A one-pot synthesis of new oxindole-fused polycyclic scaffolds is reported. The process involves a three-component [3+2] cycloaddition followed by cyclization through an intramolecular Michael addition. The reaction gives easy access to oxindole-fused spirotetrahydrofurochromans in moderate to good yields with high regio- and diastereoselectivity. These compounds could be useful for for drug discovery. Further modification was achieved by reduction of the nitro group, and intramolecular amide formation to give the corresponding lactams. The resulting heterocyclic products show good inhibitory activity against the enzyme PTP1B in vitro.

An elegant synergistic catalytic system comprising a ruthenium complex with a chiral Brønsted acid was developed for a four-component Mannich/cascade aza-Michael reaction. The ruthenium-associated ammonium ylides successfully trapped with in situ generated imines indicates a stepwise process of proton transfer in the ruthenium-catalyzed carbenoid NH insertion reaction. The different decomposition abilities of various ruthenium complexes towards diazo compounds were well explained by the calculated thermodynamic data. The transformation features a mild, rapid, and efficient method for the synthesis of enantiomerically pure 1,3,4-tetrasubstituted tetrahydroquinolines bearing a quaternary stereogenic carbon center from simple starting precursors in moderate yields with high diastereo- and enantioselectivity.

The chiral Rh^I–diene-catalyzed asymmetric three-component reaction of aryldiazoacetates, aromatic amines, and β-nitroacrylates was achieved to obtain γ-nitro-α-amino-succinates in good yields and with high diastereo- and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of Rh^I-associated ammonium ylides by nitroacrylates. This new transformation represents the first example of Rh^I-carbene-induced ylide transformation.

The chiral Rh^I–diene-catalyzed asymmetric three-component reaction of aryldiazoacetates, aromatic amines, and β-nitroacrylates was achieved to obtain γ-nitro-α-amino-succinates in good yields and with high diastereo- and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of Rh^I-associated ammonium ylides by nitroacrylates. This new transformation represents the first example of Rh^I-carbene-induced ylide transformation.

Au-Fe₃O₄ nanoparticles were widely used as nanoplatforms for biologic applications through readily further functionalization. Dopamine (DA)-coated superparamagnetic iron oxide (SPIO) nanoparticles (DA@Fe₃O₄) have been successfully synthesized using a one-step process by modified coprecipitation method. Then 2–3 nm gold nanoparticles were easily conjugated to DA@Fe₃O₄ nanoparticles by the electrostatic force between gold nanoparticles and amino groups of dopamine to afford water-soluble Au-Fe₃O₄ hybrid nanoparticles. A detailed investigation by dynamic light scatting (DLS), transmission electron microscopy (TEM), fourier transform infrared (FT-IR) and X-ray diffraction (XRD) were performed in order to characterize the physicochemical properties of the hybrid nanoparticles. The hybrid nanoparticles were easily functionalized with a targeted small peptide A54 (AGKGTPSLETTP) and fluorescence probe fluorescein isothiocyanate (FITC) for liver cancer cell BEL-7402 imaging. This simple approach to prepare hybrid nanoparticles provides a facile nanoplatform for muti-functional derivations and may be extended to the immobilization of other metals or bimolecular on SPIO surface.

Gold nanoshells have shown a great potential for use as agents in a wide variety of biomedical applications, and some of which require the delivery of large numbers of gold nanoshells onto or into the cells. Here, we develop a ready method to enhance the cellular uptake of gold nanoshells by modifying with meso-2,3-dimercaptosuccinic acid (DMSA). The quantifiable technique of inductively coupled plasma atomic emissions spectroscopy (ICP-AES) and transmission electron microscopy (TEM) were used to investigate the cellular uptake of unmodified and DMSA-modified gold nanoshells. Three cell lines (RAW 264.7, A549, and BEL-7402) were involved and the results indicated that the cellular uptake of the DMSA-modified gold nanoshells was obviously enhanced versus the unmodified gold nanoshells. The reason possibly lies in the nonspecific adsorption of serum protein on the DMSA-modified gold nanoshells (DMSA-GNs), which consequently enhanced the cellular uptake. As a continued effort, in vitro experiments with endocytic inhibitors suggested the DMSA-GNs internalized into cells via receptor-mediated endocytosis (RME) pathway. This study has provided a valuable insight into the effects of surface modification on cellular uptake of nanoparticles. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.

A novel organic-inorganic nanohybrided receptor 4 functionalized with bis-thiourea arms and then assembled on gold nanoparticles was synthesized. The preorganized system possesses phenylthiourea units for the spectrophotometric sensing of dicarboxylates, especially malonate, based on changes in the surface plasmon absorption of the gold nanoparticles (GNPs). The intensity of the absorbance band increases gradually with the concentration of dicarboxylates increasing. But such an ion-selective change in the plasmon band was not observed in control tests carried out by mono-thiourea-modified GNPs, receptor 3and the free receptor2. As it is shown from the association constants, derived from quantitative titrations, receptor 4 can selectively recognize dicarboxylate anions of shorter carbon chain, and has the highest affinity to malonate. The interaction properties for anions of receptor 4 were evaluated by ¹H NMR and UV-vis spectroscopic methods.