Fluorescent Metal Nanoclusters Research Articles

A new luminescent nickel nanocluster with solvent and ion induced emission enhancement toward heavy metal analysis

Expanding the family of fluorescent metal clusters beyond gold, silver, and copper has always been an issue for researchers to solve. In this study, a novel type of cysteine-capped nickel nanoclusters (Cys-Ni NCs) with bright turquoise emission was developed. The as-synthesized Ni NCs showed aggregation-induced emission enhancement (AIEE) properties across Cd2+ and various polar organic solvents. Concurrently, solvents with different viscosities were used to explore the principle of solvent-induced AIEE of Cys-Ni NCs, revealing a positive correlation between fluorescence intensity and solution viscosity. In addition, the concentration of Cd2+ that induced the AIEE effect was reduced by nearly two orders of magnitude in highly viscous solvents, indicating the possibility of Cys-Ni NCs as a promising nanomaterial platform for Cd2+ sensing analysis. Moreover, we propose a novel fluorescent sensing method for rapid detection of Cu2+ based on the carboxyl group of Cys-Ni NCs coupling with Cu2+. Further, validation of Cu2+ detecting methodologies in environmental water samples with the accuracy up to 93.94% underscores their potential as robust and efficient sensing platforms. This study expands the repertoire of fluorescent metal nanoclusters for highly sensitive and selective sensing of hazardous ions and paves the way for further exploration and wide applications in Cu2+ detection in biological and medicine fields.

Fluorescence 'turn-off-on' assays for neomycin sulphate and K+ ions with orange-red fluorescent molybdenum nanoclusters.

Fluorescent metal nanoclusters (MNCs) have found extensive application in recognizing molecular species. Here, orange-red fluorescent Arg-A. paniculata-MoNCs were synthesized using Andrographis paniculata leaf extract, arginine as a ligand, and MoCl5 as a metal precursor. The Arg-A. paniculata-MoNCs complex exhibited a quantum yield (QY) of 16.91% and excitation/emission wavelengths of 400/665 nm. The synthesized Arg-A. paniculata-MoNCs successfully acted as a probe for assaying neomycin sulphate (NS) via fluorescence turn-off and K+ ions via fluorescence turn-on mechanisms, respectively. Moreover, the developed probe was effectively used to develop a cellulose paper strip-based sensor for detection of NS and K+ ions. Arg-A. paniculata-MoNCs demonstrated great potential for sensing NS and K+ ions, with concentration ranges of 0.1-80 and 0.25-110 μM for NS and K+ ions, respectively. The as-synthesized Arg-A. paniculata-MoNCs efficiently detected NS and K+ ions in food and biofluid samples, respectively.

Fluorescent metal nanoclusters: prospects for photoinduced electron transfer and energy harvesting.

Research on noble metal nanoclusters (MNCs) (elements with filled electron d-bands) is progressing forward because of the extensive and extraordinary chemical, optical, and physical properties of these materials. Because of the ultrasmall size of the MNCs (typically within 1-3 nm), they can be applied in areas of nearly all possible scientific domains. The greatest advantage of MNCs is the tunability that can be imposed, not only on their structures, but also on their chemical, physical, and biological properties. Nowadays, MNCs are very effectively used as energy donors and acceptors under suitable conditions and hence act as energy harvesters in solar cells, semiconductors, and biomarkers. In addition, ultrafast photoinduced electron transfer (PET) can be practised using MNCs under various circumstances. Herein, we have focused on the energy harvesting phenomena of Au-, Ag-, and Cu-based MNCs and elaborated on different ways to apply them.

DNA-templated fluorescent metal nanoclusters and their illuminating applications.

After the discovery of DNA during the mid-20th century, a multitude of novel methodologies have surfaced which exploit DNA for its various properties. One such recently developed application of DNA is as a template in metal nanocluster formation. In the early years of the new millennium, a group of researchers found that DNA can be adopted as a template for the binding of metal nanoparticles that ultimately form nanoclusters. Three metal nanoclusters have been studied so far, including silver, gold, and copper, which have a plethora of biological applications. This review focuses on the synthesis, mechanisms, and novel applications of DNA-templated metal nanoclusters, including the therapies that have employed them for their wide range of fluorescent properties, and the future perspectives related to their development by exploiting machine learning algorithms and molecular dynamics simulation studies.

