螢光淬滅

螢光淬滅（英語：Quenching）是指螢光物質的螢光強度降低的任何過程。許多過程都會導致淬滅現象，例如激發態反應、能量轉移、配合物的形成和碰撞淬滅。氧分子、碘離子和丙烯醯胺都是常見的化學淬滅劑^[1]，氯離子是常見的奎寧淬滅劑^[2]^[3]^[4]。

淬滅被用於製造光極（英語：optode）傳感器，例如氧對某些釕配合物的淬滅效應可以用於測量溶液中的氧飽和度；淬滅是螢光共振能量轉移（FRET）分析技術的基礎^[5]^[6]^[7]；特定標靶分子結合時的淬滅與去淬滅效應可用作光學造影劑 ^[8]^[9]；許多染料有自淬滅現象，導致螢光顯微鏡的蛋白質-染料偶聯物的亮度降低^[10]；或是用作檢測蛋白酶解傳感器^[11]。

淬滅機理

螢光共振能量轉移

螢光淬滅可以用多種機制解釋，其中的FRET是動態淬滅機制，供體與受體通過非輻射的方式轉移能量。因為能量轉移的過程基於二者的躍遷偶極間的經典偶極-偶極相互作用，因此極其依賴於供體-受體間的距離R，以E∝1/R⁶的效率下降^[12]，通常FRET過程在100 Å的距離內發生。FRET的過程還取決於供體-受體的重疊（如圖）以及躍遷偶極矩的相對取向。

德克斯特電子轉移

德克斯特電子轉移（英語：Dexter electron transfer）（或稱為德克斯特電子交換、碰撞能量轉移等）是另一種動態淬滅機制^[13]，同樣此過程依賴於供體和受體間的距離，能量轉移速率由下式所示，此過程通常在10 Å的距離內發生^[14]，式中 $r$ 是供體與受體間的距離， $L$ 與 $P$ 是不易由實驗得到的常量， $J$ 是重疊光譜的積分^[15]。

k_{ET}\varpropto P^{2}J\mathrm {exp} \left[{\frac {-2r}{L}}\right]

激基配合物

激發態配合物的形成過程是第三種動態淬滅過程。

靜態淬滅

剩餘的能量轉移機理是靜態淬滅，靜態淬滅發生在基態的螢光分子與淬滅劑通過結合形成配合物時，即激發發生之前。靜態淬滅形成的配合物會失去螢光性。

碰撞淬滅

激發態的螢光基團與淬滅劑原子或分子碰撞時，以無輻射躍遷的方式回到基態，此種淬滅過程稱為碰撞淬滅。

參考文獻

^ Acrylamide and iodide fluorescence quenching as a structural probe of tryptophan microenvironment in bovine lens crystallins. Phillips SR, Wilson LJ, Borkman RF. Curr Eye Res. 1986 Aug;5(8):611-9.
^ Fluorescence experiments with quinine James E. O'Reilly J. Chem. Educ., 1975, 52 (9), p 610 doi:10.1021/ed052p610
^ Photophysics in a disco: Luminescence quenching of quinine LouAnn Sacksteder , R. M. Ballew , Elizabeth A. Brown , J. N. Demas , D. Nesselrodt and B. A. DeGraff J. Chem. Educ., 1990, 67 (12), p 1065 doi:10.1021/ed067p1065
^ Halide (Cl-) Quenching of Quinine Sulfate Fluorescence: A Time-Resolved Fluorescence Experiment for Physical Chemistry Jonathan H. Gutow J. Chem. Educ., 2005, 82 (2), p 302 doi:10.1021/ed082p302
^ Peng X, Draney DR, Volcheck WM. Quenched near-infrared fluorescent peptide substrate for HIV-1 protease assay. Achilefu S, Bornhop DJ, Raghavachari R (編). Optical Molecular Probes for Biomedical Applications 6097. 2006: 60970F. S2CID 98507102. doi:10.1117/12.669174.
^ Peng X, Chen H, Draney DR, Volcheck W, Schutz-Geschwender A, Olive DM. A nonfluorescent, broad-range quencher dye for Förster resonance energy transfer assays. Analytical Biochemistry. May 2009, 388 (2): 220–8. PMID 19248753. doi:10.1016/j.ab.2009.02.024.
^ Osterman H. The Next Step in Near Infrared Fluorescence: IRDye QC-1 Dark Quencher.. Review Article. 2009, 388: 1–8. （原始內容存檔於20 March 2020）.
^ Blum G, Weimer RM, Edgington LE, Adams W, Bogyo M. Comparative assessment of substrates and activity based probes as tools for non-invasive optical imaging of cysteine protease activity. PLOS ONE. July 2009, 4 (7): e6374. Bibcode:2009PLoSO...4.6374B. PMC 2712068 . PMID 19636372. doi:10.1371/journal.pone.0006374 .
^ Weissleder R, Tung CH, Mahmood U, Bogdanov A. In vivo imaging of tumors with protease-activated near-infrared fluorescent probes. Nature Biotechnology. April 1999, 17 (4): 375–8. PMID 10207887. S2CID 12362848. doi:10.1038/7933.
^ Jacobsen MT, Fairhead M, Fogelstrand P, Howarth M. Amine Landscaping to Maximize Protein-Dye Fluorescence and Ultrastable Protein-Ligand Interaction. Cell Chem Biol. August 2017, 24 (8): 1040–1047. PMC 5563079 . PMID 28757182. doi:10.1016/j.chembiol.2017.06.015 .
^ Voss EW J, Workman CJ, Mummert ME. Detection of protease activity using a fluorescence-enhancement globular substrate. BioTechniques. February 1996, 20 (2): 286–291. PMID 8825159. doi:10.2144/96202rr06. 溫哥華格式錯誤 (幫助)
^ Moens P. Fluorescence Resonance Energy Transfer spectroscopy. [July 14, 2012]. （原始內容存檔於2016-07-26）.
^ 國際純化學和應用化學聯合會，化學術語概略，第二版。（金皮書）(1997)。在線校正版: (2006–) "Dexter excitation transfer (electron exchange excitation transfer)"。doi:10.1351/goldbook.D01654
^ Dexter Energy Transfer. chemwiki.ucdavis.edu. 2 October 2013 [8 July 2014]. （原始內容存檔於2014-07-14）.
^ 國際純化學和應用化學聯合會，化學術語概略，第二版。（金皮書）(1997)。在線校正版: (2006–) "Dexter excitation transfer (electron exchange excitation transfer)"。doi:10.1351/goldbook.D01654

