One-pot synthesis of water-dispersible Ag2S quantum dots with bright fluorescent emission in the second near-infrared window.

The second near-infrared window (NIR-II, wavelength of 1.0-1.4 µm) is optimal for the bioimaging of live animals due to their low albedo and endogenous autofluorescence. Herein, we report a facile and one-pot biomimetic synthesis approach to prepare water-dispersible NIR-II-emitting ultrasmall Ag(2)S quantum dots (QDs). Photoluminescence spectra showed that the emission peaks could be tuned from 1294 to 1050 nm as the size of the Ag(2)S QDs varied from 6.8 to 1.6 nm. The x-ray diffraction patterns and x-ray photoelectron spectra confirmed that the products were monoclinic α-Ag(2)S. Fourier transform infrared spectrograph analysis indicated that the products were protein-conjugated Ag(2)S QDs. Examination of cytotoxicity and the hemolysis test showed that the obtained Ag(2)S QDs had good biocompatibility, indicating that such a nanomaterial could be a new kind of fluorescent label for in vivo imaging.

Shape-controlled synthesis of protein-conjugated silver sulfide nanocrystals and study on the inhibition of tumor cell viability.

Stable protein-conjugated silver sulfide nanoparticles, nanorods and nanowires have been prepared by an aqueous chemistry method and the study results showed they had potential applications for tumor treatment.

Antineoplastic activities of protein-conjugated silver sulfide nano-crystals with different shapes.

In this paper, antineoplastic activities of protein-conjugated silver sulfide nano-crystals with different shapes were described in detail. Transmission electron microscope analysis demonstrated that stable and well-disperse protein-conjugated silver sulfide nano-particles, nano-rods, and nano-wires could be prepared by aqueous chemistry method. The Fourier transform infrared spectrograph analysis indicated the strong coordination between silver sulfide surfaces and -OH and -NH groups in bovine serum albumin. The antineoplastic activities of protein-conjugated silver sulfide nano-crystals were examined by cell viability analysis, optical and electron microscopy methods. The results showed that nano-particles, nano-rods and nano-wires could inhibit the proliferations of human hepatocellular carcinoma Bel-7402 cells and C6 glioma cells, and the activities were size-dependent.

Detection of homo- or hetero-association of Doks by fluorescence resonance energy transfer in living cells.

PURPOSE: The Dok proteins represent a family of adaptor proteins serving as common substrates for protein tyrosine kinases and play an important role in regulating signal transduction in multiple cell functions. Dimerization of Dok proteins may represent a powerful and flexible regulatory mechanism that can achieve a variety of consequences. This study aims to detect the homo- or hetero-association of Doks in living cells. PROCEDURE: The transfection of CFP or YFP fusion protein constructs was carried out using lipofectamine 2000. FRET Measurements were performed using three-channel microscopy and Spectroscopy. RESULTS: By using fluorescence resonance energy transfer technology, we demonstrated, for the first time to our knowledge, that Dok5 and Dok1 could form homomeric and heteromeric associations in living cells. Moreover, pleckstrin homology (PH) domain was found to be essential for homomeric associations of Dok5, while PH domain and phosphotyrosine binding domain were found to be crucial for homomeric associations of Dok1 or heteromeric associations between Dok1 and Dok5. CONCLUSION: The mechanisms underlying Doks' association may benefit the further understanding of the important role of Dok proteins in regulating signal transduction activated by tyrosine kinases.

Detection of constitutive heterodimerization of the integrin Mac-1 subunits by fluorescence resonance energy transfer in living cells.

Macrophage differentiation antigen associated with complement three receptor function (Mac-1) belongs to beta2 subfamily of integrins that mediate important cell-cell and cell-extracellular matrix interactions. Biochemical studies have indicated that Mac-1 is a constitutive heterodimer in vitro. Here, we detected the heterodimerization of Mac-1 subunits in living cells by means of two fluorescence resonance energy transfer (FRET) techniques (fluorescence microscopy and fluorescence spectroscopy) and our results demonstrated that there is constitutive heterodimerization of the Mac-1 subunits and this constitutive heterodimerization of the Mac-1 subunits is cell-type independent. Through FRET imaging, we found that heterodimers of Mac-1 mainly localized in plasma membrane, perinuclear, and Golgi area in living cells. Furthermore, through analysis of the estimated physical distances between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) fused to Mac-1 subunits, we suggested that the conformation of Mac-1 subunits is not affected by the fusion of CFP or YFP and inferred that Mac-1 subunits take different conformation when expressed in Chinese hamster ovary (CHO) and human embryonic kidney (HEK) 293T cells, respectively.