ABSTRACT
Metallic nanoparticles (NPs), as an efficient substrate for surface-enhanced Raman scattering (SERS), attract much interests because of their various shapes and sizes. The appropriate size and morphology of metallic NPs are critical to serve as the substrate for achieving an efficient SERS. Pulsed laser deposition (PLD) is one of the feasible physical methods employed to synthesize metallic NPs with controllable sizes and surface characteristics. It has been recognized to be a successful tool for the deposition of SERS substrates due to its good controllability and high reproducibility in the manufacture of metallic NPs. This review provides an overview about the recent advances for the preparation of SERS substrates by PLD technique. The influences of parameters on the sizes and morphologies of metallic NPs during the deposition processes in PLD technique including laser output parameters, gas medium, liquid medium, substrate temperature, and properties of 3D substrate are presented. The applications of SERS substrates produced by PLD in the environmental monitoring and biomedical analysis are summarized. This knowledge could serve as a guideline for the researchers in exploring further applications of PLD technique in the production of SERS substrate.
ABSTRACT
Phosphorescent nanospheres of a carboxyl-functionalized iridium complex ([Ir(ppy)2(Hdcbpy)], ppy: 2-phenylpyridine; Hdcbpy: 4-carboxy-2,2'-bipyridyl-4'-carboxylate) were prepared by a conventional precipitation method. Driven by hydrogen bond interaction between carboxylic groups of the complex and the guest molecule tris(imidazoline), these nanospheres can be transformed into 1-dimensional nanowires in the presence of tris(imidazoline) at the concentration of the iridium complex higher than 4.8 mM, while nanowires change back to nanospheres with the diameter obviously smaller than that of the sole complex of [Ir(ppy)2(Hdcbpy)]. The interaction between carboxylic groups and tris(imidazoline) molecules was confirmed by FT-IR spectra. The structures of the nanowires and nanospheres were further studied by XRD diffraction analysis. With the morphological transformation from nanospheres to nanowires, the phosphorescence of nanostructures was blue shifted from 590 to 564 nm.
Subject(s)
Nanospheres/chemistry , Nanowires/chemistry , 2,2'-Dipyridyl/chemistry , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Crystallography, X-Ray , Hydrogen Bonding , Iridium/chemistry , Molecular Conformation , Nanospheres/ultrastructure , Pyridines/chemistryABSTRACT
A d-f heteronuclear complex (Ir-Gd) by coupling an iridium(III) complex to a macrocycle-based gadolinium complex has been developed as as a dual-mode bioimaging probe for luminescence imaging and magnetic resonance imaging (MRI). The cyclometalated iridium complex showed an intense visible metal-to-ligand charge transfer (MLCT) absorption and strong yellow phosphorescent luminescence. It has specificity of staining in murine mitochondria confirmed by confocal laser scanning microscopy. The macrocycle-based gadolinium complex provides the longitudinal relaxivity of 3.36 mm(-1)s(-1) on a 3 T system, which has been applied to MRI for liver in mice. Furthermore, the biodistribution of Ir-Gd has been investigated using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses. Such platform should be extended to further applications in the identification and diagnosis of liver diseases.
