Fluorescent Ag Research Articles

A low-cost biotin-streptavidin amplified quantum dot fluorescence immunosensor for enhancing cancer detection and imaging

Cancer is disease that among the leading causes of death, and the early accurate diagnosis are key to improve and the survival rate. However, developing the reliable, sensitive, cost-effective diagnostic tool remains a challenge. Although the quantum dots (QDs)-based fluorescence-linked immunosorbent assays (QD-FLISA) has the advantages of shorter detection time and high-through detection, the reliability with high sensitivity and cost-effectiveness need to be fully considered before their clinical application. In this study, the biotin-streptavidin (Bio-SA) system with high affinity were introduced into the QD-based fluorescence immunosensor to enhance the performance of cancer diagnosis. The Bio-SA FLISA was firstly constructed to detect alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA). Due to the high affinity of Bio-SA and the lower steric hindrance of long PEG length, the Bio-SA FLISA not only obtained excellent linear relationship between the fluorescence signal and Ag concentration, but also achieved low detection limits of 0.18 ng/mL for AFP and 0.08 ng/mL for CEA. Ever better, the cost of expensive primary antibodies in Bio-SA FLISA has been greatly reduced by 80–90 %, lowering the cost of this immunosensor. Clinical samples test also validated the accuracy of Bio-SA FLISA for AFP and CEA detection. Furthermore, the Bio-SA-QDs probes showed brighter fluorescent cellar imaging at the less usage of antibodies. In conclusion, this Bio-SA QDs-based immunosensor owned the advantages of low cost, sensitivity, stability and accuracy for cancer biomarkers detection, and exhibited excellent cellular imaging capacity, which was a powerful tool for enhancing cancer diagnosis.

Thermally Activated Delayed Fluorescent Ag(I) Complexes for Highly Efficient Scintillation and High‐Resolution X‐Ray Imaging

AbstractOrganic thermally activated delayed fluorescent (TADF) scintillators hold promising potential for applications in medical radiography and security detection, but the poor X‐ray absorption ability and inferior radioluminescence (RL) hampered their progression. Herein, the study has pioneered the development of high‐performance TADF Ag(I)‐based scintillators from M2X2(dppb)2 (M = Ag, Cu; X = Cl, Br, I) complexes with 1,2‐Bis(diphenylphosphino)benzene (dppb) ligand. In comparison with Cu(I) complexes, the Ag(I) series generally exhibited superior scintillation performance. Notably, Ag2Cl2(dppb)2 (Ag1) stands out with exceptionally high RL intensity (≈125% higher than that of CsI:Tl) and a low detection limit of 59.8 nGy s−1. The outstanding scintillation performance of Ag1 is primarily attributed to the synergistic effect of the high exciton utilization efficiency origin from a small singlet‐triplet energy gap, enhanced X‐ray absorption capacity by heavy atoms, and the high photoluminescence quantum yield (76.47% in ambient atmosphere). By fabricating a flexible film constructed with Ag1 submicron crystalline powders, a high spatial resolution of 25.0 lp mm−1 for X‐ray imaging is obtained. It offers new opportunities for utilizing TADF metal–organic complexes for highly efficient X‐ray scintillation and imaging.

Exploring the interaction between a fluorescent Ag(I)-biscarbene complex and non-canonical DNA structures: a multi-technique investigation.

Silver compounds are mainly studied as antimicrobial agents, but they also have anticancer properties, with the latter, in some cases, being better than their gold counterparts. Herein, we analyse the first example of a new Ag(I)-biscarbene that can bind non-canonical structures of DNA, more precisely G-quadruplexes (G4), with different binding signatures depending on the type of G4. Moreover, we show that this Ag-based carbene binds the i-motif DNA structure. Alternatively, its Au(I) counterpart, which was investigated for comparison, stabilises mitochondrial G4. Theoretical in silico studies elucidated the details of different binding modes depending on the geometry of G4. The two complexes showed increased cytotoxic activity compared to cisplatin, overcoming its resistance in ovarian cancer. The binding of these new drug candidates with other relevant biosubstrates was studied to afford a more complete picture of their possible targets. In particular, the Ag(I) complex preferentially binds DNA structures over RNA structures, with higher binding constants for the non-canonical nucleic acids with respect to natural calf thymus DNA. Regarding possible protein targets, its interaction with the albumin model protein BSA was also tested.

