A ratiometric fluorescent chemosensor for iron: discrimination of Fe2+ and Fe3+ and living cell application.
A newly designed probe, 6-thiophen-2-yl-5,6-dihydrobenzo[4,5]imidazo-[1,2-c] quinazoline (HL(1)) behaves as a highly selective ratiometric fluorescent sensor for Fe(2+) at pH 4.0-5.0 and Fe(3+) at pH 6.5-8.0 in acetonitrile-HEPES buffer (1/4) (v/v) medium. A decrease in fluorescence at 412 nm and increase in fluorescence at 472 nm with an isoemissive point at 436 nm with the addition of Fe(2+) salt solution is due to the formation of mononuclear Fe(2+) complex [Fe(II)(HL)(ClO(4))(2)(CH(3)CN)(2)] (1) in acetonitrile-HEPES buffer (100 mM, 1/4, v/v) at pH 4.5 and a decrease in fluorescence at 412 nm and increase in fluorescence at 482 nm with an isoemissive point at 445 nm during titration by Fe(3+) salt due to the formation of binary Fe(3+) complex, [Fe(III)(L)(2)(ClO(4))(H(2)O)] (2) with co-solvent at biological pH 7.4 have been established. Binding constants (K(a)) in the solution state were calculated to be 3.88 × 10(5) M(-1) for Fe(2+) and 0.21 × 10(3) M(-1/2) for Fe(3+) and ratiometric detection limits for Fe(2+) and Fe(3+) were found to be 2.0 μM and 3.5 μM, respectively. The probe is a "naked eye" chemosensor for two states of iron. Theoretical calculations were studied to establish the configurations of probe-iron complexes. The sensor is efficient for detecting Fe(3+)in vitro by developing a good image of the biological organelles.
Department of Chemistry, Burdwan University, Golapbag, Burdwan-713104, West Bengal, India.
Supriti
S
Sen
Sandipan
S
Sarkar
Basab
B
Chattopadhyay
Anuradha
A
Moirangthem
Anupam
A
Basu
Koushik
K
Dhara
Pabitra
P
Chattopadhyay
D000042:Absorption; D002470:Cell Survival; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007501:Iron / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D057054:Molecular Imaging; D010084:Oxidation-Reduction; D011799:Quinazolines / Q000138:chemical synthesis / Q000737:chemistry; D013050:Spectrometry, Fluorescence
D005456:Fluorescent Dyes; D011799:Quinazolines; D007501:Iron