Phosphorescence Imaging of Homocysteine and Cysteine in Living Cells Based on a Cationic Iridium(III) Complex

Abstract

Homocysteine (Hcy) and cysteine (Cys) are crucial to the physiological balance in living systems. Specific detection of intracellular Hcy and Cys is of growing importance. Herein, we demonstrated phosphorescence imaging of intracellular Hcy and Cys using a cationic iridium(III) complex Ir(pba)(2)(bpy)(+).PF(6)(-) [pba = 4-(2-pyridyl)benzaldehyde, bpy = bipyridine] containing aldehyde groups as a luminescent probe. Upon addition of Hcy or Cys to a semiaqueous solution of Ir(pba)(2)(bpy)(+), a change in luminescence from yellow to red was visible to the naked eye. The successful chemical reaction of the aldehyde in Ir(pba)(2)(bpy)(+) with Hcy and Cys to form thiazinane and thiazolidine was confirmed by (1)H NMR. Moreover, complexation with Hcy and Cys disturbed the p-pi conjugation between the aldehyde group and the bpy moiety, and led to the excited states switching to [dpi(Ir)-pi(N(wedge)N)*] (3)MLCT and [pi(C(wedge)N)-pi(N(wedge)N)*] (3)LLCT from (pi-pi*)(pba(-)) (3)IL. Furthermore, the MTT assay was used to determine that the probe has low cytotoxicity. Importantly, cell imaging experiments demonstrated that the probe is membrane permeable and can monitor the changes of Hcy/Cys within living cells in a ratiometric mode.

Incorporation of the fluoride induced SiO bond cleavage and functionalized gold nanoparticle aggregation into one colorimetric probe for highly specific and sensitive detection of fluoride

“…It is well-known that pyridine group is an effective hydrogen bonding donor, which is often used in chemosensors for anions detection [38][39][40][41][42]. In addition, F − induced Si O bond cleavage reaction had also been well documented in the chemosensors to selectively target F − due to the highly special affinity between fluorine and silicon [43][44][45].…”

Peptide‐Functionalized Luminescent Iridium Complexes for Lifetime Imaging of CXCR4 Expression

“…[31,32] Complexes based on rhenium(I) [33,34] and ruthenium(II) [35,36] have been conjugated to peptides for cell imaging applications. Pioneering studies on applications of iridium(III) (Ir III ) for diagnostic imaging have been performed by Lo et al, [20][21][22] Li et al [25,26] and Williams et al [27,37] using cationic Ir III complexes.…”

Differential Anticancer Activities of the Geometric Isomers of Dinuclear Iridium(III) Complexes

“…[32] Furthermore, while there have been some recent studies of the cytotoxicity of tris(bidentate) (pyridyl)iridium(III) complexes, they have generally utilised C-metallated ligands. [33][34][35] The results of this study demonstrate that the kinetically inert (in the absence of strong light), non-organometallic, chlorido-bearing poly(pyridyl)iridium(III) complexes, Cl-Irbb n , can have significant cytotoxic properties. The anticancer activity increased with alkane chain length, Cl-Irbb 16 showing the best activity against both cell lines.…”