Lian Xie

Preparation of strongly fluorescent silica nanoparticles of polyelectrolyte-protected cadmium telluride quantum dots and their application to cell toxicity and imaging

Based on the polyelectrolyte-protected CdTe quantum dots (QDs), which were prepared by self-assembling of QDs and poly-diallyldimethylammonium chloride (PDADMAC) in the help of electrostatic attraction, the strong fluorescence silica nanoparticles (QDs-PDADMAC@SiO(2)) have been prepared via a water-in-oil reverse microemulsion method. Transmission electron microscopy and Zeta potential analysis were used to characterize the as-prepared nanoparticles. All of the particles were almost spherical and there is a uniform distribution of the particle size with the average diameter about 25 nm. There is a large Zeta potential of -35.07 mV which is necessary for good monodispersity of nanoparticles solution. As compared with the QDs coated by SiO(2) (QDs@SiO(2)), the QDs-PDADMAC@SiO(2) nanoparticles have much stronger fluorescence, and their fluorescence stability could be obviously improved. Moreover, QDs-PDADMAC@SiO(2) exhibits good biological compatibility which promotes their application in cellular imaging.

Polyelectrolyte-based electrochemiluminescence enhancement for Ru(bpy)32+ loaded by SiO2 nanoparticle carrier and its high sensitive immunoassay

In this paper the strong electrochemiluminescence (ECL) nanoparticles have been prepared based on the anionic polyelectrolyte sodium polyacrylate (PAA)-ECL enhancement for Ru(bpy)3(2+), which were loaded by the carrier of SiO2 nanoparticle. There were two kinds of Ru(bpy)3(2+) for the as-prepared nanoparticles, the doped one and the exchanged one. The former was loaded inside the ECL nanoparticles by doping, in a form of ion-pair macromolecules PAA-Ru(bpy)3(2+). The corresponding ECL was enhanced about 2 times owing to the doping increase of Ru(bpy)3(2+). The latter was loaded on the PAA-doped Nafion membrane by ion exchange. The corresponding ECL was enhanced about 3 times owing to the ion-exchanging increase of Ru(bpy)3(2+). At the same time, ECL intensity of the doped-inside Ru(bpy)3(2+) was further enhanced 13 times because polyelectrolyte PAA in the doped membrane could obviously enhance electron transfer between the doped Ru(bpy)3(2+) and the working electrode. Furthermore, based on hydrophobic regions of the doped membrane antibody labeling could be easily realized by the as-prepared nanoparticles and then a high sensitive ECL immunoassay for HBsAg was developed. The linear range was between 1.0 and 100 pg mL(-1) (R(2)=0.9912). The detection limit could be as low as 0.11 pg mL(-1) (signal-to-noise ratio=3).

Cytotoxicity and cellular imaging of quantum dots protected by polyelectrolyte

The nanocomposites of poly-diallyldimethylammonium chloride (PDADMAC) and CdTe quantum dots (QDs) (i.e. QDs-PDADMAC nanocomposites) have been prepared based on electrostatic interaction and their fluorescence stability in aqueous solution has been investigated. MTT method (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method) was used to study their cytotoxicity and A549 lung cancer cell as a model cell was also used to evaluate their cellular imaging. It was shown that the fluorescence stability of QDs-PDADMAC nanocomposites was much better than that of bare QDs both in aqueous solution and cell. Meanwhile, QDs-PDADMAC nanocomposites display very low cytotoxicity in the low concentrations and better staining ability compared with QDs. QDs-PDADMAC nanocomposites will have great advantage on the cell analysis detection and imaging.

Preparation of immuno-probes based on europium-chelate-adsorbed silica nanoparticles and magnetic nanoparticles and their application in detection of hepatitis B surface antigen

In this paper, a simple and reproducible method to synthesize intense fluorescence and photostable silica nanoparticles has been developed. Firstly, silica nanoparticles were prepared based on the Stober method, and hydrophobic europium chelates were adsorbed into their micro-holes by ultrasonication and phase-transfer solvent. Then they were modified by cationic polyelectrolyte polydiallyldimethylammonium chloride (PDAC) and anionic polyelectrolyte poly(acrylic acid) (PAA) layer by layer. Using them as detection probes and magnetic nanoparticles as capture probes, a novel immunoassay for determination of hepatitis B surface antigen (HBsAg) was proposed. Under the optimal experimental conditions, the immuno-probes performed with a good linear range over 10–200 ng mL−1 with a calibration curve equation of y = −549.24 + 652.44x (R = 0.9901). Based on the hydrophobicity and intense fluorescence europium chelates absorbed into silica nanoparticles, one-step fluorescence immunoassay has been realized and may have potential applications in clinical assays.

The discrimination of three genotypes in STR locus D5S818 based on ultraviolet spectroscopy-chemical pattern recognition

A simple, sensitive and low-cost approach for genotyping of a short tandem repeat (STR) based on ultraviolet spectroscopy (UVS)-chemical pattern recognition is presented. Genotypes 10-11, 11-11 and 11-12 of STR locus D5S818 are selected as the objective subjects. Through optimized polymerase chain reaction and ultraviolet spectrum measurement, ultraviolet spectra of all samples are obtained. Based on principal discriminant variate (PDV) and discriminant partial least squares (DPLS), PDV and DPLS models are established by using ultraviolet spectra as recognition variables. By optimizing the weight parameter λ in PDV algorithms and the number of latent variables in DPLS algorithms, optimal PDV and DPLS models are obtained. The two optimal models have good separability and robustness, as well as excellent prediction accuracy, which provides a methodological support for establishing ultraviolet spectrum-based classification for all genotypes of D5S818 locus and other STR loci.