Ni/Au and Ni/Ag hybrid magnetic nanoparticles have been prepared via a facile solution growth method, in which 1-hexadecylamine is used and can function as both reducing agent and stabilizer during the synthetic process. By reduction of Au or Ag in the reaction system, the reduced Au or Ag nanoparticles can adhere on the surface of Ni nanoparticles to form uniform hybrid structures after Ni nanoparticles were formed. From the surface-enhanced Raman scattering (SERS) spectrum of rhodamine 6G that obtained on the Ni/Au, Ni/Ag nanoparticles modified substrates; it is believed that the as-synthesized Ni/Au and Ni/Ag hybrid magnetic nanoparticles have great potential for high sensitive optical detection application. © 2012 Elsevier B.V.

Hou Xiaomiao    Xiaoling Zhang    Shutang Chen    Huaizhi Kang    谭蔚泓    

Colloids and Surfaces A: Physicochemical and Engineering Aspects

2012

Several heavy metal ions (HMIs), such as Cd , Pb , and Hg , are highly toxic even at very low concentrations. Although a large number of fluoroionphores have been synthesized for HMIs, only a few of them show detection limits that are below the maximum contamination levels in drinking water (usually in the nM range), and few of them can simultaneously detect and remove HMIs. In this work, we report a new fluoroionphore-ionic liquid hybrid-based strategy to improve the performance of classic fluoroionphores via a synergistic extraction effect and realize simultaneous instrument-free detection and removal of HMIs. As a proof-of-concept, Hg was chosen as a model HMI, and a rhodamine thiospirolactam was chosen as a model fluoroionphore to construct bifunctional fluoroionphore-ionic liquid hybrid 1. The new sensing system could provide obviously improved sensitivity by simply increasing the aqueous-to-ionic liquid phase volume ratio to 10:1, resulting in a detection limit of 800 pM for Hg , and afford extraction efficiencies larger than 99% for Hg . The novel strategy provides a general platform for highly sensitive detection and removal of various HMIs in aqueous samples and holds promise for environmental and biomedical applications. © 2012 American Chemical Society.

Jin Zhen    Xie De-Xun    Xiaobing Zhang    Gong Yi-Jun    谭蔚泓    

Analytical Chemistry

2012

The last two decades have witnessed the development and application of nucleic acid aptamers in a variety of fields, including target analysis, disease therapy, and molecular and cellular engineering. The efficient and widely applicable aptamer selection, reproducible chemical synthesis and modification, generally impressive target binding selectivity and affinity, relatively rapid tissue penetration, low immunogenicity, and rapid systemic clearance make aptamers ideal recognition elements for use as therapeutics or for in vivo delivery of therapeutics. In this feature article, we discuss the development and biomedical application of nucleic acid aptamers, with emphasis on cancer cell aptamer isolation, targeted cancer therapy, oncology biomarker identification and drug discovery. © 2012 The Royal Society of Chemistry.

Guizhi Zhu    Mao Ye    Donovan Michael J.    Erqun Song    Zilong Zhao    谭蔚泓    

Chemical Communications

2012

Continuing improvement in the pharmacological and therapeutic properties of drugs is driving the revolution in novel drug delivery systems. In fact, a wide spectrum of therapeutic nanocarriers has been extensively investigated to address this emerging need. Accordingly, this article will review recent developments in the use of nanoparticles as drug delivery systems to treat a wide variety of diseases. Finally, we will introduce challenges and future nanotechnology strategies to overcome limitations in this field. © 2012 Future Medicine Ltd.

Suwussa Bamrungsap    Zilong Zhao    Tao Chen    Wang Lin    Li Chunmei    Ting Fu    谭蔚泓    

Nanomedicine

2012

Fluorescence resonance energy transfer (FRET) strategy has been widely applied in designing ratiometric probes for bioimaging applications. Unfortunately, for FRET systems, sufficiently large spectral overlap is necessary between the donor emission and the acceptor absorption, which would limit the resolution of double-channel images. The through-bond energy transfer (TBET) system does not need spectral overlap between donor and acceptor and could afford large wavelength difference between the two emissions with improved imaging resolution and higher energy transfer efficiency than that of the classical FRET system. It seems to be more favorable for designing ratiometric probes for bioimaging applications. In this paper, we have designed and synthesized a coumarin-rhodamine (CR) TBET system and demonstrated that TBET is a convenient strategy to design an efficient ratiometric fluorescent bioimaging probe for metal ions. Such TBET strategy is also universal, since no spectral overlap between the donor and the acceptor is necessary, and many more dye pairs than that of FRET could be chosen for probe design. As a proof-of-concept, Hg was chosen as a model metal ion. By combining TBET strategy with dual-switch design, the proposed sensing platform shows two well-separated emission peaks with a wavelength difference of 110 nm, high energy transfer efficiency, and a large signal-to-background ratio, which affords a high sensitivity for the probe with a detection limit of 7 nM for Hg. Moreover, by employing an Hg-promoted desulfurization reaction as recognition unit, the probe also shows a high selectivity to Hg. All these unique features make it particularly favorable for ratiometric Hg sensing and bioimaging applications. It has been preliminarily used for a ratiometric image of Hg in living cells and practical detection of Hg in river water samples with satisfying results. © 2012 American Chemical Society.

