Engineering of new microsystems for the study of biological phenomena

Our understanding of biological processes has the potential to be vastly increased by the development of appropriate microscale tools. Current approaches to microfabrication in biology have primarily focused on the enhancement of existing techniques and technologies by the scale-down and integration of conventional instruments. An alternative approach is to identify phenomena that are inherent to the microscale and exploit these phenomena to perform tasks in a manner that is not possible at a conventional laboratory scale. In this thesis, we utilize the latter approach to address two specific challenges: (1) the measurement of enzyme kinetics in microreactors and (2) the investigation of the effects of subcellular protein organization on cellular behavior.; We describe a new technique—microscale steady-state kinetic analysis (μSKA)—that enables the rapid and parallel analysis of enzyme kinetics. Rather than physically defining a microscopic reactor through microfabrication, we show how the relative rates of reaction and transport in a macroscopic flow chamber, where the enzyme is immobilized on one wall of the chamber, results in the confinement of an enzyme-catalyzed reaction to a microscopic reactor volume adjacent to this volume. This technique provides a rapid and simple method for determining enzyme kinetics using small amounts of sample material and may be useful for applications in proteomics, drug discovery, biocatalyst development and clinical diagnostics.; We describe a simple method for controlling the organization of proteins on surfaces using two-dimensional arrays of micron-sized colloidal particles. The applicability of this approach to the promotion of fibroblast cell adhesion and spreading is demonstrated using particles coated with the cell adhesion protein fibronectin. Behavior of adherent cells varied with particle density. This method provides a general strategy for controlling the organization of functional proteins at surfaces on three length scales: the size of individual colloidal particles, the spacing between particles and the organization of particles in patterned arrays. We believe the strategy described here will open new opportunities for controlling the behavior of cells by controlling the size and spacing of adhesive sites. It will also be useful in mediating interactions with and improving biocompatibility of synthetic materials.