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Alzheimer's disease (AD) has gradually received enthusiastic attention with the aging process, and studying its biological relevance is expected. Excitingly, fluorescence probes were considered to be powerful tools for exploring biological correlations. Therefore, a highly selective near-infrared (NIR) fluorescent probe (DCM-Cl-Acr) for imaging cysteine (Cys) in AD was designed and synthesized. Through structural optimization, the probe exhibited high fluorescence quantum yield and low detection limit (20 nM) towards Cys. Meanwhile, based on the high selectivity and high sensitivity response exhibited by the probe to Cys, it was successfully applied to visualize endogenous and exogenous Cys in living cells and zebrafish, and showed good discrimination from homocysteine (Hcy) and glutathione (GSH). Further, the correlation between AD and Cys concentration was clarified by imaging studies in hippocampus tissue of AD mouse, and the abnormal accumulation of Cys in the hippocampus of AD brain was demonstrated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: To evaluate the efficacy and safety of patient-tailored 3D printed brace in the treatment of adolescent idiopathic scoliosis (AIS), and to compare the health-related quality of life (HRQoL) of patients treated with 2 different types of brace., Materials and Methods: From September 2017 to August 2020, 103 AIS patients requiring non-operative management were prospectively recruited in this study. All patients were followed up every 6 months, clinical and radiologic examination were assessed at each follow-up time. Full-length anteroposterior radiographs of the spine in the standing position were obtained. At the last follow-up, each patient completed a standardized HRQoL questionnaire. Compliance is defined as that the patient insists on wearing the brace for ≥23 hours every day (full-time wearing) and follow-up every 6 months until bone maturity. The rate of major curve Cobb progression was defined that maximum Cobb angle of major curve greater than 6° compared with that at the initial diagnosis, or aggravated to more than 45° so that orthopedic surgery was recommended during treatment, which was defined as the rate of conversion to surgery. The effects of these 2 types of braces on the rate of major curve Cobb progression and HRQoL were analyzed by independent sample t test and χ 2 test., Results: The thickness was 4 mm for thoracolumbosacral orthosis (TLSO) and 3 mm for 3D-printed brace (3DPB). In addition, compared with the material used in TLSO, the weight (600-800 g) of the 3DPB materials with the same area is reduced by about 25% to 30%. In our sample, 55 patients (49.1%) and 48 patients (33.1%) were respectively included in the 3DPB cohort and the TLSO cohort. The maximum Cobb angle of major curve in the 3DPB cohort was significantly lower than those in the TLSO cohort at 6 months, 12 months, and the last follow-up (P < 0.01). The thoracic kyphosis (TK) and lumbar lordosis (LL) of the 2 cohorts at the last follow-up were lower than those before brace treatment, in addition, there was a significant difference in TK (P = 0.001) and LL (P = 0.004) between the 2 cohorts at the follow-up. The scores of physical function, pain, self-image, mental health, and treatment satisfaction in the Chinese version of the 22-item questionnaire of the Scoliosis Research Society in the 3DPB cohort were higher than those in the TLSO cohort (P < 0.01 and P < 0.05, respectively). The scores of the 3DPB cohort were significantly higher than those of the TLSO group in the 4 dimensions (P = 0.008, 0.013, 0.015, and 0.002, respectively) of the EuroQol-5D health description system except for mobility, and the overall health status of EuroQol-5D was higher for the 3DPB cohort (P < 0.001). At the last follow-up, 1 patient in the 3DPB cohort and 10 patients in the TLSO cohort had major curve Cobb progression of greater than 6°, and the rate of major curve Cobb progression in the 3DPB cohort was significantly lower than that in the TLSO cohort (OR 14.2, 95% CI 1.7∼115.8, P < 0.01). One patient in the 3DPB and 7 patients in the TLSO cohorts received subsequent surgery or were recommended for surgery, and the rate of conversion to surgery was significantly lower than in the 3DPB cohort (OR 9.2, 95% CI 1.1∼77.9, P < 0.05)., Conclusions: A patient-tailored 3D-printed brace is lighter, thinner, and more comfortable than conventional braces in the treatment of AIS. It can substantially improve the HRQoL of patients and can significantly reduce the progression of major curve Cobb progression and rate of conversion of surgery., (Copyright © 2024. Published by Elsevier Inc.)

Nonalcoholic fatty liver disease (NAFLD) poses a significant global health concern, necessitating precise diagnostic tools and effective treatment strategies. Peroxynitrite (ONOO - ), a reactive oxygen species, plays a pivotal role in NAFLD pathogenesis, highlighting its potential as a biomarker for disease diagnosis and therapeutic evaluation. This study reports on the development of a near-infrared (NIR) fluorescent probe, designated DRP-O, for the selective detection of ONOO - with high sensitivity and photostability. DRP-O exhibits rapid response kinetics (within 2 min) and an impressive detection limit of 2.3 nM, enabling real-time monitoring of ONOO - dynamics in living cells. Notably, DRP-O demonstrates excellent photostability under continuous laser irradiation, ensuring reliable long-term monitoring in complex biological systems. We apply DRP-O to visualize endogenous ONOO - in living cells, demonstrating its potential for diagnosing and monitoring NAFLD-related oxidative stress. Furthermore, DRP-O effectively evaluates the efficacy of therapeutic drugs in NAFLD cell models, underscoring its potential utility in drug screening studies. Moreover, we confirm DRP-O to enable selective identification of fatty liver tissues in a mouse model of NAFLD, indicating its potential for the early diagnosis of NAFLD. Collectively, DRP-O represents a valuable tool for studying ONOO - dynamics, evaluating drug efficacy, and diagnosing NAFLD, offering insights into novel therapeutic strategies for this prevalent liver disorder., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The development of efficient, accurate, and high-throughput technology for gut microbiota sensing holds great promise in the maintenance of health and the treatment of diseases. Herein, we developed a rapid fluorescent sensor array based on surface-engineered silver nanoparticles (AgNPs) and vancomycin-modified gold nanoclusters (AuNCs@Van) for gut microbiota sensing. By controlling the surface of AgNPs, the recognition ability of the sensor can be effectively improved. The sensor array was used to successfully discriminate six gut-derived bacteria, including probiotics, neutral, and pathogenic bacteria and even their mixtures. Significantly, the sensing system has also been successfully applied to classify healthy individuals and colorectal cancer (CRC) patients rapidly and accurately within 30 min, demonstrating its clinically relevant specificity., Competing Interests: Declaration of competing interest We declare that we have no financial and relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The