Bovine serum albumin protected Cd8 nanoclusters as efficient two-photon absorbers for near-infrared excited fluorescence imaging of intracellular pH

Metal nanocluster-based fluorescent sensors have made great progress in the field of analytical chemistry, but their practical applications in biological sensing were limited by poor stability, short wavelength excitation and low quantum yield. It is of great significance to develop NIR-excited metal nanocluster-based fluorescence sensors with high quantum yield. In contrast to noble metal nanoclusters (e.g., Au, Ag, and Pt), stable and affordable fluorescent metal nanoclusters have received relatively less research attention, with the exception for Cu nanoclusters. Herein, we developed a rapid one-pot route to synthesize cadmium nanoclusters employing bovine serum albumin (BSA) as both reducing and templating agent. The obtained Cd8NCs exhibited bright fluorescence emission with quantum yield of 13.8%. Of particular interest, the Cd8NCs showed remarkable capability as two-photon absorbers, with a two-photon absorption (TPA) cross section up to 1588 GM (excited at 730 nm). The TPA cross section was higher than that of BSA-protected AuNCs, and even exceeded that of conventional dyes by two orders of magnitude. In addition, the Cd8NCs exhibited pH-sensitive photoluminescence, and the pH-responsive mechanism was revealed by time-resolved fluorescence spectroscopy, transient absorption spectroscopy, etc. Benefiting from protein coating, Cd8NCs showed excellent biocompatibility and were successfully utilized as two-photon excited fluorescence sensors for intracellular pH.

Towards Green Synthesis of Fluorescent Metal Nanoclusters.

In the modern development of nanoscience and nanotechnology, metal nanoclusters have emerged as a foremost category of nanomaterials exhibiting remarkable biocompatibility and photo-stability having dramatically distinctive optical, electronic, and chemical properties. This review focuses on synthesizing fluorescent metal nanoclusters in a greener way to make them suitable for biological imaging and drug delivery application. The green methodology is the desired route for sustainable chemical production and should be utilized for any form of chemical synthesis including nanomaterials. It aims to eliminate harmful waste, uses non-toxic solvents, and employs energy-efficient processes for the synthesis. This article provides an overview of conventional synthesis methods, including stabilizing nanoclusters by small organic molecules in organic solvents. Then we focus on the improvement of properties, applications of green synthesized metal nanoclusters, challenges involved, and further advancement required in the direction of green synthesis of MNCs. There are plenty of problems for scientists to solve to make nanoclusters suitable for bio-applications, chemical sensing, and catalysis synthesized by green methods. Using bio-compatible and electron-rich ligands, understanding ligand-metal interfacial interactions, employing more energy-efficient processes, and utilizing bio-inspired templates for synthesis are some immediate problems worth solving in this field that requires continued efforts and interdisciplinary knowledge and collaboration.

Fabrication of water-soluble blue emitting molybdenum nanoclusters for sensitive detection of cancer drug methotrexate

• 6-aza 2-thiothymine was as a ligand for fabrication of fluorescent Mo NCs. • ATT-Mo NCs showed a strong emission peak at 448 nm when excited at 370 nm. • ATT-Mo NCs acted as a sensor for sensing of methotrexate. • ATT-Mo NCs-based fluorescence method exhibited impressive detection limit of 1.28 nM. • Methotrexate was quantified in its pharmaceutical compositions. Fluorescent metal nanoclusters have been widely applied for sensing of biologically active species, drugs and biomolecules. Herein, fabrication of molybdenum nanoclusters is performed via ligand mediated synthesis where 6-aza-2-thiothymine (ATT) is used as a capping agent. The as-synthesized ATT-Mo NCs have shown high ability to recognize cancer drug methotrexate. The as-prepared ATT-Mo NCs exhibited a quantum yield of 14.34%, and good stability, showing λ Em/Ex = 448/370 nm. Significantly, the fluorescence intensity of ATT-Mo NCs was effectively quenched with addition of MTX drug, showing a linear response toward MTX in the range of 62 nM – 10 μM, with a detection limit of 1.28 nM. Moreover, the as-synthesized ATT-Mo NCs have proven to be an inexpensive analytical method for the selective assay of methotrexate in real biological samples (urine). This method also shows practical applicability for the detection of methotrexate in its pharmaceutical compositions.