A wearable gloved sensor based on fluorescent Ag nanoparticles and europium complexes for visualized assessment of tetracycline in food samples.

The abuse of tetracycline antibiotics leads to accumulating residues in the human body, seriously affecting human health. Establishing a sensitive, efficient, and reliable method for qualitative and quantitative detection of tetracycline (TC) is necessary. This study integrated silver nanoclusters and europium-based materials into the same nano-detection system to construct a visual and rapid TC sensor with rich fluorescence color changes. The nanosensor has the advantages of a low detection limit (10.5nM), high detection sensitivity, fast response, and wide linear range (0-30μM), which can meet the analysis requirements of different types of food samples. In addition, portable devices based on paper and gloves were designed. Through the smartphone's chromaticity acquisition and calculation analysis application (APP), the real-time rapid visual intelligent analysis of TC in the sample can be realized, which guides the intelligent application of multicolor fluorescent nanosensors.

Nitrogen-contained Nanoporous Hyper-cross-linked Polymer: A New Turn-on Fluorescence Probe for Detection of Ag+ Ions in Aqueous Media.

A fluorescence probe was designed using a nitrogen-contained mesoporous hyper-cross-linked polymer precursor (NH2-HCP) in order to selectively detect silver (Ag+) ions. NH2-HCP exhibits fluorescence intensity, but upon the addition of Ag+, a significant enhancement in fluorescence signal is observed. The relationship between fluorescence intensity enhancement and Ag+ concentration shows a linear and monotonic trend. The probe's response to various other cations such as Al3+, Fe3+, Cd2+, Ni2+, Cu2+, Fe2+, Hg2+, Mg2+, Zn2+, Pb2+, Mn2+, Co2+, Ca2+, Na+, and K+, as well as halogen anions like F-, Cl-, Br-, and I- was also investigated. Under optimal conditions, the probe demonstrated a linear range of 0.1-3 μM and a detection limit of 0.01 μM.

General Gel-sol Method to Synthesize Various Highly Fluorescent Nanoclusters and Assay of Nuclease with the Near Infrared-emitting Gold Nanoclusters.

A general egg white gel-sol strategy for fabrication of highly fluorescent Au, Ag, Cu, and Pt nanoclusters (NCs) and the first example of using Au NCs for assay of nuclease activity and inhibition were described. The Au NCs enabled bright red fluorescence, and the other Ag, Cu, and Pt NCs have highly blue emission. The red-emitting Au NCs were further applied in assay of S1 nuclease activity and inhibition. Free hemin efficiently quenches the emission of Au NCs by photoinduced electron transfer due to the formation of Au NCs-hemin conjugates. However, G-quadruplex/hemin exerts negligible effect on its fluorescence due to no Au NCs-hemin conjugate formed. There are stronger electrostatic repulsion effects between both negatively charged G-quadruplex and Au NCs. Therefore, a novel G-quadruplex/hemin-based Au NCs fluorescent sensor for S1 nuclease was designed. A known G-rich oligonucleotide (ODN) serves as not only substrate for S1 nuclease but also for the construction of G-quadruplex/hemin. The G-rich ODN is hydrolyzed into fragments by S1 nuclease resulting in no G-quadruplex/hemin formation. Therefore, the free hemin quenches Au NCs fluorescence remarkably and the assay of S1 nuclease activity and inhibition has accomplished. Both the fluorescent NCs syntheses and the detection of S1 nuclease are facile and efficient.

Targeting of Silver Cations, Silver-Cystine Complexes, Ag Nanoclusters, and Nanoparticles towards SARS-CoV-2 RNA and Recombinant Virion Proteins.

