William F. Heinz

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The spatial and temporal changes of the mechanical properties of living cells reflect complex underlying physiological processes. Following these changes should provide valuable insight into the biological importance of cellular mechanics and their regulation. The tip of an atomic force microscope (AFM) can be used to indent soft samples, and the force(More)
During development inherited information directs growth and specifies the complex spatial organization of cells and molecules. Here we show that a new information metric, the k-space information (kSI), captures the growth and emergence of spatial organization in a developing embryo. Using zebrafish as a model, we quantify the rate of development over the(More)
The spatial distribution of intermolecular forces governs macromolecular interactions. The atomic force microscope, a relatively new tool for investigating interaction forces between nanometer-scale objects, can be used to produce spatially resolved maps of the surface or material properties of a sample; these include charge density, adhesion and stiffness,(More)
An experimental approach for producing relative charge density maps of biological surfaces using the atomic force microscope is presented. This approach, called D minus D (D-D) mapping, uses isoforce surfaces collected at different salt concentrations to remove topography and isolate electrostatic contributions to the tip-sample interaction force. This(More)
The mechanical properties of the extracellular microenvironment regulate cell behavior, including migration, proliferation and morphogenesis. Although the elastic moduli of synthetic materials have been studied, little is known about the properties of naturally produced extracellular matrix. Here we have utilized atomic force microscopy to characterize the(More)
Controlling the organization of proteins on surfaces provides a powerful biochemical tool for determining how cells interpret the spatial distribution of local signaling molecules. Here, we describe a general high fidelity approach based on electron beam writing to pattern the functional properties of protein-coated surfaces at length scales ranging from(More)
During bacterial chemotaxis, a cell acquires information about its environment by sampling changes in the local concentration of a chemoattractant, and then uses that information to bias its motion relative to the source of the chemoattractant. The trajectory of a chemotaxing bacteria is thus a spatial manifestation of the information gathered by the cell.(More)
Protein micropatterned substrates have emerged as important tools for studying how cells interact with their environment, as well as allowing useful experimental control over, for example, cell shape and cell position on a surface. Here we present a new approach for protein micropatterning in which a focused laser is used to locally inactivate proteins on a(More)
The spatial relationships between molecules can be quantified in terms of information. In the case of membranes, the spatial organization of molecules in a bilayer is closely related to biophysically and biologically important properties. Here, we present an approach to computing spatial information based on Fourier coefficient distributions. The Fourier(More)
Microstructured polydimethylsiloxane (PDMS) is an important and widely used material in biology and chemistry. Here we report that micrometer- and nanometer-scale features can be introduced into the surface of PDMS in a process that is functionally equivalent to embossing. We show that surface features <50 nm can be replicated onto the surface of previously(More)