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Joint analysis of varied biomarkers in blood sample will provide more accurate results for the monitoring and management of Alzheimer's disease (AD). In addition to the known β-amyloid protein (Aβ) used as a reliable clinical marker for AD diagnosis, Fetuin B also demonstrates a strong correlation with AD progression. Especially, for medical diagnostics, on-site detection of multi-analyte is quite important and therefore, it is desirable to develop a rapid and portable, multiplex electrochemical assay for simultaneous detection of Aβ and Fetuin B, which has been seldomly reported before. To achieve this goal, a multiplex paper-based electrode was prepared via vacuum filtration, by which, single-walled carbon nanotubes (SWCNTs) and AuNPs were sequentially filtered through cellulose paper with a five-electrode pattern to form a conductive underlay and electrical connections. A nanocomposite of AuNPs-loaded dendritic mesoporous silica nanoparticles (dmSiO 2 -Au) was firstly synthesized and further deposited thionine (Thi) for signal amplification. An immunosensor was correspondingly fabricated, which involved a combination of multiplex electrodes and dmSiO 2 -Au-Thi nanocomposite to facilitate simultaneous monitoring of Aβo and Fetuin B. Additionally, ferrocene (F c) was applied onto a separate working electrode to perform a ratiometric electrochemistry for enhancing accuracy. The outcomes demonstrated high specificity, sensitivity, and stability, and no obvious cross-talking between three working electrodes. Application of this sensor resulted in a successful determination of Aβo and Fetuin B levels in serum and brain tissue of transgenic AD mice. Overall, the presented electrochemical immunosensors for performing multiplex diagnostics may facilitate to the exploration of more AD-related blood markers. • A multiplex paper-based electrode was prepared. • A sandwich-based immunosensor enabled simultaneous monitoring of Aβo and Fetuin B. • Ferrocene was applied onto electrode to construct a ratiometric electrochemistry. • Analysis of Aβo and Fetuin B in APP/PS1 transgenic AD mice was realized. [ABSTRACT FROM AUTHOR]

Graphical abstract WO 3 nanoparticles, nanoflakes and nanorods are synthesized via a facile solvothermal route. The organic solvents with different polarity play an important role in regulating the morphologies of as-synthesized WO 3. Gas sensor based on WO 3 nanoparticles exhibits faster response and recovery behaviour and much higher response toward Cl 2 compared to those based on nanoflakes and nanorods. It is suggested to arise from good crystallinity and high concentration of oxygen vacancy at the surface of WO 3 nanoparticles. Highlights • Different nanostructured WO 3 are synthesized by facile solvothermal route. • WO 3 nanoparticles sensor exhibits more rapid and higher response to Cl 2 compared to WO 3 nanoflakes and nanorods. • These properties are due to good crystallinity and high oxygen vacancy concentration on the surface of WO 3 nanoparticles. Abstract By varying different solvents, WO 3 nanoparticles, nanorods, and nanoflakes were synthesized via facile solvothermal processes without structure-directing agent. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements. The effect of the polarity of organic solvents used in the synthesis procedure on the morphologies of as-synthesized WO 3 materials was proposed. Gas sensors based on the synthesized products were fabricated and their gas sensing properties were tested towards a variety of target gases. The results indicated that the sensor based on WO 3 nanoparticles exhibited excellent selectivity, better response and recovery behavior and much higher sensitivity toward Cl 2 compared to those based on WO 3 nanorods, and nanoflakes, although three samples have similar specific surface areas. These characteristics are suggested to arise from good crystallinity and high concentration of oxygen vacancy on the surface of WO 3 nanoparticles. [ABSTRACT FROM AUTHOR]

Due to the prominent photochemical and photophysical properties, the benzofurazan (NBD) fluorophore is a popular platform for constructing fluorescencet sensors. We reported herein a strategy to tune the fluorescence of NBD by modulating the push-pull pairs on the benzene ring, and obtained two novel fluorescent probes, MeS-DMAB and EtS-DMAB , which can selectively detect hypochlorous acid (HOCl) over other reactive oxygen species in aqueous solution with a large stokes shift (∼170 nm). The synthesis and optical properties of these two probes were described. The reaction products of HOCl with MeS-DMAB were isolated and characterized. It turns out that oxidation of the thioether to the corresponding sulfoxide accounts for the turn-on fluorescence. Finally, the probe EtS-DMAB was successfully applied to image exogenous and endogenous HOCl in live cells. [ABSTRACT FROM AUTHOR]

Most of the current graphene transistor based deoxyribonucleic acid (DNA) sensors are based on dip-and-dry methods The flow-through approach for graphene transistor based DNA sensors have not been explored yet. Moreover, the effect of probe immobilization strategies on the performance of a graphene transistor biosensor in flowing environment was rarely studied. In this paper, a microfluidic integrated reduced graphene oxide (rGO) transistor was developed for H5N1 influenza virus gene detection with high stability and sensitivity via a flow-through strategy. Different DNA probe immobilization approaches including extended long capture probe via π-π stacking, short capture probe via π-π stacking and covalent immobilization via linker were studied. Both fluorescence measurement and electrical detection were performed to evaluate the performance of rGO transistors in flowing environment for these probe immobilization strategies. The results showed that among these approaches, extended long capture probe could provide both high sensitivity and stability in flowing environment while short capture probe suffered by the low stability in flowing environment and covalent immobilization via linker had relatively low sensitivity. This microfluidic integrated rGO transistor with extended capture probe immobilization approach could provide a promising platform for nucleic acid detection with high sensitivity and stability for potential flow-through chip application. [ABSTRACT FROM AUTHOR]