Background: Nanosilver possesses antiviral, antibacterial, anti-inflammatory, anti-angiogenesis, antiplatelet, and anticancer properties. The development of disinfectants, inactivated vaccines, and combined etiotropic and immunomodulation therapy against respiratory viral infections, including COVID-19, remains urgent. Aim: Our goal was to determine the SARS-CoV-2 molecular targets (genomic RNA and the structural virion proteins S and N) for silver-containing nanomaterials. Methods: SARS-CoV-2 gene cloning, purification of S2 and N recombinant proteins, viral RNA isolation from patients’ blood samples, reverse transcription with quantitative real-time PCR ((RT)2-PCR), ELISA, and multiplex immunofluorescent analysis with magnetic beads (xMAP) for detection of 17 inflammation markers. Results: Fluorescent Ag nanoclusters (NCs) less than 2 nm with a few recovered silver atoms, citrate coated Ag nanoparticles (NPs) with diameters of 20–120 nm, and nanoconjugates of 50–150 nm consisting of Ag NPs with different protein envelopes were constructed from AgNO3 and analyzed by means of transmission electron microscopy (TEM), atomic force microscopy (AFM), ultraviolet-visible light absorption, and fluorescent spectroscopy. SARS-CoV-2 RNA isolated from COVID-19 patients’ blood samples was completely cleaved with the artificial RNase complex compound Li+[Ag+2Cys2−(OH−)2(NH3)2] (Ag-2S), whereas other Ag-containing materials provided partial RNA degradation only. Treatment of the SARS-CoV-2 S2 and N recombinant antigens with AgNO3 and Ag NPs inhibited their binding with specific polyclonal antibodies, as shown by ELISA. Fluorescent Ag NCs with albumin or immunoglobulins, Ag-2S complex, and nanoconjugates of Ag NPs with protein shells had no effect on the interaction between coronavirus recombinant antigens and antibodies. Reduced production of a majority of the 17 inflammation biomarkers after treatment of three human cell lines with nanosilver was demonstrated by xMAP. Conclusion: The antiviral properties of the silver nanomaterials against SARS-CoV-2 coronavirus differed. The small-molecular-weight artificial RNase Ag-2S provided exhaustive RNA destruction but could not bind with the SARS-CoV-2 recombinant antigens. On the contrary, Ag+ ions and Ag NPs interacted with the SARS-CoV-2 recombinant antigens N and S but were less efficient at performing viral RNA cleavage. One should note that SARS-CoV-2 RNA was more stable than MS2 phage RNA. The isolated RNA of both the MS2 phage and SARS-CoV-2 were more degradable than the MS2 phage and coronavirus particles in patients’ blood, due to the protection with structural proteins. To reduce the risk of the virus resistance, a combined treatment with Ag-2S and Ag NPs could be used. To prevent cytokine storm during the early stages of respiratory infections with RNA-containing viruses, nanoconjugates of Ag NPs with surface proteins could be recommended.

Fluorescent garlic-capped Ag nanoparticles as dual sensors for the detection of acetone and acrylamide.

In order to protect human health from the adverse impacts of acrylamide and acetone, simple analytical processes are required to detect low concentrations of acrylamide and acetone. Dual functional garlic-capped silver nanoparticles (G-Ag NPs) have been used as fluorescent sensors for acrylamide and acetone. This technique depends on the quenching of the photoluminescence (PL) intensity of G-Ag NPs with the interaction of either acrylamide or acetone. This fluorescent probe presented high selectivity toward acrylamide with a wide linear response of 0.01-6 mM with a limit of detection (LOD) of 2.9 μM. Moreover, this probe also acted as a selective and sensitive fluorescent sensor for the detection of acetone in the range of 0.1-17 mM with LOD of 55 μM. The applicability of G-Ag NPs as a proposed sensor for acrylamide was evaluated using a potato chips sample with a recovery percentage of 102.4%. Acetone concentration is also quantified in human urine samples and the recoveries ranged from 98.8 to 101.7%. Repeatability and reproducibility studies for acrylamide and acetone offered relative standard deviation (RSD) of 0.9% and 1.5%, and 0.77% and 1.1%, respectively.

