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Tyrosine kinase inhibitors (TKIs) are commonly used in tumor targeting therapy. However, the rapid analysis of TKIs remains a significant challenge, especially in complex biological fluid environments. In this work, we have constructed a supramolecular fluorescence sensor array based on a cucurbituril-dye host-guest complex. The binding affinity between the three complexes and each TKI is different, resulting in different cross-response signals of the complexes to the fluorescence of each TKI. Combined with linear discriminant analysis(LDA), five kinds of TKIs can be well identified. The supramolecular fluorescence sensor array could accurately identify and distinguish the five TKIs in water and could classify mixtures containing different concentrations of TKIs in serum. The concentration and Factor 1 exhibited a good linear relationship and the detection limit (LOD) was as low as 10−7 mol L−1. The method has good reproducibility and stability. In addition, the differentiation of four clinical concentrations of first-generation TKIs further validated the potential application of arrays in drug monitoring. Finally, our proposed array enabled drug imaging in living cells. Our array platform provided the foundation for the rapid and easy monitoring of 4-anilinoquinazoline TKIs. [Display omitted] • A supramolecular fluorescence array sensor was constructed based on the dye-cucurbit [8]uril host-guest complexes. • The sensor array can identify five 4-anilinequinoline TKIs. • Five 4-anilinequinolines TKIs in serum were detected by sensor array. [ABSTRACT FROM AUTHOR]

Monoaromatic molecules are a category of molecules containing a single aromatic ring which generally emit light in the ultraviolet (UV) region. Despite their facile preparation, the UV emission greatly limits their application as organic probes. In this study, we developed a general method to red shift the emission of monoaromatic molecules. Significant fluorescence red-shift (∼100 nm per intramolecular hydrogen bonding) can be achieved by introducing intramolecular hydrogen bonding units to benzene, a typical monoaromatic molecule. Upon increasing the number of hydrogen bonding units on the benzene ring, UV, blue, and green emissions are screened, which are switchable by simply breaking/restoration the intramolecular hydrogen bonding. As a demonstration, with the breaking of one intramolecular H-bonding, the green emission (λ em max = 533 nm) of 2,5-dihydroxyterephthalic acid (DHTA) changed to cyan (λ em max = 463 nm) upon the formation of its phosphorylated form (denoted as PDHTA), which, in the presence of alkaline phosphatase (ALP), hydrolyzed and recovered the green emission. By taking advantage of the switchable emission colors, ratiometric in vitro and endogenous ALP sensing was achieved. This general approach offers a great promise to develop organic probes with tunable emissions for fluorescence analysis and imaging by different intramolecular hydrogen bonding. Image 1 • Intramolecular hydrogen bonding-induced large red emission-shift of monoaromatics was presented. • Ratiometric fluorescence variation of monoaromatics by altering intramolecular hydrogen bonding was realized. • A sensitive and selective ratiometric fluorescence probe for evaluating alkaline phosphatase activity was proposed. • The visualization of endogenous alkaline phosphatase was achieved. [ABSTRACT FROM AUTHOR]

A deep-red emission and lipid droplets-targeted fluorescence probe (named ZFPy) for effective bioimaging of bisulfite was developed from flavone moiety and benzoindole derivative based on intramolecular charge transfer (ICT) and Förster resonance energy transfer (FRET) platform. ZFPy displayed promising fluorescence parameters including bright deep red fluorescence (615 nm), large Stokes shift (205 nm), extended emission window gap (140 nm), high absolute fluorescence quantum yield (4.1%) and stable emission signal output. In addition, ZFPy realized ratiometric fluorescence monitoring for SO 2 derivatives with low detection limit (30 nM), preferable linearity, high sensitivity and selectivity. Interestingly, dual fluorophores (i.e. the donor moiety and 1,1,2,3-tetra-substituent-1H-benzo[e]indol-3-ium iodide moiety) released the same emission band about 475 nm to enhance the emission signal when ZFPy reacted with SO 2 derivatives, to the best of our knowledge, this is the first synergetic FRET/ICT platform for fluorescence probe, which might effectively offer ZFPy a high sensitivity and low detection limit in the detection of SO 2 derivatives. More importantly, ZFPy could image exogenous and endogenous SO 2 derivatives in living HeLa, HepG2 and L-O2 cells with good biocompatibility and photostability. ZFPy also preferred to load on lipid droplets with high Pearson's coefficient (0.95). Image 1 • A ratiometric fluorescent probe (ZFPy) for rapidly monitoring SO 2 derivatives was developed. • FRET-based ZFPy displayed larger gap (140 nm) between two emission spectra. • This is a first synergetic FRET/ICT platform for fluorescence probe. • ZFPy was applied to image exogenous and endogenous SO 2 derivatives in living Hela, HepG2 and L-O2 cells. • ZFPy showed lipid droplets-targeted ability (Pearson's coefficient 0.95). [ABSTRACT FROM AUTHOR]

An effective ratiometric fluorescent probe based on silicon particles/gold nanoclusters (SiNPs/AuNCs) nanohybrid has been fabricated and applied to be a "on-off-on" switch sensing platform for detection of Hg2+ and cysteine. In this elaborated sensing platform, the SiNPs just acted as internal reference signal, providing a build-in correction for background interferences and environmental effects, to which the AuNCs as a signal report unit for Hg2+ response was covalently grafted by amidation reaction. The fluorescence intensity of SiNPs/AuNCs could be effectively quenched upon adding Hg2+, accompanied with an easily distinguishable fluorescent color change. The ratiometric fluorescence signal (F 649 /F 511) of the established nanoprobe was linearly proportional to the concentration of Hg2+ ranging from 0.02 to 24 μM with a low detection limit of 5.6 nM, which is below the guideline value of Hg2+ in drinking water set by the World Health Organization. Interestingly, upon addition of cysteine, the Hg2+-quenched fluorescence intensity was recovered gradually. Furthermore, the approach developed has also been utilized for Hg2+ detection in real complex biological samples with satisfactory results. More importantly, benefiting from the good water-solubility and excellent biocompatibility, this nanoprobe can monitor the intracellular Hg2+ and cysteine in living cells, indicating its potential applications in advanced biosensing and bioimaging. Herein, we reported an effective dual-emission ratiometric probe for "on-off-on" detection of Hg2+ and cysteine. Image 1 • An efficient dual-emission fluorescent probe for simultaneously and visual detecting Hg2+ and L-Cys was constructed. • The probe could simultaneously detection of Hg2+ in human serum and urine samples. • Due to the ratiometric fluorescence model, the background interference was extincted. • The developed probe was successfully used for the fluorescence bioimaging of Hg2+ and L-Cys in live cells. [ABSTRACT FROM AUTHOR]