heavy metal Cr (VI) will remain, accumulate, and migrate after entering the environment or ecosystem, causing serious harm to the environment. Here, a photoelectrochemical sensor was developed for Cr (VI), utilizing the Ag 2 S quantum dots (QDs) and MnO 2 nanosheets as photoactive components. By introducing Ag 2 S QDs with a narrow gap, a staggered energy level match is created which effectively prevents the carrier recombination in MnO 2 nanosheets, resulting in an enhanced photocurrent response. In the presence of the electron donor, l-ascorbic acid (AA), the photocurrent of the Ag 2 S QDs and MnO 2 nanosheets modified photoelectrode is further enhanced. As AA has the ability to convert Cr (VI) to Cr (Ⅲ), the photocurrent may decline due to the decrease in the electron donors when Cr (VI) is added. This phenomenon can be utilized for the sensitive detection of Cr (VI) over a wider linear range (100 pM-30 μM) with a lower detection limit of 6.46 pM (S/N = 3). This work using the strategy that the targets induced the variations of the electron donor shows the advantages of good sensitivity and nice selectivity. The sensor holds many advantages such as simple fabrication process, economical material expense, and consistent photocurrent signals. It also holds significant potential for environmental monitoring and serves as a practical photoelectric sensing approach for detecting Cr (VI)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Oxidative stress is closely related to the crop health status under stress conditions. H 2 O 2 is an important signaling molecule in plants under stress. Therefore, monitoring H 2 O 2 fluctuations is of great significance when risk-assessing oxidative stress. However, few fluorescent probes have been reported for the in situ tracking of H 2 O 2 fluctuations in crops. Herein, we designed a "turn-on" NIR fluorescent probe (DRP-B) to detect and in situ-image H 2 O 2 in living cells and crops. DRP-B exhibited good detection performance for H 2 O 2 and could image endogenous H 2 O 2 in living cells. More importantly, it could semi-quantitatively visualize H 2 O 2 in cabbage roots under abiotic stress. Visualization of H 2 O 2 in cabbage roots revealed H 2 O 2 upregulation in response to adverse environments (metals, flood, and drought). This study provides a new method for risk-assessing oxidative stress in plants under abiotic stress and is expected to provide guidance for the development of new antioxidant defense strategies to enhance plant resistance and crop productivity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Nitrite is a commonly used food additive and water contaminant that has received widespread attention due to its harmful effects on humans. Here, a colorimetric ratio sensing platform for the detection of nitrite in foods as well as aquatic systems was developed via the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by CoOOH nanosheets (CoOOH NSs). Interestingly, in the presence of nitrite, TMB complexes in acidic environments can be oxidized and diazotized to produce yellow oxidized TMB (oxTMB) and diazotized TMB, resulting in the nitrite concentration-dependent ratio variation for the absorbance peaks at 655 and 450 nm (A 655 /A 450 ). The colorimetric ratio sensing offers higher sensitivity and better selectivity compared to conventional detection methods because of the specific target-induced reduction-oxidation and diazotized reaction, as well as the excellent mimetic oxidase activity of CoOOH NSs. Based on this strategy, a smartphone-assisted portable approach was designed for the in-situ/visual detection of nitrite, which has good application prospects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Viscosity changes in mitochondria are closely associated with numerous cellular processes and diseases. Currently available fluorescence probes used in mitochondrial viscosity imaging are not very photostable or sufficiently permeable. Herein, a highly photostable and permeable mitochondria-targeting red fluorescent probe (Mito-DDP) was designed and synthesized for viscosity sensing. Viscosity was imaged in living cells using a confocal laser scanning microscope, and the results suggested that Mito-DDP penetrated the membrane and stained the living cells. Importantly, practical applications of Mito-DDP were demonstrated: viscosity visualization was realized for mitochondrial malfunction, cellular and zebrafish inflammation, and Drosophila Alzheimer's disease models, i.e., for subcellular organelles, cells, and organisms. The excellent analytical and bioimaging performance of Mito-DDP in vivo makes it an effective tool for exploring the physiological and pathological effects of viscosity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Aeromonas salmonicida (A. salmonicida) is an important opportunistic pathogen to aquatic animals that causes severe economic losses to aquaculture, which makes its rapid detection and prevention are critical. In this work, a single-stranded DNA (ssDNA) aptamer (A.s-2) with high specificity to the bacteria was selected by Systematic Evolution of Ligands by Exponential Enrichment (SELEX). The selected aptamer was confirmed with high binding ability and specificity (K d  = 32 ± 8 nM). Furthermore, a novel dual-model colorimetric and ratiometric fluorescent aptasensor was constructed based on the G-quadruplex-modified aptamer and g-C 3 N 4 for sensitive, reliable, and visual detection of the diseased bacteria in fishes. The quantitative detection was achieved in the linear range of 10 3 -10 7  CFU mL -1 with a detection limit of 1.9 × 10 2  CFU mL -1 . Meanwhile, the semi-quantitative detection can also be performed visually through fluorescence or color changes of the solution, which is suitable for the early diagnosis of pathogen infection in grassroots farms. Moreover, the developed aptasensor was successfully applied to detect A. salmonicida infection in zebrafish samples with satisfactory results. This work provides a framework for the rapid detection of pathogens in aquaculture, indicating its great prospects in food safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A rhodamine-based fluorescent probe (Rho-GSH) was rationally designed and synthesized, using nitrobenzene as recognition group for monitoring and imaging GSH in vitro and in vivo. In the presence of GSH, Rho-GSH undergoes sequential nucleophilic substitution and spiro-ring-opening reaction, resulting the fluorescence increase of probe, which enables quantitative detection of GSH with "off-on" fluorescence. The cascade reaction also enables Rho-GSH to rapidly detect GSH (3 s). In addition, Rho-GSH exhibited outstanding selectivity in detecting GSH vs cysteine (Cys) and homocysteine (Hcy). Based on the outstanding detection performance and superior biocompatibility of Rho-GSH, it was used to visualize GSH in vitro and in vivo, demonstrating its highly selectivity for GSH detection (with respect to Cys and Hcy). Rho-GSH can help visually distinguishing cancer cells from normal cells by fluorescence imaging, demonstrating the overexpression of GSH in cancer cells. Because of the outstanding analytical capabilities of Rho-GSH for GSH detection, Rho-GSH may be useful for cancer diagnosis and clinical evaluation., (Copyright © 2022. Published by Elsevier B.V.)

