No abstract

Both curiosity and a desire for efficiency have advanced our ability to manipulate materials with great precision on the micrometer and, more recently, on the nanometer scale. Certainly, the semiconductor and integrated circuit industry has put the pressure on scientist and engineers to develop better and faster nanofabrication techniques. Furthermore, our curiosity as to how life works, and how it can be improved from a medical perspective, stands to gain a great deal from advances in nanotechnology. Novel nanofabrication techniques are opening up the possibilities for mimicking the inherently nano-world of the cell, i.e., the nanotopographies of the extracellular matrix (ECM) and the nanochemistry presented on both the cell membrane and the ECM. In addition, biosensing applications that rely on fabrication of high-density, precision arrays, e.g., DNA or gene chips and protein arrays, will gain significantly in efficiency and, thus, in usefulness once it becomes possible to fabricate heterogeneous nanoarrays. Clearly, continued advances in nanotechnology are desired and required for advances in biotechnology. In this review, we describe the leading techniques for generating nanopatterns with biological function including parallel techniques such as extreme ultraviolet interference lithography (EUV-IL), soft-lithographic techniques (e.g., replica molding (RM) and microcontact printing (muCP)), nanoimprint lithography (NIL), nanosphere lithography (NSL) (e.g., colloid lithography or colloidal block-copolymer micelle lithography) and the nanostencil technique, in addition to direct-writing techniques including e-beam lithography (EBL), focused ion-beam lithography (FIBL) and dip-pen nanolithography (DPN). Details on how the patterns are generated, how biological function is imparted to the nanopatterns, and examples of how these surfaces can and are being used for biological applications will be presented. This review further illustrates the rapid pace by which advances are being made in the field of nanobiotechnology, owing to an increasing number of research endeavors, for an ever increasing number of applications.

We present a novel approach for the fabrication of tailored nanomorphology gradients on metal oxide surfaces. We first show the direct formation of a nanocolloidal density gradient by a dip-coating process. The obtained silica nanoparticle gradients are then subjected to a heat treatment. Control of this sintering step allows the precise tailoring of the particle morphology on the surface. Both these processes together provide a new tool to form precise, tunable, and material-independent nanomorphology gradients.

Pure and CoO1–x‐doped Ce0.8Gd0.2O1.9 (CGO) have been analyzed with constant heating rate dilatometry. Doping changes the grain boundary structure of CGO resulting in enhanced mass transport and in increased densification rates. Significant changes in activation energies have been detected. While pure CGO exhibits a significant amount of surface diffusion, cobalt oxide doping enhances grain boundary diffusion. The obtained activation energies are 4.70±0.32 eV for CGO and 6.24±0.32 eV for CoO1−x‐doped CGO. The higher activation energy of CoO1−x‐doped CGO is a result of the formation of intergranular films. It is suggested that sintering of CoO1−x‐doped CGO occurs by rearrangement and grain boundary diffusion whereas grain boundary and volume diffusion govern the densification of pure CGO.