Dopamine β-hydroxylase (DBH) is involved in various neuronal transmission processes in the brain. Due to the severe diseases caused by abnormity levels of such important enzyme in human serum, sensitive and rapid detection of DBH at early stages is crucial, particularly for clinical analysis. Herein, we developed optical sensors for DBH that include the following: (i) a ratiometric fluorescence sensor that hybridizes the bovine serum albumin (BSA)-gold nanoclusters (BSA-AuNCs) and nitrogen doped carbon dots (N-CDs). The sensor proved to be highly selective and sensitive, achieving a linear range of 0.02–0.16 μg mL−1 and a limit of detection of 4.0 ng mL−1. In the presence of DBH, the fluorescence intensity of BSA-AuNCs (λ em = 615 nm) was remarkably quenched by DBH serving as a reporter signal, whereas the N-CDs fluorescence intensity at 440 nm was almost kept unchanged serving as a reference signal. The developed ratiometric sensor is capable of demonstrating a color change from pink to violet and blue with a gradual increase in DBH concentration, which is discernible by the naked-eye. A test strip is prepared for semi-quantitative assay and convenient use. Intriguingly, by taking advantage of the inter-AuNCs aggregation in the presence of DBH, (ii) a resonance light scattering (RLS) sensor was also developed based on the nanohybrid probe (detection limit 95 ng mL−1). Fluorescence imaging in PC12 cell lines demonstrated that the BSA-AuNCs could be utilized in visualization assay towards intracellular DBH. Additionally, the sensors were tested in a real matrix by spiking serum samples with satisfactory recoveries. Image 1 • Ratiometric fluorescence method for Dopamine β-hydroxylase was developed for the first time. • Dopamine β-hydroxylase assay was performed for the first time based on a nontoxic and simple method. • A resonance light scattering detection of Dopamine β-hydroxylase was developed. • A portable and visual test strip was developed for Dopamine β-hydroxylase as a point of care testing. • Cellular imaging of the BSA-AuNCs was achieved successfully on brain cells. [ABSTRACT FROM AUTHOR]

Telomerase, as a potential biomarker for early cancer diagnostics and therapies, has attracted considerable interests concerning its detection and monitoring. Herein, we develop a novel method for sensitive detection of telomerase activity by designing a gold nanoparticles/graphene oxide (AuNPs/GO) probe. The AuNPs were functionalized with a telomerase substrate (TS) primer and a 6-carboxy-fluorescein (FAM)-modified complementary DNA (P1). In the absence of telomerase, P1 exists in the random-coiled conformation, and the fluorescence resonance energy transfer (FRET) from FAM to AuNPs and GO results in efficient fluorescence quenching. In the presence of telomerase, the multiple hybridization between TS extension products and P1 leads to the conformation transition of P1 from single-stranded DNA to double-stranded rigid structure, and thus the FRET process can be prevented with the efficient fluorescence recovery. The metal enhanced fluorescence (MEF) effect between FAM and AuNPs can further effectively enhance the fluorescence of FAM, and thus the sensitivity and specificity of telomerase detection can be remarkably improved. It is worth mentioning that the proposed strategy does not need to design complex hairpin structure and allows the measurement of telomerase activity in three crude cell extracts equivalent to 7 HeLa cells, 8 A549 cells and 8 L929 cells in 1 h. In addition, the present sensing platform can be applied to inhibitor screening, in situ telomerase imaging, and intracellular drug delivery. Image 1 • The metal enhanced fluorescence effect can be regulated to generate significant fluorescence enhancement. • Weak background fluorescence can be realized via efficient fluorescence resonance energy transfer. • Telomerase activity down to 7 HeLa cells can be sensitively detected. • The method facilitates cellular imaging, inhibitor screening and drug delivery. [ABSTRACT FROM AUTHOR]

A multiple turn-on fluorophore (FHCS), combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone into a molecule, was identified and developed based on density functional theoretical calculation. It was expected that FHCS could express exclusive fluorescent signals and improved Stokes shifts when chelating Al3+ or Zn2+. After it was synthesized and characterized in detail, it was noted that FHCS could turn-on fluorescently discriminate trace Al3+ and Zn2+ under the optimized conditions, i.e., from no-fluorescence to strong blue fluorescence for Al3+ and to green fluorescence for Zn2+ with low detection limits of 5.37 × 10−8 M and 7.90 × 10−8 M respectively. Owing to its low toxicity, FHCS was successfully applied for quantitative determination of Al3+ and Zn2+ in natural aqueous samples and toxicity evaluation of Al3+ and Zn2+ in living cells and bio-tissues with excellent linear relationships. The action mechanisms for FHCS with Al3+ and Zn2+ were confirmed to form stable 5-member-co-6-member condensed rings between Al3+/Zn2+ and N/O atoms in FHCS by both theoretic and experimental methods, which resulted in turn-on fluorescence with different dipolar moments and improved Stokes shifts. A multiple turn-on fluorophore, combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone into a molecule (FHCS), was identified and developed for turn-on fluorescently discriminate trace Al3+ and Zn2+ in natural aqueous, living cells and bio-tissue samples with quite low detection limits of 5.37 × 10−8 M and 7.90 × 10−8 M respectively. The action mechanisms for FHCS with Al3+ and Zn2+ were confirmed by both theoretic and experimental methods to form stable 5-member-co-6-member condensed rings between Al3+/Zn2+ and N/O atoms, which resulted in turn-on fluorescence with different dipolar moments and improved Stokes shift. Image 1 • A multiple turn-on fluorophore combining fluorescein, hydrazone, cyanuric chloride and salicylaldehyde chromone was developed. • It could turn-on fluorescently monitor Al3+ and Zn2+ in aqueous. • It was applied for cell imaging of Al3+ and Zn2+ in bio-samples. • The reaction mechanism was to form stable 5-member-co-6-member condensed rings with improved Stokes shift. [ABSTRACT FROM AUTHOR]

