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Photomechanical actuator with large deformation and rapid response is highly desirable for smart textiles and soft robots. However, the conventional polydimethylsiloxane (PDMS) elastomer-based actuators with multilayered or blocky configuration suffer from interlayer instability, low effective utilization area, and manual assembly process, which limit their practical application. Herein, a series of PDMS composite fibers were fabricated through a scalable wet-spinning approach. To investigate the effects of light-responsive material dimension on the photomechanical performance of PDMS composite fibers, pseudo-1D gold nanorod (AuNR), 1D carbon nanotube (CNT), and 2D reduced graphene oxide (RGO) were used as photoresponsivity materials. To obtain a superior photomechanical property of these fibers, the effects of the light intensity, pre-train, fiber diameter, filler concentration and chemical structure were discussed, and their light-induced actuation mechanisms were presented. Among them, the RGO/PDMS fiber actuator showed the highest actuation stress (72.1 kPa at 40 % pre-stain), while the AuNR/PDMS fiber actuator exhibited the fastest response times of 12.6 s at 40 % pre-strain. This study provides valuable insights for the design and development of fiber actuators with outstanding photomechanical performance. [Display omitted] • PDMS-based fiber actuators are fabricated through a scalable wet-spinning approach. • Dimension, chemical composition, and content of the photoactive filler affects the actuation performance. • Graphene exhibits the best photoresponsivity when compared with carbon nanotubes and gold nanorods. • RGO/PDMS fiber actuator achieves a high actuation stress of 72.1 kPa at 40 % pre-stain with fast response. [ABSTRACT FROM AUTHOR]

Time-temperature indicators (TTIs) with the capability to visually reflect the accumulated time and temperature effect for real time are of substantial significance for securing the safety and quality of perishable products, such as foods and medical products. Herein, we design a novel TTI with high accuracy and low cost based on a ratiometric fluorescent nanosensor capable of self-calibration. The nanosensor was fabricated via the co-assembly of amphiphilic block copolymer and a responsive triplet-triplet annihilation upconversion (TTA-UC) system. The pH responsiveness of the triplet-sensitized nanomicelle was well investigated experimentally and theoretically. A linear relationship between the intensity ratio (of the integrated upconversion emission to the integrated phosphorescence emission) and pH was revealed for the ratiometric fluorescent nanomicelle. The TTA-UC functionalized nanomicelle turned out to be an extraordinary nanosensor with excellent sensitivity, reliability, and anti-reference. Subsequently, the nanomicelle was firstly applied for enzymatic time-temperature indicators (TTIs). Comprehensive kinetic study of the TTI prototype and the released total volatile basic nitrogen during meat storage was conducted under isothermal and non-isothermal conditions, which demonstrated remarkable correlation between the TTI response and the food spoilage. The activation energy of the TTI prototype could be readily modified to satisfy diverse food products including meat, diary, and aquatic products. The TTI based on triplet-sensitized ratiometric fluorescent nanosensor could be employed for visual monitoring food quality with low cost, high accuracy, and good reliability. [Display omitted] • A novel TTI prototype is designed for monitoring food quality for real time. • The TTI is fabricated with a ratiometric fluorescent nanosensor based on triplet-triplet annihilation upconversion. • It shows self-calibration and superior accuracy more than excellent sensitivity, reliability, and anti-reference ability. • Comprehensive kinetic study validates the high accuracy of the TTI prototype. [ABSTRACT FROM AUTHOR]

Notum, a negative regulator of the Wnt signaling cascade via removing the essential palmitoleate moieties on the Wnt proteins, has been validated as a promising target for treating various Wnt/β-catenin related diseases. Herein, a rational substrate design strategy was used to construct a highly specific and high-affinity fluorogenic substrate for real-time sensing and functional imaging of hNotum in complex biological systems. Utilizing computer-aided substrate design and phenotyping assays, 3- O -methyl-6- O -octanoylfluorescein (MOF) was selected as an ideal enzyme-activatable fluorogenic substrate for hNotum from a set of ester derivatives of the fluorophores bearing an optically adjustable phenolic group. Under physiological conditions, MOF could be readily hydrolyzed by hNotum to release a brightly fluorescent product 3- O -methylfluorescein (3-MF), which could be easily captured by the devices equipped with fluorescence detector(s). Further studies showed that MOF displayed good performance for sensing hNotum in complex biological samples with rapid response, ultrahigh sensitivity, excellent specificity, and high binding affinity (K m = 101.4 nM). MOF also exhibited excellent performance for in-situ functional imaging of hNotum in living cells, cancerous tissues, and tumor-xenograft mice. MOF was then used to construct a fluorescence-based biochemical assay for high-throughput screening (HTS) of hNotum inhibitors, while isoalantolactone (IAL) was identified as a potent hNotum inhibitor and an efficacious activator of Wnt signaling cascade from an in-house compound library. Collectively, this study devised the first-generation fluorogenic substrate for sensing and imaging hNotum activities in various biological systems, which offered a practical tool for deciphering the biological roles of hNotum and its relevance to human diseases. • A highly specific fluorogenic substrate (MOF) for hNotum was rationally constructed. • MOF displayed good performance for sensing hNotum, with high sensitivity, excellent specificity, and high binding affinity. • MOF was successfully used for sensing and imaging of hNotum in living cells, cancerous tissues, and tumor-xenograft mice. • MOF was used to construct a fluorescence-based biochemical assay for high-throughput screening of hNotum inhibitors. [ABSTRACT FROM AUTHOR]

We present a facile strategy for fabrication of excitation-independent yellow-fluorescent nitrogen-doped carbon nanodots (y-CDs) and illuminate their applications for biological imaging and paper-based sensing. The y-CDs have been synthesized using 4-amino salicylic acid as raw material via one-step hydrothermal treatment without further surface passivation or modification. As-prepared y-CDs exhibit exceptional advantages including unique excitation-independent emission, respectable fluorescence quantum yield (11.0%), superior biocompatibility, low toxicity, and satisfactory optical stability. Depending on these eminent properties, the y-CDs have been utilized for intracellular Al 3+ imaging and paper-based Al 3+ sensing. They could image Al 3+ fluctuations in living cells without interference of autofluorescence based on their high selectivity and sensitivity detection for Al 3+ ions in aqueous solution with a good linearity in the concentration range of 10–200 μM and 225–400 μM and a detection limit of 1.69 μM. Moreover, a paper-based sensor strip containing y-CDs has been prepared for Al 3+ sensing, which provides a convenient and user-friendly approach for the visual detection of Al 3+ . [ABSTRACT FROM AUTHOR]

