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Fluorescent Ag clusters conjugated with anterior gradient-2 antigen aptamer for specific detection of cancer cells
摘要： Fluorescent probes with small size, low toxic and specific recognition are of fundamental interests as well as of practical prospects in bioimaging. Though various probes have been reported up to now, including traditional organic dye, quantum dots, rare earth-based particles, and recently emerged carbon dots, silicon dots, polymer dots and metal cluster et al., the relatively large size and lack of specify are far from satisfaction in cellular imaging. As confirmed in previous reports, the large size might influence the functions of target, where the consequent drawback of non-specific is requiring conjugate with additional ligands which brings even larger size and complex procedures. In such a context, fluorescent metal nanoclusters have rapidly attracted widely concern for their integrated advantages of small size, high stability, unique selectivity and tunable properties by simply selecting different stabilizer. In considering a wide variety of stabilizer, aptamer, as a class of ssDNA, has received particular interest because of the easy production, reduced size comparing with antibody and selectively binding ability in molecule level with specific structures. Former researches have proved that cytosine has strong interaction with Ag cations. Therefore, colorful Ag clusters (AgNCs) have been continuously prepared using different DNA sequences in a simple reductive reaction after mixing both aptamer and Ag cation. Additionally, the as synthesized AgNCs do not influence the selectivity of the aptamer itself. For example, Sun et al. reported a one-step process to synthesize silver nanoclusters by specific aptamer which can selectively image the nuclei of CCRF cells, clearly demonstrates the strength of the aptamer capsulated Ag clusters. Anterior gradient protein 2 homolog (AGR), a homolog of xenopus anterior gradient-2 (XAG-2) of Xenopus laevis, is a typical protein that secret by gland cancer cell. Since being discovered as a pro-oncogenic protein that weakens p53 gene activity in 2004. Clinical studies have shown that AGR is highly expressed in pancreatic, breast, and prostate cancer cells, etc. The molecular function and clinical relevance of AGR with variety cancers have thus been increasingly investigated. Specifically, it is a functional protein that plays a key role in variety of biological systems, including the development of vertebrate tissue and the inflammatory tissue injury response. Overall, Tian's results demonstrated that AGR overexpression could predict poor overall survival (OS) and poor time to tumor progression (TTP) of all solid tumor patients. Therefore, fluorescence recognizing of AGR is important for detecting gland cancer cells. At present, a number of reports related with AGR have been reported, but few on specific recognition probes. Through a series of screening, Wu et al. discovered AGR's corresponding aptamer “C14B1”. Few years later, Hu et al. successfully achieved the direct detection of AGR in vitro. However, in the cell imaging field, there is scarcely report on AGR detection. Therefore, synthesis of fluorescent AgNCs conjugating with aptamer to target AGR could provide a novel method for recognizing human gland cancer cell with a high selectivity, efficiency, and low cytotoxicity. In this paper, modified AGR aptamer (MA) were used as template to synthesize AgNCs. Specifically, MA's sequence is 5′-CGG GTG GGA GTT GTG GGG GGG GGT GGG AGG GTT TTTTT CCC CCC CCC CCC-3′ (50 bases). This sequence consists of two functional parts, AGR-apt sequence for recognition AGR in breast cancer (MCF-7) cells, where 12 cytosine base sequence (12C) for effectively preparing fluorescent AgNCs. According to Li's research, a T5 loop (-TTTTT-) could enhance the fluorescence intensity and avoid the influence of space hindrance. It was incorporated between the 3′ end of the apt and 12C sequence. Eventually, according to optimized reaction conditions, MA stabilized silver nanocluster (MA@AgNCs) with a small size, suitable stability, good selectivity was prepared. The fluorescence excitation peak and emission peak of MA@AgNCs were located at 510 nm and 565 nm respectively with a quantum yield as high as 87.43%. Moreover, MA@AgNCs shows descent specific recognition of MCF-7 cells, suggesting the prepared MA@AgNCs have the ability to selective target gland cancer cell and potentially utilized for clinical diagnosis and treatment.