Nanoscale metal-organic frameworks (NMOFs) have been widely employed in biological diagnosis and treatment system. In this work, glutathione stabilized gold nanoclusters (GSH-AuNCs) were successfully encapsulated in NMOFs and the as-obtained nanocomposites (named as AuNCs@NMOFs) showed nearly 10 times enhancement in fluorescence intensity and longer fluorescence lifetime relative to GSH-AuNCs. In addition, the fluorescence intensity of AuNCs@NMOFs was quenched by highly reactive oxygen species (hROS) due to their strong oxidation ability. Based on the fact, the nanocomposites were used for the detection of hROS with a linear range from 80 nM to 1.0 μM toward hypochlorite (as the representative of hROS). The limit of detection (LOD) was about 30 nM, which was about 30 times lower than that of GSH-AuNCs (LOD = 0.96 μM). With the features of good biocompatibility, excellent luminescence and efficient cellular uptake, AuNCs@NMOFs were successfully applied in fluorescence imaging of hROS in living cells. Au nanoclusters@NMOF nanocomposites were prepared and further applied for hROS detection with high sensitivity in living cells. Image 1 • Au nanoclusters@NMOF composites were prepared as nanoprobe for hROS through a facile in-situ growth method. • The nanoprobe was developed to detect hROS with a fast response time and nearly 30 times sensitive than AuNCs. • The nanoprobe had been successfully applied in the imaging of exogenous and endogenous hROS in living cells. [ABSTRACT FROM AUTHOR]

Since inorganic phosphate ion (PO 4 3−) plays very important roles in environment or living organisms, developing a selective and sensitive detection method for PO 4 3− is highly desired. Owing to the superior optical properties, graphene quantum dots (GQDs) have been developed as a promising emitting material in fluorescence analysis. Herein, we reported the first example of negatively charged molybdate-mediated nitrogen doped graphene quantum dots (Mo 7 O 24 6--mediated N-GQDs) as a fluorescence "off-on" probe for PO 4 3− via "anion ion-mediated" strategy. The N-GQDs was firstly modified with Mo 7 O 24 6− through a complex bonding system containing ionic and hydrogen bonds. The formation of N-GQDs/Mo 7 O 24 6− complex leaded to photoluminescence (PL) quenching of N-GQDs. In the presence of PO 4 3−, strong affinity between PO 4 3− and Mo 7 O 24 6− produced ammonium phosphomolybdate, which destroyed the pre-formed N-GQDs/Mo 7 O 24 6− structure and detached Mo 7 O 24 6− from N-GQDs surface. Thus, the PL of N-GQDS was in turn switched on. Under optimal conditions, this probe exhibited a good linear relationship between PL response and PO 4 3− concentration in the range from 7.0 to 30.0 μM with a limit of detection of 50 nM. Also this probe with high selectivity and sensitivity has been successfully used to sense PO 4 3− in natural water, biological fluid, and living cells. A negatively charged molybdate mediated nitrogen-doped graphene quantum dots (Mo 7 O 24 6--mediated N-GQDs) as a fluorescent off-on probe for PO 4 3− has been developed and successfully utilized in real samples and live cells imaging. Image 1 • A fluorescence "turn on" N-doped graphene quantum dots nanocomposite for inorganic phosphate ion. • The nanocomposite working in "anion ion-mediated" principle. • The probe exhibiting the excellent PO 4 3− detection performance in biological fluids and living cells. • Presenting the possible detection mechanism. [ABSTRACT FROM AUTHOR]

This study examined the efficiency of pH-dependent, fluorescent carbon dots for the sensing of hazardous anions in aqueous media and cell imaging. The nitrite anion, an important water-soluble element for environmental and biological systems, requires continuous monitoring because a high concentration can affect the systems severely. The as-synthesized carbon dots efficiently detected the nitrite anion in aqueous solution through a fluorescent 'Turn Off' phenomenon. The quenching mechanism was investigated through proper microscopic and spectroscopic studies. The limit of detection and linear detection range were 7.9 nM and 2.3μM-7.7 mM, respectively. The sensitivity was tested with different water samples. In a parallel experiment, the as-synthesized carbon dots were used as a cell-imaging probe for HeLa cells, highlighting their potential in different biological studies. Image 1 • Fluorescent nitrogen-doped carbon nanodots were synthesized using a facile green chemical pathway. • The as-synthesized carbon dots showed selective and sensitive nitrite ion detection. • The as-synthesized carbon dots exhibited high efficiency for cell imaging. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) are an important organelle as the main energy storage site in cells. LDs viscosity controls the material and energy exchange between it and other organelles. Furthermore, the LDs metabolic abnormalities, cell dysfunction, some diseases may be attributed to the singular LDs viscosity. Currently, the fluorescent probes for sensing the variations of LDs viscosity are still scarce and expose some drawbacks of low fluorescence quantum yield, low sensitivity and LDs polarity interference. Thus, the development of high performance probes is significant to detect LDs viscosity. We hereby provide a lipophilic fluorescent probe (TPE-BET) with high fluorescence quantum yield (Φ f , 0.91 in glycerol) for imaging LDs viscosity in living cells. With the increase of viscosity from 0.54 cp to 934 cp, the fluorescence at λ ex /λ em = 405/520 nm and the fluorescence quantum yield of TPE-BET linearly increased by 64.9 and 128.5 folds, respectively. Meanwhile, the outstanding LDs staining capability of TPE-BET may provide a high spatial resolution for LDs imaging. The cell imaging of TPE-BET not only successfully observed the viscosity variations of LDs in cell stress models, e.g., ferroptosis, inflammation and mitophagy, but also revealed the increased viscosity and extracellular delivery of LDs in heavy metal cell injury models (Hg/As) for the first time, which may supply concrete evidence for understanding the structure and function of LDs. This represents a new fluorescent probe TPE-BET with high fluorescence quantum yield for imaging LDs viscosity, which may decrease the dose of probe and excitation light intensity along with the improvement on signal noise ratio (S/N). The imaging results of TPE-BET clarified that LDs viscosity may be an appraisal index on cell differentiation, state evaluation and drug screening. [Display omitted] • A lipophilic probe (TPE-BET) with high fluorescence quantum yield was developed for imaging lipid droplet (LDs) viscosity. • TPE-BET shows high spatial resolution, which provide information including the distribution, size and morphology of LDs. • The LDs viscosity was detected in various cell models such as ferroptosis, mitophagy and heavy metal cell injury models. • LDs viscosity may be an appraisal index on cell differentiation, state evaluation and drug screening. [ABSTRACT FROM AUTHOR]