On May 14, 1999, LSI Logic Corporation’s Fab in Santa Clara, California experienced a leak of BF 3 which was not detected by the Telosense Air Composition Monitoring system. This event lead to a question–the reliability of leak detection techniques currently employed for toxic BF 3 . In this work, a novel FRET fluorescence chemosensor RN for BF 3 has been designed and synthesized conveniently by incorporating rhodamine B and 1, 8-naphthalimide. Compared with other chemosensors, this chemosensor displayed ratiometric fluorescence that can overcome shortcomings of intensity-based fluorescent chemosensors. The ratio ( I 586 / I 533 ) of chemosensor RN showed a remarkable increase (21-fold) in less than 1 min and a distinct colour change for naked-eye detection in present BF 3 . The response of BF 3 at this sensor was linear in the wide range of 130–200 μM with a detection limit of 2.7 × 10 −5 M. This chemosensor also had excellent reversibility. The 19 F NMR and 1 H NMR test were performed to investigate the mechanism of the chemosensor RN towards BF 3 . Furthermore, we evaluated its feasibility for real-time detection of BF 3 in a portable manner. The facts and evidence indicated that this chemosensor had potential applications in industrial production. [ABSTRACT FROM AUTHOR]

A novel turn-on fluorescence probe based on rhodamine B for Fe 3+ has been synthesized and characterized by various analytical techniques. Compared with other commonly coexisting metal ions, the probe showed 100-fold fluorescence enhancement for detecting Fe 3+ with a 1:1 stoichiometry in MeOH/H 2 O (1:1, v/v) solution. After adding Fe 3+ , the rapid enhancement of fluorescence intensity provided a rapid method for detection of Fe 3+ . The color change was visible, so it could be used for naked-eye detection. The association constant between the probe and Fe 3+ was detected to be 0.67 × 10 4 M −1 and the corresponding detection limit were calculated to be 5.7 × 10 −8 M according to fluorescence titration analysis. The reversible binding of probe L to Fe 3+ was confirmed by reacting with Na 4 P 2 O 7 , which captured the Fe 3+ from the L-Fe 3+ complex and turned off the L-Fe 3+ complex. Fluorescence imaging experiments demonstrated that this probe was cell permeable and suitable for monitoring intracellular Fe 3+ in living cells by confocal microscopy. What’s more, MTT assay indicated that this probe had no significant cytotoxicity to living cells. [ABSTRACT FROM AUTHOR]

Detecting trace ppb-level of formaldehyde (HCHO) in indoor ambient and human exhaled breath using metal oxide semiconductor (MOS) gas sensor has attracted increasing attention. Herein, Ag nanoparticles (Ag NP) modified In 2 O 3 and Au nanocage (Au NC) modified In 2 O 3 as well as bimetal Ag NP and Au NC co-modified In 2 O 3 were successfully prepared via one-step microwave-assisted solvothermal method and were used to construct semiconductor gas sensor. It is exciting to observe that the sensor based on Ag 6 Au 1 /In 2 O 3 exhibits the highest response of 277 toward 5 ppm HCHO at low operating temperature (170 °C), which is about 7 times, 38 times and 102 times higher than 6 wt. % Ag/In 2 O 3 , 1 wt. % Au/In 2 O 3 and pristine In 2 O 3 , respectively. Moreover, the selectivity and detection limit (down to 26 ppb) of Ag 6 Au 1 /In 2 O 3 sensor to HCHO have been proven to be greatly improved. This excellent sensing performance indicates that the proposed bimetal Ag and Au co-modification with synergistic catalysis effect offers an effective design for highly sensitive and efficient HCHO detection devices. Moreover, the mechanism of HCHO sensing with Au and Ag co-loaded In 2 O 3 was explored by the calculations obtained from first-principle density functional theory studies. [Display omitted] • Ag 6 Au 1 /In 2 O 3 is synthesized via one-step microwave-assisted solvothermal method. • Ag 6 Au 1 /In 2 O 3 sensor shows high response, excellent selectivity, short response, as well as low HCHO detection limit (0.026 ppm) at 170 °C. • The property is due to synergistic catalysis effect of bimetal Ag and Au on In 2 O 3. • The enhanced HCHO sensing mechanism of Ag 6 Au 1 /In 2 O 3 is explored by the calculations from the first-principle studies. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) enables the biofilm detection by the characteristic Raman spectrum of extracellular polymeric substance (EPS). However, its clinical application in wound biofilm delineation is hindered by long sampling time and unpredictable sampling errors. To overcome these limitations, we propose a two dimensional (2D) scanning SERS probe that combines the advantages of galvo mirrors and a custom designed SERS active substrate. In this design, the SERS active substrate with dendritic nano-silver structure is fixed on the focal plane of the scan lens to maintain not only the required distance of the sampling plane but also the stable sampling condition as the excitation laser beam driven by the galvo mirrors scans quickly over the region of interest (ROI). Our benchtop study shows that the ± 3.75 mm offset between the sampling plane and the focal plane results in less than 10% change in both laser spot size and fluctuation in Raman peak intensity for the 2D scanning SERS probe, superior to the commercial Raman probe where 1700% change in laser spot size and 95% fluctuation in Raman peak intensity. Our in vitro study in two typical biofilms shows that the 2D SERS scanning probe can detect the biofilm as early as 4 h of cultivation and delineate the biofilm boundary with accuracy at 8 h of cultivation. Furthermore, this substrate is disposable, antibacterial, and capable of enhancing Raman intensity with consistency. Our studies imply the clinical potential of using the 2D SERS scanning probe for biofilm delineation in chronic wound management. • A probe combining 2D scan mechanism and disposable SERS active substrate is proposed. • This system acquires the Raman signal insensitive of sample surface fluctuations. • The integration of the SERS substrate with the probe eliminates laser refocusing time. • The custom designed disposable SERS active substrate is antibacterial and antibiofilm. [ABSTRACT FROM AUTHOR]