Target-Activating and Toehold Displacement Ag NCs/GO Biosensor-Mediating Signal Shift and Enhancement for Simultaneous Multiple Detection.

Herein, we demonstrate that a new multicolor silver nanoclusters/graphene oxide (Ag NCs/GO) hybrid material, upon target response, undergoes a configuration transformation, based on entropy-driven enzyme-free toehold-mediated strand displacement reaction, achieving emission shift and enhancement. To realize the aim above, two different synthesis routes (route I and II) of synthesizing fluorescent Ag NCs for constructing toehold displacement Ag NCs/GO biosensor is designed and performed. Influenza A virus subtype genes (H1N1 and H5N1) as a model can efficiently initiate the operation of entropy-driven displacement reaction, resulting in activatable fluorescence. Red-emitting and green-emitting Ag NCs tethering the complementary sequence of H1N1 (pDNA1) and H5N1 (pDNA2) are indirectly immobilized on GO surface through binding with capture DNA (cDNA1 and cDNA2), respectively, forming multicolor pDNA-Ag NCs/GO nanohybrid materials. However, they do not exhibit nearly fluorescence signals attributed to energy transfer from donor Ag NCs to acceptor GO. Upon adding targets H1N1 and H5N1 (tDNA1 and tDNA2), pDNA1-Ag NCs and pDNA2-Ag NCs detach from GO, based on toehold-mediated strand displacement reaction, which interferes the energy transfer and leads to significant fluorescence enhancement. More interestingly, the activatable process is accompanied by remarkable hypsochromic shift (19 nm) or bathochromic shift (21 nm) emission with quite high fluorescence recovery rates (823.35% and 693.62%). Therefore, based on these phenomena, a novel multiple approach has been developed with the assistance of toehold displacement and Ag NCs/GO nanohybrid materials. As for the remarkable emission recovery and multichannel signal, the proposed approach displays the promising application prospect in accurate diagnosis and treatment.

Viable Severe Acute Respiratory Syndrome Coronavirus 2 Isolates Exhibit Higher Correlation With Rapid Antigen Assays Than Subgenomic RNA or Genomic RNA.

Background: Rapid identification and effective isolation are crucial for curbing the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To meet this requirement, antigen-detection rapid diagnostic tests (Ag-RDTs) are essential.Methods: Between February 2020 and August 2020 we performed a cohort study of patients with confirmed COVID-19. The clinical performance of Ag rapid fluorescence immunoassay (FIA) and Ag Gold was evaluated and compared in parallel with genomic and subgenomic real-time reverse transcription-polymerase chain reaction (rRT-PCR) and cell culture-based assays.Results: In total, 150 samples were tested. Of these, 63 serial samples were obtained from 11 patients with SARS-CoV-2 and 87 from negative controls. Serial respiratory samples were obtained 2 days prior to symptom onset (-2) up to 25 days post-symptom onset. Overall, for rRT-PCR-positive samples (n = 51), the detection sensitivity of Ag rapid FIA and Ag Gold was 74.5% and 53.49%, respectively, with a specificity of 100%; however, for samples with low cycle threshold (Ct) values, Ag rapid FIA and Ag Gold exhibited a sensitivity of 82.61% (Ct ≤ 30, 5.6 log10RNA copies/mL) and 80% (Ct ≤ 25, 6.9 log10RNA copies/mL), respectively. Despite low analytical sensitivity, both Ag-RDTs detected 100% infection in cell culture-positive samples (n = 15) and were highly effective in distinguishing viable samples from those with subgenomic RNA (66.66%). For both Ag-RDTs, all samples that yielded discordant results (rRT-PCR + ve/Ag-RDT -ve) were also negative by culture.Conclusion: The data suggest that Ag-RDTs reliably detect viable SARS-CoV-2; thus, they may serve as an important tool for rapid detection of potentially infectious individuals.