Detection of cyanide (CN-) ion is of essential importance due to its high toxicity to human life. Herein, we developed a gold nanoclusters (AuNCs)-peroxyoxalate chemiluminescence (CL) system for ultrasensitive detection of CN- in environmental water samples. Bis (2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO)-hydrogen peroxide (H 2 O 2) CL reaction was utilized to produce high energy intermediates, namely energy donors, and AuNCs served as the acceptors to harvest the energy via CL resonance energy transfer (CRET) process. Besides, it was demonstrated that AuNCs also could act as a catalyst to enhance the generation of the high energy intermediate; and the AuNCs also had an aggregation induced emission (AIE) effect in the organic solvent that was used in CPPO-based CL system. In the presence of CN-, AuNCs can be etched by CN- due to the Elsner complexation reaction between CN- and AuNCs, and thus both of the quantum yield and catalytic activity decreased remarkably. As a result, significant quenching of CPPO-AuNCs CL was observed. The CL intensity decreased linearly in the concentration range of 2.5–125 μg/L CN-, and the detection limit was calculated to be 0.55 μg/L, 10-fold lower than that obtained by the fluorescent sensing of AuNCs. The relative standard deviation was 4.3% for seven parallel measurements of 100 μg/L CN-. It also exhibited high selectivity and favorable anti-interference capability. The sensing system was used for detection of CN- in five standard water samples, and the analytical results were in good agreement with the certified values. Overall, the simple and sensitive CL sensing platform offers a promising tool for convenient detection of CN- in environmental water samples. [Display omitted] • A CPPO-AuNCs CL system was developed for ultrasensitive detection of CN- in environmental water samples. • The etching of AuNCs by CN- lead to the decrease of both quantum yeilds and catalytic activity. • The quenching effect allow detection of 2.5–125 μg/L CN- withi an LOD down to 0.26 μg/L. [ABSTRACT FROM AUTHOR]

Detection of cyanide (CN-) ion is of essential importance due to its high toxicity to human life. Herein, we developed a gold nanoclusters (AuNCs)-peroxyoxalate chemiluminescence (CL) system for ultrasensitive detection of CN- in environmental water samples. Bis (2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO)-hydrogen peroxide (H 2 O 2) CL reaction was utilized to produce high energy intermediates, namely energy donors, and AuNCs served as the acceptors to harvest the energy via CL resonance energy transfer (CRET) process. Besides, it was demonstrated that AuNCs also could act as a catalyst to enhance the generation of the high energy intermediate; and the AuNCs also had an aggregation induced emission (AIE) effect in the organic solvent that was used in CPPO-based CL system. In the presence of CN-, AuNCs can be etched by CN- due to the Elsner complexation reaction between CN- and AuNCs, and thus both of the quantum yield and catalytic activity decreased remarkably. As a result, significant quenching of CPPO-AuNCs CL was observed. The CL intensity decreased linearly in the concentration range of 2.5–125 μg/L CN-, and the detection limit was calculated to be 0.55 μg/L, 10-fold lower than that obtained by the fluorescent sensing of AuNCs. The relative standard deviation was 4.3% for seven parallel measurements of 100 μg/L CN-. It also exhibited high selectivity and favorable anti-interference capability. The sensing system was used for detection of CN- in five standard water samples, and the analytical results were in good agreement with the certified values. Overall, the simple and sensitive CL sensing platform offers a promising tool for convenient detection of CN- in environmental water samples. [Display omitted] • A CPPO-AuNCs CL system was developed for ultrasensitive detection of CN- in environmental water samples. • The etching of AuNCs by CN- lead to the decrease of both quantum yeilds and catalytic activity. • The quenching effect allow detection of 2.5–125 μg/L CN- withi an LOD down to 0.26 μg/L. [ABSTRACT FROM AUTHOR]

Abstract: A sulfur sensor Mo|Mo, Mo2S3|ZrS2 +MgS|ZrO2(MgO)|ZrS2 +MgS|[S]Fe|Mo was developed and tested in carbon-saturated liquid iron. The auxiliary electrode was ZrS2 +MgS, which was formed on the surface of ZrO2(MgO) electrolyte by: ZrO2(MgO)(s)+3H2S(g)=ZrS2(s)+MgS(s)+3H2O(g). The results indicate that the auxiliary electrode is dense, and has a good adhesion to the solid electrolyte. ZrS2 and MgS are stable in the carbon-saturated liquid iron where the a O <1.25×10−7 at 1550K and a O <2.10×10−7 at 1600K. The variations of the EMF versus [wt% S] can be obtained as follows: [Copyright &y& Elsevier]

• A multi-functional sensing platform based on red fluorescent carbon dots (R-CDs) was built. • The fluorescence of R-CDs can be significantly enhanced in the presence of TCs. • The R-CDs showed a distinct pH-sensitive luminescence emission feature with a pKa of 7.08. • The nanosensor can be utilized to image the intracellular TCs and pH in living cells. Red fluorescent carbon dots (R-CDs) have been developed for the "turn-on" determination of pH and tetracycline antibiotics (TCs), including tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). The CDs were fabricated via one-pot hydrothermal treatment using neutral red and thiourea as precursors. As-obtained CDs possess excellent photobleaching resistance, good photostability and biocompatibility, and low cytotoxicity. Importantly, the CDs displayed a remarkable emission enhancement upon the introduction of TCs based on aggregation induced emission enhancement (AIEE) mechanism. For TC, OTC, and CTC, the linear correlation detection ranges are 3 − 35 μM, 2 − 50 μM, and 5 − 50 μM, respectively, and the limit of detections are 12, 23, and 25 nM, respectively. The proposed method has been successfully applied to the determination of TCs in milk products. Furthermore, the CDs exhibited a distinct H+-sensitive feature, and have been used to construct fluorescent pH sensor in linear range of 6.0–8.0 with a pKa of 7.08. Notably, the nanosensor has been also extended to monitor TCs and pH in cellular systems, demonstrating the proposed methodology presents promising biosensing application prospect. [ABSTRACT FROM AUTHOR]

A photocatalytic sensor was developed for visual detection of SOD at nM level using photoresponsive g-C 3 N 4 as the O 2 − producer and azo dyes as the colorant indicator. • Pt doped g-C 3 N 4 can photo-catalytically produce O 2 − upon violet LED illumination. • The azo dye amaranth (AM) was demonstrated to be the best indicator for O 2 − generated from Pt doped g-C 3 N 4. • The photocatalytic sensor allows visual detection of SOD at nM level without sophisticated instrument. In this work, we reported a photocatalytic biosensor for visual detection of superoxide dismutase (SOD) based on Pt-doped graphite phase carbon nitride (g-C 3 N 4). Upon illumination by a violet light-emitting diode (LED), Pt-doped g-C 3 N 4 absorbed the light energy and catalytically produced O 2 − which further oxidized the dyes into a colorless end product. In the presence of SOD, it can specifically catalyze O 2 − into oxygen and hydrogen peroxide, leading to a reduced photooxidation and a visual color display. After screening a series of dyes, the azo dye amaranth (AM) was proven to be the best indicator for O 2 − since the azo bond is active and easily oxidized by O 2 −, resulting in a low background. Such a simple photocatalytic sensor allows visual detection of SOD at a nM level without the need of any sophisticated instrument; using spectrometry, the linear response for SOD detection ranges from 1.5 to 4500 nM with a limit of detection (LOD, 3σ) down to 0.3 nM. The sensor was also successfully applied for label-free and wash-free detection of SOD in human serum samples with a satisfactory recovery. [ABSTRACT FROM AUTHOR]

