Nanotechnology was defined by the National Nanotechnology Initiative as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). At this scale, commonly known as the nanoscale, surface area and quantum mechanical effects become important in describing properties of matter. The definition of nanotechnology is inclusive of all types of research and technologies that deal with these special properties. It is therefore common to see the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to the broad range of research and applications whose common trait is size. An earlier description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology.
Nanomedicine is the medical application of nanotechnology. Nanomedicine ranges from the medical applications of nanomaterials and biological devices, to nanoelectronic biosensors, and even possible future applications of molecular nanotechnology such as biological machines. Current problems for nanomedicine involve understanding the issues related to toxicity and environmental impact of nanoscale materials.
Quantum dots (QDs) or semiconductor nanocrystals are semiconductor particles a few nanometres in size with optical and electronic properties that differ from those of larger particles via quantum mechanical effects. They are a central topic in nanotechnology and materials science. When a quantum dot is illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band. The excited electron can drop back into the valence band releasing its energy as light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the conductance band and the valence band, or the transition between discrete energy states when the band structure is no longer well-defined in QDs.
Nanosensors are nanoscale devices that measure physical quantities and convert these to signals that can be detected and analyzed. There are several ways proposed today to make nanosensors; these include top-down lithography, bottom-up assembly, and molecular self-assembly. There are different types of nanosensors in the market and in development for various applications, most notably in defense, environmental, and healthcare industries. These sensors share the same basic workflow: a selective binding of an analyte, signal generation from the interaction of the nanosensor with the bio-element, and processing of the signal into useful metrics.
Nanomaterials describe, in principle, materials of which a single unit is sized between 1 and 100 nm.
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
Armand Paul Alivisatos is an American chemist and academic administrator who has served as the 14th president of the University of Chicago since September 2021. He is a pioneer in nanomaterials development and an authority on the fabrication of nanocrystals and their use in biomedical and renewable energy applications. He was ranked fifth among the world's top 100 chemists for the period 2000–2010 in the list released by Thomson Reuters.
Cadmium selenide is an inorganic compound with the formula CdSe. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. It is a pigment, but applications are declining because of environmental concerns.
Nanochemistry is an emerging sub-discipline of the chemical and material sciences that deals with the development of new methods for creating nanoscale materials. The term "nanochemistry" was first used by Ozin in 1992 as 'the uses of chemical synthesis to reproducibly afford nanomaterials from the atom "up", contrary to the nanoengineering and nanophysics approach that operates from the bulk "down"'. Nanochemistry focuses on solid-state chemistry that emphasizes synthesis of building blocks that are dependent on size, surface, shape, and defect properties, rather than the actual production of matter. Atomic and molecular properties mainly deal with the degrees of freedom of atoms in the periodic table. However, nanochemistry introduced other degrees of freedom that controls material's behaviors by transformation into solutions. Nanoscale objects exhibit novel material properties, largely as a consequence of their finite small size. Several chemical modifications on nanometer-scaled structures approve size dependent effects.
The following outline is provided as an overview of and topical guide to nanotechnology:
Core–shell semiconducting nanocrystals (CSSNCs) are a class of materials which have properties intermediate between those of small, individual molecules and those of bulk, crystalline semiconductors. They are unique because of their easily modular properties, which are a result of their size. These nanocrystals are composed of a quantum dot semiconducting core material and a shell of a distinct semiconducting material. The core and the shell are typically composed of type II–VI, IV–VI, and III–V semiconductors, with configurations such as CdS/ZnS, CdSe/ZnS, CdSe/CdS, and InAs/CdSe Organically passivated quantum dots have low fluorescence quantum yield due to surface related trap states. CSSNCs address this problem because the shell increases quantum yield by passivating the surface trap states. In addition, the shell provides protection against environmental changes, photo-oxidative degradation, and provides another route for modularity. Precise control of the size, shape, and composition of both the core and the shell enable the emission wavelength to be tuned over a wider range of wavelengths than with either individual semiconductor. These materials have found applications in biological systems and optics.
Professor Warren Chan is a full professor at the Institute of Biomedical Engineering and Terrence Donnelly Centre for Cellular and Biomolecular Research at the University of Toronto. He received his B.S. and PhD degree, and post-doctoral training from the University of Illinois, Indiana University, and University of California, San Diego.
Quantum dots (QDs) are semiconductor nanoparticles with a size less than 10 nm. They exhibited size-dependent properties especially in the optical absorption and the photoluminescence (PL). Typically, the fluorescence emission peak of the QDs can be tuned by changing their diameters. So far, QDs were consisted of different group elements such as CdTe, CdSe, CdS in the II-VI category, InP or InAs in the III-V category, CuInS2 or AgInS2 in the I–III–VI2 category, and PbSe/PbS in the IV-VI category. These QDs are promising candidates as fluorescent labels in various biological applications such as bioimaging, biosensing and drug delivery.
Serena Corr is a chair in Functional Materials and Professor in Chemical and Biological Engineering at the University of Sheffield. She works on next-generation battery materials and advanced characterisation techniques for nanomaterials.
Sara E. Skrabalak is a James H. Rudy Professor at Indiana University. Skrabalak leads a research group in the department of chemistry which focuses on the development of new nanomaterials. She has an adjunct appointment in the department of intelligent systems engineering.
Sandra J. Rosenthal is the Jack and Pamela Egan Professor of Chemistry, professor of physics and astronomy, pharmacology, chemical and biomolecular engineering, and materials science at Vanderbilt University. She is a joint faculty member at Oak Ridge National Laboratory in the Materials Science and Technology Division and the director of the Vanderbilt Institute of Nanoscale Science and Engineering.
Emily A. Weiss is the Mark and Nancy Ratner Professor of Chemistry and director of the Photo-Sciences Research Center at Northwestern University. Her research considers the optical and electronic properties of nanostructures, including hybrid organic–inorganic quantum dots. She was a two-time finalist in the Blavatnik Awards for Young Scientists.
Silicon quantum dots are metal-free biologically compatible quantum dots with photoluminescence emission maxima that are tunable through the visible to near-infrared spectral regions. These quantum dots have unique properties arising from their indirect band gap, including long-lived luminescent excited-states and large Stokes shifts. A variety of disproportionation, pyrolysis, and solution protocols have been used to prepare silicon quantum dots, however it is important to note that some solution-based protocols for preparing luminescent silicon quantum dots actually yield carbon quantum dots instead of the reported silicon. The unique properties of silicon quantum dots lend themselves to an array of potential applications: biological imaging, luminescent solar concentrators, light emitting diodes, sensors, and lithium-ion battery anodes.
Teresa Pellegrino is an Italian chemist who is Professor of Chemistry at the Istituto Italiano di Tecnologia. Her research considers nanomaterials for biomedical applications. She was appointed Associate Editor of Nanoscale in 2022.
Rebekah Anna Drezek is an American bioengineer and Professor of Bioengineering, Electrical and Computer Engineering at Rice University. Her research uses optical molecular imaging for in vivo assessment of biological tissue. She is a Fellow of the American Institute for Medical and Biological Engineering and was awarded the 2009 Optica Adolph Lomb Medal.