Magnetic-metals sunflower nanocomposites for significant fluorescence enhancement

The surface enhanced fluorescence effect of metal-enhanced substrates has been intensively investigated. However, recent developments of fluorescence substrates based on novel composites have attracted much attention. In this paper, Ag@Fe3O4 nanocomposites with special sunflower structures were synthesized by a typical solvothermal method. The fluorescence enhancement of as-prepared substrates was able to be optimized by adjusting the concentration of fluorescent molecules and Ag@Fe3O4 within the appropriate range. Moreover, the calculated fluorescence enhancement factor reached 13.2 fold while the concentration of detected Rhodamine B was 10−6 mol/L and limit of detection was as low as 7.59 × 10−8 mol/L. The significantly enhanced fluorescence mainly resulted from great electromagnetic enhancement and good stability could derive from appropriate distance between the fluorescent molecules and Ag nanoparticles in these special nanostructures. Furthermore, the excellent recyclability was ascribed to fast and reversible magnetic response of Fe3O4 nanoparticles surrounding the surface of Ag core. Therefore, sensitive and reproducible magnetic-metal substrates were obtained for efficient fluorescence detection.

A rapid fluorescent ratiometric Ag+ sensor based on synthesis of a dual-emission ternary nucleotide/terbium complex probe

To develop a fast, isothermal, enzyme-free and visible method for the on-site detection of silver ions (Ag+), a ratiometric Ag+ sensor was constructed based on a dual-emission ternary nucleotide terbium probe, fabricated by synthesizing the luminescent nanomaterial Luminol-GMP-Tb (LGT). We repositioned the fluorescent properties of the nanomaterial from the perspective of the inherent optical properties of two signal reporters (luminol and Tb3+) through highlighting the absorption, fluorescence steady-state measurement and time-resolved properties. Furthermore, based on the ingenious coordination interaction and energy transfer among Ag+, luminol and GMP-Tb, we hypothesized and confirmed that Ag+ induced morphology and luminescence changes of LGT through scanning electron microscopy and lifetime changes as well as fluorescence changes. Meanwhile, by means of a portable ultraviolet detector with dual wavelengths, based on the fluorescence excitation characteristics of each component, different photoluminescence color phenomena presented at different excitation wavelengths. Therefore, visual qualitative detection could be realized under a portable UV lamp with 254 nm for mainly visible green color change while 365 nm as built-in reference for blue-emitting luminol. The ratio calculation method and the enhanced luminescence ratio mechanism made LGT exhibited extremely high selectivity to Ag+. Quantitative detection Ag+ was realized in two ranges of 0.1 μM ~ 6 μM and 6 μM ~ 100 μM with a minimum detection limit of 65 nM. The method has been successfully exploited in real water samples with recovery rate between 99.7% and 106.38%, showing broad application prospects in food safety and environmental monitoring for the on-site detection of Ag+.

A novel disease-associated nucleic acid sensing platform based on split DNA-scaffolded sliver nanocluster

Disease-associated nucleic acids, such as DNAs and miRNAs, are important biomarkers for the diagnosis, prognosis and treatment guidance of human diseases. Therefore, the accurate and sensitive detection of nucleic acid is of great significance for the early diagnosis of diseases. DNA-scaffolded silver nanocluster (DNA-Ag NC) is a new type of probe with good photostability and low toxicity that has been widely used in biomedical analysis. In this work, a new universal sensing platform based on target triggered labeling luminescent DNA-Ag NC for disease-related nucleic acids detection was constructed. The assembled split DNA fragment pair (C4AC4T and C3GT4) could be used as a template to develop a bright green fluorescent Ag NC. According to this phenomenon, we devised two probe sequences DNA 1 and DNA 2, which could hybridize to the same one target and contained a different split fragment of Ag NC’ scaffold. The target compelled the split fragments close to each other through base pairing with DNA 1 and DNA 2, thus quantification of the target could be achieved through measuring green fluorescence of Ag NC that produced by assembled scaffold in ternary hybrid products. We applied this platform successfully for miR-362, a potential biomarker of inflammatory bowel diseases (IBD), or HIV-related DNA (hDNA) detection, achieving the detection limits of 6.5 nM and 1.7 nM, respectively. Both of the assays showed excellent reproducibility, selectivity and potential applications in human serum samples. In summary, an economic and convenient universal platform was developed for disease-associated nucleic acid detection.