• First use of conjugated organic microporous polymers to build a novel peroxynitrite anion sensors. • The sensor showed an excellent performance in a wide range of four orders of magnitude and a super low detection limit (1.54 ± 0.5 nM). • Direct electrochemical measurements of peroxynitrite anion released from cells, • Explored the ability of antioxidants (especially reduced glutathione) to protect cells in an oxidative stress environment for the first time. • Effective differentiation and quantification of ROS and RNS in cells. The aberrant expression levels of reactive oxygen and nitrogen species (ROS and RNS) in human cells are related with many diseases, including cancer. In recent years, the primary RNS, peroxynitrite anion (ONOO−), has aroused immense research interest in the biological and biomedical fields. Herein, we build a novel sensing platform by the hollow tubular organic conjugated microporous polymer (HTCMPs) modified glassy carbon electrode (GCE) for directly monitoring of ONOO−. Specifically, the HTCMP was used to develop an electrochemical sensor for the first time. This as-prepared amperometric sensor showed an excellent activity toward the oxidation of ONOO− with a wide range of four orders of magnitude and a super low detection limit reached 1.54 ± 0.5 nM (S/N = 3). With these properties, the sensor was used for measuring the ONOO− released from glioma cells (U87) during oxidative stress induced by biochemical reagent stimulation. For the more, a new strategy to verify antioxidant protection was developed by stimulating cells at low or high doses of stimulus in a vitro simulation environment. The results showed that reduced glutathione (GSH) had great protective effect on cells in the case of oxidative stress. Last but not least, based on a battery of control tests, the concentrations of two key ROS/RNS (H 2 O 2 , ONOO−) in the cells were determined. This study essentially offers a reproducible platform for assessing the oxidative stress metabolites (ROS/RNS) in a vivo assays. [ABSTRACT FROM AUTHOR]

Insufficient sensitivity caused by low radiative intensity of employed fluorescent material is the main obstacle toward early accurate diagnosis of fatal diseases when applying fluorescence analysis. Herein, we have developed a dual amplification procedure to overcome this issue. We first synthesize high-quality CdSe@ZnS@SiO 2 core/shell quantum dots (QDs) with type-I band alignment to confine the carrier wave functions, thus ensuring high quantum yield (∼ 80%). The fluorescence intensity of those QDs is further amplified by localized surface plasmon resonance effect enabled by gold nanoparticles. We finally construct CdSe@ZnS@SiO 2 and Au@SiO 2 immune sandwich biosensor platform, and take C-reaction protein (CRP) as a test case. It is shown that this biosensor platform exhibits a wide detecting range between 0.5 and 100 ng/mL, and detecting limit of 0.076 ng/mL. We further apply this detecting scheme in serum and actual clinical, competing performance compared with the prevailing standard measurements in hospital has been obtained. Both experiment and the finite element analysis (FEA) approach calculation results indicate that a highly enhanced electric field between Au@SiO 2 and CdSe@ZnS@SiO 2 enhances the radiative recombination rates of the QDs@SiO 2 and decreases the fluorescence lifetime of that. The fluorescence intensity amplification scheme proposed herein is of great significance for the real-time and high-sensitivity early detection of biomarkers in the biomedicine. • Designing novel route of biological sensing via high-quality QDs-Gold system. • Highly enhanced electric field between Au@SiO 2 and QDs exists by Experiment and theoretical results. • By LSPR effect, the platform exhibits high sensitivity and wide detection range. [ABSTRACT FROM AUTHOR]

We herein provide a facile and green strategy for the fabrication of red fluorescence gold nanoclusters (AuNCs@ew) with low toxicity, good stability and excellent fluorescence (λ em = 650 nm, λ ex = 320 nm) by mixing aqueous tetrachloroauric acid with diluted egg white under alkaline environment using microwave-assisted method. Confocal fluorescence imaging showed that the AuNCs@ew can enter living cells and distribute in the cytoplasm. In addition, the fluorescence of AuNCs@ew is sensitive to the response of Cu 2+ and Hg 2+ with a detection limit of 14.48 nM and 0.81 nM, respectively. Interestingly, we found that the fluorescent signal of the quenched AuNCs@ew-Hg(II) system could be recovered in the presence of the glutathione (GSH) in Tris-HCl medium (pH 6.5). This assay displayed a rapid response and highly selectivity toward GSH with a detection limit of 91.9 nM. More excitingly, the fluorescent signal of the AuNCs@ew-Hg(II) system (OFF) could be activated in living tumor cells (ON) such as HepG2 cells rather than in living normal cells (HT22 cells, OFF) without any exogenous GSH. The result showed that the system can be successfully applied for tumor cells recognition, which implied its great potential application in early prevention of cancer. Furthermore, the AuNCs@ew can also be used for patterning, staining and temperature sensing. We propose that the highly fluorescent AuNCs@ew can be eco-friendly and potentially large-scale development for versatile applications and so merits further study. [ABSTRACT FROM AUTHOR]

Nonalcoholic fatty liver disease (NAFLD) has emerged as a prevalent chronic liver condition worldwide. The dysregulated metabolism of lipid droplets (LDs) in cells is physiologically and pathologically linked to NAFLD. The development of fluorescent probes for imaging LD metabolism holds promise for noninvasive diagnosis and understanding of NAFLD. However, the development of such probes is challenging, and their in vivo diagnostic potential remains largely unexplored. Here, we present the synthesis of ZP-1 , a bright fluorophore serving as a specific probe for LDs. ZP-1 possesses a donor-acceptor electronic structure with intramolecular charge transfer characteristics and shows polarity-dependent emission. In highly polar solvents, such as water, ZP-1 exhibits minimal fluorescence, while in low-polarity solvents, it displays strong fluorescence. This property enables high-specificity LD detection with excellent imaging contrast. Attributed to its high photostability and pH stability, ZP-1 effectively visualizes LD metabolism in live cells via real-time imaging, encompassing processes such as growth, migration, fusion, and fission. Moreover, we demonstrate in vivo diagnosis of NAFLD in a mouse model, providing rich information regarding LD morphology, numbers, volumes, and tissue structures. This work introduces ZP-1 as a valuable tool for NAFLD diagnosis and research, facilitating noninvasive assessment and improved understanding of the disease. • An ICT-type fluorophore, ZP-1 , has been synthesized. • ZP-1 shows polarity-dependent emission. • ZP-1 targets lipid droplets (LDs) in live cells. • ZP-1 can monitor LD metabolism. • ZP-1 is capable of diagnosing NAFLD in vivo. [ABSTRACT FROM AUTHOR]

Currently, the development of simple, fast, low-cost, and environmentally friendly MAO-A specific detection methods remains a huge challenge. Herein, a simple in situ fluorescent copolymer dots (FCDs)-based kit is constructed for the specific detection of monoamine oxidase-A in cell, tissue and human prostate cancer. The developed kit is depended on the high reaction activity between epinephrine and polyethyleneimine to form FCDs and the selective catalyzing activity of MAO-A on epinephrine. The gained FCDs are identified and characterized by high-resolution TEM, absorption and fluorescence spectrum. The present kit achieves highly sensitive detection of MAO-A with a limit of detection (LOD) of 20 ng/mL as well as screening of inhibitor with an IC50 (the concentration responding to 50% inhibition) of 1.071 μM by using clorgyline as a model. The MAO-A and MAO-B as the two isoforms of MAO are discriminated successfully, demonstrating the excellent selectivity of our kit. Noteworthy, the proposed method is applicable for measuring MAO-A not only from serum samples, but also for endogenous MAO-A in cells, mouse tissues and human prostate tumors with satisfied results. The proposed kit will be a great potential tool for human prostate cancer (PCa) diagnosis and the development of anti-PCa drug screening. [Display omitted] • We construct a simple in situ fluorescent copolymer dots (FCDs)-based kit for the specific detection of monoamine oxidase-A. • The developed kit is based high reaction activity between epinephrine and PEI to form FCDs for selective detection of MAO-A. • The present kit achieves a limit of detection of 20 ng/mL for MAO-A and screening of clorgyline with an IC50 of 1.071 μM. • The developed kit is successful applied to evaluate the MAO-A levels in cell, tissueand human prostate cancer. [ABSTRACT FROM AUTHOR]