Synthesis of red emissive copper nanoclusters with 2-mercaptopyrimidine for promoting selective and sensitive fluorescent sensing of creatinine as a kidney disease biomarker in biofluids

Fluorescent metal nanoclusters synthesized from organic ligands have been proved best sensing tools for the detection of biologically active species. In this work, we have designed a simple one-step strategy for the preparation of red fluorescent copper nanoclusters (Cu NCs) using 2-mercaptopyrimidine (2-MPY). The 2-MPY-Cu NCs act as an efficient probe for promoting selective and sensitive fluorescence recognition of creatinine as a biomarker in biofluids. The as-prepared 2-MPY-Cu NCs exhibit a strong emission peak at 728 nm when excited at 390 nm. It is observed that several interactions (intramolecular H-bonding and π-π) between 2-MPY-Cu NCs and creatinine, leading to a dramatic fluorescence quenching (∼92 %), which promotes for fluorescent sensing of creatinine. As a result, 2-MPY-Cu NCs display remarkable quantitative fluorescence response to creatinine concentration (0.0625 × 10-6 to 5 × 10-6 mol/dm−3(−|-)) with the detection limit of 9.91 × 10-9 mol/dm−3(−|-). The developed analytical strategy was applied to assay creatinine in biofluids with promising analytical results. This method offers a simple and rapid analytical approach for fluorescent sensing of creatinine in real samples.

Metal nanoclusters combined with CRISPR-Cas12a for hepatitis B virus DNA detection

Since hepatitis B virus (HBV) infection can cause chronic viral hepatitis, increase the risk of liver fibrosis and cirrhosis, and ultimately result in hepatoma, it is of great significance to explore convenient, rapid, and sensitive diagnostic strategies for HBV DNA detection. In this study, we developed a novel and sensitive fluorescent biosensor for HBV detection based on the sensing system consisting of CRISPR-Cas12a enzymes and metal nanoclusters as the luminescent nanoprobes, involving gold nanoclusters (AuNCs), silver nanoclusters (AgNCs), and copper nanoclusters (CuNCs). The DNA probes could effectively be applied as the template for the preparation of fluorescent metal nanoclusters. In the presence of the HBV target, the trans-cleavage capability of Cas12a was able to be initiated to degrade DNA probes, which brought about the inhibition of metal nanoclusters formation, thereby giving minimal fluorescence signals. In comparison with AuNCs and AgNCs, the CuNCs-based nanosensor exhibited much higher sensitivity. In addition, the fluorescence response of CuNCs to HBV detection was significantly faster, which could be completed within 25 min without the requirements of sophisticated equipment or harsh reaction conditions. Moreover, the practical application of this analysis method was also demonstrated to detect HBV DNA target in human serum samples with satisfactory recovery, which was promising for simple, rapid, sensitive, and label-free HBV DNA bioanalysis.

Light-patterned fluorescent gold nanoclusters in polycarbonate films

Fluorescent metal nanoclusters embedded in rigid matrices are attractive for many applications, such as for use as light-emitting diodes and for optical data storage. Given the advantages of polycarbonate films, like high transparency and excellent toughness, the development of metal nanoclusters in these films could further enhance various applications. Herein, we fabricated fluorescent gold nanoclusters in a polycarbonate film using a photochemical process. The polymer film is doped with gold chloride and a photoinitiator and then irradiated by a light-emitting diode (365 nm), leading to the photoreduction of gold ions and the formation of bright fluorescent nanoclusters with a quantum yield of 15%. The as-formed nanoclusters display good photostability and retain their emission spectral shape over an extended period of time. These highly fluorescent structures have potential applications in the fabrication of authenticity markings and optoelectronic devices.

State of the Art and Perspectives on the Biofunctionalization of Fluorescent Metal Nanoclusters and Carbon Quantum Dots for Targeted Imaging and Drug Delivery.

