Editing Lanthanide (section)

==Applications==

===Industrial===
Lanthanide elements and their compounds have many uses but the quantities consumed are relatively small in comparison to other elements. About 15000 ton/year of the lanthanides are consumed as [[catalyst]]s and in the production of glasses. This 15000 tons corresponds to about 85% of the lanthanide production. From the perspective of value, however, applications in phosphors and magnets are more important.<ref name=Ullmann/>

The devices lanthanide elements are used in include [[superconductors]], [[Samarium–cobalt magnet|samarium-cobalt]] and [[Neodymium magnet|neodymium-iron-boron]] high-flux [[rare-earth magnet]]s, [[magnesium alloy]]s, electronic polishers, refining catalysts and [[hybrid car]] components (primarily batteries and magnets).<ref name=Haxel02>{{cite book |url=http://pubs.usgs.gov/fs/2002/fs087-02/fs087-02.pdf |title=Rare earth elements critical resources for high technology |vauthors=Haxel G, Hedrick J, Orris J |year=2006 |place=Reston (VA) |publisher=United States Geological Survey. USGS Fact Sheet: 087‐02 |access-date=19 April 2008 |archive-date=14 December 2010 |archive-url=https://web.archive.org/web/20101214095306/http://pubs.usgs.gov/fs/2002/fs087-02/fs087-02.pdf |url-status=live }}</ref> Lanthanide ions are used as the active ions in luminescent materials used in [[optoelectronics]] applications, most notably the [[Nd:YAG]] laser. Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems. [[Phosphor#Cathode-ray tubes|Phosphors]] with lanthanide dopants are also widely used in [[cathode-ray tube]] technology such as television sets. The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible. [[Yttrium iron garnet]] (YIG) spheres can act as tunable microwave resonators. 

Lanthanide oxides are mixed with [[tungsten]] to improve their high temperature properties for [[TIG welding]], replacing [[thorium]], which was mildly hazardous to work with. Many defense-related products also use lanthanide elements such as [[night-vision device|night-vision goggles]] and [[rangefinders]]. The [[AN/SPY-1|SPY-1 radar]] used in some [[Aegis Combat System|Aegis]] equipped warships, and the hybrid propulsion system of {{sclass|Arleigh Burke|destroyer|1}}s all use rare earth magnets in critical capacities.<ref name=Livergood2010>{{cite web |author=Livergood R. |url=http://csis.org/files/publication/101005_DIIG_Current_Issues_no22_Rare_earth_elements.pdf |title=Rare Earth Elements: A Wrench in the Supply Chain |year=2010 |access-date=22 October 2010 |publisher=Center for Strategic and International Studies |archive-date=12 February 2011 |archive-url=https://web.archive.org/web/20110212024126/http://csis.org/files/publication/101005_DIIG_Current_Issues_no22_Rare_earth_elements.pdf |url-status=live }}</ref>
The price for [[lanthanum oxide]] used in [[fluid catalytic cracking]] has risen from $5 per kilogram in early 2010 to $140 per kilogram in June 2011.<ref name=doeRem>{{cite web |last= Chu |first= Steven |author-link= Steven Chu |url= https://www.energy.gov/sites/prod/files/2019/06/f63/DOE_CMS2011_FINAL_Full_1.pdf |title= Critical Materials Strategy |page= 17 |publisher= [[United States Department of Energy]] |date= December 2011 |access-date= 23 December 2011}}</ref>

Most lanthanides are widely used in [[laser]]s, and as (co-)dopants in doped-fiber optical amplifiers; for example, in Er-doped fiber amplifiers, which are used as repeaters in the terrestrial and submarine fiber-optic transmission links that carry internet traffic. These elements deflect [[ultraviolet]] and [[infrared]] radiation and are commonly used in the production of sunglass lenses. Other applications are summarized in the following table:<ref name=aspinall>{{cite book|url=https://books.google.com/books?id=bLI2maI1_xAC|page=8| title=Chemistry of the f-block elements| author =Aspinall, Helen C. | publisher=CRC Press| year = 2001| isbn=978-90-5699-333-7}}</ref>
{| class="wikitable" |+ The applications of lanthanides
!Application
!Percentage
|-
|Catalytic converters
|45%
|-
|Petroleum refining catalysts
|25%
|-
|Permanent magnets
|12%
|-
|Glass polishing and ceramics
|7%
|-
|Metallurgical
|7%
|-
|Phosphors
|3%
|-
|Other
|1%
|}

The complex Gd([[DOTA (chelator)|DOTA]]) is used in [[magnetic resonance imaging]].