Nitroreductase (NTR) is an overexpressed enzyme in hypoxic tumor microenvironment that can be a specific recognition site for tumor diagnosis in clinical trials. Therefore, the development of probs for NTR activity with precision and instantaneity is significant. In this work, a NTR probe (ZJ) was constructed on the structure of pyrimidine derivatives with 4-animobenzyl carbamate groups. ZJ exhibited a responsive "turn-on" two-photon excited fluorescence by NTR recognition in cells and in vivo. The 4-nitrobenzyl carbamate groups in ZJ could be reduced by NTR to 4-animobenzyl carbamate groups in the presence of reduced nicotinamide adenine dinucleotide (NADH). Attributed to its self-immolation property, 4-animobenzyl carbamate would release to generate primary amine on pyrimidine, accompanied by fluorescence signal recovery of ZJ. Such responsive fluorescence turn-on process accomplished as fast as within 20 mins. The favorable stability and specificity of ZJ on NTR activity sensing was further illustrated according to the negligible interference by biological factors and the distinguishing on different NTR types. ZJ successfully visualized the distribution of over-expressed NTR in hypoxic cancer cells and in zebrafish using two-photon fluorescence microscopy, which demonstrated the potential application in studying the relationship between tumor hypoxic microenvironment and cancer. • The probe (ZJ) is two-photon fluorogenic probes for NTR detection. • ZJ can rapidly detect NTR activity. • ZJ can recognize different NTRs. • ZJ can visualize NTR in hypoxic cells and deep tissue of zebrafish. [ABSTRACT FROM AUTHOR]

Highlights • Ce 0.75 Zr 0.25 O 2 was used as dense diffusion barrier in limiting current oxygen sensor. • 9YSZ solid electrolyte and Ce 0.75 Zr 0.25 O 2 dense diffusion barrier were selected to prepare limiting current oxygen sensor. • The influence of water vapor pressure on the dense diffusion barrier limiting current oxygen sensor was studied. • The sensor exhibits good sensing performance and has good selectivity to oxygen. Abstract Ce x Zr 1- x O 2 (x = 0.25, 0.5 and 0.75) was synthesized by solid phase chemical reaction synthesis and characterized by X-ray diffraction (XRD), thermal expansion, Hebb-Wagner method and DC van der Pauw method. ZrO 2 has a high melting point and CeO 2 has a variable valence state, which can make the Ce x Zr 1- x O 2 material have mixed ionic-electronic conductivity and stability. The synthesis method has the advantages of having a lower synthesis temperature and no waste liquid discharge, which is beneficial to energy conservation and environmental protection. A limiting current oxygen sensor was prepared with Ce 0.75 Zr 0.25 O 2 dense diffusion barrier and ZrO 2 stabilized by 9 mol% Y 2 O 3 (9YSZ) solid electrolyte by Pt sintered-paste method. Limiting current plateau of the oxygen sensor was obtained and the effects of operate temperature (T), oxygen concentration (x (O 2)) and water vapor pressure (p (H 2 O)) on the limiting current was studied, respectively. The results show that the Ce 0.75 Zr 0.25 O 2 material has maximum electronic and total conductivity at 800 ºC and is the most suitable ceramic material to be a dense diffusion barrier of limiting current oxygen sensor. The oxygen sensor exhibits good sensing characteristics under different research conditions, including different T , x (O 2) and p (H 2 O). The limiting current is related to various research factors, for example, log(I L · T) depends linearly on 1000/ T , I L depends linearly on x (O 2) and I L is not influenced obviously by p (H 2 O). The experiment supplements the application of mixed conductor material Ce x Zr 1- x O 2 (x = 0.25, 0.5 and 0.75) as a dense diffusion barrier in limiting current oxygen sensor. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We developed a deep-red fluorogenic probe (BT-NH), with high sensitivity and good selectivity to detect NO. • The probe was successfully used to visualize exogenous/endogenous NO level in living cells. • The probe was further applied to detect NO in PD models. Abstract Nitric oxide (NO), as one of important gaseous signaling molecule in human body, has been associated with a variety of physiologic processes. However, excessive production of NO has been profoundly implicated in the pathogenesis of neurodegenerative disorders in particular, Parkinson's disease (PD). Therefore, accurate and facile detection of NO is of great significance for investigating its functions in PD, and the subsequent diagnosis and/or treatment. Herein, we developed a deep-red fluorogenic probe (BT-NH), with high sensitivity and good selectivity to detect NO, which was successfully used to visualize exogenous/endogenous NO level in living cells, and further applied to in vitro and in vivo PD models. Therefore, BT-NH could be a potential biological fluorogenic tool to explore the roles of NO in PD. [ABSTRACT FROM AUTHOR]

Highlights • A novel strategy to create fluorescence nanoprobe is developed. • Thiol-ene click reaction is used to synthesize materials containing QDs. • The separated BSQD nanoprobes could be well-dispersed into water once again. • Fluorescence probe shows interfacial activity, photostability and biocompatibility. • Successfully fluorescence imaging application of BSQDs nanoprobes in porous media. Abstract Quantum dots (QDs) as fluorescence probes have attracted increasing attention for their fluorescence imaging applications. In this work, we developed a novel strategy to create bifunctional silica-protected QD (BSQD) nanoparticles as nanoprobes for fluorescence imaging. The thiol-ene click reaction of monounsaturated fatty acid salts with mercapto silane as an efficient method for the synthesis of the bifurcated surface modifier was presented. BSQD nanoprobes were prepared by a facile one-pot method. The whole reaction process was carried out in an aqueous solution under relatively low temperature, which makes the synthesis environment eco-friendly and the products cost-effective. The synthesized BSQD nanoprobes have a structure consisting of hydrophilic and hydrophobic arms that afforded an amphiphilic feature to the silica-protected QD (SQD) nanoparticles. The separated solid BSQD nanoprobes could be well dispersed into aqueous solution once again, and the quantum yield of the BSQD nanoprobes was higher than that of the SQD naoprobes. BSQD nanoprobes exhibited high interfacial activity, strong photostability and good biocompatibility. BSQD nanoprobes were successfully applied for fluorescence imaging. The strategy for the construction of the functionalized SQD nanoparticles provides a promising approach for modifying the surface of materials containing QDs. [ABSTRACT FROM AUTHOR]