Au-loaded ZnO nanorod arrays sensor exhibits high response, short response and recover times, excellent selectivity, as well as low HCHO detection limit at 70 °C. Moreover, the mechanism of HCHO sensing with Au-loaded ZnO was explored by the calculations obtained from the first-principle studies. The outstanding sensing properties could be ascribed to large surface area and good gas diffusion of the nanorods arrays, Au spillover mechanism, as well as high contents of chemisorbed oxygen on the its surface derived from electrons transfer from Au to ZnO. [Display omitted] • Au/ZnO nanorod arrays are synthesized via seed-assisted solvothermal methods. • Au/ZnO sensor shows excellent response to HCHO at 70 °C. • The mechanism of HCHO sensing with Au/ZnO is explored by the calculations obtained from the first-principle studies. Au-loaded ZnO were successfully prepared by means of seed-assisted solvothermal methods. The vertically ordered nanorod arrays are uniformly grown on the Al 2 O 3 substrate. The sensing properties of ZnO and Au-loaded ZnO sensors toward HCHO were investigated. Remarkably, the sensor based on 4 wt%Au-loaded ZnO nanorod arrays exhibits high response, short response and recover times, excellent selectivity, as well as low HCHO detection limit at 70 °C. After the incorporation of Au nanoparticle, the detection limit decreases from 10 ppm to 0.25 ppm, and the response increases more than 20 times under 100 ppm HCHO at 70 °C. Moreover, the mechanism of HCHO sensing with Au-loaded ZnO was explored by the calculations obtained from the first-principle studies. [ABSTRACT FROM AUTHOR]

CuPc-doped ZnO nanorods have been prepared by one-step microwave-assisted solvothermal method. Unusually, the red-light activated sensor based on CuPc/ZnO displays higher response, better selectivity, faster response-recovery behavior, superior humidity resistance and ultralow detection limit towards NH 3 at room temperature compared to CuPc/ZnO in the dark condition and previously reported ZnO-based sensor. Such good sensing performance could be owing to its high adsorption capacity to NH 3 , fast moving speed of the electrons, as well as high contents of chemisorbed oxygen derived from electrons transfer from the CuPc to ZnO under red light illumination. • CuPc/ZnO nanorods were synthesized via one-step microwave assisted hydrothermal method. • CuPc/ZnO sensor shows high response, excellent selectivity, rapid response/recovery rate, good humidity resistance and low detection at 27 °C under red light illumination. • These properties are due to fast moving speed of the electrons, and enhanced chemisorbed oxygen derived from electrons transfer from CuPc to ZnO under red light illumination. A one-step microwave-assisted hydrothermal synthetic approach was used to synthesize CuPc-loaded ZnO nanorods. Several characterization techniques were applied to analyze the compositional, structural and morphological information of the products, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV − vis spectrophotometer (UV-vis) and X-ray photoelectron spectroscopy (XPS). Both pure ZnO and CuPc-loaded ZnO were characterized in terms of their gas sensing performances towards various gases under light illumination. The results indicated that CuPc/ZnO sensor delivers excellent sensitivity and selectivity towards ammonia, accompanied with rapid response/recovery rate, remarkable humidity resistance and a low detection limit down to 0.8 ppm at room temperature under red light illumination. This work will open-up new vistas in the development of room temperature gas sensors based on wide-band gap semiconductors with visible-light irradiation. [ABSTRACT FROM AUTHOR]

Au/Pd-doped ZnO nanorods with various doping contents are synthesized by one-step microwave-assisted solvothermal method. The sensor based on 2.0 wt% Au-doped ZnO exhibits low operating temperature, ultralow detection limit, faster response and recovery behavior, better selectivity and much higher response towards ppb level acetone in contrast to those based on ZnO and other Au/Pd-doped ZnO. Such good sensing performance could be owing to the high contents of chemical adsorbed oxygen arising from large surface area of the porous doped ZnO nanorods and Au spillover mechanism, as well as improvement of modulation of nano-Schottky barriers due to the presence of Au particle. ZnO nanorods doped by different amount of Au and Pd were successfully synthesized via one-step microwave-assisted hydrothermal method. The structure, morphology and composition of the as-synthesized products were characterized by X-ray diffraction (XRD), field-emission electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Gas sensors based on ZnO and Au/Pd-doped ZnO nanorods were fabricated and their gas sensing properties were tested for various gases. The results indicate that the incorporation of Au and Pd elements can greatly enhance the gas sensing properties of ZnO sensors. Specifically, the sensor based on 2.0 wt% Au-doped ZnO exhibits the highest response, quickest response and recovery characteristics, best selectivity, low operating temperature, as well as good long-term stability towards acetone. After incorporation of Au (2.0 wt%), the detection limit of Au-doped ZnO sensor decreases to 5 ppb and the response increases to 17 under 1 ppm acetone at 150℃, which is more than triple the responses of ZnO sensor. The results demonstrate that the developed Au-doped ZnO sensor has great potential for ppb-level acetone detection in human breath for diagnosing diabetes. [ABSTRACT FROM AUTHOR]

