The potential benefits of sonovoltammetry are illustrated with two examples. First, the Fladè potential for the passivation of nickel in air-saturated aqueous KOH solution is shown to be anodically shifted in the presence of ultrasound. Second, the voltammetric study of Cr(CO)6 in acetonitrile solution is shown to be feasible without the passivation observed under silent conditions where the electrolysis results in surface-active species the adsorption of which block further electron transfer. © 1994 American Chemical Society.