Chemistries for Interfaces between Neurons and Artificial Su bstrates: Interpretations and Applications A neuron is an electrically excitable cell that processes and transmits information by electrical chemical s...
숙명여자대학교 기능성 에너지 전달 나노 시스템 실험실 Home ｜ Login ｜ Join What is the Nano-Bio? Chemistries for Interfaces between Neurons and Artificial Su bstrates: Interpretations and Applications A neuron is an electrically excitable cell that processes and transmits information by electrical chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form neural networks. A growth cone is a dynamic, actin-supported extension of a developing axon seeking its synaptic target. The dynamic stability of filopodia and lamellipodia allows neuronal cells to recognize the surrounding environments at the nanometer scale and to subsequently modify their cytoskeletal structures in response to stimuli/cues. Stages (1-5) of development of hippocampal neurons in vitro. Axon fate determination occurs between stage 2 and 3. BioEssays, 2000, 22, 172-179 Neuron - Topography Silica nanobead arrays In Group-I, Most of neurons had either lamellopodia or short minor neurites. In Group-ll, More than 80% neurons had neurites at 1DIV, and the length of the neurites was significantly longer than that of Group-I neurons. Neurons sprouted neurites faster, and the polarization process was also accelerated on the substrates with beads larger than 200 nm, filopodial size, in diameter. Angew. Chem. Int. Ed., 2012, 51, 2855 - 2858 Transfection Vertical Si Nanowire Vertical Si NW substrates ocan be prepared by either growing the NWs epitaxially from a silicon wafer using chemical vapor deposition (CVD) or reactive ion etching (RIE) them from a wafer using standard semiconductor techniques . The densities, diameters, and heights of the NWs can be precisely controlled by varying the processing parameters. Nanowire surface modification By altering the NW surface chemistry using a variety of alkoxysilane treatments, different tethering chemistries can be achieved. -NH2 for amide formation (e.g. succinimidyl esters) or "electrostatic" binding (e.g., nucleic acids, carboxylated quantum dots)-SH for reactions with maleimides and iodoacetamides, or disulfide formation Nanowire internalization Schematic renderings of cells (Pink) on Si NWs (Green) at early and late stages of penetration, respectively. At 15 min after plating, most of the cells were resting on top of the Si. By 1 h after plating, however, most of those cells were impaled by the NWs. Delivering biomolecules PNAS, 2010, 107, 1870-1875
Direct access to the cells' interiors enables NWs to efficiently deliver a broad range of exogenous materials into multiple cell types, without the need for chemical or viral packaging protocols required by other methods. Left images show immortalized (HeLa) and primary cells (human fibroblasts, rat neural progenitor cells (NPCs), and rat hippocampal neurons) expressing fluorescent proteins encoded by plasmid DNAs that were administered using Si NWs, whereas right images demonstrate the delivery of various biomolecules (siRNAs, peptides, DNAs,and proteins). Axon Guidance Growth cone Model of growth cone-mediated axon guidance. From left to right, this model describes how the cytoskeleton responds and reorganizes to grow towards a positive stimulus (+) detected by receptors in the growth cone or away from a negative stimulus (-). Chemical Cue Topological Cue Typical image of a patterned neuronal network at DIV 7. Cell bodies adhere to the node points of the grid and connect along the pathways defined by the micropattern.
Pattern : Poly-D-lysine Background : Polystyrene Three cells attaching to the node points of the grid pattern in the process of forming an interconnected network. S: Somata/A: Axon/D: Dendrite/G: Growth cone Row: 10 μm, oriented 30o Periodicity① Parallel: 8.7 μm② Perpendicular: 15 μm Length: 4μm Diameter: 75 nm Axonal outgrowth on rectifying nanowire patterns (ganglion mounted to the right). Three-dimensional reconstructions of β-tubulin-labeled axons in the nanowire tracks. Scanning electron micrographs of sympathetic nerve Sfibers on rectifying nanowire patterns. Langmuir, 2009, 25(8),4343–4346 Biomaterials, 26 (2005), 2549–2557