Mixtures containing all of the lanthanides operating as a single-atom catalysts have been proposed for the [[Electrochemical reduction of carbon dioxide|electroreduction]] of carbon dioxide (CO2) to carbon monoxide (CO) with a faradaic efficiency greater than 90%. <ref>{{Cite journal |last=Wang |first=Qiyou |last2=Luo |first2=Tao |last3=Cao |first3=Xueying |last4=Gong |first4=Yujie |last5=Liu |first5=Yuxiang |last6=Xiao |first6=Yusen |last7=Li |first7=Hongmei |last8=Gröbmeyer |first8=Franz |last9=Lu |first9=Ying-Rui |last10=Chan |first10=Ting-Shan |last11=Ma |first11=Chao |last12=Liu |first12=Kang |last13=Fu |first13=Junwei |last14=Zhang |first14=Shiguo |last15=Liu |first15=Changxu |date=2025-03-27 |title=Lanthanide single-atom catalysts for efficient CO2-to-CO electroreduction |url=https://www.nature.com/articles/s41467-025-57464-8 |journal=Nature Communications |language=en |volume=16 |issue=1 |pages=2985 |doi=10.1038/s41467-025-57464-8 |issn=2041-1723|pmc=11947204 }}</ref>

===Life science===
Lanthanide complexes can be used for optical imaging. Applications are limited by the [[lability]] of the complexes.<ref>{{cite book |first1=Thomas Just |last1=Sørenson|first2=Stephen |last2=Faulkner|title=Metal Ions in Bio-Imaging Techniques|publisher=Springer|year=2021|pages=137–156 |chapter=Chapter 5. Lanthanide Complexes Used for Optical Imaging |doi=10.1515/9783110685701-011|s2cid=233653968}}</ref> 

Some applications depend on the unique luminescence properties of lanthanide [[chelates]] or [[cryptate]]s.<ref>Daumann, Lena J.; Op den Camp, Huub J.M.; "The Biochemistry of Rare Earth Elements" pp 299-324 in "Metals, Microbes and Minerals: The Biogeochemical Side of Life" (2021) pp xiv + 341. Walter de Gruyter, Berlin. Editors Kroneck, Peter M.H. and Sosa Torres, Martha. [https://www.de Gruyter.com/document/doi/10.1515/9783110589771-010 DOI 10.1515/9783110589771-010] {{Webarchive|url=https://web.archive.org/web/20220908150824/https://www2022.de/ |date=8 September 2022 }}</ref><ref>{{cite journal|last1=Bunzil|first1=Jean-Claude|first2=Claude|last2=Piguet|title=Taking advantage of luminescent lanthanide ions|journal=Chemical Society Reviews|date=September 2005|doi=10.1039/b406082m|url=http://lib.semi.ac.cn:8080/tsh/dzzy/wsqk/selected%20papers/Chemical%20Society%20Reviews/34-1048.pdf|access-date=22 December 2012|volume=34|issue=12|pages=1048–77|pmid=16284671|archive-url=https://web.archive.org/web/20130118024445/http://lib.semi.ac.cn:8080/tsh/dzzy/wsqk/selected%20papers/Chemical%20Society%20Reviews/34-1048.pdf|archive-date=18 January 2013|url-status=dead}}</ref> These are well-suited for this application due to their large [[Fluorescence|Stokes shifts]] and extremely long emission lifetimes (from [[microsecond]]s to [[millisecond]]s) compared to more traditional fluorophores (e.g., [[fluorescein]], [[allophycocyanin]], [[phycoerythrin]], and [[rhodamine]]). 

The biological fluids or serum commonly used in these research applications contain many compounds and proteins which are naturally fluorescent. Therefore, the use of conventional, steady-state fluorescence measurement presents serious limitations in assay sensitivity. Long-lived fluorophores, such as lanthanides, combined with time-resolved detection (a delay between excitation and emission detection) minimizes prompt fluorescence interference.

[[Time-resolved spectroscopy|Time-resolved fluorometry (TRF)]] combined with [[Förster resonance energy transfer|Förster resonance energy transfer (FRET)]] offers a powerful tool for drug discovery researchers: Time-Resolved Förster Resonance Energy Transfer or TR-FRET. TR-FRET combines the low background aspect of TRF with the homogeneous assay format of FRET. The resulting assay provides an increase in flexibility, reliability and sensitivity in addition to higher throughput and fewer false positive/false negative results.

This method involves two fluorophores: a donor and an acceptor. Excitation of the donor fluorophore (in this case, the lanthanide ion complex) by an energy source (e.g. flash lamp or laser) produces an energy transfer to the acceptor fluorophore if they are within a given proximity to each other (known as the [[Förster resonance energy transfer|Förster's radius]]). The acceptor fluorophore in turn emits light at its characteristic wavelength.