关键词： Bio-probe,Cell imaging,Anterior gradient-2 antigen,Silver nanoclusters,Aptamer
更新于2025-09-23 15:23:52
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Diamond like carbon films with embedded Cu nanoclusters deposited by reactive high power impulse magnetron sputtering: Pulse length effects
摘要： In the present study diamond like carbon films with embedded Cu nanoclusters (DLC:Cu films) were deposited by reactive high power impulse magnetron sputtering (HIPIMS). HIPIMS pulse length (pulse on time) effects were considered. The dependence of the chemical composition on pulse length was found. Structure of diamond like carbon matrix of the nanocomposite films studied by Raman scattering spectroscopy has indicated weak increase of the sp3/sp2 carbon bond ratio with HIPIMS pulse length. Studies of the shape and dimensions of copper nanoclusters performed by He ion microscopy have shown that increase of the HIPIMS pulse on time resulted in increased number of the nanoclusters and subsequent increase of the Cu nanoclusters size. Study of optical properties revealed surface plasmon resonance effect in all investigated films. Correlation between the optical absorption spectra and photoexcited charge carrier relaxation time recorded by the pump probe spectroscopy was found. The highest relaxation time was observed at the excitation wavelength close to the absorption surface plasmon resonance peak wavelength The highest maximum relaxation time was observed for the DLC:Cu film deposited by using HIPIMS pulse of 400 μs on time. It was explained by the dependence of the relaxation time on Cu nanocluster size.
关键词： Pulse length,Diamond-like carbon,High-power pulsed magnetron sputtering,Structure,Optical properties,X-ray photoelectron spectroscopy,Copper,Nanoclusters
更新于2025-09-23 15:23:52
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Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications
摘要： Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.
关键词： luminescence,spectroscopy,GSH-Ag Nanoclusters,optical absorption
更新于2025-09-23 15:23:52
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Atomically Precise Bimetallic Nanoclusters as Photosensitizers in Photoelectrochemical Cells
摘要： The atomically precise bimetallic nanocluster, Au24Ag20(PhCC)20(SPy)4Cl2 (1), is for the first time employed as a stable photosensitizer for photoelectrochemical applications. The sensitization of TiO2 nanotube arrays (TNA) with 1 greatly enhances the light harvest ability of the composite, as 1 shows high molar-extinction-coefficient in the UV-Vis region. Compared to a more standard Au25(SG)18 -TNA (2-TNA, SG: Glutathione), 1-TNA shows a much better stability under illumination both in neutral and basic conditions. The precise composition of the photosensitizers enables a direct comparison of the sensitization ability between 1 and 2. With the same cluster loading, the photocurrent produced by 1-TNA is 15 times larger than 2-TNA. The superior performance of 1-TNA over 2-TNA is attributed not only to the higher light absorption ability of 1, but also to the higher charge-separation efficiency. Besides, a ligand effect on the stability of the photoelectrode and charge-transfer between the NCs and the semiconductor is revealed. Our work paves the way to study the role of metal nanoclusters as photosensitizers at the atomic level, which is essential for the design of better material for light energy conversion.
关键词： Energy Conversion,Bimetallic Nanoclusters,Photosensitizers,Nanostructured Materials,Photoelectrochemical Cells
更新于2025-09-23 15:23:52
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Selective reduction of CO2 to CO under visible light by controlling coordination structures of CeOx-S/ZnIn2S4 hybrid catalysts
摘要： Engineering the electronic properties of heterogeneous catalysts is an important strategy to enhance their activity towards CO2 reduction. Herein, we prepared partially sulfurized cerium oxide (CeOx-S) nanoclusters with the size less than 2 nm on the surface of ZnIn2S4 layers. Surface electronic properties of CeOx-S nanoclusters are facilely modulated by cerium coordination to sulfur, inducing the emergence of abundant Ce3+ and oxygen vacancies. For the photoreduction of CO2, CeOx-S/ZnIn2S4 hybrid catalysts exhibited a CO productivity of 1.8 mmol g?1, which was twice as higher as that of ZnIn2S4 catalyst using triethylamine as a sacrificial electron donor. Further mechanistic studies reveal that the photogenerated electrons are trapped by oxygen vacancies on CeOx-S/ZnIn2S4 catalysts and subsequently transfer to CO2, benefiting the activation of CO2. Moreover, the extremely high selectivity of CO is derived from the weak adsorption of CO on the surface of CeOx-S/ZnIn2S4 catalysts.