Abstract MicroRNA (miRNA) plays significant roles in cell proliferation, differentiation and apoptosis, and has been considered to be valuable biomarker for cancer. Accurate and sensitive detection of miRNA is crucially significant for cancer diagnosis and treatment. Here, a MnO 2 nanosheet-mediated ratiometric fluorescence biosensor was designed for miRNA detection and imaging in living cells. It contained MnO 2 nanosheets acting as DNA carrier, and fluorescent donor (FAM)-labeled hairpin H1 (recognition probe) and fluorescent acceptor (TAMRA)-labeled hairpin H2 (amplification probe). When the biosensor entered cell by endocytosis, MnO 2 nanosheets were degraded to Mn2+ via intracellular glutathione (GSH) and the adsorbed hairpins H1 and H2 were released. The intracellular target miRNA-21 hybridized with the recognition unit of H1 to initiate catalyzed hairpin assembly (CHA) and a large amount of H1-H2 duplexes were produced. This brought fluorescent donor FAM and fluorescent acceptor TAMRA into close proximity to produce fluorescence resonance energy transfer (FRET), inducing a ratiometric fluorescent response (donor signal decreased and acceptor signal enhanced) for miRNA-21 detection. Furthermore, this method could be applied to differentiate the expression levels of miRNA-21 in HeLa, HepG-2 and L02 cells. These results indicated that the proposed method possessed great potential in the early diagnosis of miRNA-related diseases. Graphical abstract Image 1 Highlights • A ratiometric fluorescence biosensor was designed for miRNA detection. • The strategy had been applied to differentiate miRNA expression levels in cells. • The CHA displayed signal amplification ability, ensuring the sensitive detection. • The strategy held great potential for the early clinical diagnostics. [ABSTRACT FROM AUTHOR]

Abstract Characterizing cell behavior is important to modern medical diagnoses as the changes of cell behavior are often indicators of huge diseases. In order to gain enough information about cells, developing novel methods of cell sorting and imaging is an important task. With development of micro-fabrication technologies, more advanced miniaturized devices are applied to cell research. Here, a portable and easy-to-use chip with high-density periodic micro-well array is designed and fabricated to capture target cells specifically. Combining with aptamer-silver conjugates and FAM functioned report probes, the sandwich assay was successfully applied for imaging cells. Any well of the chip is carefully designed to provide abundant information on single cells. Since there are 19,200 microwells in a single chip, more information is available. Compared to other cells, such as HEK-293, MCF-7, U 2 OS and Ramos cells, the sandwich assay shows high specificity towards target cell CCRF-CEM. What's more, the applications of the chip can be further expanded to other cells imaging if suitable aptamers were selected. This high-density micro-well array of aptamer-silver conjugates is hopeful to play an important role in medical diagnosis in the future. Graphical abstract Image 1 Highlights • The aptamer-silver conjugates can effectively capture cells and amplify signal. • The well-designed chip eliminates the non-specific adsorption and enhance specificity. • Different cells can be detected simultaneously if different aptamers were applied. • The captured cells can be easily localized and analyzed at the same time. [ABSTRACT FROM AUTHOR]

Abstract Organic-inorganic hybrid nanomaterial has gained much attention due to its excellent performances in bioanalysis and biomedicine. However, the preparation of DNA-inorganic hybrid nanomaterial with suitable size for cell uptake remains a huge challenge. Herein, a moderate biomineralization strategy for synthesis of Y-DNA@Cu 3 (PO 4) 2 (Y-DNA@CuP) hybrid nanoflowers is reported. Y-DNA with a loop structure is used as both the biomineralization template and the recognition unit for thymidine kinase 1 (TK1) mRNA. The Y-DNA probe can linearly response to TK1 mRNA target sequence in a range from 2 nM to 150 nM with the limit of detection as low as 0.56 nM. Interestingly, the presence of Y-DNA significantly decreases the size of Cu 3 (PO 4) 2 (CuP) particles, which allows them suitable for intracellular applications as gene nanocarriers. Once inside the cells, the hybrid nanoflowers dissolve and release the Y-DNA probes. Then, the intracellular TK1 mRNA hybridizes with the loop region of Y-DNA, which dissociates the Cy3-labeled loop strand and turns on the red fluorescence. Through the real-time imaging of the intracellular TK1 mRNA, the assessment of tumor cells before and after the treatment of drugs including β-estradiol and tamoxifen is achieved. Graphical abstract Image 1 Highlights • A biomineralization strategy mediated by Y-shaped DNA was proposed for preparing Y-DNA@CuP hybrid nanoflowers. • The hybrid nanoflowers were employed as gene carriers for intracellular detection of tumor-related TK1 mRNA. • The hybrid nanoflowers allowed distinguishing tumor cells from normal ones. • The hybrid nanoflowers also enabled the assessment of the effectiveness of drugs like β-estradiol and tamoxifen. [ABSTRACT FROM AUTHOR]

Abstract A novel bifunctional thiophene-based Schiff base TS as a colorimetric and fluorescent turn-on sensor for rapid and simultaneous detection of Al3+ and Zn2+ ions with high selectivity and sensitivity has been developed. The sensor shows remarkable fluorescence enhancement response for Al3+ and Zn2+ over a broad pH range with good anti-interference capability, which accompanied with an obvious color change easily detected by naked eyes. Sensor TS can detect as low as 3.7 × 10−9 M for Al3+ and 3.0 × 10−8 M for Zn2+, whereas respective association constants are 1.16 × 104 M−1 and 2.08 × 104 M−1. With the help of fluorescence titration and Job's plot, the stoichiometric ratio of TS with Al3+/Zn2+ was determined to be 1:1. The sensing mechanism of sensor TS with Al3+/Zn2+ based on the chelation-enhanced fluorescence (CHEF) was analyzed in detail through 1H NMR titration, FTIR, HRMS and DFT studies. Moreover, sensor TS has been applied to the detection of Al3+ and Zn2+ in real environmental water and food samples as well as the filter paper-based test strips. Furthermore, sensor TS has good cell-permeability and can be used to selectively sense intracellular Al3+ and Zn2+ by bioimaging. Graphical abstract Image 1 Highlights • A novel thiophene-based colorimetric and fluorescent turn-on sensor TS was developed for Al3+ and Zn2+ ions detection. • Sensor TS shows rapid response, remarkable sensitivity, excellent selectivity and high anti-interference capability. • Sensor TS has been used for determination of Al3+ and Zn2+ in real environmental water, food samples and test strips. • Sensor TS can be used to image intracellular Al3+ and Zn2+ in living cells. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) fluorescent probes provide extremely sensitive Al3+ detection for human health purposes. This research develops novel Al3+ response molecules (HCMPA) and NIR upconversion fluorescent nanocarriers (UCNPs), which respond to Al3+ through ratio NIR fluorescence. UCNPs improve photobleaching and visible light lack in specific HCMPA probes. Additionally, UCNPs are capable of ratio response, which will further enhance signal accuracy. The NIR ratiometric fluorescence sensing system has been successfully used to detect Al3+ within the range 0.1–1000 nM with an accuracy limit of 0.06 nM. Alternatively, a NIR ratiometric fluorescence sensing system integrated with a specific molecule can image Al3+ within cells. This study demonstrates that a NIR fluorescent probe is an effective and highly stable method of measuring Al3+ in cells. Due to the excellent fluorescence properties and good biocompatibility of UCNPs and the design and synthesis of the Al3+ molecule HCMPA with excellent specificity, the probe has been used for sensitive sensing and imaging of Al3+ in cells. [Display omitted] • The HCMPA molecule was designed and prepared specifically for Al3+. • FRET-based NIR UCNP nanocarriers provide photobleaching and visible light enhancement in HCMPA. • Further improving the accuracy of Al3+ by achieving the ratio response. • Al3+ has been reliably detected within the range of 0.1–1000 nM with a detection limit of 0.06 nM. • A NIR fluorescent probe offers a highly stable and sensitive method for imaging Al3+ in cells. [ABSTRACT FROM AUTHOR]

