- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
AuxAg1-x Nanocomposites with 40-Fold Emission Enhancement Formed by the Electrostatic Assembly of Gold Nanoclusters and Silver Nanoclusters for Bioimaging and Bioanalysis
摘要： Noble metal nanoclusters (NCs) have been widely used in bioimaging and bioanalysis due to their unique molecular-like structures and good biocompatibility. Bright nanomaterials with high quantum yields are in need for widespread applications. Unfortunately, the weak photoluminescence (PL) of metal NCs hampers their biomedical applications, and thus it is urgent to develop effective routes to enhance their brightness, especially in aqueous solutions. In this work, we reported a facile strategy to prepare highly luminescent AuxAg1-x nanocomposites (x: molar ratio of Au) by electrostatic-induced assembly of non-luminescent glutathione (GSH) stabilized silver NCs (GSH-Ag NCs) and weak orange-emitting GSH stabilized gold NCs (GSH-Au NCs) in aqueous solutions. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), UV-vis absorption spectroscopy and dynamic light scattering (DLS) shed light on the mechanism of PL enhancement. It was found that the positively charged gold nanoclusters and the negatively charged silver nanoclusters formed aggregates by electrostatic force, leading to a 40-fold fluorescence intensity enhancement compared with GSH-Au NCs. This was a novel method to strengthen the fluorescence of nanoclusters with such large enhancement in aqueous solutions. With the molar ratio of Au and Ag changing from 80:1 to 2:3, the emission maximum of the AuxAg1-x nanocomposites could be tuned from 590 to 548 nm. The electrostatic force of the Au0.50Ag0.50 nanocomposites enabled them to respond to pH. The Au0.50Ag0.50 nanocomposites were fluorescent turn-on and turn-off at pH 2.6 and pH 7.5, respectively. In this respect, they can be used as a fluorescent switch and be further used as a general recyclable pH probe in the range of 2.6-7.5. This work will inspire even better strategies to further improve the brightness of noble metal NCs.
关键词： nanocomposites,fluorescent switch,electrostatic force,silver nanoclusters,fluorescence enhancement,gold nanoclusters
更新于2025-11-14 15:23:50
-
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
-
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
-
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
-
A Single Fluorophore Ratiometric Nanosensor Based on Dual-Emission DNA-templated Silver Nanoclusters for Ultrasensitive and Selective Pb2+ Detection
摘要： Lead ion (Pb2+) is known as a major non-degradable environmental pollutant and is quite harmful to human health. In our investigation, a novel ratiometric fluorescent nanosensor with DNA-AgNCs as single fluorophore has been successfully constructed for ultrasensitive and specific detection of Pb2+. The single-strand DNA templated silver nanoclusters present green emission, which can be converted into red emission after approaching a specific DNA segment by forming duplex with its complementary DNA strands (ds-DNA-AgNCs). The ds-DNA-AgNCs contains rA cleavage site of Pb2+-dependent DNAzyme configuration. In the presence of Pb2+, the specific DNA segment would be released from the ds-DNA-AgNCs, resulting in discoloration of DNA-AgNCs from red to green. Since Pb2+ can successively cleave the rA site, the signal change from red to green emission is amplified. Thus, benefiting from the Pb2+-dependent DNAzyme and the charming properties of DNA-AgNCs, the proposed platform exhibits a good linear relationship from 0.001 nM to 10 nM with a detection limit of 1.0 pM for Pb2+ determination, which is lower than most of the reported Pb2+ biosensors. Moreover, this sensitive ratiometric fluorescent probe exhibits excellent selectivity toward Pb2+ detection in real samples, such as lake water, tap water, and human serum samples, illustrating the huge potential applications for complicated samples in the future.
