Development of multifunctional nanoscale coordination polymers (NCPs) allowing for T₁- and T₂-weighted targeted magnetic resonance (MR) imaging of tumors could significantly improve the diagnosis accuracy. In this study, nanoscale coordination polymers (NCPs) with a diameter of ≈80 nm are obtained with 1,1′-dicarboxyl ferrocene (Fc) as building blocks and magnetic gadolinium(III) ions as metallic nodes using a nanoprecipitation method, then further aminated through silanization. The amine-functionalized Fc-Gd@SiO₂ NCPs enable the covalent conjugation of a fluorescent rhodamine dye (RBITC) and an arginine-glycine-aspartic acid (RGD) peptide as a targeting ligand onto their surface. The formed water-dispersible Fc-Gd@SiO₂(RBITC)–RGD NCPs exhibit a low cytotoxicity, as confirmed by MTT assay. They have a longitudinal relaxivity (r₁) of 5.1 mM⁻¹ s⁻¹ and transversal relaxivity (r₂) of 21.7 mM⁻¹ s⁻¹, suggesting their possible use as both T₁-positive and T₂-negative contrast agents. In vivo MR imaging experiments show that the signal of tumor over-expressing high affinity α_vβ₃ integrin from T₁-weighted MR imaging is positively enhanced 47±5%, and negatively decreased 33±5% from T₂-weighted MR imaging after intravenous injection of Fc-Gd@SiO₂(RBITC)–RGD NCPs.

The development of magnetic nanoparticles (MNPs) with functional groups has been intensively pursued in recent years. Herein, a simple, versatile, and cost-effective strategy to synthesize water-soluble and amino-functionalized MNPs, based on the thermal decomposition of phthalimide-protected metal–organic precursors followed by deprotection, was developed. The resulting amino-functionalized Fe₃O₄, MnFe₂O₄, and Mn₃O₄ MNPs with particle sizes of about 14.3, 7.5, and 6.6 nm, respectively, had narrow size distributions and good dispersibility in water. These MNPs also exhibited high magnetism and relaxivities of r₂=107.25 mM⁻¹ s⁻¹ for Fe₃O₄, r₂=245.75 mM⁻¹ s⁻¹ for MnFe₂O₄, and r₁=2.74 mM⁻¹ s⁻¹ for Mn₃O₄. The amino-functionalized MNPs were further conjugated with a fluorescent dye (rhodamine B) and a targeting ligand (folic acid: FA) and used as multifunctional probes. Magnetic resonance imaging and flow-cytometric studies showed that these probes could specifically target cancer cells overexpressing FA receptors. This new protocol opens a new way for the synthesis and design of water-soluble and amino-functionalized MNPs by an easy and versatile route.

Water-soluble phosphorescent polymeric nanoparticles with an average diameter of approximately 100 nm were synthesized by a coordination cross-linking reaction. The pyridine blocks in poly(4-vinyl pyridine-b-ethylene oxide) (P4VP-b-PEO) were cross-linked by the iridium chloride-bridged dimer in DMF solution. Owing to the presence of an iridium complex with different ligands in the core of the polymeric nanoparticles, NP-1, NP-2, and NP-3 showed bright green, yellow, and red phosphorescence, respectively. PEG chains in the shell gave the polymeric nanoparticles solubility and biocompatibility, which was confirmed by an MTT assay using HeLa cells as a model cancer cell line. The flow cytometry and laser confocal fluorescence microscopy results revealed NP-2, as an example, could be effectively uptaken by HeLa cells. Therefore, these polymeric nanoparticles can be used as luminescent probes for living cells. In addition, ¹O₂ could be effectively generated in the presence of NP-2 upon irradiation with visible light (λ>400 nm, 300 mW cm⁻²), which was confirmed by a clear decrease in the fluorescence intensity of 9,10-dimethylanthracene (DMA). After incubation with NP-2 at a concentration of 200 μg mL⁻¹ for 6 h, approximately 90 % of HeLa cells were effectively ablated upon irradiation with visible light for only 10 min, indicating the potential for photodynamic therapy with polymeric nanoparticles.

Monodisperse silica-coated manganese oxide nanoparticles (NPs) with a diameter of ∼35 nm are synthesized and are aminated through silanization. The amine-functionalized core–shell NPs enable the covalent conjugation of a fluorescent dye, Rhodamine B isothiocyanate (RBITC), and folate (FA) onto their surface. The formed Mn₃O₄@SiO₂(RBITC)–FA core–shell nanocomposites are water-dispersible, stable, and biocompatible when the Mn concentration is below 50 µg mL⁻¹ as confirmed by a cytotoxicity assay. Relaxivity measurements show that the core–shell NPs have a T₁ relaxivity (r₁) of 0.50 mM⁻¹ s⁻¹ on the 0.5 T scanner and 0.47 mM⁻¹ s⁻¹ on the 3.0 T scanner, suggesting the possibility of using the particles as a T₁ contrast agent. Combined flow cytometry, confocal microscopy, and magnetic resonance imaging studies show that the Mn₃O₄@SiO₂(RBITC)–FA nanocomposites can specifically target cancer cells overexpressing FA receptors (FARs). Findings from this study suggest that the silica-coated Mn₃O₄ core–shell NPs could be used as a platform for bimodal imaging (both magnetic resonance and fluorescence) in various biological systems.

Three silver(I) complexes, namely [Ag(L)(NO₃)]_∞ (1), [Ag(L)₂(NO₃)] (2) and [Ag(L)₂](BF₄) (3) {L = 9,10-dihydro-7H-benzo[de]imidazo[2,1-a]isoquinolin-7-one}, have been synthesized and characterized by X-ray crystallography, elemental analyses and FTIR spectra. The counteranions in the Ag^I salts and the ligand/Ag^I ratio play fundamental roles in the formation of Ag^I complexes having different crystal structures. The Ag^I ions in 1 and 2 are both three-coordinate, but they are two-coordinate in 3. Complex 1 adopts the polymeric chain-like structure mainly bridged by nitrate anions. These chains are assembled into 2D sheets by the π–π stacking interaction of the ligands between the adjacent chains and weak intermolecular hydrogen bonds. They are further packed into 3D networks by C–H···O hydrogen bonds. For 2 and 3, mononuclear silver(I) complexes are formed. Complex 2 is extended into an infinite zigzag chain with knots by the π–π stacking interactions of the ligands and further assembled by C–H···O interactions. However, the tetrafluoroborate anions in 3 are not coordinated but are connected by intermolecular hydrogen bonds to form an infinite molecular ladder with ligand-supported Ag–N inner rungs. All the complexes display room-temperature photoluminescence in the visible region, which may be assigned to ligand-centred π–π* transitions supported by the theory calculation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

In this study, crystal silver nanoparticle clusters, prepared by the reduction of AgNO₃ in the presence of third-to-sixth-generation dendrimers with a trimesyl core, were characterized with ultraviolet–visible spectroscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The results showed that the particle size of the silver nanoparticles was considerably affected by the generation of the dendrimers as well as the dendrimer concentration. When the concentration ratios of Ag⁺ to the third-to-sixth-generation dendrimers were all 4 : 1, the average diameters of the obtained particles were 6.7, 6.0, 5.2, and 4.3 nm, respectively. The data from high-resolution transmission electron microscopy and electron diffraction indicated that the particles belonged to a simple cubic crystal structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008