Gong Yi-Jun    Xiaobing Zhang    Zhang Cui-Cui    Luo Ai-Li    Ting Fu    谭蔚泓     沈国励    俞汝勤   

Analytical Chemistry

2012

In this paper, CN-DPA was prepared as an effective colorimetric and fluorescent probe for copper ions (Cu) in aqueous solution. It exhibits good sensitivity and selectivity for Cu over other metal ions both in aqueous solution and on a simple colorimetric paper-made test kit. Upon addition of Cu, a remarkable color change from purple to colorless was easily observed by the naked eye, and a fluorescence quenching was also determined. Furthermore, CN-DPA can be used to quantitatively detect Cu. The linear range was 0-5 μM determined by absorption spectrometry. All these selective and sensitive results indicate that CN-DPA could meet the selective requirements for biomedical and environmental application and be sensitive enough to detect Cu in environmental water samples, even in drinking water, which has a limit of 20 μM defined by the U.S. Environmental Protection Agency. © 2011 The Royal Society of Chemistry.

Yamin Li    Xiaoling Zhang    Baocun Zhu    Xue Juan    Zhi Zhu    谭蔚泓    

Analyst

2011

We report here a carbon nanotube-based approach for label-free and time-resolved luminescent assay of lysozyme (LYS) by engineering an antilysozyme aptamer and luminescent europium(III) (Eu) complex. The sensing mechanism of the approach is based on the exceptional quenching capability of carbon nanotubes for the proximate luminescent Eu complex and different propensities of single-stranded DNA and the DNA/protein complex to adsorb on carbon nanotubes. The luminescence of a mixture of chlorosulfonylated tetradentate β-diketone-Eu and the antilysozyme aptamer was efficiently quenched by single-walled carbon nanotubes (SWNTs) unless the aptamer interacted with LYS. Due to the highly specific recognition ability of the aptamer for the target and the powerful quenching property of SWNTs for luminescence regents, this proposed approach has a good selectivity and high sensitivity for LYS. In the optimum conditions described, >700-fold signal enhancement was achieved for micromolar LYS, and a limit of detection as low as 0.9 nM was obtained, which is about 60-fold lower than those of commonly used fluorescent aptamer sensors. Moreover, due to the much longer lifetime of the Eu luminescence than those of the ubiquitous endogenous fluorescent components, the timeresolved luminescence technique could be conveniently used for application in complicated biological samples. LYS concentrations in human urine were thus detected using time-resolved luminescence measurement with satisfactory recoveries of 95-98%. © 2011 American Chemical Society.

Ouyang Xiangyuan    俞汝勤    Jianyu Jin    Jishan Li    Ronghua Yang    谭蔚泓     袁景利   

Analytical Chemistry

2011

Water-soluble CdSe quantum dots (QDs) were synthesized using mercaptosuccinic acid (MSA) as a stabilizer. The growth process and characterization of CdSe quantum dots were determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, Ultravioletvisible (UVvis) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Results demonstrated the MSA-capped CdSe QDs were highly crystalline and possessed good optical properties. Further, the resulting products could be used as fluorescent probes to detect Cu ions in physiological buffer solution. The response was linearly proportional to the concentration of Cu ion in the range 2×10 3.5×10 mol L with a detection limit of 3.4 nmol L. © 2010 Elsevier B.V. All rights reserved.

Shutang Chen    Xiaoling Zhang    Zhang Qiuhua    Hou Xiaomiao    Zhou Qi    Jilin Yan    谭蔚泓    

Journal of Luminescence

2011

Aptamers have emerged as promising molecular probes for in vivo cancer imaging, but the reported "always-on" aptamer probes remain problematic because of high background and limited contrast. To address this problem, we designed an activatable aptamer probe (AAP) targeting membrane proteins of living cancer cells and achieved contrast-enhanced cancer visualization inside mice. The AAP displayed a quenched fluorescence in its free state and underwent a conformational alteration upon binding to target cancer cells with an activated fluorescence. As proof of concept, in vitro analysis and in vivo imaging of CCRF-CEM cancer cells were performed by using the specific aptamer, sgc8, as a demonstration. It was confirmed that the AAP could be specifically activated by target cancer cells with a dramatic fluorescence enhancement and exhibit improved sensitivity for CCRF-CEM cell analysis with the cell number of 118 detected in 200 μl binding buffer. In vivo studies demonstrated that activated fluorescence signals were obviously achieved in the CCRF-CEM tumor sites in mice. Compared to always-on aptamer probes, the AAP could substantially minimize the background signal originating from nontarget tissues, thus resulting in significantly enhanced image contrast and shortened diagnosis time to 15 min. Furthermore, because of the specific affinity of sgc8 to target cancer cells, the AAP also showed desirable specificity in differentiating CCRF-CEM tumors from Ramos tumors and nontumor areas. The design concept can be widely adapted to other cancer cell-specific aptamer probes for in vivo molecular imaging of cancer.

Hui Shi    He Xiaoxiao    王柯敏    Wu Xu    Xiaosheng Ye    Guo QiuPing    谭蔚泓     Zhihe Qing    Xiaohaio hai Yang    Zhou Bing   

Proceedings of the National Academy of Sciences of the United States of America

2011

This article is a review of the development and application of aptamer probes for cell imaging. Aptamers selected against whole cells have been modified with different fluorescent dyes and nanomaterials, such as gold nanoparticles, quantum dots, and superparamagnetic iron oxide, for their use as imaging probes of live cells. These probes have been successfully used for cell imaging both in vitro and in vivo by optical imaging, magnetic resonance imaging (MRI), computed tomography (CT), and positron-emission tomography (PET). In this article, we discuss the development of different aptamer-based probes currently available for imaging of live cells and their applications in the biomedical field. © 2011 John Wiley & Sons, Inc.

Lopez-Colon    Jimenez Elizabeth    Mingxu You    Gulbakan Basri    谭蔚泓    

Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology

2011