Highlights • A new ratiometric and NIR fluorogenic probe (NIR-HP1) for detecting H 2 O 2 in Parkinson's disease models was developed. • NIR-HP1 shows specific H 2 O 2 -induced emission shift from visible light to NIR region. • NIR-HP1 has been utilized to realize the in vivo ratiometric H 2 O 2 imaging in living cells and zebrafish. • NIR-HP1 was successfully applied to the detection of endogenous H 2 O 2 in parkin-null Drosophila brain. Abstract Parkinson's disease (PD) is a neurological disorder which will significantly overwhelm the life for the patient. Numerous studies have proved that hydrogen peroxide plays an important role in the pathogenesis of PD. To detect hydrogen peroxide in PD in live, here we report the design and synthesis of a new ratiometric and NIR fluorescence probe (NIR-HP1) for hydrogen peroxide, utilizing an excited state intramolecular proton transfer strategy to control the fluorescence. NIR-HP1 showed a highly selective ratiometric response to hydrogen peroxide over other reactive oxygen/nitrogen species, biothiols and various ions in aqueous solution at physiological pH. The observed pseudo-first-order rate constant for the reaction of NIR-HP1 with hydrogen peroxide was calculated to be 0.042 s−1. The detection limit of this sensor for hydrogen peroxide was 0.27 μM. Moreover, NIR-HP1 worked well in living systems for hydrogen peroxide sensing as displayed by confocal fluorescence microscopy imaging, indicating potential application in PD study. [ABSTRACT FROM AUTHOR]

Highlights • LSGMC, 0.1≤ x ≤0.9 were used as dense diffusion barrier in limiting current oxygen sensor for the first time. • LSGM solid electrolyte and LSGMC (x = 0.7) were perfectly selected for the first time. • The sensor was prepared by a co-pressing and co-sintering technique and the method represents great advantages. Abstract La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3– δ (LSGM) and La 0.8 Sr 0.2 (Ga 0.8 Mg 0.2) 1– x Cr x O 3– δ (LSGMC, 0.1 ≤ x ≤ 0.9) were synthesized by a solid-state reaction and characterized by X-ray powder diffraction (XRD), thermal expansion, and DC four-probe method. A limiting current oxygen sensor using LSGM solid electrolyte and LSGMC (x = 0.7) dense diffusion barrier was prepared by a co-pressing and co-sintering technique and the sensing performances were evaluated. XRD shows the presence of a crystal structure in the series belonging to Pm-3m (No. 221) for x = 0–0.9. Electrical conductivity and thermal expansion coefficients first decrease and then increase with increasing x. LSGMC (x = 0.7) is the most suitable ceramic material and is selected as dense diffusion barrier. There is a directly proportional relationship between limiting current and oxygen concentration, and the equation i L (mA) = 3.65 C O 2 (%) is established from the measured data by simple regression analysis. The Arrhenius model for limiting current is log i L (mA) = 3.11 − 2.16 / T (K) , and the activation energy for oxygen diffusion is 0.43 eV. [ABSTRACT FROM AUTHOR]

(M = Fe, Cr and Co) doped CaZrO 3 , CaZr 0.7 M 0.3 O 3 (M = Fe, Cr and Co), was synthesized by solid state reaction method. Crystalline structure, microstructures, electronic conductivity, total conductivity and sensing performance were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Hebb-Wagner, DC van der Pauw and voltammetry method, respectively. XRD measurements show that the CaZr 0.7 M 0.3 O 3 (M = Fe, Cr and Co) samples belong to an orthorhombic perovskite structure. SEM measurements show that the CaZr 0.7 M 0.3 O 3 (M = Fe, Cr and Co) samples have fine grains with average grain size of 0.5–2 μm. Electrical property measurements show that the CaZr 0.7 Fe 0.3 O 3 and CaZr 0.7 Cr 0.3 O 3 samples have the highest electronic conductivity and total conductivity in air, respectively. Sensing performance measurements show that limiting current-type oxygen sensors with 9YSZ solid electrolyte and CaZr 0.7 M 0.3 O 3 dense diffusion barrier exhibit good limiting current ( I L ) plateau. Log I L depends linearly on 1000/ T . I L depends linearly on oxygen partial pressure. [ABSTRACT FROM AUTHOR]

With the emerging "Internet of Things" technology, humidity sensors are becoming indispensable in agriculture, industry, medicine, and environmental monitoring. However, the development of high-performance and multifunctional humidity sensors in the field of human-computer interaction still remains a challenge. Herein, Sm 2 O 3 nanoflowers with hierarchical structure were synthesized by modulating the material morphology. The unique hierarchical structure could provide more active sites, which is beneficial for the adsorption and desorption of water molecules. Furthermore, by compounding with KCl, the KCl/Sm 2 O 3 composite demonstrated enhanced humidity sensitivity and rapid response in diverse humidity conditions on account of that the introduced K+ and Cl- could participate in the conduction process. The humidity sensor based on KCl/Sm 2 O 3 showed extremely high response value of 127121 (60 times higher than that of pure Sm 2 O 3) with ultrafast response (0.1 s) at 11%−95% RH. Besides, the sensor exhibited excellent application potential for human health, activity monitoring, non-contact sensing, and alcohol count measurement. This work proves that KCl/Sm 2 O 3 is a promising candidate for high-performance humidity sensing in the application of intelligent perception. • Sm 2 O 3 is applied in the humidity sensor field for the first time. • Sm 2 O 3 nanoflowers were controlled by adjusting the alcohol to water ratio. • The sensor exhibited ultrahigh sensitivity (127121) with rapid response (0.1 s). • The sensor demonstrated multifunctional application potential in humidity sensing. [ABSTRACT FROM AUTHOR]

Fluorescence resonance energy transfer (FRET) is a reliable, sensitive, and robust assay method for detection of many biological targets. However, it generally needs an externally-introduced label to form the donor-acceptor pair, which could alter the accuracy of the detection. To address this issue, we report herein the FRET-based reactive copper ion sensors by using in situ fluorescent proteins (FP) of human urine or blood serum as the energy donor. Using Bull Serum Albumin (BSA) as model proteins, the sensor exhibits a remarkably fluorescence enhancement when BSA binds to the surface of copper clusters (Cu NCs) base on electrostatic interaction. Conversely, low fluorescence enhancement is observed without using BSA. As proof-of-principle, this positive approach is directly applied to detect Cu 2+ using urine as the energy donor, accompanying with a signal enhancement by two factors and low detection limit of 0.5 μM Cu 2+ . Moreover, the proposed sensor could be applied in other complex environments, such as blood serum or cell culture medium. Consequently, the effectiveness, simplicity and diversity of our proposed strategy enable the development of a class of probes toward complex human environment for rapid, sensitive, and selective detection of targets. [ABSTRACT FROM AUTHOR]