• m-BP successfully incorporate in In 2 O 3 nanorods, developing the hetero-structured BP-In 2 O 3 composites. • BP-In 2 O 3 exhibits the better sensing properties to NO 2 compared to In 2 O 3 and the reported BP-based materials. • These properties are due to large surface area, excellent carrier mobility and enhanced chemisorbed oxygen in presence of BP. In 2 O 3 nanorods were successfully incorporated by different amount of multi-layer black phosphorus (m-BP), forming the hetero-structured BP-In 2 O 3 composites. The structure, morphology and composition of the as-synthesized composites were characterized by X-ray diffraction (XRD), field-emission electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Interestingly, the environmental stability of BP can be notably improved by the introduction of In 2 O 3. Moreover, NO 2 sensing properties of BP-In 2 O 3 composites were tested at room temperature (25 °C) with relative humidity of 30%. It is demonstrated that the sensor based on BP-In 2 O 3 composites exhibits high response, lower detect limit, short response-recovery time and outstanding selectivity at room temperature. Such sensing behavior can be attributed to high adsorption capacity to NO 2 , large surface area, excellent carrier mobility of BP-In 2 O 3 in presence of BP, as well as high concentration of chemisorbed oxygen on the In 2 O 3 surface derived from electrons transfer from BP to In 2 O 3. [ABSTRACT FROM AUTHOR]

• A novel cholesterol electrochemical biosensor based on graphene-based nanocomposites by LBL technique was fabricated. • The PEI-GP provided well biocompatible microenvironment for the immobilized cholesterol oxidase to keep its bioactivity. • The cholesterol oxidase/PEI-GP modified electrodes show ultrasensitive biosensing detection performance towards cholesterol. • The fabricated biosensor exhibited good selectivity, reproducibility, stability and practical application. A novel electrochemical platform composed of water soluble polyethylene imine-reduced graphene oxide (PEI-rGO) composites and cholesterol oxidase (ChOx) based on layer-by-layer (LBL) technique has been triumphantly developed. The PEI-rGO composites could effectively improve the electron transfer ability between the assembled enzyme and the surface of electrode. Furthermore, LBL technique could immobilize more enzyme under mild conditions, which was benefit to keep the bioactivity of redox enzyme. TEM, UV–vis and FT-IR showed that the PEI-rGO composites behaved as individual nanosheet structure and were successfully prepared. The self-assembly process of (ChOx/PEI-rGO) n film was monitored by UV–vis spectroscopy, demonstrating that the ChOx had been immobilized orderly without denaturation. Owing to the good conductivity of the PEI-rGO composites, the electron transfer ability of the immobilized ChOx was greatly improved on glassy carbon electrode (GCE). The PEI/(ChOx/PEI-rGO) 3 /GCE showed excellent electrochemical performances toward the detection of cholesterol. Under optimized conditions, the fabricated electrode exhibited a wide linear range in the cholesterol concentration from 0.10 × 10−6 to 9.331 × 10−3 mol L−1 with a detection limit of 0.021 μmol L−1 estimated at a signal-to-noise ratio of 3. The apparent Michaelis-Menten constant (K m) was 0.0431 mmol L−1. This result indicated that a good affinity between the immobilized ChOx and the cholesterol. Meanwhile, the biosensor presented good stability, reproducibility and anti-interference ability with good recoveries for real sample detection. [ABSTRACT FROM AUTHOR]

Ratiometric near-infrared fluorescent probes are powerful tools for studying the biological roles of hypochlorite in biological systems. However, due to the lack of suitable fluorescent molecular platforms, the development of near-infrared ratiometric hypochlorite probes remains a challenge. Here, we report the design and synthesis of a near-infrared fluorescent probe PTZCy , which is constructed using a phenothiazine-hemicyanine hybrid framework. The incorporation of phenothiazine into the hemicyanine scaffold enables the probe to exhibit a near-infrared emission maximum at approximately 820 nm, along with a rapid and highly selective ratiometric response to hypochlorite. Importantly, PTZCy can be used to image both endogenous and exogenous hypochlorite in RAW264.7 cells, as well as to perform ratiometric imaging of hypochlorite during the acute liver injury process in living mice. [Display omitted] • A phenothiazine-hemicyanine hybrid framework was rationally designed for detecting ClO−. • The probe exhibited an emission maximum at 820 nm, along with a rapid and highly selective ratiometric response to ClO−. • The probe was employed for ratiometric imaging of ClO− in living cells and in mice experiencing acute liver injury. [ABSTRACT FROM AUTHOR]