关键词： Pb2+ detection,Ratiometric fluorescent nanosensor,DNA-templated silver nanoclusters,Single fluorophore
更新于2025-09-10 09:29:36
-
Detection of Various Biomarkers and Enzymes via Nanocluster-Based Fluorescence Turn-On Sensing Platform
摘要： The profiling of disease-related biomarkers is an essential procedure for the accurate diagnosis and intervention of metabolic disorders. Therefore, the development of ultrasensitive and highly selective fluorogenic biosensors for diverse biomarkers is extremely desirable. There is still a considerable challenge to prepare nanocluster-based fluorescence turn-on probes capable of recognizing multiple biomolecules. We herein provide a novel nanocluster-based chemical information processing system (CIPS) for the programmable detecting various metabolites and enzymes. This CIPS consists of the biocatalytic reactions between substrates and their respective oxidases to generate H2O2, which was then employed to synthesize bright fluorescent silver nanoclusters (Ag NCs). Utilizing this system, we are able to accurately probe a series of substrates/ corresponding oxidases with high sensitivity and specificity, including glucose/ glucose oxidase, uric acid/ uric acid oxidase, sarcosine/ sarcosine oxidase, choline/ choline oxidase, xanthine/ xanthine oxidase, and lactic acid/ lactic acid oxidase. Furthermore, this metabolite profiling CIPS can integrate with binary logic operations, which create an intelligently tool for the high throughput screening of various diseases in vitro (e.g., diabetes, gout, prostate cancer, cardiovascular disease, and lactic acidosis).
关键词： nanocluster-based fluorescence turn-on sensing platform,silver nanoclusters,chemical information processing system,biomarkers,enzymes
更新于2025-09-09 09:28:46
-
Effects of Rare-Gas Matrices on the Optical Response of Silver Nanoclusters
摘要： The optical response of silver clusters, Agn with n = 8, 20, 35, 58, 92, embedded in a rare-gas matrix are calculated in the framework of the Time-Dependent Density Functional Theory (TDDFT). We present a methodology able to reproduce with unprecedented accuracy the experimental spectra measured on metal clusters embedded in neon, argon, krypton and xenon solid matrices. In our approach, the metal cluster is surrounded by explicit rare-gas atoms and embedded in a polarizable continuum medium. Interactions with the surrounding medium affects both the position and the width of the surface plasmon absorption band of metal clusters. The size dependent shift of the surface plasmon band is evaluated in the case of a neon matrix. While the band shifts to lower energies (red shift) for large clusters, it shifts to higher energies (blue shift) for very small clusters.
关键词： Silver Nanoclusters,Optical,TDDFT,Plasmonics,Magnetic,Hybrid Materials,Rare-Gas Matrices
更新于2025-09-09 09:28:46
-
DNA-Stabilized Silver Nanoclusters for Label-Free Fluorescence Imaging of Cell Surface Glycans and Fluorescence Guided Photothermal Therapy
摘要： A multifunctional nanoplatform that enables the integration of biological detection, imaging diagnosis, and synergistic therapy into a single nanostructure holds great promise for nanoscience and nanomedicine. Herein, a novel theranostic platform was presented for label-free imaging of cell surface glycans based on DNA/silver nanoclusters (AgNCs) via hybridization chain reaction (HCR) and fluorescence guided photothermal therapy (PTT). In this strategy, a dibenzocyclooctyne (DBCO)-functionalized DNA and two hairpin structures of DNA/AgNCs probes were involved. Following metabolic glycan labeling, the binding of DBCO-functionalized DNA to cell surface initiated HCR, and then cell surface glycans were specifically labeled by DNA/AgNCs fluorescent probes. Furthermore, this signal amplification strategy was adopted in quantitative analysis, and the detection limit could be achieved as low as 20 cells in 200 μL binding buffer. Moreover, the remarkable photothermal properties of DNA/AgNCs via HCR, led to efficient killing of cancer cell and inhibited the tumor growth under imaging guide. In this strategy, DNA/AgNCs were utilized to detect the cellular glycans, which aided in overcoming the high cost and instability of fluorescent dyes. Simultaneously, the HCR process avoided the introduction of excessive azido-sugars under the precondition of ensuring apparent fluorescence. These results indicated that the developed nanoplatform has great potential for specific cell surface glycans imaging and fluorescence guided PTT.
关键词： DNA-stabilized silver nanoclusters,fluorescence guided photothermal therapy,hybridization chain reaction,cell surface glycans,label-free fluorescence imaging
更新于2025-09-09 09:28:46