The widespread use of bromadiolone and brodifacoum poses a threat to public health and initiates poisoning incidents. Conventional colorimetric enzyme-linked immunosorbent assays (ELISAs) suffer from poor sensitivity, making it difficult to meet the trace detection of analytes. In this work, we constructed a sensitive and label-free fluorescence immunoassay based on the in situ formation strategy, for the quantification of bromadiolone and brodifacoum in biological and food samples. Alkaline phosphatase, an essential enzyme in ELISA, catalyzed the substrate sodium ascorbyl phosphate to L -ascorbic acid, which reacted with ο-phenylenediamine and triggered an in situ fluorescence signal with excitation/emission wavelengths of 350/430 nm. To reduce the reaction time, Fe3+ was utilized for the in situ immunoassay system. The fluorescence signal system was introduced to conventional ELISA without any label procedures, thus resulting in higher sensitivity with a 3.8-fold improvement in the half-maximal inhibitory concentration for bromadiolone, compared with colorimetric ELISA. The calculated limits of detection for bromadiolone and brodifacoum were 0.45–0.76 and 0.34–0.58 ng/mL (ng/g) in the human serum and corn samples, respectively, with recovery values ranging from 82.0 % to 93.1 %, and a coefficient of variation lower than 13.4 %. Due to its advantages of high sensitivity, cost-effectiveness, and easy substrate fabrication, this immunoassay may offer promise for applications in poisoning diagnosis and food analysis of bromadiolone and brodifacoum. • The signal transfer mechanism of in situ fluorescence immunoassay is explored. • The assay is applied for the simultaneous detection of bromadiolone and brodifacoum. • Oxidation action of Fe3+ reduces reaction time by 30 min in fluorescence immunoassay. • A 3.8-fold improvement for IC 50 is observed compared with colorimetric ELISA. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots (QDs) have been widely used as fluorescent labeling materials in the field of in vitro diagnostics (IVD). In spite of the significant development of direct single-signal response fluorescent immunosensors, it is still a challenge to obtain the high accuracy and sensitivity of quantitative results of these sensors due to the influence of several factors unrelated to the analysis. Herein, we present a delicate design and synthesis of dual-color QDs bilayer nanobeads (red and green QDs nanobeads, R&G-QD nanobeads), achieving the precisely control of growth of the silicon layer with different proportions of ammonia, and inhibiting fluorescence resonance energy transfer (FRET) successfully. The dual-color QDs bilayer nanobeads have realized dual-channel detection (the acquisition of two emission wavelengths) of the target, and avoided the problems of low analytical accuracy and imprecise sensitivity of single-signal response. A proof-of-concept demonstration of a fluorescence-linked immunosorbent assay (FLISA) platform is conducted for the quantitative detection of prostate-specific antigen (PSA) with a sensitivity of 49 pg/mL and a linear range of 0.2–800 ng/mL. The dual-color QDs bilayer nanobeads FLISA platform with high sensitivity and accuracy holds great potential for early diagnosis of cancer or other diseases and provides a new approach for IVD. [Display omitted] • Dual-color QDs bilayer nanobeads were designed to synthesize by layer-by-layer assembly method. • Controlled growth of alternate red and green QD layers on pre-synthesized SiO 2 beads can suppress energy transfer. • Such dual-color QDs nanobeads deliver dual single calibration and can avoid errors caused from the single signal response. • A proof-of-concept demonstration of a FLISA platform is conducted for detecting PSA with high sensitivity and accuracy. [ABSTRACT FROM AUTHOR]

A water-soluble fluorescence probe (TF) derived from fluorescein has been developed. This probe can be used to detect ClO − and Cd 2+ under physiological condition based on oxidation and coordination reactions, exhibiting almost 64-fold and 4-fold fluorescence enhancement. The experimentally observed changes in the structure and electronic properties of the probe in the presence of ClO − and Cd 2+ were modeled by density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations. Moreover, the present probe was successfully applied to the fluorescence imaging of ClO − and Cd 2+ in living cells. [ABSTRACT FROM AUTHOR]

A novel AIE-active diketopyrrolopyrrole (DPP) derivative containing anthranone and para -iodophenyl units ( Monomer 1 ) are synthesized. Due to the presence of polymerisable group, Monomer 1 can be polymerized with 2,7-diethynyl-9,9-bis[6′-( N , N -diethylamino)-octyl]fluorene to yield corresponding neutral polymer N1 , where AIE-acitve DPP and ACQ-active fluorene units are linked together with a flexible alkyl spacer in main chain. N1 is transformed to its polyelectrolyte P1 via ionization by CH 3 I. P1 emits purple fluorescence with two emission peaks at 440 and 625 nm in DMSO and is AIE-inactive due to its amphiphilic performance and the presence of ACQ-active fluorene unit. A fluorescence turn-on probe for bovine serum albumin (BSA) detection and quantification is developed by taking advantage of the deaggregating process of P1 . It is found that the fluorescence intensity of P1 in DMSO/PBS buffer (v/v = 1/1) at 450 and 645 nm is increased by 2.94 and 2.11-fold when the concentration of BSA increased from 0 to 70 μM. In addition, P1 can be utilized as a fluorescent probe for cellular imaging of HeLa cells, where red fluorescence is observed in the cytoplasm. The CCK-8 assay shows that the cytotoxicity of P1 is low. [ABSTRACT FROM AUTHOR]

Mitochondria are key organelles in mammalian cells whose dysfunctions are linked to various diseases. Numerous gold nanoparticles functionalized with lipophilic cation categories via Au-S bond for mitochondria targeting have been reported. However, cleavage of the Au-S bond by biothiols and other chemicals is a long-standing problem hindering practical applications, especially for intracellular detection and bioimaging. Herein, we report a mitochondria-targeting AuNP-based nanosensor with negatively charged peptide modification. Furthermore, we directly introduce the peptide motif via diselenide-modified AuNPs instead of traditional Au-S bonds. In vitro and living cell-based assays show that our designed strategy is simple to prepare, but ultrastable under thiol-rich physiological conditions. Furthermore, we have demonstrated that the nanosensor AuNP@DSe-P linker TMR can monitor enterokinase (ENTK) levels in the mitochondria of HeLa cells with a high-fidelity fluorescent signal under physiological conditions, thus providing a new idea for the design and preparation of ultrastable AuNP-based nanosystem. • The strategy with negatively charged peptide-assistant AuNPs for mitochondria targeting were successfully developed. • Diselenide-modified AuNPs showed more excellent resistance to high physiological levels of biothiols than Au-S bond. • The nanosensor can monitor the ENTK levels in HeLa cells with a high-fidelity signal under physiological conditions. • Our strategy could offer perspectives in future design of ultrastable AuNP-based nanosensor for mitochondria targeting. [ABSTRACT FROM AUTHOR]

Rapid and accurate detection of early cancer biomarkers not only provides a scientific tool for cancer diagnosis, but also helps prevent further cancer progression. Herein, a mitochondrial-targeted two-photon fluorogenic probe (CQ-1) is designed to visualize the changes of nitroreductase (NTR) and viscosity in mitochondria of cancer cells. The CQ-1 consists of the N , N -dimethylnaphthalen-2-amine, pyridine salt and p -nitrobenzene. It shows the significant fluorescence enhancement of CQ-1 with the increase of viscosity due to the limited intramolecular rotation, and turn-on fluorescence signal after CQ-1 reacted with NTR since intramolecular charge transfer generation. Meanwhile, CQ-1 displays fascinating mitochondrial targeting ability. Due to the satisfactory detection capability of CQ-1 , we further apply CQ-1 to monitor variations of mitochondrial viscosity and NTR in cancer cells by two-photon fluorescent microscope, as well as for specific imaging of NTR in zebrafish. We expect that this dual-response fluorogenic probe will provide a convenient and effective chemical tool for understanding the physiological functions of NTR and viscosity as well as for the diagnosis of important markers associated with cancer. • The probe (CQ-1) can simultaneously detect mitochondrial NTR and viscosity. • The response mechanism is investigated by theoretical simulations and experiments. • CQ-1 can monitor variations of mitochondrial viscosity and NTR in cancer cells. [ABSTRACT FROM AUTHOR]