A long-standing goal has been to create a high-energy transfer system for food safety detection. Herein, gold nanoclusters-anchored manganese dioxide (AuNCs@MnO 2) nanocomposites are designed by using co-template assembly. Bovine serum albumin is utilized as both skeletons of nucleation and stabilizer to guide the synthesis of the AuNCs@MnO 2 nanocomposites under physiological conditions without the use of any potent oxidants and the hazardous organic solvent. The AuNCs@MnO 2 nanocomposites exhibit good energy transfer efficiency and structural stability even under high salt conditions and a wide range of pH values. A sensitive sensing platform for the detection of methyl paraoxon has been constructed as a result of the excellent performance of AuNCs@MnO 2 nanocomposites. Acetylcholinesterase catalyzes the conversion of the substrate to produce thiocholine, which induces the decomposition of MnO 2 and the fluorescence recovery of AuNCs. Coupling with the pesticide inhibition effect, the platform can be employed to quantify methyl parathion with a detection limit of 3.1 pg mL−1. The AuNCs@MnO 2 -based platform displays high stability and anti-interference capability in food and environment samples, endowing practical application in food safety monitoring. • A highly sensitive FL detection method was constructed to detect methyl paraoxon (detection limit of 3.1 pg mL-1). • Synthesis of AuNCs@MnO 2 using a safe and effective synergistic template method. • The proposed FL detection method has strong anti-interference ability and stability in real sample testing. • Simplifies the analysis process by directly capturing the FL color signal to determine analyte concentration. [ABSTRACT FROM AUTHOR]

Peptidoglycan (PG) is the main substance for cell wall synthesis and plays an essential role in bacterial physiological activities such as proliferation and division. It protects bacterial from external environment and resists pressure generated by bacterial internal expansion. Despite the incredible importance, there is still lack of effective tools for direct imaging and quantitative analysis of PG. Herein, we designed a D -luciferin/luciferase bioluminescent system to visualize and quantify PG levels in living bacterial cells. In our system, we metabolically label PG through aryl azide modified D -amino acid (DAz). Afterwards, TL-PDC , in which the phenolic hydroxyl of D -luciferin is initially protected through "caged" strategy, is introduced to react with DAz through Staudinger ligation reaction and releases the free D -luciferin. This will initiate luciferase catalyzed bioluminescence reaction and generates a strong luminescence signal. It is demonstrated that TL-PDC has good selectivity and sensitivity towards DAz and DAz -labeled PG. Moreover, the system was used to evaluate PG level in living mice by bioluminescent imaging. Most importantly, this method has potential value in biological experiments related to bacterial detection. [Display omitted] • A novel bioluminescent system was developed to image peptidoglycan in bacterial cells. • D -luciferin-derivative, TL-PDC , was designed based on Staudinger ligation reaction. • DAz can be metabolically fused to bacterial cell wall by its own synthesis machinery. • This system can be used for bioluminescent imaging of nascent peptidoglycan in vitro. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescence pH probe 2-(N-ethylcarbazole-3-vinyl)-benzothiazole ( ECBT ) is facilely developed by ethylene bridging of N-ethyl-3-carbazolecarboxaldehyde and benzothiazole, which is a useful fluorescent probe for strongly acidic pH sensing. The pH titration indicates remarkable fluorescence enhancement effect and an emission red-shift of 87 nm with pH decreasing from 7.00 to 1.00. Furthermore, the solution color changes from light blue to orange under a UV lamp illumination. A p K a value of 1.62 and a good linearity in the pH range of 1.23–2.10 indicate that the probe can be used in quantitative fluorescence imaging under strongly acidic condition. In addition, ECBT exhibits high selectivity and sensitivity, good photostability and excellent reversibility for pH sensing. The probe is further applied successfully to imaging extreme acidity in Escherichia coli cells without influence of autofluorescence in biological systems. [ABSTRACT FROM AUTHOR]

Despite the tremendous advances that have been made in selective detection of a wide range of inorganic anions and cations, a single fluorescent probe possessing a high discrimination ability for these ions and their analogues is still very rare. Herein we propose a mononuclear europium-macrocycle complex Eu - 2 l which employs the imine bond interaction sites and embeds europium ion into a Schiff-base macrocyclic cavity interior to construct the dual-emission matrix for the lab-on-a-molecule fluorescent probe. Eu - 2 l not only allows the conventional spectral analysis for significant intensity changes of emission bands but also enables the statistical analysis for different levels of fluorescence sensing signals. As a result, this novel fluorescent platform Eu - 2 l shows the great real-time, selective, sensitive and quantitative detection ability for PO 4 3- or Al3+ among common inorganic ions. Furthermore, when sensing signals of anions and cations on different fluorescence channels are systematically evaluated by principal component analysis (PCA) and hierarchical cluster analysis (HCA) methods, Eu - 2 l allows the high-through discrimination of not only 18 anions and 12 cations but also several analogues and their proportional mixtures, even in real environmental water sample. This work enriches the PO 4 3- and Al3+ chemosensors, highlights huge benefits of the combination multi-emission fluorescent matrix and statistical analysis methods and thus provides a vital reference to construct the lab-on-a-molecule probe by a single chemical entity for multianalyte detection and discrimination in various fields. [Display omitted] • Mononuclear Eu-macrocycle Eu - 2 l is fabricated into a lab-on-a-molecule fluorescence probe for multianalyte detection. • Spectral analyses verify fast, selective, and sensitive detection ability of Eu - 2 l for PO 4 3- and Al3+. • Statistical analyses make Eu - 2 l efficiently discriminate 18 anions and 12 cations, even several analogues and mixtures. [ABSTRACT FROM AUTHOR]