Dual-Channel Logic Gates Operating on the Chemopalette ssDNA-Ag NCs/GO Nanocomposites.

In this work, we demonstrate that the emission wavelength and intensity of silver nanoclusters (Ag NCs) can be facilely tuned by the configuration transformation from the adsorption of Ag NCs to the graphene oxide (GO) surface to the desorption of Ag NCs from GO. Bicolor Ag NCs tethering the complementary sequence of influenza A virus genes are prepared, named green-emitting G-Ag NCs-CH5N1 (530 nm) and red-emitting R-Ag NCs-CH1N1 (589 nm). As for the high affinity of the complementary fragment of genes to GO, the adsorption of Ag NCs to GO leads to the formation of G-Ag NCs-CH5N1/GO and R-Ag NCs-CH1N1/GO nanocomposites, leading to fluorescent quenching due to energy transfer. By conjugating complementary sequences as capturing probes for targets, the formation of genes/Ag NC duplex-stranded structures results in the desorption of Ag NCs from GO, activating the fluorescence signal. More interestingly, compared with sole single-stranded DNA-templated fluorescent Ag NCs (ssDNA-Ag NCs), the activatable emission wavelength of the G-Ag NCs-CH5N1/H5N1 complex exhibits a notable red shift (555 nm) with a 49% recovery rate, while that of the R-Ag NCs-CH1N1/H1N1 complex shows a distinct blue shift (569 nm) with a 200% recovery rate. Via target-responsive configuration transformation of Ag NCs/GO hybrid materials, the emission wavelength and intensity of Ag NCs are effectively regulated. Based on the output changes according to different input combinations, novel dual-channel logic gates for multiplex simultaneous detection are developed by using the tunable color and intensity of ssDNA-Ag NCs. Our observation may open a new path for multiplex analysis in a facile and rapid way combining the logic gate strategy.

Controllable synthesis of fluorescent silver nanoparticles with different length oligonucleotides.

Silver nanomaterials have become important research topics in recent years. As a new type of fluorescent material, silver nanomaterials have been applied to fluorescent sensors, bioimaging and materials targeting cancer cells. Here, an approach to the oligonucleotide‐templated controllable formation of fluorescent Ag nanomaterials is reported. In this experiment, silver nanoparticles (NPs) were synthesised from oligonucleotides chains, sodium borohydride (NaBH4) and silver nitrate (AgNO3) by changing the molar ratio of DNA to sodium borohydride (NaBH4) and silver nitrate (AgNO3). Fluorescent assay and transmission electron microscopy were used to characterise the silver NPs. The optimal selection of DNA chains with different lengths as templates for the synthesis of silver NPs was found. This work successfully develops the capping oligonucleotides scaffolds of silver nanoclusters.

Green Synthesis of Fluorescent Ag Nanoclusters for Detecting Cu2+ Ions and Its “Switch-On” Sensing Application for GSH

Herein, we prepared the L-histidine- (His-) protected silver nanoclusters (Ag NCs) by the microwave synthesis method. The synthesis process was rapid, facile, and environmentally friendly. Under 356 nm excitation, the as-prepared Ag NCs exhibited the blue fluorescence, and the fluorescence emission peak was located at 440 nm. The Ag NCs could successfully detect trace copper (Cu2+) ions in the aqueous solution and the limit of detection (LOD) was as low as 0.6 pM. Interestingly, the Ag NCs showed a different pH-dependent selectivity for both Cu2+ and iron (Fe3+) ions with no responses to other heavy metal ions. Furthermore, the as-fabricated fluorescent sensing system was utilized to detect glutathione (GSH, the LOD was 0.8 nM) by using the “switch-on” fluorescence recovery of Ag NCs through adding glutathione (GSH) to the Cu2+-Ag NCs solution.

