Distance-dependent Fluorescence Quenching and Binding of CdSe Quantum Dots by Functionalized Nitroxide Radicals.
Quantum dot (QD) fluorescence is effectively quenched at low concentration by nitroxides bearing amine or carboxylic acid ligands. The association constants and fluorescence quenching of CdSe QDs with these derivatized nitroxides have been examined using electron paramagnetic resonance (EPR) and fluorescence spectroscopy. The EPR spectra in the non-protic solvent toluene are extremely sensitive to intermolecular and intramolecular hydrogen bonding of the functionalized nitroxides. Fluorescence measurements show that quenching of QD luminescence is nonlinear, with a strong dependence on the distance between the radical and the QD. The quenched fluorescence is restored when the surface-bound nitroxides are converted to hydroxylamines by mild reducing agents, or trapped by carbon radicals to form alkoxyamines. EPR studies indicate that photoreduction of the nitroxide occurs in toluene solution upon photoexcitation at 365 nm. However, photolysis in benzene solution gives no photoreduction, suggesting that photoreduction in toluene is independent of the quenching mechanism. The fluorescence quenching of QDs by nitroxide binding is a reversible process.
Tansakul
Chittreeya
C
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064 USA.
Lilie
Erin
E
Walter
Eric D
ED
Rivera
Frank
F
Wolcott
Abraham
A
Zhang
Jin Z
JZ
Millhauser
Glenn L
GL
Braslau
Rebecca
R
Nat Methods. 2008 Sep;5(9):763-75
18756197
Faraday Discuss. 2004;125:279-91; discussion 293-309
14750677
Nature. 2008 May 15;453(7193):345-51
18480816
Comb Chem High Throughput Screen. 2007 Jul;10(6):473-9
17896943
J Am Chem Soc. 2006 Oct 18;128(41):13320-1
17031920
Phys Chem Chem Phys. 2007 May 7;9(17):2036-43
17464385
J Am Chem Soc. 2001 Sep 19;123(37):9164-5
11552826
Anal Sci. 2005 May;21(5):553-9
15913147
Photochem Photobiol. 2006 Sep-Oct;82(5):1211-8
16608386
Photochem Photobiol. 2004 Nov-Dec;80(3):377-85
15623319
J Am Chem Soc. 2009 Mar 18;131(10):3700-12
19231866
Talanta. 2005 Oct 31;67(5):979-83
18970268
Free Radic Biol Med. 1998 Mar 1;24(4):649-52
9559877
Chem Commun (Camb). 2005 Jul 7;(25):3201-3
15968371
Biochem Biophys Res Commun. 2005 Sep 9;334(4):1317-21
16039606
Methods Enzymol. 1994;233:105-11
8015448
J Am Chem Soc. 2005 Jul 27;127(29):10221-6
16028933
J Phys Chem. 1996 Nov 21;100(47):18592-18602
34032396
Talanta. 2006 Mar 15;69(1):126-30
18970543
Angew Chem Int Ed Engl. 2007;46(15):2655-8
17309085
J Phys Chem B. 2005 Apr 21;109(15):7012-21
16851797
Chem Commun (Camb). 2006 Jan 21;(3):257-9
16391726
J Biochem Biophys Methods. 2002 Mar 4;51(1):1-15
11879915
J Am Chem Soc. 2004 Aug 4;126(30):9221-32
15281811
Spectrochim Acta A Mol Biomol Spectrosc. 2009 Jan;71(5):2030-9
18790663
J Biochem Biophys Methods. 1999 Jan 13;38(1):29-42
10078871
Curr Opin Biotechnol. 2005 Feb;16(1):63-72
15722017
J Phys Chem B. 2006 Aug 24;110(33):16353-8
16913763
Biol Chem. 2000 Jul;381(7):575-82
10987364
J Am Chem Soc. 2008 Jan 9;130(1):168-75
18076165
J Fluoresc. 2008 Mar;18(2):527-32
18157738
Anal Biochem. 2004 Mar 15;326(2):139-45
15003554
Science. 2006 Apr 14;312(5771):217-24
16614209
Org Lett. 2008 Jun 5;10(11):2147-50
18465870
Small. 2008 Jun;4(6):759-64
18500770
J Am Chem Soc. 2008 Jan 30;130(4):1274-84
18177042
Chem Soc Rev. 2007 Apr;36(4):579-91
17387407
J Am Chem Soc. 2007 Jun 6;129(22):7018-27
17497854
J Phys Chem B. 2007 May 3;111(17):4327-34
17428081
Biophys Chem. 2005 Apr 1;114(1):53-61
15792861
J Org Chem. 2001 Feb 23;66(4):1146-56
11312941
Photochem Photobiol. 2007 Jul-Aug;83(4):871-81
17645658
J Am Chem Soc. 2003 Jan 22;125(3):620-1
12526647
Analyst. 2004 Aug;129(8):672-7
15344262
Angew Chem Int Ed Engl. 2007;46(14):2448-52
17318931
Photochem Photobiol. 2003 Oct;78(4):416-9
14626672
Angew Chem Int Ed Engl. 2006 Jun 2;45(23):3829-32
16646092