Editing Nanosensor (section)

== Characteristics ==
[[Nanomaterials]]-based sensors have several benefits in [[sensitivity and specificity]] over sensors made from traditional materials, due to nanomaterial features not present in bulk material that arise at the nanoscale.<ref>{{Cite journal|title=Nanomaterial Properties: Size and Shape Dependencies|last1=Guisbiers|first1=Grégory|last2=Mejía-Rosales|first2=Sergio|date=2012|journal=Journal of Nanomaterials|language=en|doi=10.1155/2012/180976|last3=Leonard Deepak|first3=Francis|volume=2012|pages=1–2|doi-access=free}}</ref><ref>{{Cite journal |last1=Prosa |first1=Mario |last2=Bolognesi |first2=Margherita |last3=Fornasari |first3=Lucia |last4=Grasso |first4=Gerardo |last5=Lopez-Sanchez |first5=Laura |last6=Marabelli |first6=Franco |last7=Toffanin |first7=Stefano |date=2020-03-07 |title=Nanostructured Organic/Hybrid Materials and Components in Miniaturized Optical and Chemical Sensors |journal=Nanomaterials |language=en |volume=10 |issue=3 |pages=480 |doi=10.3390/nano10030480 |issn=2079-4991 |pmc=7153587 |pmid=32155993 |doi-access=free }}</ref> Nanosensors can have increased specificity because they operate at a similar scale as natural biological processes, allowing functionalization with chemical and biological molecules, with recognition events that cause detectable physical changes. Enhancements in sensitivity stem from the high surface-to-volume ratio of nanomaterials, as well as novel physical properties of nanomaterials that can be used as the basis for detection, including [[nanophotonics]]. Nanosensors can also potentially be integrated with [[nanoelectronics]] to add native processing capability to the nanosensor.<ref name=":0">{{Cite web|url=https://www.nano.gov/node/100|title=Nanotechnology-Enabled Sensing|date=2009|website=National Nanotechnology Initiative|access-date=2017-06-22}}</ref>{{Rp|4–10}}

In addition to their sensitivity and specificity, nanosensors offer significant advantages in cost and response times, making them suitable for high-throughput applications. Nanosensors provide real-time monitoring compared to traditional detection methods such as chromatography and spectroscopy.  These traditional methods may take days to weeks to obtain results and often require investment in capital costs as well as time for sample preparation.<ref name="GarciaAnoveros">{{cite journal | last1 = GarciaAnoveros | first1 = J | last2 = Corey | first2 = DP | year = 1997 | title = The molecules of mechanosensation | journal = Annual Review of Neuroscience | volume = 20 | pages = 567–94 | doi=10.1146/annurev.neuro.20.1.567| pmid = 9056725 }}</ref><ref name="pmid28285124">{{cite journal | vauthors =  Callaway DJ, Matsui T, Weiss T, Stingaciu LR, Stanley CB, Heller WT, Bu ZM| title = Controllable Activation of Nanoscale Dynamics in a Disordered Protein Alters Binding Kinetics | journal = Journal of Molecular Biology | volume = 427 | issue = 7  | pages = 987–998 | date = 7 April 2017 | pmid =  28285124 |  pmc = 5399307 | doi =  10.1016/j.jmb.2017.03.003  }}</ref><ref>{{cite journal|last1=Langer|first1=Robert|title=Nanotechnology in Drug Delivery and Tissue Engineering: From Discovery to Applications|pmc=2935937|pmid=20726522|doi=10.1021/nl102184c|volume=10|issue=9|journal=Nano Lett|pages=3223–30|bibcode=2010NanoL..10.3223S|year=2010}}</ref><ref>{{cite journal |doi=10.1016/j.arabjc.2016.09.022|title=Nanobiotechnology approach using plant rooting hormone synthesized silver nanoparticle as "nanobullets" for the dynamic applications in horticulture – an in vitro and ex vitro study|journal=Arabian Journal of Chemistry|volume=11|pages=48–61|year=2018|last1=Thangavelu|first1=Raja Muthuramalingam|last2=Gunasekaran|first2=Dharanivasan|last3=Jesse|first3=Michael Immanuel|last4=s.u|first4=Mohammed Riyaz|last5=Sundarajan|first5=Deepan|last6=Krishnan|first6=Kathiravan|doi-access=free}}</ref>