Healthcare-associated infections (HAIs) have increasingly become a threat to global health. Rapid, accurate, and reliable detection of HAI-related bacteria is urgently needed. Here, we presented a novel antimicrobial peptide-based surface-enhanced Raman scattering lateral flow assay (SERS-LFA) for the detection of multiple HAI-related bacteria. Antimicrobial peptide cecropin 1(CP1) was immobilized on the surface of Fe 3 O 4 @Au by the streptavidin-biotin system to capture Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli O157:H7 (E. coli O157:H7) simultaneously. The synthesized Fe 3 O 4 @Au-CP1 exhibits excellent broad-spectrum capturing ability, rapid magnetic enrichment function, and superior antibacterial activity. LFA strips enable the specific detection of two target bacteria in a quick and simple manner, with bacterial type differentiation via corresponding monoclonal antibodies sprayed. The highly sensitive SERS signals and the amplification effect of streptavidin-biotin significantly improved the sensitivity of detection. The LODs of P. aeruginosa and E. coli O157:H7 were 12 and 16 cells/mL, respectively. This assay also exhibited good specificity and reproducibility when applied to urine samples. Therefore, Fe 3 O 4 @Au-CP1-based SERS-LFA has great potential for detecting multiple bacteria after infection as well as regularly monitoring therapeutic efficacy. • CP1 was first utilized as a broad-spectrum recognition element in SERS-LFA to detect multiple bacteria simultaneously. • The amplification effect of the streptavidin-biotin system enhances the binding efficiency of Fe 3 O 4 @Au-CP1 to bacteria. • Fe 3 O 4 @Au-CP1 MNPs enable quick capture and enrichment of bacteria. • CP1-based SERS-LFA can achieve highly sensitive and quantitative detection for P. aeruginosa and E. coli O157:H7. • The LODs for P. aeruginosa and E. coli O157:H7 were 12 cells/mL and 16 cells/mL, respectively. [ABSTRACT FROM AUTHOR]

The aberrant deposition of lipid droplets (LDs) is a pivotal feature in foam cells formation and has significant implications for understanding the pathogenesis and early diagnosis of atherosclerosis (AS). In this study, we engineered a fluorescent probe, PyTPA-LD, for the reliable tracking of intracellular LDs. Through the application of PyTPA-LD, we monitored LD generation during the transition of macrophages induced by oxidized low-density lipoprotein (ox-LDL) into foam cells. Furthermore, we observed dynamic changes in lysosomes and LDs during lipophagy in this transitional process. Our study unveiled the dual role of lysosomes in LD formation: the degradation and release of ox-LDL within lysosomes promote LDs formation, while concurrently, lipophagy contributes to LDs clearance. This novel perspective provides a comprehensive understanding of the dynamic generation and clearance of LDs during foam cells formation. This work offers crucial insights into the pathogenic mechanisms underlying AS, deepening our understanding of AS development and providing valuable insights into lipid metabolism-related diseases. • A fluorescent probe was successfully developed to target LDs by molecular structure engineering and optimization. • This probe can be used to observe and validate LDs involvement in autophagy and transport in situ and in real-time. • During LDs formation, the dual role of lysosomes was revealed in macrophage transition induced by ox-LDL into foam cells. • This work significantly advances our understanding of the pathogenic mechanisms underlying atherosclerosis. [ABSTRACT FROM AUTHOR]

In the present study, a dual-dielectric planar waveguide (PWG) coupling sensor was developed to break the waveguide performance limit. Its designs consisted of a sensor planar waveguide (PWG1) for the realization of multimode sensing and a reference planar waveguide (PWG2) for the realization of Fano and electromagnetically induced transparency (EIT)-like resonance. The sensitivity and quality (Q) factor of the device were shown to achieve values of up to 7.8 × 104 nm/RIU and 4843.75, respectively, allowing its applicability for bulk refractive index (RI) sensing. This yielded an impressive Figure of Merit (FOM) of 2.2 × 105 RIU−1, which was the highest reported FOM for an RI sensor. Furthermore, the reaction between the Streptomycin monoclonal antibody and Streptomycin-BSA measured in this work displayed high resolution capability and good linearity. This suggests the vast potential for environmental protection, drinking water safety, and biomedical discoveries. • The limitations of sensor performance were broken by both enhancing sensitivity and quality factor. • Multimode sensing of ultra-high sensitivity with planar waveguide has been experimentally realized for the first time. • High-quality peak can be clearly identified by the shape difference of EIT-like and Fano resonances. [ABSTRACT FROM AUTHOR]

J-aggregate dyes have been widely used in biomedicine, chemical engineering, etc., due to their structure and photophysical properties. J-aggregation theory describes the nearest-neighbor molecules' transition dipole moments in a sliding stacking arrangement. However, we found that the intervention of polyvalent anions can induce the J-aggregation of dyes via the intermolecular van der Waals and electrostatic interactions, which is an essential way once overlooked. Experimental results and theoretical calculations revealed that the more negatively charged or large size of anions within a specific range, the more efficiently the dye will form J-aggregates. As an application, the content of polyvalent anion salts in a salt-stressed Arabidopsis model was evaluated based on the ratiometric fluorescence emission resulting from the polyvalent anion-induced dye J-aggregation. • A new form of J-aggregation induction, polyvalent anion-induced aggregation was proposed. • Two probes with similar chemical structures to JC-1 were developed. • All three probes can be induced to J-aggregation by polyvalent anions. • The content of polyvalent anions in salt-stressed Arabidopsis model was quantified by JC-OH. [ABSTRACT FROM AUTHOR]