Nitric oxide (NO), an essential biological messenger molecule, participates in various physiological and pathological processes. The sensitive and specific detection of NO is of great significance for understanding the biological function of NO. Here, we synthesized a fluorescent probe (Rho-NO) for highly selective detection of NO both in vitro and in vivo. The high selectivity of Rho-NO is attributed to the fact that NO is easily replaced by electron donor amino group to form N-nitrosation products, causing rhodamine spiro ring open and fluorescence emit. Rho-NO showed a good linear response to NO (0-100 µM) with a low detection limit (0.06 µM). Importantly, it exhibited excellent specificity for NO detection in human serum and was also applied for imaging NO in living cells and inflammatory model of zebrafish. This work proves the potential of Rho-NO in pathological research and disease diagnosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Two-dimensional luminescence metal organic framework nanosheets (LMOF) named NH 2 -CuMOFs were synthesized using Cu (II) nodes coordinated with negatively charged 2-aminoterephthalic acid (NH 2 -BDC) via a bottom-up strategy, which were first used as the fluorescent probes for the detection of chromium Cr (VI). The nanosheets possess stable fluorescence with the maximum emission wavelength of 436 nm at excitation of 338 nm that can be effectively quenched by hexavalent chromium Cr (VI). The NH 2 -CuMOFs nanosheets show superior advantage over the linker of NH 2 -BDC for the excellent selectivity to Cr (Ⅵ) without the interferences of other metal ions. The mechanism investigation suggested that the sensitive detection of Cr (VI) was attributed to the chemical oxidation-reduction (redox) reaction and internal filtration effect (IFE) between Cr (VI) and NH 2 -CuMOFs nanosheets. Based on this mechanism, the quantitation of Cr (VI) was realized in the linear range of 0.1-20 μM with a detection limit of 18 nM. Moreover, the detection of Cr (VI) in real samples was also conducted with good recovery. This work provides an optical sensing nanoplatform for heavy metal ions based on two-dimensional LMOFs via a novel mechanism integrating chemical redox reaction and IFE, which may promise broad application prospect for two-dimensional luminescence nanosheets., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Due to similar charges, atomic radii, and chemical properties of most metal ions, the selective sensing of these metal ions and imaging in vivo is still a challenge. A DNAzyme assemblied and near-infrared (NIR) light excited nanosensor was developed to detect and image Pb 2+ . In this nanosensor, NaYF 4 :Yb, Er upconversion nanoparticles (UCNPs) introduced as NIR-to-Vis transducer were the donor of luminescence resonance energy transfer (LRET), and DNAzyme-functionalized black hole quencher 1 (BHQ1) acted as energy transfer acceptor. This proposed nanosensor was applied to detecting Pb 2+ in solution with high sensitivity and selectivity. Furthermore, we have successfully demonstrated the imaging ability of this nanosensor towords Pb 2+ in living cells and early-stage zebrafish with negligible autofluorescence and good photostability. The UCNP-DNAzyme nanosensor would enrich the method of imaging Pb 2+ in vivo, and might serve as a potential tool for understanding the metabolic pathways of Pb 2+ and the mechanism of lead poisoning in biological system., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Rational design of detection strategy is the key to high-performance fluorescence analysis. In this article, we found that the glucose-induced limitations can greatly enhance the fluorescence of functionalized carbon nanoparticles (CNPs), which are synthesized through one-step thermal pyrolysis method using phenylboronic acid derivative as the precursors. The glucose can assembly onto the surface of the CNPs to form a "shell", limiting the surfaces' intramolecular rotation and reducing non-radiative decay, which hence resulted in enhanced fluorescence of the CNPs. Under optimal conditions, the fluorescence intensity of the CNPs is nearly 70-fold enhanced, and the method has low detection limit (10 μM) and linear response in the concentration range from 50 μM to 2000 μM. Based on this interesting "target-triggered limitation-induced fluorescence enhancement" phenomenon, a simple and effective non-enzymatic fluorescence enhancement method was developed and successfully applied to the determination of glucose in spiked serum samples. This work provides new insight into the design of fluorescence-enhanced detection strategies based on the limitation-induced property., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Understanding cellular metabolism holds immense potential for developing new drugs that regulate metabolic pathways. Two gas signal molecules, SO 2 and H 2 S, are the main metabolites from cysteine (Cys) via oxidation and desulfurization pathways, respectively. However, a few fluorescent probes for real-time monitor of the metabolic pathways of cysteine have been reported. To understand metabolic alterations of cysteine, we have rationally designed and prepared a dual-signal fluorescent probe HN, which could differentiate SO 2 and H 2 S through two different fluorescence channels simultaneously, along with similar reaction kinetics and both "off-on" fluorescence responses. Probe HN exhibits the potential to monitor the metabolism pathways of cysteine, and the distinguishment of cancer cells from normal cells could be realized. This methodology will promote further understanding of the physiological and pathological roles of cysteine., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

β-Galactosidase (β-gal) which is overexpressed in primary ovarian cancer can be employed as a valuable biomarker for ovarian cancer. Thus, monitoring and imaging endogenous β-gal in living cells is of great importance. Herein, a dicyanoisophorone-based near-infrared (NIR) fluorescent probe 2-(5,5-dimethyl-3-((E)-4-(((2R,3S,4R,5S,6S)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)oxy)styryl)cyclohex-2-en-1-ylidene)malononitrile named DP-βgal, was rationally designed and synthesized for the monitoring of β-gal activity in living cells. In the presence of β-gal, with the breaking of the glycosidic bond, the NIR fluorescence of the dicyanoisophorone derivative gradually recovered, enabling the fluorescence "off-on" quantitative determination of β-gal activity. DP-βgal has the advantages of good selectivity and high sensitivity for the detection of β-gal, with the limit of detection (LOD) of 3.2 × 10 -3 U. Furthermore, based on its advantages of long-wavelength emission and excellent biocompatibility, the practical applications of DP-βgal in NIR imaging of β-gal in living ovarian cancer cells (SKOV-3) were demonstrated., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Hypochlorous acid (HOCl) acts as crucial roles in pathologica processes and relevant diseases. Thus, it is meaningful to explore a reliable method for monitoring HClO in biosystem. In this work, a ratiometric fluorescent probe 2-(benzo[d]thiazol-2-yl)-4-(methylthio)phenol (BTMSP) has been constructed for HClO by adopting ICT-ESIPT strategy. The probe possessed itself red fluorescence due to the electron-donating capability of sulfur atom and showed remarkable blue fluorescence response to HClO by oxidizes the sulfur atom to a sulfoxide. The ratiometric probe exhibited highly specific, rapid response and excellent sensitivity toward HClO as well as a low detection limit (4.2 × 10 -7  M). Moreover, the ratiometric probe showed well-separated dual emission (450/580), and a large pseudo Stokes shift (190 nm). In addition, the probe was used for the imaging of HClO with satisfying results., Competing Interests: Declaration of competing interest The authors declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2020 Elsevier B.V. All rights reserved.)