One-dimensional nanomaterials such as [[nanowire]]s and [[nanotube]]s are well suited for use in nanosensors, as compared to bulk or [[Thin film|thin-film]] planar devices.  They can function both as transducers and wires to transmit the signal.  Their high surface area can cause large signal changes upon binding of an analyte.  Their small size can enable extensive [[multiplexing]] of individually addressable sensor units in a small device.  Their operation is also "label free" in the sense of not requiring fluorescent or radioactive labels on the analytes.<ref name=":0" />{{Rp|12–26}} Zinc oxide nanowire is used for gas sensing applications, given that it exhibits high sensitivity toward low concentration of gas under ambient conditions and can be fabricated easily with low cost.<ref>{{Cite journal|last1=Lupan|first1=O.|last2=Emelchenko|first2=G. A.|last3=Ursaki|first3=V. V.|last4=Chai|first4=G.|last5=Redkin|first5=A. N.|last6=Gruzintsev|first6=A. N.|last7=Tiginyanu|first7=I. M.|last8=Chow|first8=L.|last9=Ono|first9=L. K.|last10=Roldan Cuenya|first10=B.|last11=Heinrich|first11=H.|date=2010-08-01|title=Synthesis and characterization of ZnO nanowires for nanosensor applications|url=http://www.sciencedirect.com/science/article/pii/S0025540810001212|journal=Materials Research Bulletin|language=en|volume=45|issue=8|pages=1026–1032|doi=10.1016/j.materresbull.2010.03.027|issn=0025-5408|url-access=subscription}}</ref>

There are several challenges for nanosensors, including avoiding drift and [[fouling]], developing reproducible calibration methods, applying preconcentration and separation methods to attain a proper analyte concentration that avoids saturation, and integrating the nanosensor with other elements of a sensor package in a reliable manufacturable manner.<ref name=":0" />{{Rp|4–10}}  Because nanosensors are a relatively new technology, there are many unanswered questions regarding nanotoxicology, which currently limits their application in biological systems.

Potential applications for nanosensors include medicine, detection of contaminants and pathogens, and monitoring manufacturing processes and transportation systems.<ref name=":0" />{{Rp|4–10}} By measuring changes in physical properties ([[volume]], [[concentration]], [[Displacement (vector)|displacement]] and [[velocity]], [[Gravitational force|gravitational]], [[Electric field|electrical]], and [[Magnetic field|magnetic]] forces, [[pressure]], or [[temperature]]) nanosensors may be able to distinguish between and recognize certain cells at the molecular level in order to deliver medicine or monitor development to specific places in the body.<ref name="F2">{{cite book|date=1999|title=Nanomedicine, Volume 1: Basic Capabilities|place=Austin |publisher=Landes Bioscience|isbn=1-57059-680-8|author=Freitas Jr. RA}}</ref> The type of signal transduction defines the major classification system for nanosensors. Some of the main types of nanosensor readouts include optical, mechanical, vibrational, or electromagnetic.<ref>Lim, T.-C.; Ramakrishna, S. A Conceptual Review of Nanosensors. http://www.znaturforsch.com/aa/v61a/s61a0402.pdf.</ref>

As an example of classification, nanosensors that use [[molecularly imprinted polymer]]s (MIP) can be divided into three categories, which are [[electrochemical]], [[Piezoelectric sensor|piezoelectric]], or [[Spectroscopy|spectroscopic]] sensors.  Electrochemical sensors  induce a change in the electrochemical properties of the sensing material, which includes [[Charge density|charge]], [[Conductivity (electrolytic)|conductivity]], and [[electric potential]]. Piezoelectric sensors either convert mechanical force into electric force or vice versa. This force is then [[Transducer|transduced]] into a signal. MIP spectroscopic sensors can be divided into three subcategories, which are [[Chemiluminescence|chemiluminescent]] sensors, [[surface plasmon resonance]] sensors, and [[fluorescence]] sensors. As the name suggests, these sensors produce light based signals in forms of chemiluminescence, resonance, and fluorescence. As described by the examples, the type of change that the sensor detects and type of signal it induces depend on the type of sensor<ref name=":9"/>
[[File:Overview_of_Nanosensor_Workflow.jpg|thumb|Overview of a general nanosensor workflow.]]