Quality assessment of cellular and tissue-based products using liquid chromatography-tandem mass spectrometry.

We are currently conducting clinical research on cell sheets for cartilage regeneration. One issue with the future use of chondrocyte sheets as cellular and tissue-based products is quality assessment. Currently, chondrocyte sheets are evaluated using invasive methods that cannot be performed on every sheet produced. We report here on our liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique that allows the noninvasive assessment of every sheet using only 50 µl of culture medium. We found that LC-MS/MS could be used to confirm cell sheet viability through the measurement of glucose and glutamine uptake, to estimate extracellular matrix production by measuring serine consumption, to estimate cell kinetics by measuring cytidine and uracil concentrations, and to estimate melanoma inhibitory activity level by measuring pyridoxal concentration. LC-MS/MS may be useful for the noninvasive assessment of products to be used in regenerative medicine.

Biotemplated Synthesis of TiO2-Coated Gold Nanowire for Perovskite Solar Cells.

Fibrous nanomaterials have been widely employed toward the improvement of photovoltaic devices. Their light-trapping capabilities, owing to their unique structure, provide a direct pathway for carrier transport. This paper reports the improvement of perovskite solar cell (PSC) performance by a well-dispersed TiO2-coated gold nanowire (GNW) in a TiO2 cell layer. We used an artificially designed cage-shaped protein to synthesize a TiO2-coated GNW in aqueous solution under atmospheric pressure. The artificially cage-shaped protein with gold-binding peptides and titanium-compound-biomineralizing peptides can bind GNWs and selectively deposit a thin TiO2 layer on the gold surface. The TiO2-coated GNW incorporated in the photoelectrodes of PSCs increased the external quantum efficiency within the range of 350-750 nm and decreased the internal resistance by 12%. The efficient collection of photogenerated electrons by the nanowires boosted the power conversion efficiency by 33% compared to a typical mesoporous-TiO2-nanoparticle-only electrode.

Thermo-stable carbon nanotube-TiO2 nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process.

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.