Construction of RNA–Quantum Dot Chimera for Nanoscale Resistive Biomemory Application

RNA nanotechnology offers advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA–QD (quantum dot) chimera for resistive biomolecular memory application. Each QD holds two copies of the pRNA three-way junction (pRNA-3WJ) of the bacteriophage phi29 DNA packaging motor. The fixed quantity of two RNAs per QD was achieved by immobilizing the pRNA-3WJ with a Sephadex aptamer for resin binding. Two thiolated pRNA-3WJ serve as two feet of the chimera that stand on the gold plate. The RNA nanostructure served as both an insulator and a mediator to provide defined distance between the QD and gold. Immobilization of the chimera nanoparticle was confirmed with scanning tunneling microscopy. As revealed by scanning tunneling spectroscopy, the conjugated pRNA-3WJ–QD chimera exhibited an excellent electrical bistability signal for biomolecular memory function, demonstrating great potential for the development of resistive biomolecular memory and a nano-bio-inspired electronic device for information processing and computing

Electrically Controlled Delivery of Cargo into Single Human Neural Stem Cell

Nanoprobe-based techniques have emerged as an efficient tool for the manipulation and analysis of single cells. Here, we report a powerful whole-electrical single-cell manipulation tool that enables rapid and controllable delivery of cargo into single neural stem cells with precision monitoring of the cell penetration process using a conductive nanoprobe. The highly electrically sensitive nanoprobes that were fabricated and the indium tin oxide electrode-integrated cell chip were found to be very effective for monitoring the cell penetration process via current changes that appear as spike-like negative currents. Moreover, the assembly of cargoes onto the nanoprobes was controllable and could reach its maximum load in a very short period of time (<10 min) based on the same electrical system that was used for monitoring cell penetration and without the need for any complex chemical linkers or mediators. Even more remarkably, the cargo assembled on the surface of the nanoprobe was successfully released in a very short period of time (<10 s), regardless of the surrounding intracellular or extracellular environments. The monitoring of cell penetration, assembly of quantum dots (QDs), and release of QDs into the intracellular environment were all accomplished using our whole-electrical system that combined a conductive nanoprobe with cell chip technology. This is a novel technology, which can eliminate complex and time-consuming steps owing to chemical modifications, as well as reduce the time needed for the delivery of cargo into the cell cytosol/nucleus during cell penetration, which is very important for reducing cell damage

Synthesis of 3D Silver-Graphene-Titanium Dioxide Composite via Aerosol Spray Pyrolysis for Sensitive Glucose Biosensor

<div><p>A sensitive glucose biosensor was developed based on the adsorption of glucose oxidase by a three-dimensional silver-graphene-titanium dioxide (3D Ag-GR-TiO₂) composite electrode. Aerosol spray pyrolysis was employed to synthesize the 3D Ag-GR-TiO₂ composite using a colloidal mixture of a silver acetate precursor (C₂H₃AgO₂), graphene oxide, and TiO₂ nanoparticles. The effects of the operating temperature, gas flowrate, and TiO₂ concentration on the particle properties were investigated. The particle morphology of all 3D Ag-GR-TiO₂ composites was spherical in shape. The average sizes of composites could be controlled from 0.45 to 0.64 μm with the variation of process variables. Ag nanoparticles less than 10 nm in diameter were deposited on the surfaces of the TiO₂ nanoparticles and GR after a reduction process. The characteristics of the glucose biosensor fabricated with the as-prepared 3D Ag-GR-TiO₂ composite were assessed through cyclic voltammetry measurements. The biosensor exhibited a high current flow as well as clear redox peaks, resulting in a superior ability of the catalyst in terms of the electrochemical reactions. The highest sensitivity of glucose biosensor was obtained by 3D Ag-GR-TiO₂ composite, which was 12.2 μA/mM·cm², among 3D Ag-GR-TiO₂, 3D Ag-GR, and 3D GR-TiO₂ composites.</p><p>Copyright 2015 American Association for Aerosol Research</p></div