关键词： CeOx-S Nanoclusters,CO2 photoreduction,Electronic properties,Partial sulfurization,Visible light
更新于2025-09-23 15:22:29
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Photoluminescent Ag nanoclusters for reversible temperature and pH nanosenors in aqueous solution
摘要： A facile, straightforward, and green method was reported for the preparation of water-soluble and highly luminescent silver nanoclusters (AgNCs) using captopril (Capt) as a stabilizing agent. The as-prepared Capt@AgNCs exhibited bright red emission with a strong peak centered at 637 nm and showed low toxicity and good stability. Interestingly, the AgNCs displayed temperature sensitivity based on obvious temperature dependence of the fluorescence emission intensity. Furthermore, the AgNCs showed a good reversible and linear response to the environment temperature over the range from 10 °C to 45 °C with a high resolution and activation energy, which allowed its potential application as a fluorescent nanothermometer. In addition, the AgNCs were prepared to monitor pH via the fluorescence intensity of AgNCs responding sensitively to pH fluctuating within a wide range from 2.08 to 6.06. The study provides promising applications as a convenient and eco-friendly fluorescent temperature and pH nanosenser in environmental and biological fields.
关键词： pH nanosensors,Temperature nanosensors,Fluorescence,Silver nanoclusters
更新于2025-09-23 15:22:29
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Properties of Au incorporated In2O3 films
摘要： Effect of gold loading on the structural, morphological, optical and electrical properties of RF magnetron sputtered In2O3 films is discussed. Annealing is done to analyse the properties of heavily Au loaded In2O3 film after thermal treatment. Au acts as a nucleation centre and improves the crystalline quality of cubic bixbyite In2O3 films with moderate Au loading concentration. FESEM and AFM images of the as-deposited films present smooth surface morphology with a dense distribution of small grains. Random distribution of Au nanorods can be seen in the FESEM image of the 10 wt% Au incorporated film annealed at a temperature of 400 °C. The present study reveals the formation of smooth, crack-free, crystalline In2O3 films with Au incorporation. XPS analysis suggests the predominance of metallic state of Au in the Au loaded films. Absorption studies show an enhanced absorption in both as-deposited and annealed Au loaded films. Transmittance of In2O3 films is considerably modified but electrical properties are not much modified by Au incorporation. Enhancement in UV luminescence emission of In2O3 films ~378 nm is observed with Au incorporation up to 3 wt%. Intense UV emission in Au incorporated films opens a possibility of using these films for UV light emission applications.
关键词： Au incorporation,In2O3,UV emission enhancement,Au nanoclusters,Surface plasmon resonance
更新于2025-09-23 15:22:29
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Ag-location-based color-tunable fluorescent AuAg nanoclusters for “turn-on” and “turn-off” detection of l-cysteine
摘要： The color-tunable AuAg nanoclusters (AuAg NCs) are designed by adjusting the location of Ag element, in which β-lactoglobulin (β-Lg) serves as the capping and reducing agent. The mono-metal Au NCs emit red-fluorescent emission (red-Au NCs@β-Lg); however, the stronger metallophilic interaction between Au and Ag facilitate the smaller size, and then the bimetal AuAg NCs@β-Lg present yellow emission (yellow-AuAg NCs@β-Lg). A "Ag+ shell" outside the AuAg NCs@β-Lg cause the emission change to orange (orange-AuAg NCs@β-Lg-Ag+). This is the first time for Ag+ to tune continuously the emission wavelength of AuAg NCs. TEM proves that the size of particle has a close relationship with the fluorescence emissions. L-cysteine (Cys) stabilized the protective effect of β-Lg and shows a "turn on" effect on the fluorescence intensity of yellow-AuAg NCs@β-Lg. In contrary, the strong interaction between Cys and Ag+ destroys the protection of β-Lg to the core of yellow-AuAg NCs@β-Lg and shows a distinct "turn off" effect on the fluorescence intensity of orange-AuAg NCs@β-Lg-Ag+. The above phenomenon has been successfully applied to the detection of Cys in the Hela cells. This location-based color-tunable strategy is expected to open up a new potential to improve the performance of NCs.