β-Galactosidase (β-gal) is an important biomarker for primary ovarian cancers. Developing noninvasive bioimaging probes for studying the activity of β-gal is highly desirable for cancer diagnosis. Herein, a turn-on near-infrared (NIR) fluorescent probe， 2-((6-(((2S, 3R, 4S, 5R, 6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran -2-yl)oxy)-2,3-dihydro-1H-xanthen-4-yl)methylene)malononitrile named DXM-βgal, was rationally designed based on enzymatic reaction for the detection of β-gal activity both in vitro and in vivo. Upon incubating with β-gal, DXM-βgal displayed a significant fluorescence enhancement at 640 nm, accompanying by a color change of solution color from red to purple. DXM-βgal exhibited high selectivity and sensitively to β-gal with low limit of detection (2.92 × 10 -4 U mL -1 ). Besides, based on its advantages of long-wavelength emission and excellent biocompatibility, DXM-βgal was successfully applied to imaging β-gal in living cells and zebrafish. Given these prominent properties, we believe that DXM-βgal will be a potential tool for investigating β-gal activity in biomedical research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Thiophenol has a broad application in agriculture and industry. However, thiophenol can harm to the environment and health for its high toxicity. Developing an effective method for detection of thiophenol in the field of environmental and biology is valuable. In this work, we construct a reaction-based ratiometric fluorescent probe (E)-4-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1-(4-(2,4-dinitrophenoxy)benzyl)pyridin-1-ium bromide (DCVP-DNP) for probing thiophenol in environment and cells by employing (E)-7-(diethylamino)-3-(2-(pyridin-4-yl)vinyl)-2H-chromen-2-one (DCVP) as the fluorophore and 2,4-dinitrophenyl (DNP) ether as the recognition group for the first time. The probe has high selectivity for thiophenol though thiophenol-triggered nucleophilic substitution reaction. In addition, the ratio of emission intensities of the probe has linearly with thiophenol concentration in the range of 0-65 μM and the detection limit of thiophenol is as low as 4.8 × 10 -8  M. Moreover, the probe can not only be applied for detection of thiophenol in water samples, but also image thiophenol in living cells, suggesting its potential application in environment and biological system., Competing Interests: Declaration of competing interest The authors declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A new strategy endowing probe with large Stokes shift, high quantum yield and red emission was developed by incorporating tetrahydroquinoxaline unit and five-membered pyrrolidine ring on fluorophore. As demonstrated, a novel probe was rationally designed and synthesized for sensitive monitor of cellular cysteine (Cys) and endogenous aminoacylase with large Stokes shift and high quantum yield., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Peroxynitrite (ONOO - ) is a primary kind of reactive oxygen species. Excessive ONOO - can induce oxidative damage to biomolecules and further results in various diseases. So, quantitative monitoring ONOO - with excellent selectivity and sensitivity is imperative for elucidating its role in biological processes. In this study, a novel pyridinium fluorescent ONOO - probe (CPC) has been constructed base on ICT-modulated by combining coumarin fluorophore and diphenylphosphinate recognition group. The fluorescence response of CPC for ONOO - is realized via the removal of diphenylphosphinate group. The probe CPC shows prominent features for detection of ONOO - including fast response rate (within 3 min), excellent selectivity and sensitivity, distinct colorimetric (red to green), and a large emission wavelength shift (105 nm). The emission intensity ration (I 538 /I 643 ) exhibits 153-fold enhancement along with the increasing ONOO - and the detection limit is as low as 1.60 × 10 - 8  M. These good response properties make CPC possible to quantitative detection of ONOO - concentration. By using the strategy, the ratiometric CPC has been employed to detection of mitochondrial ONOO - in live cell successfully., Competing Interests: Declaration of competing interest The authors declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herein, we report a novel ultrasensitive upconversion intense red fluorescence and colorimetric dual-readout strategy for the determination of alkaline phosphatase (ALP) that initially integrates enzyme-triggered cascade signals amplification (ECSAm) with rapid fusing reaction of label-free silver triangular nanoplates (AgTNPs). The sensing strategy involves four aspects. Firstly, AgTNPs with an absorption band at ∼610 nm was synthesized, which can effectively quench upconversion nanoparticles (UCNPs) fluorescence at 670 nm through the fluorescence resonance energy transfer (FRET). Secondly, when in the presence of ALP, l-ascorbic acid 2-phosphate (AAP) was transformed into ascorbic acid (AA) which can react with KIO 3 to produce I 2 . Thirdly, the procreant I 2 can quickly adsorb onto the surface of AgTNPs, then etch AgTNPs and the I 2 is reduced to I - . Fourthly, the generated I - can further accelerate the fusion of AgTNPs by adsorption effect, which helps achieve ECSAm, allowing the quantitative evaluation of ALP with a satisfying detection limit of 0.035 mU/mL. In addition, the developed method has been further applied to the detection of ALP in human serum with satisfactory results. These results indicate that the dual-readout assay with a well-defined response mechanism shows good prospects in physiological and pathological studies., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Alkaline phosphatase (ALP) is a non-specific phosphate monoesterase and often regarded as an important biomarker of hypothyroidism and hepatobiliary diseases in medical diagnosis. In-situ detection of endogenous ALP and exploration of the distribution of ALP in cells are of great importance for the diagnosis of diseases associated with ALP. In this work, we designed and synthesized an aggregation-induced emission (AIE) fluorescent probe, (E)-2-(((9H-fluoren-9-ylidene) hydrazono)methyl)phenyl dihydrogen phosphate (FAS-P), that can respond to ALP with a remarkable large Stokes shift (>200 nm) based on excited state intramolecular proton transfer (ESIPT) mechanism. The probe FAS-P has high selectivity and sensitivity to the detection of ALP. And there is a linear relationship between the fluorescence intensity of FAS-P and ALP activity in the range of 1-100 U L -1 , the limit of detection (LOD) is as low as 0.6 U L -1 . More importantly, we successfully applied FAS-P to detect ALP in living cells and the monitoring of ALP in real time., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Developing specific and sensitive method for endogenous peroxynitrite (ONOO - ) in living systems is valuable to understand its various pathological events. In this work, a simple and novel fluorescent probe (HPP) based on aggregation induced emission (AIE) as well as excited state intramolecular proton transfer (ESIPT) processes for endogenous ONOO - detection was constructed containing a diphenylphosphinate as the reactive site and a salicylaldehyde azine as the fluorophore. The probe showed specific fluorescence turn-on response toward ONOO - owing to the diphenylphosphinate group of HPP reacted with ONOO - , releasing the salicylaldehyde azine with both AIE and ESIPT characteristics. In addition, the probe exhibited a large Stokes shift, an excellent light-up ratio, high selectivity and excellent sensitivity with a low detection limit of 8 × 10 -8  M for endogenous ONOO - . Moreover, the probe could be applied to bioimaging of endogenous ONOO - in live cell, which demonstrated the probe can be used as effective tool for investigation of ONOO - in biological systems., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A novel catalyst of FeCo nanoparticles (FeCo NPs) incorporated porous nanocages (FeCo NPs@PNC) was first synthesized by encapsulating of FeCo alloy into ZIF-8 and further carbonation of the composite. The FeCo NPs@PNC displays enhanced intrinsic oxidase-like activity compared to the individual FeCo NPs and porous nanocages (PNC). The FeCo NPs@PNC can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB) without H 2 O 2 , producing a blue color with a maximum absorption peak at 652 nm. The catalytic mechanism was investigated and it found that the intermediate (O 2 ·- ) produced from the catalytic process in the system of TMB-O 2 -FeCo NPs@PNC can accelerate the oxidation of TMB to oxTMB. However, ascorbic acid (AA) can reduce the oxTMB and result in a conspicuous blue color fading. Therefore, a novel colorimetric platform was constructed to quantify AA with the linear range of 0.5-28 μM and detection limit of 0.38 μM (at 3σ/m). Owing to the alkaline phosphatase (ALP) can catalyze the hydrolysis of AA 2-phosphate (AAP) into AA, ALP can also be quantified by the above method. And the linear range for ALP is 0.6-10 U L -1 and the limit of detection is 0.49 U L -1 . The FeCo NPs@PNC also shows excellent stability and reproducibility. This study provides a new alternative oxidase mimetic on the basis of easily obtained metal-organic frameworks derivatives to replace the expensive natural enzymes and noble metal based nanoenzymes, which will show great potential in biological assays., (Copyright © 2019. Published by Elsevier B.V.)

