Bioimaging in the Mid-Infrared Using an Organometallic Carbonyl Tag

Abstract

Two stable and water-soluble organometallic carbonyl cluster derivatives have been prepared and shown to enter the cell with ease. The CO stretching vibrations afford strong mid-infrared signals which have been demonstrated, for the first time, to be of utility in cell imaging via an IR microscope.

Label‐Free Imaging of Metal–Carbonyl Complexes in Live Cells by Raman Microspectroscopy

“…Although the spectroscopic signature of metal-carbonyl compounds has already been used in bioanalytical techniques such as the carbonyl-metal immunoassay (CMIA), [24] their use in cellular imaging is so far unprecedented, except for an investigation of osmium-carbonyl clusters in dried cells by using infrared microscopy. [25] The IR and Raman spectra of solid [Mn(tpm)(CO) 3 ]Cl show strong CO stretching vibrations at about 1944 and 2050 cm À1 , as expected for local C 3v symmetry (Figures S1 and S2 A in the Supporting Information). The different relative intensities of the two peaks can be explained by the distinct selection rules for Raman and IR spectroscopy.…”

Subcellular IR Imaging of a Metal–Carbonyl Moiety Using Photothermally Induced Resonance

“…Thanks to their specific IR signals, it is possible to detect submicromolar concentrations of these probes quantitatively. [3] Metal-carbonyl compounds have been used as labels, [4][5][6] for immunoassays, [7][8][9] and as local pH probes [7] and in a few cases for cellular mapping, but always with spatial resolution above several micrometers using FTIR [10] or Raman microspectroscopy. [11,12] In the case of vibrational excitation in the IR, no photobleaching is induced, in contrast to what is observed with organic fluorophores in the visible or UV range.…”

A Rapid and Label‐free SERS Detection Method for Biomarkers in Clinical Biofluids

“…A class of reporters that have been shown to permit detection of protein binding events through changes in the spectrum is metal carbonyl compounds . These show strong carbonyl stretching vibrations in the mid‐infrared (1800–2200 cm −1 ), a region that is relatively free of interference from the absorbance of biomolecules; their potential has already been demonstrated in several biological applications such as glucose assay and cell imaging …”