Biomedical subjects

Nathan J Sniadecki

Publications and source records attributed to Nathan J Sniadecki.

4 recordsLinked to original sources

PubMed2006

Nanotechnology for cell-substrate interactions.

In the pursuit to understand the interaction between cells and their underlying substrates, the life sciences are beginning to incorporate micro- and nanotechnology-based tools to probe and measure cells. The development of these tools portends endless possibilities for new insights into the fundamental relationships between cells and their surrounding microenvironment that underlie the physiology of human tissue. Here, we review techniques and tools that have been used to study how a cell responds to the physical factors in its environment. We also discuss unanswered questions that could be addressed by these approaches to better elucidate the molecular processes and mechanical forces that dominate the interactions between cells and their physical scaffolds.

Animals↗

PubMed2005

Emergent patterns of growth controlled by multicellular form and mechanics.

Spatial patterns of cellular growth generate mechanical stresses that help to push, fold, expand, and deform tissues into their specific forms. Genetic factors are thought to specify patterns of growth and other behaviors to drive morphogenesis. Here, we show that tissue form itself can feed back to regulate patterns of proliferation. Using micro-fabrication to control the organization of sheets of cells, we demonstrated the emergence of stable patterns of proliferative foci. Regions of concentrated growth corresponded to regions of high tractional stress generated within the sheet, as predicted by a finite-element model of multicellular mechanics and measured directly by using a micromechanical force sensor array. Inhibiting actomyosin-based tension or cadherin-mediated connections between cells disrupted the spatial pattern of proliferation. These findings demonstrate the existence of patterns of mechanical forces that originate from the contraction of cells, emerge from their multicellular organization, and result in patterns of growth. Thus, tissue form is not only a consequence but also an active regulator of tissue growth.

Animals↗

PubMed2005

Shear force at the cell-matrix interface: enhanced analysis for microfabricated post array detectors.

The interplay of mechanical forces between the extracellular environment and the cytoskeleton drives development, repair, and senescence in many tissues. Quantitative definition of these forces is a vital step in understanding cellular mechanosensing. Microfabricated post array detectors (mPADs) provide direct measurements of cell-generated forces during cell adhesion to extracellular matrix. A new approach to mPAD post labeling, volumetric imaging, and an analysis of post bending mechanics determined that cells apply shear forces and not point moments at the matrix interface. In addition, these forces could be accurately resolved from post deflections by using images of post tops and bases. Image analysis tools were then developed to increase the precision and throughput of post centroid location. These studies resulted in an improved method of force measurement with broad applicability and concise execution using a fully automated force analysis system. The new method measures cell-generated forces with less than 5% error and less than 90 seconds of computational time. Using this approach, we demonstrated direct and distinct relationships between cellular traction force and spread cell surface area for fibroblasts, endothelial cells, epithelial cells and smooth muscle cells.

Actomyosin↗

PubMed2004

Induced pressure pumping in polymer microchannels via field-effect flow control.

Microfluidic field-effect flow control (FEFC) modifies the zeta potential of electroosmotic flow using a transverse electric field applied through the microchannel wall. Previously demonstrated in silicon-based and glass microsystems, FEFC is presented here as an elegant method for flow control in polymer-based microfluidics with a simple and low-cost fabrication process. In addition to direct FEFC flow modulation, independent transverse electric fields in connected microchannels are demonstrated to produce a differential pumping rate between the microchannels. The different electroosmotic pumping rates formed by local zeta potential control induce an internal pressure at the microchannel intersection, resulting in hydrodynamic pumping through an interconnecting field-free microchannel. Modulation of the voltages applied to the gate electrodes adjusts the magnitude and direction of the bidirectional pressure pumping, with fine resolution volume flow rates from -2 to 2 nL/min in the field-free microchannel demonstrated.

Journal Article↗