[1] Acrylamide and iodide fluorescence quenching as a structural probe of tryptophan microenvironment in bovine lens crystallins. Phillips SR, Wilson LJ, Borkman RF. Curr Eye Res. 1986 Aug;5(8):611-9.

[2] Fluorescence experiments with quinine James E. O'Reilly J. Chem. Educ., 1975, 52 (9), p 610 doi:10.1021/ed052p610

[3] Photophysics in a disco: Luminescence quenching of quinine LouAnn Sacksteder , R. M. Ballew , Elizabeth A. Brown , J. N. Demas , D. Nesselrodt and B. A. DeGraff J. Chem. Educ., 1990, 67 (12), p 1065 doi:10.1021/ed067p1065

[4] Halide (Cl-) Quenching of Quinine Sulfate Fluorescence: A Time-Resolved Fluorescence Experiment for Physical Chemistry Jonathan H. Gutow J. Chem. Educ., 2005, 82 (2), p 302 doi:10.1021/ed082p302

[5] Peng X, Draney DR, Volcheck WM. Quenched near-infrared fluorescent peptide substrate for HIV-1 protease assay. Achilefu S, Bornhop DJ, Raghavachari R (編). Optical Molecular Probes for Biomedical Applications 6097. 2006: 60970F. S2CID 98507102. doi:10.1117/12.669174.

[6] Peng X, Chen H, Draney DR, Volcheck W, Schutz-Geschwender A, Olive DM. A nonfluorescent, broad-range quencher dye for Förster resonance energy transfer assays. Analytical Biochemistry. May 2009, 388 (2): 220–8. PMID 19248753. doi:10.1016/j.ab.2009.02.024.

[7] Osterman H. The Next Step in Near Infrared Fluorescence: IRDye QC-1 Dark Quencher.. Review Article. 2009, 388: 1–8. （原始內容存檔於20 March 2020）.

[8] Blum G, Weimer RM, Edgington LE, Adams W, Bogyo M. Comparative assessment of substrates and activity based probes as tools for non-invasive optical imaging of cysteine protease activity. PLOS ONE. July 2009, 4 (7): e6374. Bibcode:2009PLoSO...4.6374B. PMC 2712068 . PMID 19636372. doi:10.1371/journal.pone.0006374 .

[9] Weissleder R, Tung CH, Mahmood U, Bogdanov A. In vivo imaging of tumors with protease-activated near-infrared fluorescent probes. Nature Biotechnology. April 1999, 17 (4): 375–8. PMID 10207887. S2CID 12362848. doi:10.1038/7933.

[10] Jacobsen MT, Fairhead M, Fogelstrand P, Howarth M. Amine Landscaping to Maximize Protein-Dye Fluorescence and Ultrastable Protein-Ligand Interaction. Cell Chem Biol. August 2017, 24 (8): 1040–1047. PMC 5563079 . PMID 28757182. doi:10.1016/j.chembiol.2017.06.015 .

[11] Voss EW J, Workman CJ, Mummert ME. Detection of protease activity using a fluorescence-enhancement globular substrate. BioTechniques. February 1996, 20 (2): 286–291. PMID 8825159. doi:10.2144/96202rr06. 溫哥華格式錯誤 (幫助)

[12] Moens P. Fluorescence Resonance Energy Transfer spectroscopy. [July 14, 2012]. （原始內容存檔於2016-07-26）.

[13] 國際純化學和應用化學聯合會，化學術語概略，第二版。（金皮書）(1997)。在線校正版: (2006–) "Dexter excitation transfer (electron exchange excitation transfer)"。doi:10.1351/goldbook.D01654

[14] Dexter Energy Transfer. chemwiki.ucdavis.edu. 2 October 2013 [8 July 2014]. （原始內容存檔於2014-07-14）.

[det1-15] 國際純化學和應用化學聯合會，化學術語概略，第二版。（金皮書）(1997)。在線校正版: (2006–) "Dexter excitation transfer (electron exchange excitation transfer)"。doi:10.1351/goldbook.D01654

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