Patterned iridium oxide film as neural electrode interface: Biocompatibility and improved neurite outgrowth with electrical stimulation.

Iridium (Ir) thin film was deposited on patterned titanium substrate by direct-current (DC) magnetron sputtering, and then activated in sulfuric acid (H2SO4) through repetitive potential sweeps to form iridium oxide (IrOx) as neural electrode interface. The resultant IrOx film showed a porous and open morphology with aligned microstructure, exhibited superior electrochemical performance and excellent stability. The IrOx film supported neural stem cells (NSCs) attachment, proliferation and improved processes without causing toxicity. The patterned IrOx films offered a unique system to investigate the synergistic effects of topographical cue and electrical stimulation on neurite outgrowth. Electrical stimulation, when applied through patterned IrOx films, was found to further increase the neurite extension of neuron-like cells and significantly reorient the neurite alignment towards to the direction of stimulation. These results indicate that IrOx film, as electrode-tissue interface is highly stable and biocompatible with excellent electrochemical properties.

Laminin functionalized biomimetic apatite to regulate the adhesion and proliferation behaviors of neural stem cells.

BACKGROUND: Functionalizing biomaterial substrates with biological signals shows promise in regulating neural stem cell (NSC) behaviors through mimicking cellular microenvironment. However, diverse methods for immobilizing biological molecules yields promising results but with many problems. Biomimetic apatite is an excellent carrier due to its non-toxicity, good biocompatibility, biodegradability, and favorable affinity to plenty of molecules. Therefore, it may provide a promising alternative in regulating NSC behaviors. METHODS: Biomimetic apatite immobilized with the extracellular protein - laminin (LN) was prepared through coprecipitation process in modified Dulbecco's phosphate-buffered saline (DPBS) containing LN. The amount of coprecipitated LN and their release kinetics were examined. The adhesion and proliferation behaviors of NSC on biomimetic apatite immobilized with LN were investigated. RESULTS: The coprecipitation approach provided well retention of LN within biomimetic apatite up to 28 days, and supported the adhesion and proliferation of NSCs without cytotoxicity. For long-term cultivation, NSCs formed neurosphere-like aggregates on non-functionalized biomimetic apatite. A monolayer of proliferated NSCs on biomimetic apatite with coprecipitated LN was observed and even more stable than the positive control of LN coated tissue-culture treated polystyrene (TCP). CONCLUSION: The simple and reproducible method of coprecipitation suggests that biomimetic apatite is an ideal carrier to functionalize materials with biological molecules for neural-related applications.