Foundations

A nanoscience glossary

Nanoscience borrows vocabulary from physics, chemistry, biology and engineering, and a single paper may use all four. The short entries below define the terms that recur most often in the literature and on these pages. Each points to the page where the idea is explained more fully.

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Entries are listed alphabetically; abbreviations follow the full term in brackets.

Abstract: The short summary at the start of a research paper, meant to let a reader judge its purpose and findings quickly. See Finding and reading papers.
Aspect ratio: The ratio of an object's length to its width; nanowires and nanotubes often have very high aspect ratios. See Molecular electronics and nanowires.
Atomic force microscope (AFM): A probe microscope that feels a surface with a sharp tip on a flexible cantilever and records the bending; it works on insulators and in liquids. See Seeing and touching atoms.
Bottom-up fabrication: Making structures by letting molecules or particles arrange themselves, rather than by carving material away. See Self-assembly.
Buckminsterfullerene (C60): A closed cage of sixty carbon atoms arranged in twelve pentagons and twenty hexagons, identified in 1985. See Fullerenes and C60.
Carbon nanotube: A seamless cylinder of carbon atoms, pictured as a rolled sheet of graphene, with a diameter of the order of a nanometre. See Carbon nanotubes.
Catenane: A molecule made of interlocked rings joined mechanically, like the links of a chain, rather than by a chemical bond. See Molecular machines.
Chirality (of a nanotube): The angle at which the graphene sheet is imagined to be rolled; it helps decide whether a tube conducts like a metal or a semiconductor. See Carbon nanotubes.
Colloid: A mixture in which tiny particles stay dispersed in a liquid without settling or dissolving. See Metal nanoparticles.
Colloidal gold: A suspension of gold nanoparticles, typically red for small spheres and bluish for larger or rod-shaped particles. See Metal nanoparticles.
Core–shell particle: A nanoparticle with a core of one material coated by a thin shell of another, often used to protect or tune the core. See Quantum dots.
Dendrimer: A highly branched, roughly spherical polymer molecule built outward from a central core in regular generations. See Nanomedicine.
Dip-pen nanolithography: A patterning method in which a probe tip deposits molecules onto a surface much as a pen deposits ink. See Nanofabrication.
DNA nanotechnology: The design of artificial structures and devices from DNA, using base pairing to decide which strands join. See DNA as a building material.
DNA origami: A method of folding a long single DNA strand into a chosen shape with the help of many short staple strands. See DNA as a building material.
DOI: Digital object identifier: a persistent identifier for a paper or other object that resolves to its current location. See Keeping up with new papers.
Electron-beam lithography: Drawing patterns directly in an electron-sensitive resist with a focused electron beam; precise but slow. See Nanofabrication.
Extracellular matrix: The network of protein fibres and other molecules that surrounds cells in tissues, a natural nanofibre scaffold. See Peptides at the nanoscale.
Field-effect transistor: A switch in which a voltage on a gate controls how many charge carriers flow through a channel. See Graphene.
Fullerene: Any closed cage molecule made entirely of carbon, usually of five- and six-membered rings. See Fullerenes and C60.
Giant magnetoresistance (GMR): A large change in electrical resistance in stacked magnetic and non-magnetic metal layers when their magnetisations switch alignment. See Spintronics.
Graphene: A single sheet of carbon atoms in a hexagonal, honeycomb arrangement, one atom thick. See Graphene.
Half-life: The time for the concentration of a substance to fall to half its starting value; a general pharmacological concept. See Peptides at the nanoscale.
Hydrogel: A soft material in which a network of polymer or peptide chains holds a large amount of water. See Peptides at the nanoscale.
Ligand (surface): A molecule bound to the surface of a nanoparticle that keeps particles apart and controls their chemistry. See Quantum dots.
Liposome: A small artificial vesicle enclosed by at least one lipid bilayer, resembling a cell membrane. See Nanomedicine.
Lithography: The family of methods that transfer a pattern onto a surface through a sensitive layer, exposure and etching. See Nanofabrication.