Abstract: Three conjugated polymers comprised of 9,9-didodecyl-2,7-diethynyl-9H-fluorene and 2-pyridine-1H-benzo[d]imidazole units, which are alternatively linked to 4,7-position (P1) and 5,5′-position (P2, P3), respectively, have been synthesized via Sonogashira reaction. P2 and P3 with the twisted conjugated backbones were proved to show selectivity for nickel ion. By contrast, P1 with the linear conjugated backbone exhibited highly selectivity for silver ion. The results suggest that the metal ion recognition feature of the chemosensors based on the conjugated polymers can be adjusted by fine-tuning the linkage pattern between the recognition group and the conjugated backbone. Thus, a selective chemosensor for detection of nickel ion was developed. [Copyright &y& Elsevier]

Abstract: A novel 2-(pyridin-2-yl)-1H-benzo[d]imidazole based conjugated polymer (P1) was synthesized and characterized. The binding and recognition behavior of P1 toward the metal ions and amino acids were investigated. The fluorescence of P1 can be completely quenched by Cu2+ and Ni2+ through a photoinduced electron transfer process, resulting in the formation of metal complexes with polymer ([P1-Cu2+] and [P1-Ni2+]), which indicates that P1 is a selective chemosensor for Cu2+ and Ni2+. Moreover, in situ formed [P1-Cu2+] complex showed excellent fluorescence “turn on” properties with high selectivity toward Cys, while [P1-Ni2+] complex with high selectivity toward His and Tryp. These complexes are promising chemosensors for amino acids due to fast response time (less than 5min), high selectivity and high sensitivity (detection limit concentration is 0.1ppm for Tryp). Hence, a facile method to tune the detection selectivity of conjugated polymeric chemosensor with metal ions has been developed. [Copyright &y& Elsevier]

Abstract: A novel conjugated polymer (P1) containing fluorene and ethyl 2-(2-(pyridin-2-yl)-1H-benzo[d]imidazol-1-yl)acetate (PBMA) was designed and successfully synthesized through the Sonogashira coupling reaction. P1 shows high sensitivity and selectivity for Ag+ detection in comparison to other metal cations. Upon addition of Ag+, the fluorescent emission of the polymer solution in THF was quenched dramatically, accompanying the color changed from blue to green. The detection limit for Ag+ was 5×10−8 molL−1. However, the similar copolymers P2 and P3 containing 2-(pyridin-2-yl)-1H-benzo[d]imidazole and 2-(thiophen-2-yl)-1H-benzo[d]imidazole, respectively, did not show such a selectivity for Ag+ detection. The 1H NMR measurements confirmed that the PBMA units play a key role for the selective recognition of Ag+. [Copyright &y& Elsevier]

Abstract: A multiplexed immunoassay biosensor for detecting serum biomarkers was developed by using photoluminescent (PL) aqueous CdSe/ZnS quantum dots (QDs) with high efficiency and stability as fluorescence labels and carboxyl functionalized microporous nylon membrane as a matrix. Two main biomarkers of Down Syndrome (DS), β-human chorionic gonadotrophin (β-HCG) and α-fetal protein (AFP), were selected for detection in this biosensor system. For specific detection of DS, antibody-immobilized microporous nylon membrane first captured the targeted antigens from the physiological samples and formed immunocomplexes (antibody–antigen) on the membrane surface. Then the immunocomplexes continued to react with QDs conjugated antibodies (labeled antibodies), and formed triplex “sandwich” structure, which was confirmed by AFM and confocal microscopy. Quantitative detection of β-HCG and AFP was also realized, the detectable level of this new biosensor was as low as 1×10−6 IU/L for β-HCG and 1ng/mL for AFP in a relatively short assay time without any enrichment. [Copyright &y& Elsevier]

Abstract: Two water-soluble cationic conjugated polyelectrolytes (linear polymer PF1 and hyperbranched polymer PF3) containing fluorene, diketopyrrolopyrrole (DPP), diacetylene and triphenylamine moieties were synthesized and used for DNA detection. The incorporation of DPP into the polymer backbone offers dual emissive polyelectrolytes with both blue and red emission bands for PF1 and PF3 in the dilute solution resulting from incomplete intramolecular energy transfer. In the solution of PF3, addition of DNA can quench the emission of fluoreneethynylene-triphenylamine units of PF3 more efficiently than that of DPP segments, which causes the fluorescent color change from light blue to light red. However, DNA causes only slight fluorescent quenching of PF1, and the blue color of PF1 solution remains unchanged. Hyperbranched PF3 shows stronger asymmetric emission quenching by DNA than linear PF1, indicating that it might become the first sensor of the hyperbranched conjugated polyelectrolytes for a real-time DNA detection. [Copyright &y& Elsevier]

• A novel method of dual protecting encapsulation for preparing quantum-dot nanobeads. • High luminescence and ultrastability in wide range of pH, temperature and salt concentrations. • Nanobeads-based LFIA nanosensor was developed for simultaneous detection of three cardiac biomarkers. • This nanosensor has high accuracy and prominent stability for clinical samples. The labeling material is a key factor that determines the ability of lateral-flow immunoassay (LFIA) for accurate and sensitive detection. Herein, a dual protection strategy with both polyvinylpyrrolidone (PVP) winding and SiO 2 coating has been first developed for generating quantum dot beads@SiO 2 -COOH (QBs@SiO 2 -COOH) nanobeads with high fluorescence and extraordinary stability, which greatly improved the sensitivity and stability of rapid LFIA. QBs@SiO 2 -COOH showed outstanding colloidal stability in complex matrices and 1,967-fold higher luminescence than that of corresponding QDs. The novel LFIA nanosensor was constructed by utilizing synthesized QBs@SiO 2 -COOH as the reporter to realize rapid quantitative detection of cardiac troponin I (cTnI) within 10 min using only 60 μL of sample. The limit of detection (LOD) was 0.036 ng mL−1 with the excellent linearity relationship between 0.12 and 125 ng mL−1. Importantly, the detection method owned good reproducibility (CV < 8 %) and predominant stability, which were demonstrated for the first time by detecting clinical serum samples preserved at different temperature in 120 days. Moreover, the developed nanosensor achieved the simultaneous quantitative detection of cTnI, creatine kinase-MB (CK-MB), and myoglobin (Myo). This QBs@SiO 2 -COOH-based rapid LFIA nanosensor holds a good prospect for rapid, stable and sensitive detection of biomarker for in vitro diagnostics. [ABSTRACT FROM AUTHOR]