关键词： L-cysteine,Color-tunable,Ag-location,AuAg nanoclusters
更新于2025-09-23 15:22:29
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Integration of fluorescence imaging and electrochemical biosensing for both qualitative location and quantitative detection of cancer cells
摘要： In this work, DNA-templated silver nanoclusters (DNA-AgNCs) with unique fluorescent and electrochemical properties are prepared as dual signal probes for both qualitative imaging and quantitative detection of cancer cells in an integrated system. ITO electrode that has good light transmittance and electric conductivity is employed as a substrate for dual analysis of cancer cells. ITO electrode is firstly modified by AS1141 aptamer, which could selectively bind to nucleolin overexpressed on the surface of a model breast cancer cell, MCF-7 cell line. The composite of mucin 1 antibody (anti-MUC1) and DNA-AgNCs then binds to MUC1 on the surface of captured MCF-7 cell, forming a sandwich-like structure. Therefore, our method allows noninvasive fluorescence imaging and amplified electrochemical detection using a single labeling platform, providing a biocompatible and highly specific method for adequate analysis of cancer cells. Experimental results demonstrate that strong red fluorescence of DNA-AgNCs clearly displays the loading of cancer cells on ITO electrode after dual recognition, and amplified electrochemical signals of DNA-AgNCs enable improved sensitivity toward quantitative analysis with a detection limit of 3 cells.
关键词： ITO electrode,DNA-templated silver nanoclusters,MCF-7 cell,fluorescent imaging,electrochemical detection
更新于2025-09-23 15:22:29
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Electrochemistry of Atomically Precise Metal Nanoclusters
摘要： Thiolate-protected metal nanoparticles containing a few to few hundred metal atoms are interesting materials exhibiting unique physicochemical properties. They encompass the bulk-to-molecule transition region, where discrete electronic states emerge and electronic band energetics yield to quantum con?nement e?ects. Recent progresses in the synthesis and characterization of ultrasmall gold nanoparticles have opened up new avenues for the isolation of extremely monodispersed nanoparticles with atomically precision. These nanoparticles are also called nanoclusters to distinguish them from other regular metal nanoparticles with core diameter >2 nm. These nanoclusters are typically identi?ed by their actual molecular formulas; prominent among these are Au25(SR)18, Au38(SR)24, and Au102(SR)44, where SR is organothiolate. A number of single crystal structures of these nanoclusters have been disclosed. Researchers have e?ectively utilized density functional theory (DFT) calculations to predict their atomic and electronic structures, as well as their physicochemical properties. The atomically precise metal nanoclusters have been the focus of recent studies owing to their novel size-speci?c electrochemical, optical, and catalytic properties. In this Account, we highlight recent advances in electrochemistry of atomically precise metal nanoclusters and their applications in electrocatalysis and electrochemical sensing. Compared with gold nanoclusters, much less progress has been made in the electrochemical studies of other metal nanoclusters, and thus, we mainly focus on the electrochemistry and electrochemical applications of gold-based nanoclusters. Voltammetry has been extremely powerful in investigating the electronic structure of metal nanoclusters, especially near HOMO and LUMO levels. A sizable opening of HOMO?LUMO gap observed for Au25(SR)18 gradually decreases with increasing nanocluster size, which is in line with the change in the optical gap. Heteroatom-doping has been a powerful strategy to modify the optical and electrochemical properties of metal nanoclusters at the atomic level. While the superatom theory predicts 8-electron con?guration for [Au25(SR)18]? and many doped nanoclusters thereof, Pt- and Pd-doped [PtAu24(SR)18]0 and [PdAu24(SR)18]0 nanoclusters show dramatically di?erent electronic structures, as manifested in their optical spectra and voltammograms, suggesting the occurrence of the Jahn?Teller distortion in these doped nanoclusters. Furthermore, metal-doping may alter their surface binding properties, as well as redox potentials. Metal nanoclusters o?er great potential for attaining high activity and selectivity in their electrocatalytic applications. The well-de?ned core?shell structure of a metal nanocluster is of special advantage because the core and shell can be independently engineered to exhibit suitable binding properties and redox potentials. We discuss recent progress made in electrocatalysis based upon metal nanoclusters tailored for water splitting, CO2 conversion, and electrochemical sensing. A well-de?ned model nanocatalyst is absolutely necessary to reveal the detailed mechanism of electrocatalysis and thereby to lead to the development of a new e?cient electrocatalyst. We envision that atomically controlled metal nanoclusters will enable us to systematically optimize the electrochemical and surface properties suitable for electrocatalysis, thus providing a powerful platform for the discovery of ?nely tuned nanocatalysts.
关键词： quantum con?nement,electrocatalysis,atomically precise metal nanoclusters,electrochemistry,electrochemical sensing
更新于2025-09-23 15:21:21