The control of cell adhesion and viability by zinc oxide nanorods.

The ability to control the behavior of cells that interact with implanted biomaterials is desirable for the success of implanted devices such as biosensors or drug delivery devices. There is a need to develop materials that can limit the adhesion and viability of cells on implanted biomaterials. In this study, we investigated the use of zinc oxide (ZnO) nanorods for modulating the adhesion and viability of NIH 3T3 fibroblasts, umbilical vein endothelial cells, and capillary endothelial cells. Cells adhered far less to ZnO nanorods than the corresponding ZnO flat substrate. The few cells that adhered to ZnO nanorods were rounded and not viable compared to the flat ZnO substrate. Cells were unable to assemble focal adhesions and stress fibers on nanorods. Scanning electron microscopy indicated that cells were not able to assemble lamellipodia on nanorods. Time-lapse imaging revealed that cells that initially adhered to nanorods were not able to spread. This suggests that it is the lack of initial spreading, rather than long-term exposure to ZnO that causes cell death. We conclude that ZnO nanorods are potentially useful as an adhesion-resistant biomaterial capable of reducing viability in anchorage-dependent cells.

Toward in situ biochemistry: combining chemical kinetics approaches with biomolecular imaging in living cells.

Our knowledge of protein-protein interactions comes primarily from experimentation with reconstituted proteins in dilute solutions. However, dilute solutions are poor approximations of the intracellular microenvironment, which contains exquisite and dynamic structure that is impossible to recreate inside test tubes. New approaches are needed that will allow the in situ characterization of protein-protein interactions inside living, intact cells. In this paper, we discuss recent efforts to measure the kinetics of protein binding within complexes inside living cells. While the experimental effort in these studies requires the confluence of techniques ranging from molecular imaging to cell and molecular biology, the experimental design and analysis requires a strong background in chemical kinetics and transport phenomena. Thus, we argue that chemical engineers can play a central role in furthering in situ approaches to cellular analysis. Such efforts may aid significantly in advancing quantitative knowledge of cellular signaling and physiology.