A novel nanosensor is developed for selective and highly sensitive detection of phytic acid (PA) based on small-sized conjugated polyelectrolyte dots (Pdots) fabricated from a new conjugated polymer (P1) by a modified reprecipitation method. P1 featuring a π-delocalized backbone bearing meta-substituted pyridyl groups can be endowed with enhanced flexibility and hence is beneficial for the synthesis of ultrasmall Pdots (i.e. Pdot-1, ∼3.8 nm in average diameter) as well as for the binding of Fe 3+ , thus leading to the obvious fluorescence quenching of Pdot-1 (∼444 nm) in the presence of Fe 3+ via an electron transfer (ET) process. In addition, phytic acid with six phosphate groups exhibits strong chelating ability. When phytic acid is added, phytic acid readily binds to Fe 3+ and the fluorescence of Pdot-1 around 444 nm can be recovered, rendering the supersensitive and selective sensing of PA. Under the optimum conditions, this ultra-small Pdot-based nanoprobe favors the fluorescent determination of PA with the detection limit as low as 10 nM. Particularly, Pdot-1 with bright blue fluorescence exhibits low cytotoxicity. Furthermore, the small-sized and biocompatible Pdot-1 can be applied to the sensitive fluorescence assay for PA in cell extracts and the efficient imaging of PA in live cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Phosgene is a highly toxic gas that poses a serious threat to public health and safety. Herein, we describe the preparation of a ratiometric fluorescence probe (Pi) bearing hydroxyl and imidazole moieties as recognition sites, and employ it for the excited-state intramolecular proton transfer-based (ESIPT-based) detection of phosgene. It is the first time that hydroxyl and imidazole have been exploited as recognition sites for phosgene. In the presence of phosgene, Pi undergoes sequential nucleophilic substitution and cyclization reactions that facilitate a rapid response, high selectivity, and excellent sensitivity (detection limit = 0.14 μM). The sensing mechanism was verified by 1 H NMR spectroscopy and high-resolution mass spectrometry. Furthermore, we fabricated a fluorescent test strip (FTS-Pi) for the detection of phosgene in the gas phase that undergoes a fluorescence color change, from green to blue, under 365 nm UV light in the presence of phosgene, which is easily observed with the naked eye., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Thiophenol is widely known as a highly toxic substance that can cause serious harm to the environment and health. Rapid and non-destructive detection of thiophenol is of great significance for environmental management. In this work, we designed and synthesized a near-infrared (NIR) fluorescent probe, (E)-4-(2-(4-(dicyanomethylene)-4H-chromen-2-yl)vinyl)-2-formylphenyl-2,4-dinitrobenzenesulfonate (DCM-CHO-D), that can respond to thiophenol rapidly (less than 3 min) based on intramolecular charge transfer (ICT) mechanism. DCM-CHO-D has high selectivity and sensitivity to the detection of thiophenol. And there is a linear relationship between the fluorescence intensity of DCM-CHO-D and thiophenol concentration in the range of 0-10 μM, the limit of detection (LOD) is as low as 0.22 μM. What's more, DCM-CHO-D can not only be used as an ideal colorimetric tool for detecting thiophenol in water samples, but also image thiophenol in living cells, indicating its potential utility for thiophenol sensing in environmental and biological samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In recent years, germanium nanoparticles (Ge NPs) have attracted considerable research attention because of its excellent electrical and optical properties. However, it is mainly applied in the field of solar cells, photodetectors and photothermal therapy. Actually, Ge NPs have the advantages of low toxicity and excellent biocompatibility, which means that they have great potential in biosensing applications. However, there are few related reports. In this paper, we discovered that Ge NPs have the intrinsic peroxidase-like catalytic activity and can significantly accelerate the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H 2 O 2 for the first time. Compared with natural enzyme (horseradish peroxidase, HRP), Ge NPs maintain higher catalytic stability after treatment at different pH, temperature and ionic strength. Furthermore, a Ge NPs-based colorimetric platform was established for the first time to detect biomolecules with favourable sensitivity and selectivity, such as uric acid, glucose and choline. This work finds the new property of Ge NPs and extends its application in biosensing., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this paper, ferrocene derivative polymer nanoparticles (FcP NPs) with uniform size and good photostability was synthesized using 1,1'-ferrocene dicarboxylic acid as precursor and methanol as solvent. FcP NPs-PDA was further obtained by coating of polydopamine (PDA) on FcP NPs in tris-HCl (pH=8.5) buffer solution at room temperature in the presence of dopamine (DA). The structure and morphology of FcP NPs and FcP NPs-PDA were characterized by transmission electron microscope (TEM), ultraviolet-visible spectroscopy (UV-Vis), and infrared radiation (FT-IR). The as-prepared FcP NPs-PDA showed better peroxidase-like activity than FcP NPs, which could catalyze the chromogenic reaction of peroxidase substrate TMB, OPD and ABTS. Based on the high peroxidase-like property of FcP NPs-PDA, a sensitive and convenient means to detect H 2 O 2 has been proposed with TMB as the substrate, which displays wide linear range of 10-600 μM and 600 μM-4 mM with low detection limit of 5 μΜ. Compared with other Fe-containing NPs, such as magnetic materials and noble metal@Fe bimetallic NPs, the preparation approach for FcP NPs-PDA is simple, time and energy saving and environment friendly. This mild and simple synthesis route of FcP NPs-PDA will provide new ideas for the preparation of non-noble metal-based peroxidase-like nanomaterials and widen the applications in the fields of catalytic and analytical chemistry., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Herein, molecular structure regulation and enzyme cascade signals amplification (MRECAmp) strategy was proposed to construct a novel upconversion ratiometric fluorescence and colorimetric dual-readout assay platform for highly sensitive and selective detection of alkaline phosphatase (ALP) activity. The detection strategy is divided into three aspects. Firstly, Ag + oxidates o-phenylenediamine (OPD) to 2,3-diaminophennazine (OPDox), which can significantly quench upconversion fluorescence at 487 nm based on inner filter effects (IFE) while the upconversion emission at 668 nm was essentially unchanged for Zn 2+ -doped NaYF 4 :Yb 3+ ,Er 3+ ,Tm 3+ upconversion nanoparticles (UCNPs) probes under the near-infrared (NIR) irradiation. Secondly, ALP catalyzes the hydrolysis of the substrate l-ascorbic acid 2-phosphate (AAP) to ascorbic acid (AA) which can consume part of Ag + to inhibit the generation of OPDox and the AA was oxidized to dehydroascorbic acid (DHAA). The specific performance of DHAA molecular structure regulation, due to the condensation reaction between dicarbonyl group of DHAA and diamine group of OPD, that is confirmed by ESI-MS and 1 H NMR spectra analysis, can remarkably enhance the selectivity of ALP detection, which is conceptually different from the previously reported ALP fluorescent assays. Thirdly, the generated DHAA reacts with OPD to form 3-(dihydroxyethyl)furo [3,4-b]quinoxaline-1-one (DFQ) that further inhibits the generation of OPDox, which makes the enzyme-controlled cascade signal amplification (ECAmp) can be realized with a great fluorescence recovery (60.04%) at 487 nm. Therefore, the fluorescence response signal ((I 487 /I 668 ) 0 /(I 487 /I 668 )) is amplified by ECAmp strategy, allowing the quantitative analysis of ALP with a detection limit of 0.03 mU/mL. The detection of ALP activity in human serum samples over the conventional methods demonstrates that the MRECAmp method provides a sensing platform for probing ALP activity and shows promising outlook in biomedical studies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel mitochondria-targeted fluorescent probe for sensing SO 2 derivatives was constructed by integrating phenanthroimidazole and cyanine moieties. Excited by different channels, this probe exhibited unique dual-channel fluorescence-enhanced emissions and colorimetric response to HSO 3 - quickly (less than 20 s). The sensing process was confirmed to undergo nucleophilic addition of HSO 3 - to C˭C double bond in the probe Mito-PTB via NMR and HRMS analyses. Furthermore, fluorescence co-localization studies demonstrated that the probe Mito-PTB was a mitochondria-targetable fluorescent probe for SO 2 derivatives with good cell membrane permeability. Thus, probe Mito-PTB has the potential applications to explore the role played by SO 2 derivatives in biology., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel lysosome-targetable phthalimide fluorescent probe was designed for detecting palladium based on ESIPT for signal transduction. The fluorescent probe conjugating with allylcarbamate displayed weak fluorescent due to the ESIPT process hinder by allylcarbamate. But with the addition of palladium, the ESIPT emission was recovery though the palladium-catalyzed deallylation reaction and the fluorescence intensity exhibited 40-fold enhancement at 511 nm. In addition, the probe showed excellent selectivity, high sensitivity, fast responds and low limit detection for palladium with a larger Stoke-shift. Moreover, the targetable probe was also successfully applied for detecting palladium in lysosomes of living cells. Hence, the probe though ESIPT modulation is a promising for monitoring palladium in practical samples., (Copyright © 2018. Published by Elsevier B.V.)

Although great advances have been achieved in synthesis of fluorescent graphitic carbon nitride quantum dots (g-C 3 N 4 -dots), it is still challenging to develop g-C 3 N 4 -dots with high fluorescence quantum yield (FLQY) and multiple sensing functionalities. Herein, the oxygen and sulfur co-doped graphitic carbon nitride quantum dots (OS-g-C 3 N 4 -dots) with high FLQY of 33.9% were firstly synthesized by a simple electrochemical "tailoring" process. It was found that OS-g-C 3 N 4 -dots could specifically bind copper ions (Cu 2+ ) and silver ions (Ag + ), accompanied with a dramatic "turn-off" fluorescence response. With the help of different masking agents, OS-g-C 3 N 4 -dots are able to selectively detect Cu 2+ and Ag + . Furthermore, the generated OS-g-C 3 N 4 -dots/Ag + displayed a "turn-on" fluorescent response specific to biothiols (HCy, Cys and GSH). Therefore, the multiple functional sensing platforms based on "ON-OFF-ON" fluorescence response of OS-g-C 3 N 4 -dots for the detection of Cu 2+ , Ag + and biothiols were constructed. Under the optimal conditions, the detection limits of Cu 2+ , Ag + , HCy, Cys and GSH were as low as 7.0 × 10 -10  M, 2.0 × 10 -9  M, 1.0 × 10 -8  M, 1.0 × 10 -8  M and 8.4 × 10 -9  M, respectively. Moreover, the prepared platforms could be successfully applied to the determination of Cu 2+ , Ag + and biothiols in practical samples and exhibited excellent sensitivity and selectivity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The selective and sensitive detection of dopamine (DA) is of great significance for the identification of schizophrenia, Huntington's disease, and Parkinson's disease from the perspective of molecular diagnostics. So far, most of DA fluorescence sensors are based on the electron transfer from the fluorescence nanomaterials to DA-quinone. However, the limited electron transfer ability of the DA-quinone affects the level of detection sensitivity of these sensors. In this work, based on the DA can reduce Ag + into AgNPs followed by oxidized to DA-quinone, we developed a novel silicon nanoparticles-based electron transfer fluorescent sensor for the detection of DA. As electron transfer acceptor, the AgNPs and DA-quinone can quench the fluorescence of silicon nanoparticles effectively through the synergistic electron transfer effect. Compared with traditional fluorescence DA sensors, the proposed synergistic electron transfer-based sensor improves the detection sensitivity to a great extent (at least 10-fold improvement). The proposed sensor shows a low detection limit of DA, which is as low as 0.1 nM under the optimal conditions. This sensor has potential applicability for the detection of DA in practical sample. This work has been demonstrated to contribute to a substantial improvement in the sensitivity of the sensors. It also gives new insight into design electron transfer-based sensors., (Copyright © 2018. Published by Elsevier B.V.)