Protein S-nitrosylation is an important post-translational modification, which has important effect on protein functions and is relevant to various diseases. For quantification of the S-nitrosated proteins, it is still challenging to establish a detection method in combination of fast and one-step determination, highly sensitivity and accuracy. Here, we develop a label-free, direct detection method for S-nitrosated proteins based on resonance Raman scattering of ferrous cytochrome c. The laser source of the Raman spectrometer is utilized both for inducing NO leakage and for Raman scattering excitation. The heme ligation alteration and oxidation enable fast quantification of the released NO by the resonance Raman spectroscopy of the cytochrome c. All the results shown in this study demonstrate the great potential of the proposed method for fast, sensitive and reliable assessment of total S-nitrosated proteins in the clinical applications. [ABSTRACT FROM AUTHOR]

Neutrophil gelatinase-associated lipocalin (NGAL) with its great potential in clinical applications is a promising biomarker for the early diagnosis of acute kidney injury (AKI). Detection capability of immunoassays for versatile molecular forms of NGAL will affect the clinical performance of NGAL as biomarker for AKI. Here a molecular form-specific immunoassay for the detection of NGAL is developed by surface-enhanced Raman spectroscopy (SERS). 4-mercaptobenzoic acid (MBA)-modified silver chips are used as SERS-active substrates for capturing NGAL antibodies via amide bonds. The typical SERS band frequency of MBA is highly sensitive to different molecular forms of NGAL. The SERS-based immunoassay has obvious advantages over other conventional enzyme-based methods in sample preparation and detection procedure. This is a first attempt to apply SERS to detect AKI biomarkers, and the results demonstrate the proposed method has potential applications in the immunoassays for not only monomer NGAL, but also homodimer NGAL. [ABSTRACT FROM AUTHOR]

Carboxylesterases in human body play pivotal roles for catalyzing the hydrolysis of endogenous and exogenous substances such as lipids, thioesters and amides. Carboxylesterase-2 (CES2) as a major isoform of carboxylesterases is highly expressed in human digestive tract, and usually serves as an important mediator for pharmacokinetics and pharmacodynamics of ester medications or ester prodrugs. Therefore, developing effective strategies to detect and track CES2 in cells or tissues is of great significance for understanding its physiological and pharmacological effects on various diseases and therapeutic outcomes. In this study, we synthesized a fluorescent probe (CHQ-E) with near-infrared (NIR) excitation and emission maxima based on dihydroxanthene fluorophore for highly selective and sensitive detection of CES2. This probe exhibited rapid response (3 min), excellent sensitivity (detection limit = 0.35 ng/mL) and high binding affinity (K m = 9.4 μM) towards CES2, as well as low cytotoxicity towards living biosamples. Significantly, the maximum fluorescence excitation and emission wavelengths led to excellent optical properties of this probe including less photodamage, few autofluorescence and superior tissue penetration depth (180 µm). Moreover, CHQ-E has been applied to monitoring CES2 activity in drug-induced liver injury and its remediation models. Results of fluorescence imaging in vivo indicate the broad potential of CHQ-E for clinical diagnosis and evaluation of pharmaceuticals. [Display omitted] • Probe for detecting CES2 with both excitation and emission maxima at NIR region. • High sensitivity (LOD = 0.35 ng/mL) and short response time (3 min) to CES2. • Great tissue penetration depth (180 µm) for bioanalysis. [ABSTRACT FROM AUTHOR]

Apoptosis is an exquisitely controlled complex process which plays key roles in maintaining cell homeostasis. Abnormal regulation of apoptosis was directly related to severe diseases including cancer, neurodegenerative diseases, and cardiovascular diseases. Herein, we proposed a chain-engineering strategy for constructing probes to distinguish the different stages of apoptosis. Two fluorescent probes (CPI-2 and CPI-3) with very similar structure were developed to detect the late and early apoptotic stages, respectively. CPI-2 with short chain could not enter live cells due to its poor membrane permeability, and thus exclusively illuminated the nucleolus of late apoptotic cells with damaged plasma membrane. CPI-3 was permeable to biomembranes and stained mitochondria in living cells, which immigrated into the nucleolus during early apoptotic procedure due to the decrease of mitochondrial membrane potential. Furthermore, CPI-2 and CPI-3 were successfully used to monitor the different stages of apoptosis induced by different concentrations of H 2 O 2 , paclitaxel, and rotenone. Particularly, we studied the heavy metals poisoning and detoxification of cysteine by CPI-2 and CPI-3. This work provides a viable strategy for constructing probes to detect the different stages of apoptosis, which is expected to promote the development of probes to monitor apoptosis processes. [Display omitted] • A chain-engineering strategy for probes to detect the early and late apoptosis was proposed. • Two probes with similar chemical structures were developed to distinguish different apoptotic stages. • CPI-2 was impermeable to intact biomembranes which enabled detection of late apoptosis. • CPI-3 exhibited good membrane permeability which could detect early apoptosis via subcellular immigration. • Both probes were used to study heavy metal poisoning and the detoxication of cysteine. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescent probe was designed and synthesized for detection of bisulfite, via pyrene as an electron donor (D) and 4, 5-dibromothiophene as an electron acceptor (A). It had good selectivity, sensitivity and short response time. The fluorescence intensity ratio at 420 nm and 530 nm (I 420 /I 530 ) displayed a good linear relationship with the concentration of HSO 3 − in the range of 0–35 μM, and the detection limit was 0.77 μM. The possible recognition mechanism of probe and HSO 3 − was illustrated by NMR, HRMS and computational analysis. Notably, the probe was successfully applied for imaging HSO 3 − in A549 cells, Caenorhabditis elegans and zebrafish, which indicated that this probe had great potential for HSO 3 − detection in vivo. [ABSTRACT FROM AUTHOR]