The two most commonly used lanthanides in life science assays are shown below along with their corresponding acceptor dye as well as their excitation and emission wavelengths and resultant [[Stokes shift]] (separation of excitation and emission wavelengths).
{| class="wikitable" |align="center" |+ Life Science lanthanide Donor-Acceptor pairings
!Donor
!Excitation⇒Emission λ (nm)
!Acceptor
!Excitation⇒Emission λ (nm)
!Stokes Shift (nm)
|-
|Eu<sup>3+</sup>
|340⇒615
|[[Allophycocyanin]]
|615⇒660
|320
|-
|Tb<sup>3+</sup>
|340⇒545
|[[Phycoerythrin]]
|545⇒575

|235
|}

===Possible medical uses===
Currently there is research showing that lanthanide elements can be used as anticancer agents. The main role of the lanthanides in these studies is to inhibit proliferation of the cancer cells. Specifically cerium and lanthanum have been studied for their role as anti-cancer agents.

One of the specific elements from the lanthanide group that has been tested and used is cerium (Ce). There have been studies that use a protein-cerium complex to observe the effect of cerium on the cancer cells. The hope was to inhibit cell proliferation and promote cytotoxicity.<ref name="Palizban 119–125">{{Cite journal|title = Effect of cerium lanthanide on Hela and MCF-7 cancer cell growth in the presence of transferring|journal = Research in Pharmaceutical Sciences|date = 1 January 2010|pmc = 3093623|pmid = 21589800|pages = 119–125|volume = 5|issue = 2|first1 = A. A.|last1 = Palizban|first2 = H.|last2 = Sadeghi-aliabadi|first3 = F.|last3 = Abdollahpour}}</ref> Transferrin receptors in cancer cells, such as those in breast cancer cells and epithelial cervical cells, promote the cell proliferation and malignancy of the cancer.<ref name="Palizban 119–125"/> Transferrin is a protein used to transport iron into the cells and is needed to aid the cancer cells in DNA replication.  Transferrin acts as a growth factor for the cancerous cells and is dependent on iron. Cancer cells have much higher levels of transferrin receptors than normal cells and are very dependent on iron for their proliferation.<ref name="Palizban 119–125"/> 
In the field of magnetic resonance imaging (MRI), compounds containing gadolinium are utilized extensively.<ref>Cundari  TR,  Saunders  LC.  Modeling  lanthanide  coordination  complexes.  Comparison  of semiempirical and classical methods. Journal of chemical information and computer sciences. 1998 May 18;38(3):523-8</ref>
The photobiological characteristics, anticancer, anti-leukemia, and anti-HIV activities of the lanthanides with coumarin and its related compounds are demonstrated by the biological activities of the complex.<ref>razul M, Budzisz E. Biological activity of metal ions complexes of chromones, coumarins and flavones. Coordination Chemistry Reviews. 2009 Nov 1;253(21-22):2588-98</ref>
Cerium has shown results as an anti-cancer agent due to its similarities in structure and biochemistry to iron.  Cerium may bind in the place of iron on to the transferrin and then be brought into the cancer cells by transferrin-receptor mediated endocytosis.<ref name="Palizban 119–125"/> The cerium binding to the transferrin in place of the iron inhibits the transferrin activity in the cell. This creates a toxic environment for the cancer cells and causes a decrease in cell growth. This is the proposed mechanism for cerium's effect on cancer cells, though the real mechanism may be more complex in how cerium inhibits cancer cell proliferation. Specifically in [[HeLa]] cancer cells studied in vitro, cell viability was decreased after 48 to 72 hours of cerium treatments. Cells treated with just cerium had decreases in cell viability, but cells treated with both cerium and transferrin had more significant inhibition for cellular activity.<ref name="Palizban 119–125"/>
Another specific element that has been tested and used as an anti-cancer agent is lanthanum, more specifically lanthanum chloride (LaCl<sub>3</sub>). The lanthanum ion is used to affect the levels of let-7a and microRNAs miR-34a in a cell throughout the cell cycle.  When the lanthanum ion was introduced to the cell in vivo or in vitro, it inhibited the rapid growth and induced apoptosis of the cancer cells (specifically cervical cancer cells). This effect was caused by the regulation of the let-7a and microRNAs by the lanthanum ions.<ref>{{Cite journal|last1=Yu|first1=Lingfang|last2=Xiong|first2=Jieqi|last3=Guo|first3=Ling|last4=Miao|first4=Lifang|last5=Liu|first5=Sisun|last6=Guo|first6=Fei|year=2015|title=The effects of lanthanum chloride on proliferation and apoptosis of cervical cancer cells: involvement of let-7a and miR-34a microRNAs|journal=BioMetals|volume=28|issue=5|pages=879–890|doi=10.1007/s10534-015-9872-6|pmid=26209160|s2cid=15715889}}<!--|access-date = 2015--></ref> The mechanism for this effect is still unclear but it is possible that the lanthanum is acting in a similar way as the cerium and binding to a ligand necessary for cancer cell proliferation.
In the field of magnetic resonance imaging (MRI), compounds containing gadolinium are utilized extensively.