A simple structured reaction-based probe for peroxynitrite (ONOO − ) was developed by using benzothiazole hydrazone base of the excited-state intramolecular proton transfer (ESIPT) dye. It was constructed from 2-hydrazinylpyridine and 3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylbenzaldehyde which possesses itself weak fluorescence and displayed prominent fluorescence response towards ONOO − by oxidizes the C=N bond to an aldehyde in aqueous solution. The probe exhibited excellent selectivity and high sensivity towards ONOO − with a low dectection limit of 5.8 × 10 −8  M in physiological condition. Moreover, the probe could realize fast recognition to ONOO − in as short as 60 s. In addition, the probe was also successfully used for living cell imaging. [ABSTRACT FROM AUTHOR]

An imidazo [1,5-α]pyridine-based fluorescent probe MIPY-DNP with a large Stokes shift (173 nm) for the sensing of thiophenols in aqueous medium has been developed. This probe with 2,4-dinitrophenyl ether as a highly thiophenol-selective group was constructed based on the combination of PET and ESIPT mechanisms. Upon the treatment with thiophenols, MIPY-DNP produced a remarkable fluorescence enhancement (209-fold) at 478 nm. The detect limit for thiophenols was calculated to be as low as 5.6 nM. Importantly, the practical utility of MIPY-DNP for the selective detection of thiophenols has been successfully demonstrated in both real water samples and living cells. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe 1 based on acridine orange was developed for the selective detection and bioimaging of biothiols. The probe exhibits higher selectivity and turn-on fluorescence response to cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) than to other amino acids. Importantly, the probe responds to GSH and Cys/Hcy with distinct fluorescence emissions in PBS buffer at pH of 7.4. The Cys/Hcy-triggered tandem S N Ar-rearrangement reaction and GSH-induced S N Ar reaction with the probe led to the corresponding amino-acridinium and thio-acridinium dyes, respectively, which can discriminate GSH from Cys/Hcy through different emission channels. Interestingly, Cys finishes the tandem reaction with the probe and subsequently forms amino-acridinium and Hcy/GSH induces S N Ar reaction with the probe to form thio-acridiniums at weakly acidic conditions (pH 6.0), enabling Cys to be discriminated from Hcy/GSH at different emissions. Finally, we demonstrated that probe 1 can selectively probe GSH over Cys and Hcy or Cys over GSH and Hcy in HeLa cells through multicolor imaging. [ABSTRACT FROM AUTHOR]

Fluorescence imaging with tumor-specific fluorescent probe has emerged as a tool to aid surgeons in the identification and removal of tumor tissue. We report here a new lysosome-targeting fluorescent probe (NBOH) with BODIPY fluorephore to distinguish tumor tissue out of normal tissue based on different pH environment. The probe exhibited remarkable pH-dependent fluorescence behavior in a wide pH range from 3.0 to 11.0, especially a sensitive pH-dependent fluorescence change at pH range between 3.5 and 5.5, corresponding well to the acidic microenvironment of tumor cells, in aqueous solution. The response time of NBOH was extremely short and the photostability was proved to be good. Toxicity test and fluorescence cell imaging together with a sub-cellular localization study were carried out revealing its low biotoxicity and good cell membrane permeability. And NBOH was successfully applied to the imaging of tumor tissue in tumor-bearing mice suggesting potential application to surgery as a tumor-specific probe. [ABSTRACT FROM AUTHOR]

SO 2 and its derivatives (bisulfite/sulfite) play crucial roles in several physiological processes. Therefore, development of reliable analytical methods for monitoring SO 2 and its derivatives in biological systems is very significant. In this paper, a FRET-based two-photon fluorescent turn-on probe, A-HCy , was proposed for specific detection of SO 2 derivatives through the bisulfite/sulfite-promoted Michael addition reaction. In this FRET system, an acedan (2-acetyl-6-dialkylaminonaphthalene) moiety was selected as a two-photon donor and a hemicyanine derivative served as both the quencher and the recognition unit for bisulfite/sulfite. A-HCy exhibited excellent selectivity and rapid response to HSO 3 − with a detection limit of 0.24 μM. More importantly, probe A-HCy was first successfully applied in two-photon fluorescence imaging of biological SO 2 derivatives in living cells and tissues, suggesting its great potential for practical application in biological systems. [ABSTRACT FROM AUTHOR]

A rhodamine spirolactam derivative ( 1 ) bearing a hydrophilic carboxylic acid group is developed as a fluorescent chemodosimeter for bivalent mercury ions (Hg 2+ ) in 100% aqueous solution. It exhibits a highly sensitive “turn-on” fluorescent response toward Hg 2+ with a 42-fold fluorescence intensity enhancement under 1 equiv. of Hg 2+ added. The chemodosimeter can be applied to the quantification of Hg 2+ with a linear range covering from 3.0 × 10 −7 to 1.0 × 10 −5 M and a detection limit of 9.7 × 10 −8 M. Most importantly, the fluorescence changes of the chemodosimeter are remarkably specific for Hg 2+ in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the experiment results show that the response behavior of 1 towards Hg 2+ is pH independent in neutral condition (pH 5.0–8.0) and the response is fast (response time less than 3 min). Furthermore, the ring-opening mechanism of the rhodamine spirolactam induced by Hg 2+ was supported by NMR, MS, and DFT theoretical calculations. In addition, the proposed chemodosimeter has been used to detect Hg 2+ in water samples and image Hg 2+ in living cells with satisfying results. [ABSTRACT FROM AUTHOR]

