Low-Temperature Vapor-Phase Synthesis of Single-Crystalline Gold Nanostructures: Toward Exceptional Electrocatalytic Activity for Methanol Oxidation Reaction.

Au nanostructures (Au NSs) have been considered promising materials for applications in fuel cell catalysis, electrochemistry, and plasmonics. For the fabrication of high-performance Au NS-based electronic or electrochemical devices, Au NSs should have clean surfaces and be directly supported on a substrate without any mediating molecules. Herein, we report the vapor-phase synthesis of Au NSs on a fluorine-doped tin oxide (FTO) substrate at 120 °C and their application to the electrocatalytic methanol oxidation reaction (MOR). By employing AuCl as a precursor, the synthesis temperature for Au NSs was reduced to under 200 °C, enabling the direct synthesis of Au NSs on an FTO substrate in the vapor phase. Considering that previously reported vapor-phase synthesis of Au NSs requires a high temperature over 1000 °C, this proposed synthetic method is remarkably simple and practical. Moreover, we could selectively synthesize Au nanoparticles (NPs) and nanoplates by adjusting the location of the substrate, and the size of the Au NPs was controllable by changing the reaction temperature. The synthesized Au NSs are a single-crystalline material with clean surfaces that achieved a high methanol oxidation current density of 14.65 mA/cm² when intimately supported by an FTO substrate. We anticipate that this novel synthetic method can widen the applicability of vapor-phase synthesized Au NSs for electronic and electrochemical devices.

Successful genetic modification of porcine spermatogonial stem cells via an electrically responsive Au nanowire injector.

Transgenic pigs are quite useful in many biomedical fields, such as xenotransplantation research and the production of biopharmaceutical materials. The genetic transformation of porcine spermatogonial stem cells (pSSCs) followed by differentiation into mature spermatozoa enables the effective production of transgenic pigs. Improving the transfection efficiency of pSSCs, however, has been much desired. Herein, we report the efficient genetic modification of pSSCs by using an electrically responsive Au nanowire injector (E-R Au NWI). This is the first study that shows an exogenous gene is directly delivered into the nucleus of a pSSC by using a 1-dimensional nanomaterial and then successfully expressed to produce a protein. The E-R Au NWI interfaced noninvasively with the nucleus of the pSSC, and the pEGFP-N1 plasmid was delivered by the application of an electrical stimulus without cell damage. Compared to the results of conventional nonviral vector-based gene delivery methods such as jetPEI, Lipofectamine, and electroporation, the E-R Au NWI-based method improved the pSSC transfection efficiency by at least 6.7-fold and even up to 46.7-fold. Furthermore, we successfully obtained transgenic pSSCs containing the human bone morphogenetic protein 2 gene by using E-R Au NWIs. This result suggests that the E-R Au NWI enables the efficient genetic modification of pSSCs and can be employed to produce diverse kinds of transgenic pigs.

Development of Au nanowire injector system to deliver plasmid into mouse embryo.

In this data article, we developed a Au nanowire injector (Au NWI) for directly delivering plasmid into the 1-cell stage of the mouse embryos designed to successfully attach and detach the plasmid on the Au NWI, highly minimizing physical and chemical damage on the embryos. This data presents that a Au NWI system does not induce detrimental damages on development of embryos and efficiently express the green fluorescence protein in vitro. The data provided herein is in association with the research article related to reduce the occurrence of mosaicism by a Au NWI," Suppressing Mosaicism by Au Nanowire Injector-driven Direct Delivery of Plasmids into Mouse Embryos" (Park et al., 2017 [1]).

Suppressing mosaicism by Au nanowire injector-driven direct delivery of plasmids into mouse embryos.

Transgenic animals have become key tools in a variety of biomedical research areas. However, microinjection commonly used for producing transgenic animals has several challenges such as physical and chemical damage to the embryos due to microinjector with buffer, and low transgene integration rates with frequent mosaicism. Here, we report direct delivery of plasmids into mouse embryos using a Au nanowire injector (NWI) that significantly improved transgene integration efficiency and suppressed mosaicism. The Au NWI could deliver plasmid into the pronucleus (PN) of a mouse zygote without buffer and rapidly release it with electric pulse. Because zygote, which is a fertilized 1-cell stage embryo, has two physical barriers (cytoplasmic membrane and zona pellucida), direct delivery of plasmids into PN of zygote is more difficult than into a normal cell type. To penetrate the two physical barriers with minimal disruption of the embryo, we optimized the diameter and length of Au NWI. The mosaicism is more reduced in the Au NWI injected embryos than in micropipette injected embryos, which was determined by the expression of transgene in a blastocyst stage. We suggest that Au NWI can increase the efficiency of gene delivery into zygote with suppressed mosaicism and become a useful alternative.