The interface of nanobio science and cancer nanomedicine is one of the most important current frontiers in research, being full of opportunities and challenges. Ultrasmall fluorescent metal nanoclusters (MNCs) and carbon quantum dots (CQDs) have emerged as promising fluorescent nanomaterials due to their unique physicochemical and optical properties, facile surface functionalization, good photostability, biocompatibility, and aqueous dispersity. These characteristics make them advantageous over conventional fluorophores such as organic dye molecules and semiconductor quantum dots (QDs) for the detection, diagnosis, and treatment of various diseases including cancer. Recently, researchers have focused on the biofunctionalization strategy of the MNCs and CQDs which can tailor their physicochemical and biological properties and, in turn, can empower these biofunctionalized nanoprobes for diverse applications including imaging, drug delivery, theranostics, and other biomedical applications. In this invited feature article, we first discuss some fundamental structural and physicochemical characteristics of the fluorescent biocompatible quantum-sized nanomaterials which have some outstanding features for the development of multiplexed imaging probes, delivery vehicles, and cancer nanomedicine. We then demonstrate the diverse surface engineering of these fluorescent nanomaterials with reactive target specific functional groups which can help to construct multifunctional nanoprobes with improved targeting capabilities having minimal toxicity. The promising future of the biofunctionalized fluorescent quantum-sized nanomaterials in the field of bioanalytical and biomedical research is elaborately demonstrated, showing selected recent works with relevant applications. This invited feature article finally ends with a short discussion of the current challenges and future prospects of the development of these bioconjugated/biofunctionalized nanomaterials to provide insight into this burgeoning field of MNC- and CQD-based diagnostics and therapeutic applications.

Fluorescent papain-encapsulated platinum nanoclusters for sensing lysozyme in biofluid and gram-positive bacterial identification

Fluorescent metal nanoclusters, a new class of fluorophores, have been widely used in the fields of biosensing, biological imaging, catalysis and advanced therapeutics. In this study, papain-encapsulated platinum nanoclusters (papain-Pt NCs) were synthesized via a biomineralization process, which showed intense green fluorescence with maximum excitation and emission wavelengths at 380 and 490 nm. A panel of characterizations was performed to investigate the optical properties, morphology and surface chemistry of Pt NCs, demonstrating the accurate formation of papain-Pt NCs with good dispersity and stability. As a “turn-off” fluorescence biosensor, papain-Pt NCs exhibited selective and relatively sensitive detection of lysozyme with an excellent linear concentration in the range of 70−1000 nM and a detection limit of 16.94 nM at a signal-to-noise ratio of 3. Meanwhile, Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus and Microbacterium) cells stained with papain-Pt NCs could emit obvious green fluorescence, whereas their counterparts of Gram-negative bacteria (Escherichia coli, Rhodobacter and Rhizobium) exhibited no fluorescence signal. These results indicate that papain-Pt NCs could be used as fluorescent label-free nanoparticles for the purpose of identifying Gram-positive bacteria. Our current study provides a highly promising fluorescent nanomaterial for lysozyme detection and bacterial differentiation, and opens crucial insights into the design of hybrid bioinspired systems intended for various diseases.

The Use of the ROS Scavenger Cysteine as a Surface Ligand of Metal Nanoclusters and Its Bactericidal Elimination Effect

The bactericidal effects of fluorescent metal nanoclusters have impeded their bacterial bioimaging applications due to the reactive oxygen species (ROS) generation that is induced by the nanoclusters in bacteria to cause bacterial death. Herein, an ROS scavenger of cysteine was exploited as a surface ligand to prepare cysteine-conjugated gold nanoclusters (Cys–AuNCs) and cysteine-conjugated silver nanoclusters (Cys–AgNCs) using a facile hydrothermal approach. The structural and optical characterizations demonstrated successful syntheses of Cys–AuNCs and Cys–AgNCs. With the same weight concentration, the bactericidal effect increased in the order of Cys–AuNCs, Cys–AgNCs, and silver nanoparticles (AgNPs), according to the results of the bacterial growth curves. Furthermore, based on the results of the standard colony-counting method, the Cys–AuNCs revealed the best biocompatibility compared to those of the Cys–AgNCs and AgNPs in Escherichia coli (E. coli). The superior biocompatibility of the Cys–AuNCs can be attributed to the use of the ligand of cysteine as an ROS scavenger to reduce ROS in E. coli. Electron paramagnetic resonance (EPR) analyses indicated that the use of the ROS scavenger cysteine as the surface ligand of the Cys–AuNCs eliminated the ROS production induced by the Cys–AuNCs in E. coli. The biocompatible Cys–AuNCs were also confirmed as a fluorescent probe using confocal microscopy. Highly biocompatible Cys–AuNCs could be a potential fluorescent probe in the application of bacterial bioimaging.

Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications.

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

Modulating fluorescence emission of l-methionine-stabilized Au nanoclusters from green to red and its application for visual detection of silver ion

Gold nanoclusters (Au NCs) have been considered as novel heavy metal ions sensors due to their ultrafine size, photo-stability and excellent fluorescent properties. This work not only demonstrated a novel strategy to modulate the emission color of l-methionine stabilized Au NCs based on a unique manner of Ag(Ⅰ) adding, but successfully applied this strategy for visual detection of Ag(Ⅰ) in environmental water samples. The Au NCs prepared here had yellow-green fluorescence with emission peaks at 536 nm. When Ag(Ⅰ) was added, the emission peak showed a clear shift from 538 nm to 590 nm and the color showed a change from yellow-green to orange. The Ag(Ⅰ) of concentration from 18.0 to 210.0 μM could be linearly detected using this method with a limit of detection (LOD) of 8.54 μM. The formation mechanisms of these Au NCs was discussed and the strategy proposed here was promising for preparing new types of fluorescent metal nanoclusters and a new analytical method.

Supramolecular self-assembly and application of metal clusters

Metal nanoclusters (NCs) are relatively stable aggregates composed of several to several thousand metal atoms through physical or chemical bonding, and their size is generally less than 3 nm. It has excellent quantum size effect and has outstanding applications in many fields such as optics, electricity, magnetism, catalysis, chirality, etc. However, NCs have poor optical properties at room temperature, which limits their further applications in the optical field. Therefore, the assembly of metal clusters with different types of molecular materials is driven by non-covalent bonds inspired by the concepts of “aggregation-induced emission” (AIE) and “supramolecular chemistry”, which can not only regulate the optical properties of metal clusters, but also can realize multi-functional coordination. As an important category of supramolecular chemistry, self-assembly provides a way to construct ordered structures from the bottom up. Self-assembly mainly uses non-covalent interactions to precisely control the specific structure of the building element to obtain functionalized micro-nano materials. Supramolecular self-assembly is one of the hot research fields in the chemical industry. It has been widely used in biomedicine, environment, sensing, optoelectronic devices and catalysis due to its simple operation and easy availability of raw materials. Herein, firstly, this paper introduces the effect of self-assembly on the assembly structure in detail combining the research work of this research group and related research on the self-assembly of design metal clusters at home and abroad. The research involving the aggregation morphology and morphology of metal nanoclusters is currently in its infancy in the world, and is a relatively popular research topic. Therefore, the self-assembly strategy to achieve the control of the aggregation morphology and morphology of metal nanoclusters can enrich the research field of self-assembly and realize the functionalization of metal nanoclusters. Secondly, fluorescence is one of the most important properties of metal clusters. Compared with traditional PL materials, the quantum yield (QY) of metal nanoclusters is relatively low. In addition, the proportion of fluorescent metal nanoclusters is also very low. Therefore, precise control of the metal composition and clearly defined surface chemistry factors not only provide a basis for a firm understanding of the structure and fluorescence, but also provide a method for the design and preparation of new nanoclusters with PL enhancement and adjustable emission wavelength. Hence, the vibration and rotation of the ligands around the metal core can be effectively restricted, and non-radiative transitions can be reduced, thereby achieving enhanced fluorescence through self-assembly. The fluorescence intensity and emission wavelength of the metal clusters can be controlled by controlling the assembly conditions of the metal clusters. The effect of self-assembly on the luminescence of metal clusters is commonly regulated by solvent regulation, pH, and co-assembly of other molecules to obtain highly stable luminescent clusters. In addition, the research progress in the application of metal cluster assembly and other aspects are summarized. Although precious metal nanoclusters have been used in chemical sensing, biological fields, catalysis and light conversion materials, the stability of the metal nanoclusters itself is relatively poor and the fluorescence is relatively weak. The assembly of nanoclusters can well solve the above shortcomings. The cluster aggregates have strong PL intensity, good light stability, and wide emission wavelength, which makes it a new type of fluorophore used in chemical sensing, biological fields, catalysis and light conversion materials. Finally, the improved scope and future prospects of the new nanoclusters are summarized and emphasized. Our review is expected to open up new horizons for these scientists to effectively control the functional properties of nanoclusters.