Stimuli responsive sensors QI 1 and QI 2 were rationally developed which exhibited diverse features of mutable mechanofluorochromism, reversible photochromism, solvatochromism, aggregation induced emission enhancement (AIEE), and metal ion sensing. After observing the exceptional structural property relationship, sensors were applied for reversible colorimetric and fluorometric determination of Ni2+ with low detection limits of 12 and 17 nM, respectively. Fluorescence emission enhancement based Ni2+ sensing was induced by chelation enhanced fluorescence (CHEF) mechanism. CHEF is triggered by the inhibition of excited state intramolecular proton transfer (ESIPT) and –C=N isomerization. The proposed Ni2+ sensing mechanism was investigated through 1H NMR, FT-IR titration, theoretical studies, and Jobs plots. Further, the developed sensors successfully demonstrated the selective acid-base induced absorption/emission switching through reversible ring-opening/closing and keto–enol tautomerization, evidenced by 1H NMR titration experiments. Additionally, the sensitivity of the sensor QI 1 towards Ni2+ was effectively mimicked in live MCF-7 cells and industrial effluents. Furthermore, monitoring of Ni2+ ions was also accessed through inexpensive and portable sensors' coated fluorescent films. Finally, an INHIBIT logic gate was fabricated imputing Ni2+ and EDTA as input signals to electronically scrutinize the targeted Ni2+. [Display omitted] • Fluorescein based sensors displayed mechanofluorochromism, photochromism, and AIEE characters. • Sensors can simultaneously detect TFA/NaOH through fluorescence emission enhancement response. • Sensors exhibited fluorescence enhancement based detection of Ni2+ in living cells and real water samples. • Detection of Ni2+ was achieved through chelation enhanced fluorescence (CHEF) and inhibition of ESIPT and C=N isomerization. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy is one of the common complications of diabetes, which has high risk of renal function. Dipeptidyl peptidase 4 (DPP4) is considered to be one of the good dynamic monitoring indicators for early diabetic nephropathy. Therefore, real-time monitoring of changes in the activity of DPP4 in organisms is helpful to the diagnosis and treatment of diabetes and its complications-diabetic nephropathy. A near-infrared fluorescent probe GP-DCMNH 2 is designed to detect the activity of DPP4. GP-DCMNH 2 is catalyzed and hydrolyzed by DPP4 into the near-infrared fluorescent dye DCMNH 2 , to achieve the purpose of detecting DPP4 in organisms. Based on the excellent near-infrared spectroscopy characteristics displayed by the probe GP-DCMNH 2 in vitro, in living cells and diabetic mouse models, GP-DCMNH 2 has been further applied in the visual fluorescence imaging of diabetic complications-diabetic nephropathy. Compared with the control group and the treatment group, GP-DCMNH 2 showed a stronger near-infrared fluorescence signal in the kidney tissue and blood of diabetic nephropathy mice. Because GP-DCMNH 2 shows high sensitivity in real-time dynamic monitoring of changes in the activity of DPP4 in organisms, and shows strong practicability in the spectral test of mouse models of diabetes and diabetic nephropathy. In clinical medicine, GP-DCMNH 2 is expected to be used in the early diagnosis, prevention and treatment of diabetes and diabetic nephropathy. [Display omitted] • GP-DCMNH 2 detects DPP4 in real time, providing a tool for early detection and prevention of diabetic nephropathy. • A near-infrared ratiometric fluorescent probe GP-DCMNH 2 for the detection of DPP4 in diabetic nephropathy was designed. • GP-DCMNH 2 has stronger fluorescence signals in diabetic mice and the kidney and blood of mice with diabetic nephropathy. • GP-DCMNH 2 showed significant spectral properties in the detection of DPP4 activity in diabetic complication-nephropathy. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) plays vital roles in a variety of biological processes, and the development of simple and effective GSH detection method is an important research topic. Herein, a multifunctional probe based on Ag&Mn:ZnInS quantum dots (QDs) was developed for bimodal imaging of GSH. MnO 2 , as an efficient fluorescence quencher, was in-situ grown on the surface of QDs, and then modified with hyaluronic acid (HA) to improve the stability and targeted recognition capability of the probe due to the binding between HA and CD44 receptors. After MnO 2 was deconstructed by GSH, the fluorescence of the probe was recovered and the generated Mn2+ could serve as good magnetic resonance imaging (MRI) contrast agent. Moreover, the near-infrared emission probe was successfully employed in living cell and zebrafish imaging due to its low toxicity and high anti-biological interference performance. This strategy provides a simple dual-mode fluorescence/MRI imaging of GSH, which may have a broad application in biological detection. [Display omitted] • We developed a GSH-responsive Ag&Mn:ZnInS QDs@SiO 2 –MnO 2 -HA probe for dual-mode fluorescence and magnetic resonance imaging. • In the presence of GSH, MnO 2 was reduced to Mn2+, causing the dual-modal property of the probe to turn on. • The near-infrared emission probe was successfully employed in imaging of GSH in living cells and zebrafish due to its low toxicity and high anti-biological interference performance. [ABSTRACT FROM AUTHOR]

We have developed a ratiometric fluorescent probe BRT based on boron dipyrromethene (BODIPY) and rhodamine-thiohydrazide Förster resonance energy transfer (FRET) platform for sensing hypochlorous acid (HOCl) with high selectivity and sensitivity. The probe can detect HOCl in 15 s with the detection limit of 38 nM. Upon mixing with HOCl the fluorescence colour of probe BRT changed from green to orange. Moreover, probe BRT was applied to successfully monitor HOCl in living RAW 264.7 cells. [ABSTRACT FROM AUTHOR]