Fluorescence nanoprobes are frequently employed to construct sensitive biosensors via turn-on and turn-off strategy. In this paper, a novel strategy for ultrasensitive detection of iodide was firstly constructed based on Ag + regulated photoluminescence enhancement of gold nanoclusters (AuNCs) as a turn-off nanoplatform. In the presence of Ag + , the fluorescence (FL) intensity of AuNCs can be enhanced obviously. When adding iodide ions (I - ) in the Ag + -AuNCs, Ag + can be pulled down from AuNCs and results in quenching of the fluorescent effectively owing to the combination between Ag + and I - . Compared with that of I - directly reaction with AuNCs, the introducing of Ag + shows improved quenching efficiency from 32% to 66% since I - can react with Ag + as well as AuNCs. Therefore, the platform could be applied to assay Ag + and I - , on the basis of the FL enhancement and the further FL quenching. The detection ranges and detection limits were 0.2-12μM and 0.06μM for Ag + , 0.001-6μM and 0.3nM for I - , respectively. The new sensing method based on ion regulation to enhance the detection sensitivity can extend to the appliance of other fluorescent materials in biosensing and biomedical field., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A simple benzothiazole fluorescent chemosensor was developed for the fast sequential detection of Cu 2+ and biothiols through modulating the excited-state intramolecular proton transfer (ESIPT) process. The compound 1 exhibits highly selective and sensitive fluorescence "on-off" recognition to Cu 2+ with a 1:1 binding stoichiometry by ESIPT hinder. The in situ generated 1-Cu 2+ complex can serve as an "on-off" fluorescent probe for high selectivity toward biothiols via Cu 2+ displacement approach, which exerts ESIPT recovery. It is worth pointing out that the 1-Cu 2+ complex shows faster for cysteins (within 1min) than other biothiols such as homocysteine (25min) and glutathione (25min). Moreover, the compound 1 displays 160nm Stoke-shift for reversibly monitoring Cu 2+ and biothiols. In addition, the probe is successfully used for fluorescent cellular imaging. This strategy via modulation the ESIPT state has been used for determination of Cu 2+ and Cys with satisfactory results, which further demonstrates its value of practical applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this paper, the colorimetric sensing of H 2 O 2 related molecules and biothiols based on etching and anti-etching strategy was firstly proposed. Ag/carbon nanocomposite (Ag/C NC) was served as the sensing nanoprobe, which was synthesized via carbon dots (C-dots) as the reductant and stabilizer. The characteristic surface plasmon resonance (SPR) absorbance of Ag nanoparticles (AgNPs) was sensitive to the amount of hydrogen peroxide (H 2 O 2 ). It exhibited strong optical responses to H 2 O 2 with the solution colour changing from yellow to nearly colourless, which is resulted from the etching of Ag by H 2 O 2 . The sensing platform was further extended to detect H 2 O 2 related molecules such as lactate in coupling with the specific catalysis oxidation of L-lactate by lactate oxidase (LOx) and formation of H 2 O 2 . It provides wide linear range for detecting H 2 O 2 in 0.1-80μM and 80-220μM with the detection limit as low as 0.03μM (S/N=3). In the presence of biothiols, the etching from the H 2 O 2 can be hampered. Other biothiols exhibit anti-etching effects well. The strategy works well in detecting of typical biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). Thus, a simple colorimetric strategy for sensitive detection of H 2 O 2 and biothiols is proposed. It is believed that the colorimetric sensor based on etching and anti-etching strategy can be applied in other systems in chemical and biosensing areas., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A novel fluorescent probe (E)-3-ethyl-2-(4-hydroxystyryl)-1,1-di-methyl-1H-benzo-[e]indolium iodide (probe EDB) based on benzo[e]indolium was synthesized, which provided the simultaneous detection of SO 3 2- /HSO 3 - and HSO 4 - ion with different emission channels. Based on the principle of ion-induced rotation-displaced H-aggregates, when treated with NaHSO 4 , a fluorescence enhancement at 580nm was observed with the excitation wavelength at 420nm. While, in the advantage of the nucleophilic addition of SO 3 2- to the vinyl group, strong fluorescence was obtained at 455nm when treated with Na 2 SO 3 with the excitation wavelength at 320nm, along with obvious color change by naked eyes. So the probe could be applied to sense SO 3 2- /HSO 3 - and HSO 4 - ion via different excited and emission channels simultaneously. The probe was also applicable for fluorescence imagings of bisulfite and hydrosulfate in HeLa cells., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In this paper, aldehyde-terminated ionic liquid was synthesized and used to fabricate a novel label-free electrochemical immunosensor for the determination of hepatitis B surface antigen. This sensor was formed from a gold electrode which was modified with a composite film containing the aldehyde-functionalized ionic liquid incorporated into nafion and anti-hepatitis B surface antigen antibody probes. Aldehyde-functionalized ionic liquid was used not only as a substrate for antibody immobilization, but also as a good material with high electrical conductivity, which greatly simplified the process of sensor fabrication. The proposed sensor exhibited a good performance in a linear range from 0.05 to 15ngmL -1 with a detection limit of 20pgmL -1 (S/N=3) and provided a novel strategy for clinical detection due to satisfying stability, selectivity and reproducibility., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Silver triangular nanoplates (STNPs) as a high efficient fluorescence quenching reagent of upconversion nanoparticles (UCNPs) was used to constract a novel label-free fluorescence nanosensor for ultrasensitive detection of protamine and trypsin based on fluorescence resonance energy transfer (FRET) between STNPs and UCNPs. In this assay, the negatively charged STNPs can bind with positively charged UCNPs through electrostatic interaction, and then quenched the fluorescence of UCNPs. When protamine was added to the mixture of UCNPs-STNPs, the STNPs interacted with protamine and then detached from the surface of UCNPs and aggregated, which result in the recovery of the fluorescence of UCNPs. Trypsin could catalyze the hydrolysis of protamine and effectively quench the fluorescence recovered by protamine. By measuring the changes of the fluorescence of UCNPs, the concentrations of protamine and trypsin were determined. Under the optimized conditions, the linear response range was obtained from 10 to 500ng/mL, 5-80ng/mL and with the low detection limit of 3.1ng/mL and 1.8ng/mL for protamine and trypsin, respectively. Meanwhile, the nanosensor shows good selectivity, sensitivity and can be successfully applied to detection of protamine and trypsin in serum samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A new turn-on phthalimide fluorescent probe has designed and synthesized for sensing cysteine (Cys) based on excited state intramolecular proton transfer (ESIPT) process. It is consisted of a 3-hydroxyphthalimide derivative moiety as the fluorophore and an acrylic ester group as a recognition receptor. The acrylic ester acts as an ESIPT blocking agent. Upon addition of cystein, intermolecular nucleophilic attack of cysteine on acrylic ester releases the fluorescent 3-hydroxyphthalimide derivative, thereby enabling the ESIPT process and leading to enhancement of fluorescence. The probe displays high sensitivity, excellent selectivity and with large Stokes shift toward cysteine. The linear interval range of