Metal‐Organic Frameworks‐Based Fluorescent Nanocomposites for Bioimaging in Living Cells and in vivo†

AbstractMetal‐organic frameworks (MOFs) as a class of porous functional materials have attracted more and more attention for biomedical applications. To date, MOFs have been developed for bioimaging based on a series of advantages such as the large surface areas, high porosity, fluorescence functionalities and good biocompatibility. It is worth noting that organic or inorganic fluorescent materials such as fluorescent dyes, quantum dots, metal nanoclusters and nanosheets can combine MOFs or be encapsulated in MOFs to form fluorescent nanocomposites for excellent imaging function. Importantly, excellent imaging capabilities are of great significance in living cells and in vivo for detection, diagnosis and cancer therapy. In this review, we focus on the recent research of the bioimaging in living cells and in vivo based on various MOF‐based nanocomposites and their potential biological clinical applications.

"Turn-off" sensing probe based on fluorescent gold nanoclusters for the sensitive detection of hemin.

Balanced level of hemin in the body is fundamentally important for normal human organ function. Therefore, environmentally benign, stable, and fluorescent metal nanoclusters (NCs) for selective and sensitive detection of hemin have been investigated and reported. Herein, highly orange red emissive gold NCs are successfully synthesized using glutathione as a reducing and stabilizing agent (GSH-Au NCs). The clusters are characterized using various techniques like Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-vis spectroscopy, and fluorescence spectrometer. The fluorescence intensity of as-synthesized Au NCs strongly quenched upon addition of different concentrations of hemin. The decrease in fluorescence intensity of GSH-Au NCs has been applied for determination of hemin concentration in the linear range from 1 to 25nM with a low limit of detection (LOD) of 0.43nM. The method was also successfully applied for quantification of hemin in human serum sample. In view of this reality, the system can be considered as a possible strategy and excellent platform for determination of hemin in various areas of application.

Biomarker sensing platforms based on fluorescent metal nanoclusters.

Metal nanoclusters (NCs) and their unique properties are increasing in importance and their applications are covering a wide range of areas. Their remarkable fluorescence properties and easy synthesis procedure and the possibility of functionalizing them for the detection of specific targets, such as biomarkers, make them a very interesting biosensing tool. Nowadays the detection of biomarkers related to different diseases is critical. In this context, NCs scaffolded within an appropriate molecule can be used to detect and quantify biomarkers through specific interactions and fluorescence properties of the NCs. These methods include analytical detection and biolocalization using imaging techniques. This review covers a selection of recent strategies to detect biomarkers related to diverse diseases (from infectious, inflammatory, or tumour origin) using fluorescent nanoclusters.

A fluorescent aptasensor based on copper nanoclusters for optical detection of CD44 exon v10, an important isoform in metastatic breast cancer.

Recent studies suggest that breast cancer cells express various CD44 isoforms. CD44 is an integral transmembrane protein encoded by a single 20-exon gene. Exon v10 of CD44 plays a critical role in promoting cancer metastasis, so sensitive detection of this isoform helps in early diagnosis of metastatic breast cancer and facilitates the treatment process. This study aimed to use v10-specific aptamers to set up an optical aptasensor based on fluorescent metal nanoclusters. For this purpose, nanoclusters of silver, gold, and copper were prepared by different CD44 v10 DNA aptamers as molecular templates. UV-vis, TEM, and fluorescence spectrometer results confirmed the accuracy and quality of the synthesized aptamer-templated nanoclusters (Apt-NCs). Finally, we compared the performance of the as-prepared Apt-NCs in response to different cultured cell lines. According to the results, the optical response of M-Apt4-CuNCs was more efficient and correlated well with the concentrations of CD44 v10-enriched cells. The detection limit of the aptasensor was 40 ± 5 cells per mL.