A new colorimetric and fluorogenic probe ( RN 3 ) based on rhodamine-B has been successfully designed and synthesized. It displays a selective response to Hg 2+ in the aqueous buffer solution over the other competing metals. Upon addition of Hg 2+ , the solution of RN 3 exhibits a ‘naked eye’ observable color change from colorless to red and an intensive fluorescence with about 105-fold enhancement. The changes in the color and fluorescence are ascribed to the ring-opening of spirolactam in rhodamine fluorophore, which is induced by a binding of the constructed receptor to Hg 2+ with the association and dissociation constants of 0.22 × 10 5 M −1 and 25.2 μM, respectively. The Job's plot experiment determines a 1:1 binding stoichiometry between RN 3 and Hg 2+ . The resultant “turn-on” fluorescence in buffer solution, allows the application of a method to determine Hg 2+ levels in the range of 4.0–15.0 μM, with the limit of detection (LOD) calculated at 60.7 nM (3σ/slope). In addition, the fluorescence ‘turn-off’ and color ‘fading-out’ happen to the mixture of RN 3 -Hg 2+ by further addition of I − or S 2− . The reversible switching cycles of fluorescence intensity upon alternate additions of Hg 2+ and S 2− demonstrate that RN 3 can perform as an INHIBIT logic gate. Furthermore, the potential of RN 3 as a fluorescent probe has been demonstrated for cellular imaging. [ABSTRACT FROM AUTHOR]

Sialic acid (SA) usually locates at the terminal position of the sugar chains on cell membranes, and its expression level is closely associated with cancer. Here polysialic acid (PSA) embedded gold nanoparticles (AuNPs) were prepared and functionalized with fluorescent 3-(dansylamino)phenylboronic acid (DAPB) for in situ imaging and detection of cell surface SA. The fluorescence resonance energy transfer (FRET) from DAPB to AuNPs quenched the fluorescence of DAPB. In the presence of additional SA or SA-abundant cells, the competitive binding of DAPB with SA and PSA led to the release of the assembled DAPB from the surface of PSA-embedded AuNPs, resulting in fluorescence of DAPB on SA-abundant cell surface. The proposed methods realized the in situ imaging and monitoring of cell surface SA, and could also be applied to the quantification of cell number and the amounts of cell surface SA. This work not only proposed a convenient visualization method for the analysis of SA on cell membranes, but also provided a potential tool for accelerating the elucidation of the basic role of SA in various biological processes and development of anti-cancer therapies. [ABSTRACT FROM AUTHOR]

A rhodamine spirolactam derivative ( 1 ) is developed as a colormetric and fluorescent probe for trivalent aluminum ions (Al 3+ ). It exhibits a highly sensitive “turn-on” fluorescent response toward Al 3+ with a 70-fold fluorescence intensity enhancement under 2 equiv. of Al 3+ added. The probe can be applied to the quantification of Al 3+ with a linear range covering from 5.0 × 10 −7 to 2.0 × 10 −5 M and a detection limit of 4.0 × 10 −8 M. Most importantly, the fluorescence changes of the probe are remarkably specific for Al 3+ in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the experiment results show that the response behavior of 1 towards Al 3+ is pH independent in neutral condition (pH 6.0–8.0) and the response of the probe is fast (response time less than 3 min). In addition, the proposed probe has been used to detect Al 3+ in water samples and image Al 3+ in living cells with satisfying results. [ABSTRACT FROM AUTHOR]

Copper (II) is one of the most important metal ions for the human body that act as a catalytic cofactor for many metalloenzymes and proteins, and its homeostasis disruption could lead to many neurological diseases. The reported probes for Cu (II) determination are mostly based on fluorescence quenching mechanism, which provides low precision and reliability. In the present work, a turn-on fluorescence probe, (Z)-1-[2-oxo-2-[2-[1-oxoaceanthrylen-2 (1 H)-ylidene]hydrazinyl]ethyl]-pyridinium (OAHP), for highly selective detection of Cu2+ was developed. Hydrazide moiety of OAHP quenches probe fluorescence; however, upon its reaction with Cu, oxidative cleavage of the hydrazide moiety and intramolecular cyclization occurs, forming oxadiazole derivative with strong fluorescent properties. In this context, OAHP displayed significant fluorescence enhancement with increasing levels of Cu2+. OAHP could detect Cu2+ selectively with a detection limit of 18 nM (1.1 ppb). This is the first report for a probe that uses the ability of Cu2+ to induce oxidative decomposition of hydrazide with intramolecular cyclization, and it showed exceptional selective performance and exquisite sensitivity. Next, the method was applied successfully for monitoring Cu2+ in tap water samples with good accuracy (found% of 95.8–101.5%) and precisions (RSD<10%). Finally, OAHP was successfully applied for imaging Cu2+ in living cells, and this result indicates the potential of OAHP for selective detection of Cu2+ in complicated matrices. [Display omitted] • OAHP, a hydrazide derivative of phenanthrenequinone, was successfully used as a turn-on fluorescence probe for Cu2+. • Cu2+ induces oxidative cleavage of the hydrazide moiety and intramolecular cyclization forming oxadiazole derivative. • OAHP showed excellent selectivity to Cu2+ even vs. Cu+. • The new probe could detect Cu2+ selectively with sensitivity down to 1.1 ppb in tap water. • OAHP was successfully applied for imaging Cu2+ in Hep G2 cells. [ABSTRACT FROM AUTHOR]

In current work, one novel benzothiazole-based fluorescent chemosensor (TZ-BO) with ESIPT luminescence mechanism was designed for the detection of hydrogen peroxide (H 2 O 2) as typical reactive oxygen species (ROS). The boronate catenary in our designed probe molecule TZ-BO is both the blocking group of ESIPT and the reactive group of H 2 O 2. The synthesized probe TZ-BO has the advantages of large Stokes shift, high sensitivity, good selectivity, and fast reaction speed to H 2 O 2. The ability of the probe to detect H 2 O 2 in aqueous media and exogenous H 2 O 2 in cells by fluorescence signal was investigated. The experimental results manifested that probe TZ-BO is able to sensitively detect H 2 O 2 using a fluorescence method in an excellent linear range of H 2 O 2 concentration from 0 to 60 μM (R2 = 0.994). The detection limit was determined as 1.0 × 10−6 M. Most importantly, the probe TZ-BO with highly low cytotoxicity can effectively detect exogenous H 2 O 2 in HeLa cells. This probe provides a promising tool for monitoring the real concentration level of H 2 O 2 in related physiological and pathological researches. [Display omitted] • Novel ESIPT-based benzothiazole derivative (TZ-BO) as a fluorescent chemosensor was synthesized for H 2 O 2 detection. • TZ-BO was stable in physiological pH and exhibited excellent H 2 O 2 -response in neutral and slightly alkaline environments. • Low cytotoxic TZ-BO exhibited good responsion and selectivity to exogenous H 2 O 2 in HeLa cells. [ABSTRACT FROM AUTHOR]

