Drop-on-demand inkjet printing is a fabrication technique that is capable of depositing materials layer-by-layer to form complex 3-dimensional (3-D) constructs. Here we present a new single drop delivery method in which both the matrix and cross-linker are present but separated through the use of vesicle packaging. Changing the printing parameters has little effect on the integrity of the calcium(II)-loaded vesicles, with calcium(II) released selectively by warming after printing. Alginate solutions containing calcium(II)-loaded vesicles were successfully printed and the printed layers were shown to gel on demand at 37 °C. The printed alginate layers were evaluated with regards to their potential to provide 3-D structures for cell culture.

Studies of hard biological materials such as marine shells, animal teeth, horns and bones have produced fascinating ideas for mimicking their micro/nanostructure in the lab. The nacre in the abalone shell has a well-defined organic/inorganic structure that has a fracture resistance that is much higher than the individual constituents. By using biocompatible materials we have fabricated zirconium nitride/ polymethylmethacrylate alternating layers that are based on the structure of nacre. A combination of DC-magnetron sputtering and pulsed laser deposition on (100) silicon substrates was used to fabricate multilayers in a single chamber without breaking the vacuum. The ZrN films showed nanocrystalline columnar growth on the silicon substrates or on the PMMA nanolayer. High resolution SEM analysis at the inorganic/organic interface revealed well formed, uniform thickness inorganic films which are separated by the polymeric layer (30-90 nm). The ratio of the ceramic/polymer is the same as in nacre. Nanoindentation hardness values of ˜ 20GPa were measured on both the ZrN single film, similar to published values, and the ZrN/PMMA composite layers and the elastic modulus remained constant, independent of the number of layers.

Over the past twenty years, the use of rapid prototyping techniques for processing of medical devices has seen rapid growth. A number of rapid prototyping techniques currently exist for producing a broad range of medical devices using metals, ceramics, polymers, and composite materials. One promising rapid prototyping technology for creating medical devices with small scale features is two photon polymerization; this scalable photopolymerization technique enables processing of photosensitive materials such as organically-modified ceramic materials. In this study, two photon polymerization was used to produce microneedles that mimic the anatomy of the mosquito fascicle. The labrum of the mosquito was replicated in the mosquito-like microneedle. On the other hand, the maxillae of the mosquito were not replicated in the mosquito-like microneedle; the absence of these features was attributed to inadequate mechanical support of the maxillae. This study suggests that two photon polymerization and other rapid prototyping technologies may be used to produce biomimetic drug delivery devices that imitate the intricate structures found in nature.

Two important goals in stem cell research are to control the cell proliferation without differentiation, and also to direct the differentiation into a specific cell lineage when desired. Recent studies indicate that the nanostructures substantially influence the stem cell behavior. It is well known that mesenchymal stem cells (MSCs) are multipotent stem cells that can differentiate into stromal lineages such as adipocyte, chondrocyte, fibroblast, myocyte, and osteoblast cell types. By examining the cellular behavior of MSCs cultured in vitro on nanostructures, some understanding of the effects that the nanostructures have on the stem cell’s response has been obtained. Here we demonstrate that TiO2 nanotubes produced by anodization on Ti implant surface can regulate human mesenchymal stem cell (hMSC) differentiation towards an osteoblast lineage in the absence of osteogenic inducing factors. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion at smaller diameter levels or a specific differentiation of hMSCs into osteoblasts using only the geometric cues. Small (˜30 nm diameter) nanotubes promoted adhesion without noticeable differentiation, while larger (˜70 - 100 nm diameter) nanotubes elicited a dramatic, ˜10 fold stem cell elongation, which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for novel orthopaedics-related hMSC treatments. The fact that a guided and preferential osteogenic differentiation of stem cells can be achieved using substrate nanotopography alone without using potentially toxic, differentiation-inducing chemical agents is significant, which can be useful for future development of novel and enhanced stem cell control and therapeutic implant development.