Thin Films and Interfaces
Many natural and synthetic biomaterials must perform well as thin films or in interfacial environments. Injected or implanted biomaterials form critically-important interfaces with surrounding cells, tissues and fluids; adhesive interactions can dictate the success or failure of surgical procedures; sensors and diagnostic devices operate primarily through interfacial interactions; and some of nature’s most intriguing materials systems (e.g. mineralized structures) are assembled through deposition and interfacing of multiple thin layers. Thus, if we are to succeed in our efforts to understand and design biomaterials systems, we must understand more thoroughly the behavior of thin films and interfaces.
New methods for imaging of surfaces, for scattering from surfaces, and for measurement of interfacial forces are providing important new insights into the roles of interfacial phenomena in determining biomaterials performance. Scanning probe microscopy, grazing incidence diffraction, and the surface forces apparatus allow us to interrogate surfaces and interfaces in new ways. Single-molecule spectroscopy and molecular force measurements now enable researchers to examine the behavior of individual molecules and cells tethered to surfaces, and traction-force microscopy is beginning to reveal the complex mechanisms and consequences of force exchange between cells and their surroundings.
We are also learning how to tailor surfaces and interfacial environments more effectively through improved methods of materials synthesis and processing. The topographic features and chemical functionality of surfaces can now be controlled on length scales of nanometers, and there is a growing appreciation of the importance of such control, both in fundamental studies of cell-material interaction and in efforts to engineer biomaterials for useful function.