Carbon dots without heteroatoms-doping and surface modifications were designed to be a novel chemosensing strategy on the quantitative detection of uric acid (UA) with the aid of uricase-induced enzymatic reaction and Fenton reaction. In this work, ascorbic acid (AA)-derived carbon dots (A-CDs) were prepared in the mixture of ethanol and water via one-step hydrothermal synthesis at a relatively low temperature (120 °C) for 10 h. The resultant A-CDs were proved to be excitation-independent. When excited at the wavelength of 420 nm, the nanodots displayed green fluorescence (535 nm) which was then linearly quenched as UA concentration increased in the range of 0–56 μM, according to which the detection limit was calculated to be 0.49 μM. With regards to the excellent sensitivity and selectivity to UA, real sample assay was performed on the A-CDs detection system, which provided relatively reliable recoveries of UA contained in human serum/urine. Besides, in view of the high quantum yield, the A-CDs were applied to live-cell imaging assay and were considered to become an alternative tracer tool in biomedical imaging. [Display omitted] • Carbon dots are prepared at a relatively low temperature without heteroatoms doping and surface modification. • The sensing system based on the carbon dots has a low detection limit to uric acid. • The system not only allows for quantifying uric acid and H 2 O 2 , but also possesses the imaging ability to living cells. [ABSTRACT FROM AUTHOR]

Highlights: [•] The chemosensor 1 developed here performed a ratiometric response to Al3+. [•] Al3+ detection can be undertaken in aqueous solution at neutral pH. [•] The sensor design was transformed into test papers for the detection of Al3+. [•] The application of 1 for Al3+ imaging in live cells was also achieved. [ABSTRACT FROM AUTHOR]

The detection of metal ions is of particular importance for monitoring environmental pollution and life metabolic activities. However, it is still a challenge to achieve Fe3+ detection with specific sensitivity and rapid response, especially in the presence of chelating agents for Fe3+ ions. Herein, a novel fluorescence probe for Fe3+, i.e., amide derivative of [1,2,4]triazolo[1,5-a] pyrimidine (TP, Id), was synthesized, featuring specific Fe3+ selectivity, rapid quenching (5 s), low limit of detection (0.82 μM), good permeability and low cytotoxicity. More importantly, Id can be used to identify and detect Fe3+ in the presence of existing strong chelating agents (e.g., EDTA) for Fe3+ ions. The results show that the as-synthesized fluorescence probe is particularly suitable as a bioimaging reagent to monitor intracellular Fe3+ in living HeLa cells. Furthermore, we proposed the binding mode for Id with Fe3+ ions and the light-emitting mechanism through high-resolution mass spectra and density function theory calculations, respectively. An Id -based test paper can be used to rapidly identify Fe3+. These results are expected to improve the development of new sensitive and specific fluorescent sensors for Fe3+. [Display omitted] • A novel amide derivative of [1,2,4]triazolo[1,5-a]pyrimidine fluorescence probe Id for Fe3+ ions was first reported with specific, rapid response to Fe3+ ions and low cytotoxicity. • The probe Id could detect Fe3+ ions in the presence of strong chelating agents (e.g., EDTA) of Fe3+ ions and the Id -based test paper could identify Fe3+ ions rapidly. [ABSTRACT FROM AUTHOR]

Highlights: [•] A “turn-on” fluorescent chemosensor for the detection of Zn(II) was facilely synthesized. [•] Detection of Zn(II) can be performed in water at neutral pH with high sensitivity. [•] The chemosensor exhibits remarkably selective to Zn(II) over other metal ions. [•] The chemosensor could be efficiently delivered to live cells for bioimaging of Zn(II). [Copyright &y& Elsevier]

Matrix metalloproteinase 2 (MMP2) plays an important role in tumor growth, invasion and metastasis. In this work, a dual-functional magnetic microsphere probe was designed for ICP-MS quantification and fluorescence imaging of MMP2 in cell secretion. In the designed probe, a NH 2 -peptide (-FAM)-biotin was used as a bridge for the combination of carboxylated magnetic beads (MBs-COOH) and streptavidin functionalized gold nanoparticle (Au NP-SA). Initially, the fluorescence of FAM was quenched by Au NP. Since the NH 2 -peptide (-FAM)-biotin had a MMP2-specifically recognized sequence, the peptide was specifically cleaved in the presence of MMP2, thus releasing Au NP for the ICP-MS quantification of MMP2 and turning on the fluorescence of FAM for the fluorescence imaging of MMP2. Under the optimal experimental conditions, a linear range of 0.05–50 ng mL−1 and a limit of detection of 0.02 ng mL−1 were obtained for MMP2. The relative standard deviation (n = 7, c = 0.1 ng mL−1) of the proposed method was 5.4%. With good sensitivity and good accuracy, the proposed method realized the quantification and imaging of MMP2 in A549 cell secretion. The proposed method was applied to monitor the expression of MMP2 in the A549 cell secretion under the stimulation of Cd2+, providing a new detection strategy in the study of MMP2-related life process. [Display omitted] • A dual-functional probe was designed and constructed. • Magnetic beads and Au NP were coupled with NH 2 -peptide (-FAM)-biotin as the bridge. • ICP-MS quantification and fluorescence imaging of MMP2 in cell secretion is realized. • The method is simple with high accuracy, sensitivity, and specificity. • It provides a new detection strategy in the study of MMP2-related life process. [ABSTRACT FROM AUTHOR]

Cancer severely threatens human health currently, promoting the rapid development of cancer treatment strategies. In addition to cancer therapy, assessment of cancer prognosis, which can evaluate the success with treatment and chances of recovery as well as assist to make subsequent therapeutic schedule, is also remarkably indispensable and important. Conventional technologies can't provide rapid and highly-sensitive assessment of cancer prognosis at cytological level. Herein, an effective nitrogen doped carbon dots with intrinsic nucleolus-targeting capability and high fluorescence quantum yield are synthesized, characterized and employed for fluorescence imaging of nucleolus, which is closely related to the biological alteration of cancer cell. The cancer prognosis thus can be accurately (limit of detection: 50 nM) and rapidly (5 min) assessed at subcellular organelle level from nucleolar characteristics, which are visualized and analyzed by the captured fluorescence images. Outstanding assessment performance endows the proposed technology with great potential for future clinical research. [Display omitted] • Nitrogen doped carbon dots are synthesized for fluorescence imaging of nucleolus related to the biological alteration of cancer cell. • The cancer prognosis can be assessed at subcellular organelle level, which is not achievable using conventional technologies. • The proposed assessment method for cancer prognosis shows faster and more sensitive features as compared with AgNOR method. [ABSTRACT FROM AUTHOR]