Fluorescent Ag–In–S/ZnS Quantum Dots for Tumor Drainage Lymph Node Imaging In Vivo

Tumor drainage lymph node imaging is crucial for oncological surgery, where the complete dissection of sentinel lymph nodes could largely prevent/delay recurrence. However, current commercially use...

Cu2+ enhanced fluorescent Ag nanoclusters with tunable emission from red to yellow and the application for Ag+ sensing

In this work, the water-soluble fluorescent Ag nanoclusters (DPA@Ag NCs) were first prepared based on D-Penicillamine (DPA) as a stabilizer, however, the fluorescence quantum yield (QY) of DPA@Ag NCs was very low, then Cu2+ was employed to improve the fluorescence QY and the doped Ag nanoclusters with Cu2+ (DPA@Ag/Cu NCs) were obtained. The study showed that the QY increased fourfold and the emission of nanoclusters changed from red to yellow after addition of Cu2+. The reasonfor change of fluorescent properties wasattributed to the change of self-assembly structures caused by adding Cu2+ into reaction system, leading to the aggregation-induced emission enhancement (AIEE) effect and enhancing the band gap (Eg) between the HOMO and LUMO in nanoclusters. Subsequently, a fluorescent Ag+ sensor with high sensitivity and selectivity was established based on the DPA@Ag/Cu NCs as probes in aqueous solution. Experiments showed that the Ag+ could significantly quench the fluorescence of DPA@Ag/Cu NCs under experimental conditions, and there was a good linear relationship between the fluorescent intensity quenching value and Ag+ concentration in the range of 0.05–800 μM, and the limit of detection (LOD) was 0.03 μM (3σ/k). Meanwhile, most of common ions had no effect on the experimental results under the same conditions. In addition, the sensor was successfully applied on the detection of Ag+ in real water samples, and the recovery rate was 80.3–99.0%.

Colorimetric detection of water content in organic solvents via a smartphone with fluorescent Ag nanoclusters.

We detected the water content in ethanol and dimethyl sulfoxide (DMSO) solvents via a smartphone with the help of fluorescent Ag nanoclusters (Ag NCs). The Ag NCs intrinsically have two emission peaks, among which the long-wavelength emission intensified with decreasing water content due to the aggregation induced emission enhancement (AIEE) effect, but in contrast the short-wavelength emission was relatively insensitive to water content. This fact makes the Ag NCs an ideal colorimetric indicator of water content in organic solvents. A smartphone was applied to take pictures of Ag NC samples and read the R, G, and B values from the images. When the water content increased from 20% to 55% in ethanol, the G/B values displayed a good linear relationship with the water content, and a limit of detection (LOD) of 4.48% was achieved. Moreover, good consistency was observed when the colorimetric fluorescent Ag NCs were applied to detect water content in real samples such as white wine and medical alcohol. These studies demonstrated a convenient and practical method for the detection of water content via a smartphone.

A facile emission wavelength tuning strategy via self-assembly of Ag nanoclusters

Self-assembly is known as a powerful method to regulate the properties of nanomaterials. In this research, we report a facile strategy to tune the photoluminescence properties of Ag nanoclusters. Self-assembled Ag nanoclusters with different morphology were obtained by controlling the experimental conditions, such as the synthetic temperature and solvents. The morphology has significant influence on the photoluminescence property of self-assembled Ag nanoclusters. The Ag nanoclusters could self-assemble to form nanostrips, and the emission wavelength redshifts with the elongation of nanostrip. We finally obtained one kind of self-assembled Ag nanoclusters with quantum yield as high as 61%, which was a great improvement comparing with previous reports. • A series of fluorescent self-assembled Ag nanoclusters were prepared by a facile method under mild condition. • The emission wavelength of self-assembled Ag nanoclusters was modulated by adopting different experiment conditions. • The relationship between the self-assembled morphology and fluorescence properties was investigated. • A high fluorescence quantum yield of 61% was achieved in the self-assembled Ag nanoclusters.