Search

Reactive oxygen species (ROS) regulating the release of free zinc ions (Zn 2+ ) in cellular lysosome is closely related to various pathways of cellular signal transduction, such as inflammation and oxidative stress. Directly visualizing Zn 2+ release in lysosome is essential for in-depth understanding these physiological processes, and is still an atelic challenge. In this work, we successfully fabricate a lysosome-specific Zn 2+ fluorescent probe and achieve the visualization of ROS-induced Zn 2+ release in lysosome of inflammatory cells. The as-prepared probe combines a green fluorophore, an ionophore with five-dentate sites, and a morpholine as the lysosome-specific localization moiety. The fluorescence of the fluorophore in the free probe is suppressed by a photoinduced electron transfer (PET) process from nitrogen atoms in the ionophore. Upon the addition of Zn 2+ , the fluorescence can be promoted immediately, achieving the real-time detection. Meanwhile, the probe is sensitive and selective to Zn 2+ , which provides the capability to detect low-concentration of free Zn 2+ in lysosomes. Accordingly, the Zn 2+ release was clearly observed in lysosome with the increase of ROS levels when the inflammation occurred in living 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]

Pesticides abuse has drawn considerable attention in agriculture, environment and food safety in recent years. How to selective and on-site detection of pesticide residues with rapid operation and low cost is still a hot topic. In this work, we report a novel method for the detection of pesticide thiram using phosphorescent Mn-doped ZnS quantum dots (ZnS:Mn 2+ QDs) combined by an affinity reaction between thiram and Ag + ions. On the one hand, the phosphorescence of as-prepared ZnS:Mn 2+ QDs at 590 nm can be effectively quenched by Ag + ions due to the direct cation-exchange reaction at the surface of QDs. On the other hand, the presence of thiram can inhibit phosphorescence quenching through the formation of stable Ag-thiram complex. This inhibition resulted in a linear recovery in emission intensity with increasing the amount of thiram, which enables thiram residues to be identified under the UV light illumination. In buffer condition, thiram could be detected within the concentration range of 50 nM–2.5 μM with a detection limit of 25 nM. Moreover, the proposed method has been successfully applied to thiram residues identification at fresh fruit peels. The investigation provides a profile for instant and visual detection of surface residues using doped quantum dots. [ABSTRACT FROM AUTHOR]

The intracellular pH value controls many aspects of cell metabolism and is considered as an integral part of many metabolic reactions by maintaining the structure and function of nearly all proteins. Detection of pH fluctuation covering the whole intracellular pH window including both neutral and acidic is essential but challenging and still needs more sensitive pH probes. We have synthesized a new near-infrared fluorescent and colorimetric probe based on cyanine dye, which can be used for monitoring the pH fluctuation. The probe has a good water solubility, excellent photostability, reversibility, low cytotoxicity and exhibits a good performance to detect pH fluctuation in both solution and live cells. Upon incubation with live cells, it responds sensitively to low pH value in cell medium by exhibiting bright red fluorescence. On the contrary, the fluorescence intensity of probe seems to be very weak in neutral cellular environment. The satisfactory results show that the probe was a highly sensitive pH probe in living cells and further demonstrate its promising biological applications. [ABSTRACT FROM AUTHOR]

• Probe DNS-M with a large Stokes shift ∼200 nm and good photostablity is synthesized by one-step reaction with high yield. • DNS-M is an excellent LDs tracker that exhibits high overlap coefficient ∼0.97 with Nile Red. • DNS-M can rapid distinguish cancer cells from normal cells within 1 min both in living and fixed cells. • The phenomenon that amounts of LDs are firstly formed and then enlarged sizes is revealed by our probe in oleic acid stimulated cells. • The significant difference of LDs behavior modes between cancer cells and normal cells is visually displayed for the first time with our probe. High lipid metabolism is one of the fundamental characteristics of cancer cells different from normal cells due to lots of energy needed for the fast proliferation of cancer cells. As an important organelle to supply cellular energy, however, the difference of lipid droplets (LDs) in their dynamic features between cancer cells and normal cells remains unclear. A key difficulty is to develop a specific fluorescence-tunable probe with high signal-to-noise for rapidly and accurately identifying cancer cells via tracking lipid droplets' dynamics. Here, we report a solvatochromic fluorescent probe, dansyl-morpholine (DNS-M), with high LDs-specificity to achieve the effective discrimination of cancer cells from normal cells by visually profiling the feature difference of LDs dynamics. Probe DNS-M is synthesized easily by one-step reaction, and possesses a large Stokes shift ∼200 nm, excellent photostablity and LDs-targeted capability with high overlap coefficient up to 0.97. Due to the remarkable biomembrance penetration, LDs-specificity and photostability, DNS-M has been applied to distinguish cancer cells from normal cells rapidly within 1 min in living cells and fixed cells, and real-time track dynamic behaviors of LDs in cancer cells, such as association, dissociation and fusion. More importantly, a significant difference in LDs behavior modes between cancer cells and normal cells is successfully visualized for the first time with our probe. We envision that our probe will become a rapid and easy-to-operate tool for cancer diagnosis and deeper understanding of LDs-related behaviors in cancer cells. [ABSTRACT FROM AUTHOR]

• A single-molecular probe specific to mitochondria was constructed by the linkage of 7-hydroxylcoumarin and rhodamine B. • The as-synthesized fluorescent probe without FRET was sensitive to pH change in the range of 3–9. • The probe with almost no cytotoxicity was suitable to track mitochondrial fusion, fission and autophagy. Tracking of mitochondrial dynamic processes including their morphology, biogenesis and elimination is of significance to deeply understand mitochondrial physiology and related diseases, which requires simultaneous and discriminative labeling of both mitochondria themselves and correlated downstream organelles. However, the combination of multiple fluorescent probes will bring the large invasive effect that seriously impacts the normal physiological processes of mitochondria within live cells. To address this issue, we herein construct a single molecular probe through the combination of two pH-sensitive fluorogens, hydroxyl-coumarin and rhodamine B, enabling the detection of intracellular microenvironmental pH variations. Importantly, the as-synthesized probe not only accumulates into mitochondria, indicated by cyan emission from hydroxyl-coumarin but also can be delivered to the downstream acidic autolysosomes upon the occurrence of mitophagy, indicated by red emission from rhodamine B. Taking advantage of a two-channel confocal microscopy strategy, we have achieved to real-time track the processes of mitochondrial replication, merge and autophagy. [ABSTRACT FROM AUTHOR]