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As a specific biological marker for the occurrence and progression of tumor cells, detection of telomerase activity is of great importance for the physiological research of tumors. However, in situ measurement of telomerase activity in living cells still remains a challenge. Herein, we report a precisely designed oligonucleotide-functionalized gold nanoparticle probe that has realized high-efficiency detection of telomerase activity for cellular imaging toward the identification of tumors. Our method has achieved intracellular imaging of telomerase activity and shows good performance towards the distinction of tumor cells from normal ones. Moreover, the method reported here for tracking tumor cells in blood has wide applications in cancer diagnosis. This strategy offers an opportunity for cancer diagnosis, guiding therapy and evaluating prognosis. [ABSTRACT FROM AUTHOR]

Thiolate-protected gold nanoclusters with high chemical stability are exploited extensively for fundamental research and utility in chosen applications. Here for the first time, the controlled destabilization of extraordinarily stable thiolated gold clusters for the growth of single-crystalline gold nanoparticles (AuNPs) is demonstrated, which was achieved simply via the oxidation of surface-protecting thiolates into disulfides by hydrogen peroxide under basic condition. By combining with our experimental observations over the entire destabilization and growth process, the new growth mechanism from clusters to AuNPs is revealed by density functional theory (DFT) calculations. It is found that the size of AuNPs decreases with the increase of hydrogen peroxide concentration due to the generation of more nuclei at the higher hydrogen peroxide concentrations. In addition, the preparation of AuNPs is tuned by changing the concentration of hydrogen peroxide, and they are self-assembled into microspheres via an evaporation-mediated process, which can induce strong plasmonic coupling between adjacent AuNPs for ultrasensitive surface-enhanced Raman scattering detection. The present work demonstrates a facile route to functionalize and engineer AuNPs via controlling the reaction conditions and the ratio of precursors, and thus bring new possibilities for using more clusters as precursors to construct novel nano/microstructures for various applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electroporation-based delivery of pH bioprobes into live cells enables rapid intracellular pH measurement and analysis. • Electroporation-based delivery of nanoprobes enables their dispersal throughout the cytoplasm, allowing for the capture of pH information throughout the cell. In this study, electroporation-surface-enhanced Raman scattering (SERS) was applied to rapidly measure intracellular pH. The generation of a sensitive SERS probe for measuring pH in the range of 6.0–8.0 was accomplished through the conjugation of the pH-sensitive molecule 4-mercaptobenzoic acid (4-MBA) to the surface of gold nanoparticles (Au NPs) through its thiol functional group. This bioprobe was then rapidly introduced into nasopharyngeal carcinoma CNE-1 cells by electroporation, followed by SERS scanning and the fitting of intensity ratios of each detection point's Raman peaks at 1423 cm−1 and 1072 cm−1, to create the pH distribution map of CNE-1 cells. The electroporation-SERS assay introduces pH bioprobes into a living cell in a very short time and disperses the nanoprobe throughout the cytoplasm, ultimately enabling rapid and comprehensive pH analysis of the entire cell. Our work demonstrates the potential of electroporation-SERS for the biochemical analysis of live cells. [ABSTRACT FROM AUTHOR]

As an essential enzyme, alkaline phosphatase (ALP) has attracted considerable attention for its regulating effect to the dephosphorylation process in living organisms. Here, we present a colorimetric and surface enhanced Raman scattering (SERS) dual-readout approach for assaying ALP activity. The major advantage of dual-readout assay is the perfect combination of the merit of colorimetric and SERS, which not only allow rapid preliminary discrimination of ALP activity by the naked eye but also greatly improved the detection sensitivity by SERS. Specifically, 4-mercaptophenylboronic acid modified Ag coated gold nanoparticles (4-MPBA-Au@Ag NPs) are employed as the colorimetric and SERS bifunctional reporting nanoprobes. Upon the presence of ALP, the phosphate group in the ascorbic acid 2-phosphate (AAP) is cleaved to produce ascorbic acid (AA), which acted as boronic acid moieties receptors to control the aggregation of 4-MPBA-Au@Ag NPs. The color of 4-MPBA-Au@Ag NPs solutions had changed from bright orange to light brown to dark gray, simultaneously accompanied by a substantial enhancement of SERS-readouts for the strong Raman hot-spots between the aggregation of 4-MPBA-Au@Ag NPs. A distinguishable change in the color was observed at an ALP activity of 5.0 U/L, meanwhile, SERS-readout sensing method showed a good linear relationship from 0.50 to 10.0 U/L (R = 0.997) with an exciting detection limit of 0.10 U/L (signal-to-noise ratio of 3). In addition, the dual-readout approach developed here was applied for ALP inhibitor evaluation. With the simple, rapid/direct readout yet outstanding sensitivity, we anticipate that this method would greatly promote practical application in ALP-related early-stage diseases diagnosis. [ABSTRACT FROM AUTHOR]

Fluorescent colorimetric test strips normally have a narrow dynamic detection–range due to the limited responsive range from single responsive materials, which cannot meet the wide detection requirement in practical applications. Herein, we developed an approach to detect uranyl ions (UO 2 2+) with a broad detection range using the synthesized ZnS:Mn quantum dots (QDs) modified Zn 2 GeO 4 nanoellipsoids (Zn 2 GeO 4 @ZnS:Mn NEs), containing two responsive materials with the opposite signal responses at different UO 2 2+ concentrations. Specifically, a red to chocolate color change was observed at low analyte concentrations (0.01–100 μM) resulting from the photoinduced electron transfer effect from ZnS:Mn QDs to UO 2 2+. A sequentially olive drab to green color change has been observed when further increasing the UO 2 2+ concentration (100–1000 μM) as a result of the antenna effect between Zn 2 GeO 4 nanoellipsoids and UO 2 2+. In addition, a low-cost and portable fluorescent test strip has been further fabricated through embedding Zn 2 GeO 4 @ZnS:Mn NEs on a microporous structure membrane, demonstrating a facile yet effective colorimetric response to UO 2 2+ in lab water, lake water, and seawater with a wide dynamic range. Therefore, it is potentially attractive for real-time and on-site detection of UO 2 2+ in sudden-onset situations. [Display omitted] • A simple hydrothermal approach to synthesize Zn 2 GeO 4 @ZnS:Mn nanoellipsoids. • Expanding UO 2 2+ detection range up to 5 orders by combining PET and antenna effect. • A distinct color change form red to green at various UO 2 2+ concentrations. • Fluorescent test strip to quantitative detect UO 2 2+ by RGB analysis. [ABSTRACT FROM AUTHOR]

Abstract: For the widely used gold nanoparticles (AuNPs)-based colorimetric probes, AuNPs generally change from dispersion to aggregation state accompanying with corresponding color turning from red to blue. Although colorimetric probes based on the anti-aggregation of AuNPs show exceptional selectivity and sensitivity, few examples have been reported in literature. A facile but highly sensitive and selective colorimetric probe based on the anti-aggregation of AuNPs transferred from the deactivation of aggregation agent 4,4′-dipyridyl by Hg2+ was developed in this work. This reported probe is suitable for real-time detection of Hg2+ in water with a detection limit of 3.0ppb for Hg2+, and exhibits a selectivity toward Hg2+ by two orders of magnitude over other metal ions. The dynamic range of this probe can be conveniently tuned by adjusting the amount of 4,4′-dipyridyl used. [Copyright &y& Elsevier]