[Display omitted] • MIP selective to certain moieties but not phosphorus of AP (acephate) was prepared. • AP captured by MIP still inhibited AChE activity. • MIP and AChE selective to different moieties of AP were incorporated in one sensor. • MIP enrich AP from samples selectively, AChE quantify levels of AP captured by MIP. • The sensor detect AP in vegetables more accurately than AChE inhibition assay. Biosensors using acetylcholinesterase (AChE) as the recognition element detect both toxicity (AChE inhibition activity) and concentration of organophosphorus pesticides (OPs). However, real application of these biosensors remains a challenge due to their low selectivity and low resistance to sample matrix, interferences and hash analytical conditions. In this study, a novel dual-recognized strategy was established by using molecularly imprinted polymer (MIP) and AChE selective to different moieties of acephate (AP) as affinity molecules simultaneously. Using AP as the model OP, MIP highly selective to certain moieties but not phosphorus of AP was prepared on the surface of microplate by self-polymerization of dopamine. The MIP enriched AP from samples selectively. Then AChE selective to phosphorus of AP quantified the levels of AP captured by MIP. AP captured by MIP still inhibited the activity of AChE because the affinity of AP to AChE was higher than to MIP. By incorporating selective sample pretreatment with AChE inhibition assay in one sensor, the biosensor identified AP from other OPs, carbamates pesticides and interferences commonly found in food and environmental samples. When vegetables with high matrix effect on AChE inhibition assay were analyzed, selective sample pretreatment ensured the biosensor to detect AP more accurately and selectively than classical AChE inhibition assay. The results of the biosensor had no statistical difference compared with those of HPLC-MS/MS. The dual-recognized strategy may provide a new solution to detect target enzyme inhibitors in complicated samples using enzyme-based biosensors selectively and accurately. [ABSTRACT FROM AUTHOR]

• A two-photon fluorescent probe for endoplasmic reticulum (ER) peroxynitrite was synthesized. • The probe showed rapidly and highly selective "turn-on" response to peroxynitrite. • The probe showed excellent ER targeting ability and worked well in Parkinson's disease models. Endoplasmic reticulum (ER) stress is implicated in the pathogenesis of diseases such as Parkinson's disease (PD). Peroxynitrite is the pivotal causative factor of ER stress. However, fluorescent probes for imaging the peroxynitrite in the ER are still lacking. In the present paper, we reported the design and synthesis of a two-photon fluorescence probe (ER-PN) for visualizing the ER peroxynitrite in PD models of living cells and C. elegans. ER-PN showed a rapidly and highly selective "turn-on" response to peroxynitrite over other biological species in vitro. Moreover, ER-PN showed excellent ER targeting ability and worked well in living systems for the ER peroxynitrite imaging. Noteworthy, ER-PN has been successfully applied for imaging the peroxynitrite in PD models, indicating its potential application for revealing the fundamental roles of peroxynitrite in ER stress-related diseases. [ABSTRACT FROM AUTHOR]

• A two-photon (TP) fluorogenic probe (DT-01) was designed and synthesized, it possesses excellent TP fluorescence and high fluorescence quantum yield. • DT-01 is able to effectively detect biothiols and H 2 S both in vitro and in vivo. • DT-01 successfully revealed the relationship between the oxidative stress level and overall concentration of biothiols and H 2 S in cellulo. Biothiols and sulfides, especially glutathione (GSH), cysteine (Cys), homocysteine (Hcy) and hydrogen sulfide (H 2 S) play important roles in an extensive range of biological processes and functions. Due to their reductivity, they are deemed as second messengers of oxidative stress, and the imbalance of these biothiols are closely associated to a variety of diseases. Herein, we report a two-photon (TP) turn-on probe DT-01 that can detect biothiols and sulfides both in vitro and in vivo. The probe was synthesized by nitrobenzoxadiazole (NBD) derivative (NBD-Cl) and pyrimidine-based TP fluorophore (FL-01), the fluorescence of DT-01 is quenched due to the photoinduced charge transfer (PET) from FL-01 moiety to NBD moiety. Upon substitution reaction by nucleophilic biothiols, TP fluorophore released and exhibited turn-on fluorescence at 550 nm. We further demonstrated that DT-01 can detect biothiols and H 2 S in living cells, mice brain slices and zebrafish. More importantly, by real-time detecting the total content of biothiols and H 2 S, we have successively measured the changes of oxidative stress levels in HeLa cells. [ABSTRACT FROM AUTHOR]

• A novel 3D vertical-flow paper-based device (3VPD) integrated with a sandwich-type fluorescent immunoassay is developed. • The 3VPD can be applied for multiplexed detection of cancer biomarkers simultaneously based on the principle of origami. • The proposed 3VPD shows high sensitivity and selectivity for detecting CEA, AFP and CA199 in human serum, respectively. A novel three-dimensional (3D) vertical-flow paper-based device (3VPD), integrated with a sandwich-type fluorescent immunoassay, was developed for multiplexed detection of cancer biomarkers simultaneously based on the principle of origami. The developed 3VPD, composed of a sample layer, a splitting layer, and a test layer, could be fabricated simply by wax-printing on paper at a large scale. Herein, a vertical-flow immunoassay was introduced into the device, in which fluorescein isothiocyanate labeled antibodies were coated on the splitting layer and mouse monoclonal capture antibodies were functionalized on the test layer. The proposed 3VPD showed high sensitivity and selectivity for detecting three cancer biomarkers, carcinoembryonic antigen (CEA), a-fetoprotein (AFP), and cancer antigen 199 (CA199) with detection limits of 0.03 ng/mL, 0.05 ng/mL, and 0.09 U/mL in human serum, respectively. The results obtained in human serum were compatible with the reference values which were acquired from parallel single-analyte. The developed 3VPD provides a new strategy to develop an inexpensive and sensitive approach for simultaneous detection of multiple analytes and comprehensive clinical diagnosis by a single test. [ABSTRACT FROM AUTHOR]

• The high-quality hydrophobic and hydrophily red-QD and green-QD were synthesized for dQDs-FLISA. • Cross-reactivity among Ag-Ab can be avoided by the specific probe adding sequence. • The simultaneous and quantitative detection was developed in one sample-well. • The assay has a wide analytical range, a low LOD, and good recovery rates. Simultaneous detections of different but clinically relevant biomarkers are of extremely importance in biomedicine. Due to their unique photophysical properties, quantum dots (QDs) are ideally suited for highly sensitive multiplexed determination. Herein, a dual quantum dots-based fluorescence-linked immunosorbent assay (dQDs-FLISA) for simultaneous and quantitative detection of inflammation biomarkers (i.e. serum amyloid A (SAA) and C-reactive protein (CRP)) has been established. After being coated by amphiphilic oligomers (polymaleic acid n-hexadecanol ester, PMAH), the red-QD and green-QD with high quantum yields were used as fluorescence probes to couple SAA and CRP antibodies, respectively. Cross-reactivity among the SAA and CRP's antibodies and antigens have been carefully examined by interference experiments, and it was successfully avoided by the specific probe adding sequence. Therefore, the assay provided a broad linear analytical range, including SAA quantitative range of 10–1,000 ng mL−1 with linear correlation (R2) of 0.992, and CRP quantitative range of 10–1,000 ng mL−1 with R2 of 0.998. The limit of detections (LODs) for SAA and CRP using dQDs-FLISA were 2.39 ng mL−1 and 6.37 ng mL−1, respectively. The accuracy of the assay has been confirmed with recoveries of 92.13%–101.85%. More importantly, the assay results showed good specificity, the QD-antibody probe could couple corresponding antigen (CRP or SAA) high-efficiently and it could be out of interference of other antigens and substances in serum. Given its good performance, the proposed dQDs-FLISA method offers great potential for simultaneous and quantitative detection of other biomarkers in in vitro diagnostic (IVD). [ABSTRACT FROM AUTHOR]