The optimization of surface-enhanced Raman scattering (SERS) activity of gold nanoparticles is essential for further enhancing SERS capability in terms of high sensitivity, stability and reproducibility. Recently, we utilized a simple seed-mediated growth method to synthesize monodisperse Au nanoparticles with controllable size from about 16 to 160 nm, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectroscopy. These nanoparticles can be easily formed as a uniform thin film on glass carbon or gold substrates with an area larger than 1 mm.(2) The nanoparticle film with the size range of 120-135 nm showed the highest SERS activity with the excitation wavelength of 632.8 nm. Using pyridine as the probe molecule, the average enhancement factorcould reach Up to 10(7). Finite difference time domain (FDTD) calculation was employed to explain the size-dependent SERS activity. The optimum-sized Au nanoparticles were utilized to further prepare Au-Pd core-shell (Au@Pd)nanoparticles in order to greatly enhance the SERS activity of the Pd shell. The enhancement factor of the ultrathin Pd shell was found to be over 5 x 10(4). Thus the originally low enhancement factor of Pd could be improved substantially. Copyright (C) 2008 John Wiley & Sons, Ltd.Natural Science Foundation of China [20433040, 26673086]; Ministry of Science and Technology [2007CB815303, 22007CB935603

Au-seed Ag-growth nanoparticles of controllable diameter (50-100 nm), and having an ultrathin SiO(2) shell of controllable thickness (2-3 nm), were prepared for shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Their morphological, optical, and material properties were characterized; and their potential for use as a versatile Raman signal amplifier was investigated experimentally using pyridine as a probe molecule and theoretically by the three-dimensional finite-difference time-domain (3D-FDTD) method. We show that a SiO(2) shell as thin as 2 nm can be synthesized pinhole-free on the Ag surface of a nanoparticle, which then becomes the core. The dielectric SiO(2) shell serves to isolate the Raman-signal enhancing core and prevent it from interfering with the system under study. The SiO(2) shell also hinders oxidation of the Ag surface and nanoparticle aggregation. It significantly improves the stability and reproducibility of surface-enhanced Raman scattering (SERS) signal intensity, which is essential for SERS applications. Our 3D-FDTD simulations show that Ag-core SHINERS nanoparticles yield at least 2 orders of magnitude greater enhancement than Au-core ones when excited with green light on a smooth Ag surface, and thus add to the versatility of our SHINERS method.

To improve the mechanical properties of bone tissue and achieve the desired bone tissue regeneration for orthopedic surgery, newly designed hydroxyapatite/polyurethane (HA/PU) porous scaffolds were developed via in situ polymerization. The results showed that the molecular modification of PU soft segments by glyceride of castor oil (GCO) can increase the scaffold compressive strength by 48% and the elastic modulus by 96%. When nano-HA (n-HA) particles were incorporated into the GCO-PU matrix, the compressive strength and elastic modulus further increased by 49 and 74%, from 2.91 to 4.34 MPa and from 95 to 165.36 MPa, respectively. The n-HA particles with fine dispersity not only improved the interface bonding with the GCO-PU matrix but also provided effective bioactivity for bonding with bone tissue. The hierarchical structure and mechanical quality of the n-HA/GCO-PU composite scaffold were determined to be appropriate for the growth of cells and the regeneration of bony tissues, demonstrating promising prospects for bone repair and regeneration.

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The development of functional materials for osteoporosis is ultimately required for bone remodeling. However, grafts were accompanied by increasing pro-inflammatory cytokines that impaired bone formation. In this work, nano-hydroxyapatite (n-HA)/resveratrol (Res)/chitosan (CS) composite microspheres were designed to create a beneficial microenvironment and help improve the osteogenesis by local sustained release of Res. Study of in vitro release confirmed the feasibility of n-HA/Res/CS microspheres for controlled Res release. Notably, microspheres had anti-inflammatory activity evidenced by the decreased expression of pro-inflammatory cytokines TNF-α, IL-1β and iNOS in RAW264.7 cells in a dose dependent manner. Further, enhanced adhesion and proliferation of BMSCs seeded onto microspheres demonstrated that composite microspheres were conducive to cell growth. The ability to enhance osteo-differentiation was supported by up-regulation of Runx2, ALP, Col-1 and OCN, and substantial mineralization in osteogenic medium. When implanted into bone defects in the osteoporotic rat femoral condyles, enhanced entochondrostosis and bone regeneration suggested that the n-HA/Res/CS composite microspheres were more favorable for impaired fracture healing. The results indicated that optimized n-HA/Res/CS composite microspheres could serve as promising multifunctional fillers for osteoporotic bone defect/fracture treatment.

The sorption properties and structural versatility of metal–organic frameworks (MOFs) make them superior chemical sensing materials with both high sensitivity and selectivity, but the fabrication of MOF sensors with optimized performances still remains a major challenge. Herein, we propose a simple yet powerful optical sensing motif based on ultrathin MOF-coated monolayer colloidal crystals (MCCs), which allows for high efficiency in vapor sensing through changes in their effective refractive index (RI). Two optical modes exist in this sensor, namely, photonic eigenmodes and Fabry–Pérot oscillations, both of which can be used as the signal transducer. Selective response to a series of alcohols, water, and acetonitrile was exhibited, reflecting well the characteristic sorption properties of the integrated MOF, with which colorimetric reporting was readily achieved. Linear response to a broad dynamic range of vapor concentration was realized. The sensitivity was found to depend closely on the thickness of the MOF coating and can be further enhanced accordingly. Ultrafast response time (<5 s) and excellent recyclability were also demonstrated. These substantial improvements in performance are attributed to the efficacy of signal transduction and the enhanced pore accessibility and diffusion efficiency, which are intrinsically endowed by the optical motif design. Our findings should provide new insights into the design and fabrication of MOF sensors toward real-world applications.

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Six new monoterpenoid indole alkaloids, kopsinidines C-E (1-3), 11,12-methylenedioxychanofruticosinic acid (4), 12-methoxychanofruticosinic acid (5), and N(4)-methylkopsininate (7), as well as chanofruticosinic acid (6, as a natural product) and 23 known alkaloids, were obtained from the twigs and leaves of Kopsia officinalis. Their structures were characterized by physical data analysis. All isolated compounds were evaluated for their immunosuppressive activity on human T cell proliferation. Rhazinilam (29) significantly inhibited human T cell proliferation activated by anti-CD3/anti-CD28 antibodies (IC = 1.0 μM) and alloantigen stimulation (IC = 1.1 μM) without obvious cytotoxicity for naïve human T cells and peripheral blood mononuclear cells (0-320 μM). Although it did not affect T cell activation, it induced T cell cycle arrest in the G/M phase and inhibited proinflammatory cytokine production in activated T cells.