TY - JOUR
T1 - A Highly Selective and Efficient Copper(II) – “Turn-On” Fluorescence Imaging Probe for l-Cysteine
AU - Maheshwaran, Duraiyarasu
AU - Nagendraraj, Thavasilingam
AU - Manimaran, Paramasivam
AU - Ashokkumar, Balasubramaniem
AU - Kumar, Mukesh
AU - Mayilmurugan, Ramasamy
N1 - Publisher Copyright:
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/2/10
Y1 - 2017/2/10
N2 - A simple copper(II) complex of the anthracenyl-appended terpyridine ligand 4′-(anthracen-9-yl)-2,2′:6′,2′′-terpyridine (L), [Cu(L)Cl2] (1, ESI-MS, m/z = 507.08), is reported as a highly selective “turn-on” optical imaging probe for l-cysteine. Probe 1 shows a CuII/CuIredox potential [E1/2= –0.194 V versus normal hydrogen electrode (NHE)] within a biologically viable range. The copper center in 1 adopts a square-pyramidal geometry (τ = 0.0851), and the Cu–Npybond (1.970 Å) of the middle pyridine (py) ring is shorter than the other two Cu–Npybonds (2.069 and 2.040 Å). The Cu–Cl bonds (2.444 and 2.027 Å) are labile enough to be replaced by solvent molecules. The square-based geometry is further supported by the A∥value of 156.8 × 10–4cm–1determined by electron paramagnetic resonance (EPR) spectroscopy at 70 K. The d–d transition of 1 in acetonitrile/4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (acetonitrile/HEPES) buffer at pH 7.34 appears at λ =760 nm (ε = 198 m–1cm–1), and the ligand-based transitions are observed at λ = 327–384 nm. The ligand shows strong fluorescence at λ = 430 nm with a quantum yield of 11 %, but its emission intensity is completely quenched on coordination with Cu2+ions, as in 1. Probe 1 detects l-cysteine selectively through turn-on fluorescence intensity at λem= 431 nm with a limit of detection of 1.9 × 10–8m at pH 7.34. Interestingly, probe 1 is able to visualize exogenously added l-cysteine in Henrietta Lack cervical cancer (HeLa) cells, human liver hepatocellular carcinoma (HepG2) cells, and human embryonic kidney 293 (HEK293) cells under identical conditions at pH 7.4 in confocal microscopy imaging.
AB - A simple copper(II) complex of the anthracenyl-appended terpyridine ligand 4′-(anthracen-9-yl)-2,2′:6′,2′′-terpyridine (L), [Cu(L)Cl2] (1, ESI-MS, m/z = 507.08), is reported as a highly selective “turn-on” optical imaging probe for l-cysteine. Probe 1 shows a CuII/CuIredox potential [E1/2= –0.194 V versus normal hydrogen electrode (NHE)] within a biologically viable range. The copper center in 1 adopts a square-pyramidal geometry (τ = 0.0851), and the Cu–Npybond (1.970 Å) of the middle pyridine (py) ring is shorter than the other two Cu–Npybonds (2.069 and 2.040 Å). The Cu–Cl bonds (2.444 and 2.027 Å) are labile enough to be replaced by solvent molecules. The square-based geometry is further supported by the A∥value of 156.8 × 10–4cm–1determined by electron paramagnetic resonance (EPR) spectroscopy at 70 K. The d–d transition of 1 in acetonitrile/4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (acetonitrile/HEPES) buffer at pH 7.34 appears at λ =760 nm (ε = 198 m–1cm–1), and the ligand-based transitions are observed at λ = 327–384 nm. The ligand shows strong fluorescence at λ = 430 nm with a quantum yield of 11 %, but its emission intensity is completely quenched on coordination with Cu2+ions, as in 1. Probe 1 detects l-cysteine selectively through turn-on fluorescence intensity at λem= 431 nm with a limit of detection of 1.9 × 10–8m at pH 7.34. Interestingly, probe 1 is able to visualize exogenously added l-cysteine in Henrietta Lack cervical cancer (HeLa) cells, human liver hepatocellular carcinoma (HepG2) cells, and human embryonic kidney 293 (HEK293) cells under identical conditions at pH 7.4 in confocal microscopy imaging.
KW - Amino acids
KW - Cell imaging
KW - Copper
KW - Fluorescent probes
KW - N ligands
UR - http://www.scopus.com/inward/record.url?scp=85013113291&partnerID=8YFLogxK
U2 - 10.1002/ejic.201601229
DO - 10.1002/ejic.201601229
M3 - Article
AN - SCOPUS:85013113291
SN - 1434-1948
VL - 2017
SP - 1007
EP - 1016
JO - European Journal of Inorganic Chemistry
JF - European Journal of Inorganic Chemistry
IS - 6
ER -