[Homogeneous phase fluorescence assay based on NaYF4 : Er3+, Yb3+ UCNPs as donors].

Upconversion nanoparticles (UCNPs) of small size have great potential in homogeneous assay based on fluorescence resonance energy transfer (FRET). A novel approach of surface ligand-exchange for preparing water-soluble and amido-functionalized NaYF4 : Er3+, Yb3+ UCNPs with 12 nm was developed. The ligand exchange process was confirmed by Fourier transform infrared spectra.

[A new optical switch using upconversion nanoparticles conjugated aptamer].

As new class of fluorescent biolabels, upconversion nanoparticles (UCNPs) were very attractive for use as labels, compared with these traditional downconversion materials. It can eliminate problems associated with autofluorescence and scattered excitation light under near infrared light (NIR) excitation. In the present work, water-soluble NaYF4:Yb3+, Er+ UCNPs were successfully prepared by solvothermal synthesis, using branched polyethylenimine as the surfactants, and a generic design strategy for UCNPs conjugated aptamer based optical switch was presented.

[Homogeneous immunoassay technology based on near infrared upconversion fluorescence resonance energy transfer].

A FRET based assay utilizing NaYF4 : Yb3+, Tm3+ UCNPs as an energy donor, which can emit intense near infrared (NIR) upconversion emission around 800 nm ranges under illumination with a 980 nm laser, and GNPs as an energy acceptor, which has an surface plasmon absorption maximum at 784 nm, was demonstrated. Their optical properties satisfy the requirement of spectral overlap between donors and acceptors for FRET. A model assay for human IgG was then constructed, in which amino-functionalized NaYF4 : Yb3+, Tm3+ UCNPs and GNPs were first prepared and then conjugated with the antibody (goat antihuman IgG) and antigen (human IgG), respectively.

[CdSe/ZnSe quantum dots via a two-phase solution system process solubilization and spectroscopic characterization].

In the present work, the CdSe/ZnSe core/shell quantum dots (QDs) were successfully transferred from organic phase to water phase via a two-phase solution system process by surface coating with amphiphilic polymer. Surface coating with amphiphilic polymer is an effective method, which can form stable soluble QDs in water. However, the conventional polymer coating method is performed in homogeneous phase, and it easily induces the aggregation of the QDs attributing to the long chain of enlace of the polymer.

[Preparation, characterization and specific biological labeling of silica coated upconversion fluorescent nanocrystals].

The authors synthesized a kind of upconversion nanocrystals NaYF4:Yb3+, Er3+ via the hydrothermal assisted homogeneous precipitation method, and then the nanocrystal was coated with silica. The SEM image demonstrated that the as-prepared samples were uniform in size distribution with ca. 25 nm before and ca.

[Effect of hole transporting materials on photoluminescence of CdSe core/shell quantum dots].

Photoluminescence quenching of colloidal CdSe core/shell quantum dots in the presence of hole transporting materials was studied by means of steady state and time resolved photoluminescence spectroscopy. With increasing hole transporting materials concentration in the CdSe core/shell quantum dot solution, the photoluminescence intensity and lifetime decreased gradually. The photoluminescence quenching of CdSe/ZnSe quantum dots with adding hole transporting material N,N'-bis(1-naphthyl)-N, N'-diphenyl-1,1 '-biphenyl-4, 4'-diamine (NPB) is more efficient than N,N'-diphenyl-N, N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD).

[Study of applying fluorescence spectrum imaging to quantitative assay of proteins in bio-chip].

In the present work, the amount and the activity of the goat anti-human IgG, to bind the human IgG labelled with fluorescein isothiocyanate (FITC), immobilized on silicon surfaces modified with APTES and APTES-Glu, respectively, were studied using the fluorescence spectrum imaging (FSI), the results of which were compared with that of ellipsometry. It is shown that the amount of the human IgG labeled with FITC on APTES-Glu measured using FSI is 2.8 times higher than that on APTES, which is nearly coincident with the 2.

[Surface enhanced Raman spectroscopic study on the gold-labeled protein self-assembled surface].

The human IgG molecules were labeled with 13 nm gold nanoparticles and the complex of the gold-labeled human IgG molecules was immobilized on a silicon surface modified by 3-aminopropyltriethoxysilane and glutaraldehyde. The method increases not only the tightness but also the surface coverage for immobilization of the complex and retains protein configuration well on the silicon surface. The self-assembled complex surface was observed by AFM.