[Show abstract][Hide abstract] ABSTRACT: The CdS and CdS-Ag core-shell quantum dots (QDs) have been prepared. The nanostructures of the QDs were revealed by transmisson electron microscopy and absorption spectra, respectively. The third-order nonlinear optical properties of the core-shell QDs have been studied by using Z-scan technique with femtosecond pulses at the wavelength of 790 nm. The value of the effective nonlinear absorption coefficient beta(eff) of CdS-Ag QDs is measured to be about 16.8 cm/GW, which is about 400 times larger than that of bare CdS QDs of 3.9 x 10(-2) cm/GW. The nonlinear refraction index gamma of CdS-Ag QDs is about -2.3 x 10(-4) cm(2)GW, which is about 200 times larger than that of bare CdS QDs of 1.0 x 10(-6) cm(2)GW.
Preview · Article · Aug 2006 · The Journal of Chemical Physics
[Show abstract][Hide abstract] ABSTRACT: A simple and convenient method for the construction of CdSe/ZnS-labeled polysaccharides as bioprobes were developed, which are highly biocompatible and photostable, and have been proven to be suitable for live cell imaging.
No preview · Article · Dec 2005 · Chemical Communications
[Show abstract][Hide abstract] ABSTRACT: Complex beads composed of alginate and carboxymethyl chitin (CMCT) were prepared by dropping aqueous alginate-CMCT into an iron(III) solution. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR confirmed electrostatic interactions between iron(III) and the carboxyl groups of alginate as well as CMCT, and the binding model was suggested as a three-dimensional structure. SEM revealed that CMCT had a porous morphology while alginate and their complex beads had a core-layer structure. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. The BSA encapsulation efficiency was fairly high (>90%). It was found that CMCT disintegrated at pH 1.2 and alginate eroded at pH 7.4 while the complex beads could effectively retain BSA in acid (>85%) and reduce the BSA release at pH 7.4. The results suggested that the iron(III)-alginate-CMCT bead could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine.
No preview · Article · Sep 2005 · Macromolecular Bioscience