the fluorescence titration ranged from 0 to 1.0×10 -5 M and detection limit is low (6×10 -8 M). In addition, the probe could be used for bio-imaging in living cells., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Diabetes mellitus is an epidemic disease that it has became a worldwide public health problem. Thus, blood glucose monitoring has attracted extensive attention. Here, we report a nanosensor based on inner filter effect (IFE) between upconversion nanoparticles (UCNPs) and squaric acid (SQA)-iron(III) for the highly sensitive and selective detection of glucose levels in human serum. In this assay, GOx-catalyzed oxidization of glucose produces gluconic acid and hydrogen peroxide (H 2 O 2 ). The latter can catalytically oxidize iron(II) to iron(III) which can rapidly (<1min) coordinate with the SQA to produce (SQA)-iron(III). The absorption band of (SQA)-iron(III) largely covered the emission band of UCNPs, resulting the fluorescence emission of UCNPs was effectively quenched. Therefore, the glucose can be monitored based on the formation of SQA-iron(III). Under the optimal condition, the fluorescence quenching efficiency shows a good linear response to glucose concentration in the ranges of 7-340μmol/L with a detection limit of 2.3μmol/L. The developed method has been further applied to monitor glucose levels in human serum with satisfactory results. Compared with other fluorescence methods, current method displayed high sensitivity and signal-to-noise ratio. Meanwhile, this nanosystem is also generalizable and can be easily expanded to the detection of various H 2 O 2 -involved analytes., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this work, a novel and convenient strategy for synthesis of a well-defined polymer containing both aldehyde and ferrocene functional groups by grafting 4-hydroxybenzaldehyde and ferrocenecarboxylhydrazide onto linear poly (vinylbenzyl chloride) was developed. The designed polymer film (polymer CAF) could be used as a new support matrix for fabrication of a label-free electrochemical immunosensor with high sensitivity, good stability and repeatability. With human IgG as an analyte model, the proposed electrochemical immunosensor showed a linear concentration range from 0.1 to 20ngmL -1 with a detection limit of 0.07ngmL -1 (S/N=3). Moreover, interfering proteins including HSA, IgM, and IgE were added into the analyte, the developed immnnosensor can detect human IgG with high specificity., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this report, carbon-based gold core silver shell Au-Ag bimetallic nanocomposite (Au-Ag/C NC) was synthesized using carbon dots (C-dots) as the reductant and stabilizer by a facile green sequential reduction approach. The structure and morphology of the nanocomposite are characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). The as synthesized Au-Ag/C NC exhibits good optic response toward hydrogen peroxide (H 2 O 2 ) without adding any other chromogenic agents. The characteristic surface plasmon resonance (SPR) absorbance peak of Au-Ag/C NC declined and red-shifted with the solution color changing from reddish orange to light pink when adding H 2 O 2 owing to the etching effect of H 2 O 2 towards Ag. Thus, a simple colorimetric and UV strategy for sensitive detection of H 2 O 2 is proposed. It provides the wide linear range for detection of H 2 O 2 from 0.8-90 μM and 90-500 μM, and the detection limit was as low as 0.3 μM (S/N = 3). In addition, this colorimetric strategy can also be applied to directly distinguish and detect of lactate by naked eye and UV-Vis. The linear range of colorimetric sensing towards lactate was 0.1-22 μM and 22-220 μM, which was successfully applied in the analysis of lactate in human serum., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H2O2) has been designed using 3,3',5,5'-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H2O2 in wide linear range of 5 μM-500 μM and 500 μM-4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Sulfur, nitrogen co-doped carbon dots (S, N co-doped C-dots) as highly selective fluorescent probe for uric acid (UA) detection were designed. The S, N co-doped C-dots with high quantum yield of 73.1% were prepared by hydrothermal method. It was found that the fluorescence of S, N co-doped C-dots was quenched apparently by hydroxyl radicals from Fenton reaction between H2O2 and Fe(2+). The production of H2O2 originated from the oxidization of UA by uricase. Therefore, an optical biosensor was developed for the detection of UA based on Fenton reaction and enzymatic reaction. Under the optimized conditions, two linear relationships between the ratio of fluorescence quenching of the C-dots and UA concentration were found in the range of 0.08-10µM and 10-50µM, respectively. The detection limit was down to 0.07µM. Moreover, the proposed biosensor was successfully applied to the detection of uric acid in human serum samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A new ratiometric nanosensor is developed for selective and ultrasensitive detection of melamine based on conjugated polyelectrolyte (CPE)-stabilized silver nanoparticles (P1-AgNPs) by perfectly combining the advantages of CPE and AgNPs. P1 featuring a π-delocalized backbone bearing pyridinyl groups can act as an excellent dual-emission fluorescent probe as well as a polymer localizer for AgNPs. In the presence of melamine, the fluorescence intensity at 386nm increases owing to the turn-on of the fluorescence of P1, whereas FL intensity at 488nm decreases due to the melamine-induced aggregation and subsequent aggregation-enhanced emission quenching of P1-AgNPs, therefore leading to the ratiometric fluorescent sensing of analyte. Moreover, analyte-induced aggregation of P1-AgNPs also allows the ratiometric colorimetric measurement of melamine. Under the optimum conditions, this facile ratiometric nanosensor favors the fluorescent and colorimetric determination of melamine in liquid milk products with the detection limit as low as 0.1 and 0.45nM, respectively., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this work, a new nanomaterial of thiol functional ferrocene derivative (Fc-SH) stabilized Au NPs/carbon dots nanocomposite (Au/C NC) coupling with graphene modified glassy carbon electrode (Fc-S-Au/C NC/graphene/GCE) was fabricated to serve as a quadruplet detection platform for ultrasensitive and simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and acetaminophen (AC). The Au/C NC was synthesized by adding HAuCl4 into carbon nanodots solution without using any additional reductant and stabilizing agent. Then the Fc-SH was utilized as the protective and capping agent to modify the Au/C NC. Transmission electron microscopy (TEM), UV-Vis, Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) were adopted to characterize the morphology and electrochemical properties of the materials and the electrodes. The Fc-S-Au/C NC/graphene/GCE exhibits a synergistic catalytic and amplification effects towards oxidation of AA, DA, UA and AC owing to the existence of the nanomaterial and electron mediator. When simultaneous detection of AA, DA, UA and AC, the oxidation peak potentials of the four compounds on the electrode can be well separated and the peak currents were linearly dependent on their concentrations. The quadruplet detection platform shows excellent linear range and ultrasensitive response to the four components, the detection limits were estimated to be as low as 1.00, 0.05, 0.12 and 0.10 μM (S/N = 3), and the modified electrode exhibits excellent stability and reproducibility. The proposed electrode has been successfully applied to detect of these four analytes in real samples with satisfactory results., (Copyright © 2015 Elsevier B.V. All rights reserved.)