We created and studied a novel nanoprobe for spectroscopic molecular imaging of the epidermal growth factor (EGF) receptor, whose over-expression is a hallmark of a wide range of cancers. Silver nanoparticles (AgNPs) of 45 nm diameter were synthesized and coupled to EGF by α-lipoic acid, a short ligand that exhibits excellent silver binding affinity. Time-of-flight mass spectroscopy demonstrates formation of the protein complex. Enzyme-linked immunosorbent assay verifies the protein complex is 100% active for the EGF receptor, alone and, following conjugation to silver nanoparticles. Compared with its monosulfide analog, 6-mercaptohexanoic acid, α-lipoic acid is stabilized by binding to silver with a total energy that is lower by 1.38 eV, as found from Density Functional Theory (DFT)/natural bond analysis calculations. A Highest Occupied Molecular Orbital (HOMO)-Lowest Unoccupied Molecular Orbital (LUMO) gap energy of 5.25 (spin-up electrons) and 5.74 eV (spin-down electrons) was obtained for the silver-α-lipoic acid complex. This is the first report of silver nanoparticles being attached to EGF, and the first theoretical and experimental report on the surface enhanced Raman spectroscopy spectral interpretation of α-lipoic acid bound to silver. These nanoprobes exhibit surface enhanced Raman spectroscopy, when aggregated in solution, at picomolar concentrations and have the necessary propertiesspecificity, sensitivity and stabilityto serve as molecular imaging agents.

The synthesis, structure, and electrochemistry in Na cells of NaFe MO positive electrode materials with M = Ni, CoNi, and Co are reported. In particular, the properties of O3-NaFeO-NaCoNiO solid solutions having compositions NaFe (CoNi)O with 0 ≤ x ≤ 0.5 are explored. It is found that the substitution of Fe in NaNiCoO causes an increase in first cycle energy density from 320 to 440 mWh/g in a 1.5-4.0 V test. However, capacity retention is generally reduced when x is increased for all M = Ni, CoNi, and Co. In general, NaFe MO samples with M = Co had the highest capacity retention for all values of x. Ex situ X-ray diffraction and Mössbauer results of as-prepared and charged materials are directly compared for NaFe (CoNi)O and NaFe CoO ( x = 0.4, 0.5). Iron was found to be in the +3 oxidation state in the as-prepared materials. A significant fraction of Fe is oxidized to Fe in these samples when they are charged to 4.0 V.

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