Localised surface plasmon resonance: A collective oscillation of electrons in a metal nanoparticle driven by light, responsible for its strong colour. See Metal nanoparticles.
Molecular electronics: The use of single molecules or small groups of molecules as electronic components. See Molecular electronics.
Molecular machine: A molecule or assembly of molecules designed to produce controlled movement in response to a stimulus. See Molecular machines.
Molecular nanotechnology: The older, narrower vision of building products atom by atom with molecular assemblers. See Where the idea came from.
Multi-walled nanotube: A carbon nanotube made of several concentric tubes nested one inside another. See Carbon nanotubes.
Nanomaterial: A material with an external dimension, or internal or surface structure, in the range of roughly 1 to 100 nanometres. See What nanotechnology is.
Nanomedicine: The research field applying nanoscale materials and devices to questions in medicine and biology. See Nanomedicine.
Nanometre: One billionth of a metre, a length spanning only a few atoms. See What nanotechnology is.
Nanopore: A hole a few nanometres wide in a membrane, used to detect single molecules as they pass through. See Molecular machines and nanopores.
Nanotoxicology: The study of how nanomaterials interact with living systems and the environment, and of their possible hazards. See Nanotoxicology.
Nanowire: A wire with a diameter of tens of nanometres or less and a much greater length. See Molecular electronics and nanowires.
National Nanotechnology Initiative (NNI): The United States framework that coordinates nanotechnology research across federal agencies, launched in 2000. See Policy and the NNI.
Peer review: Evaluation of a paper by experts in the same field before a journal decides to publish it. See Finding and reading papers.
Peptide: A short chain of amino acids joined by peptide bonds. See Peptides at the nanoscale.
Peptide amphiphile: A peptide joined to an oily tail, so that one end prefers water and the other avoids it; such molecules can assemble into fibres. See Peptides at the nanoscale.
Photolithography: Patterning a light-sensitive resist by shining light through a mask; the method used to make integrated circuits. See Nanofabrication.
Preprint: A version of a paper shared publicly before, or alongside, formal peer-reviewed publication. See Keeping up with new papers.
Protein corona: The layer of proteins and other biomolecules that coats a nanoparticle in a biological fluid. See Nanomedicine.
Proteolysis: The breakdown of proteins and peptides into smaller pieces, usually catalysed by enzymes called proteases. See Peptides at the nanoscale.
Quantum confinement: The squeezing of electron waves in a very small structure, which spaces out energy levels and makes properties depend on size. See Quantum dots.
Quantum dot: A semiconductor crystal a few nanometres across whose emitted colour depends on its size. See Quantum dots.
Rotaxane: A ring-shaped molecule threaded onto a molecular axle and held there mechanically. See Molecular machines.
Scanning electron microscope (SEM): An instrument that scans a focused electron beam across a surface and builds an image from the electrons it knocks out. See Electron microscopy.
Scanning tunnelling microscope (STM): A probe microscope that measures the tunnelling current between a sharp tip and a conducting surface, resolving individual atoms. See Seeing and touching atoms.
Self-assembly: The spontaneous organisation of components into ordered structures through their own local interactions. See Self-assembly.
Self-assembled monolayer: A single, ordered layer of molecules that forms by itself on a surface. See Self-assembly.
Single-walled nanotube: A carbon nanotube consisting of one rolled graphene layer, around a nanometre in diameter. See Carbon nanotubes.
Soft lithography: Patterning with stamps and moulds made from elastic polymers, for example by printing molecules onto a surface. See Nanofabrication.
Spintronics: Electronics that uses the spin of electrons as well as their charge. See Spintronics.
Surface-area-to-volume ratio: How much surface an object has for its volume; it rises steeply as objects shrink, which is why nanoparticles are dominated by their surfaces. See What nanotechnology is.
Transmission electron microscope (TEM): An instrument that passes electrons through a very thin sample to image its internal structure, down to columns of atoms. See Electron microscopy.

Terms not listed here are usually explained where they first appear on a page. For the journals in which these terms are used, see the journals of nanoscience.