Optical probing and imaging of live cells using SERS labels

During surface‐enhanced Raman scattering (SERS), molecules exhibit a significant increase in their Raman signals when attached, or in very close vicinity, to gold or silver nanostructures. This effect is exploited as the basis of a new class of optical labels. Here we demonstrate robust and sensitive SERS labels as probes for imaging live cells. These hybrid labels consist of gold nanoparticles with Rose Bengal or Crystal Violet attached as reporter molecules. These new labels are stable and nontoxic, do not suffer from photobleaching, and can be excited at any excitation wavelength, even in the near infrared. SERS labels can be detected and imaged through the specific Raman signatures of the reporters. In addition, surface‐enhanced Raman spectroscopy in the local optical fields of the gold nanoparticles also provides sensitive information on the immediate molecular environment of the label in the cell and allows imaging of the native constituents of the cell. This is demonstrated by images based on a characteristic Raman line of the reporter as well as by displaying lipids based on the SERS signal of the C H deformation/bending modes at ∼1470 cm⁻¹. Copyright © 2008 John Wiley & Sons, Ltd.     

X-Ray spectral determination of the effective charges on phosphorus,sulfur, and chlorine atoms in chemical compounds with a nonempirical charge scale

Linear dependence between the experimental K_a line shifts and Mulliken atomic charges obtained by SCF ab initio calculations with 4-31G, 4-31G*, and 4-31G** basis sets for the P, S, and Cl atoms have been found. The electron density redistribution of PCl₃ and SPCl₃ free ligands on their complexation with AlBr₃ has been investigated. It has been shown that a significant transfer of the total ligand electron density to the acceptor is absent, but there is an essential growth of the ionicity of all bonds on complexation. The P = S and P S bond ionicities are found to increase linearly with the growth of the positive charge on the central phosphorus atom. © John Wiley & Sons, Inc.