In this work, three anthraquione-based derivatives containing different heteroatoms (N, O or S) were designed, synthesized and characterized. The red fluorescence of compound AQ-NS was selectively quenched by Cu 2+ , and was exclusively recovered by the subsequent addition of S 2− . Quenching and recovering the fluorescence accompanies with an obvious color change that could be easily observed by naked eyes. Various experiments demonstrated that the probe binding Cu 2+ in a 1:1 ratio. In addition, the recyclability and reusability of AQ-NS towards Cu 2+ and S 2− was evaluated, and the probe shows robust response without significant loss of signals after several cycles of repeated addition of Cu 2+ and S 2− . Our results demonstrate that the probe AQ-NS can be used for detection of Cu 2+ and S 2− with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a desirable method to fight against cancer, because it can achieve selective ablation of tumor tissues via the control of incident light. Self-reporting PDT sensitizers that can in-situ and real-timely monitor cell viability during PDT process are promising tools for PDT. For lysosomal damage would release cathepsins B/D into cytoplasm and efficiently induce cell apoptosis, herein, we have constructed a unique self-reporting PDT sensitizer (NSLN) targeting lysosomes in living cells. NSLN was designed to equip both alkalescent unit and cationic group. And NSLN targeted lysosomes in living cells, and immigrated into nucleus after lysosomal damage and cell death. In this way, the cells viability could be facilely visualized via subcellular localization of NSLN. With the probe, the apoptosis induced by H 2 O 2 , rotenone, and paclitaxel has been successfully monitored. Furthermore, NSLN could generate large amount of reactive oxygen species and induce lysosomal damage and cell apoptosis upon light irradiation. The cell damage during PDT procedure could be also monitored with NSLN via its subcellular immigration. This work provides a novel method for monitoring PDT process and makes it possible to control phototoxicity. We believe that NSLN can be used as a powerful tool to promote the development of PDT. [Display omitted] • A lysosomes-targeted self-reporting photosensitizer was presented to induce and monitor photodynamic therapy. • The photosensitizer generated large amount of reactive oxygen species under light irradiation. • The fluorescent sensitizer can monitor cell death via its subcellular immigration from lysosomes to nucleolus. • Lysosomal damage and cell apoptosis were successfully induced and visualized with the photosensitizer. [ABSTRACT FROM AUTHOR]

Tau protein has attracted much research interest in recent years. Development of effective techniques for in vivo imaging of Tau protein with high sensitivity and selectivity is of great importance. Herein, we rationally designed two novel, Tau-selective and AIE-active fluorescent probes (JL-3 and JL-6). Triphenylamine (TPA) as the AIE group, was first linked with a -CN group and N , N '-dimethylaminobenzene by π-π conjugation to form a D-A-D structure. Then, a hydrophilic unit was conjugated to increase probe hydrophilicity. The AIE-activity and water-solubility characteristics contributed to larger Stokes shift and quantum yields, decreased background fluorescence and therefore enhanced the signal-to-noise ratio of the detection. An excellent discrimination between Tau and β-amyloid (Aβ) aggregates (4.3- and 3.5- times higher Tau-over-Aβ) was obtained on JL-3 and JL-6. Taking JL-3 as the example, an excellent linear relationship between Tau concentrations from 50 nM to 5 μM and fluorescence was obtained (detection limit, 14.9 nM). Finally, JL-3 demonstrated a remarkable capacity for bioimaging in living cells, brain tissues and transgenic mice. Collectively, our results illustrated the potential of the developed probes as Tau-specific fluorescent dyes for both in vitro and in vivo applications. ● Two AIE-active fluorescent probes were designed and synthesized. ● The probes were AIE-active with high selectivity and sensitivity toward Tau. ● A stronger affinity for Tau protein than Aβ was acquired on the probe. ● Imaging in living cells, tissue staining and in living transgenic mice was realized. [ABSTRACT FROM AUTHOR]

As a topoisomerase I inhibitor, the prodrug irinotecan has been widely used in the chemotherapy of metastatic cancers. However, the transformation from irinotecan to its active metabolite SN-38 is slow and non-selective in cancer cells, which is not desired for clinical oncotherapy. Additionally, the fluorescence turn-on response of irinotecan is poor, prohibiting real-time observations on SN-38 release. Here, we developed a new prodrug (BDD-SN38) that is well suited for real-time monitoring SN-38 release and reducing its activation in normal cells. The fluorescence and activity of BDD-SN38 was significantly quenched by dinitrobenzene group. The in vitro and in cell results showed that BDD-SN38 could be selectively and rapidly activated by hydrogen sulfide (H 2 S) to obtain significantly enhanced fluorescence and activity. Moreover, BDD-SN38 achieved remarkable toxicity towards H 2 S-overexpressed cancer cells. Overall, the H 2 S-responsive prodrug developed here was proved to be a promising candidate for real-time monitoring SN-38 release and improving its therapeutic effect. [Display omitted] • A hydrogen sulfide responsive prodrug was designed and synthesized. • BDD-SN38 can be rapidly activated by H 2 S. • BDD-SN38 can obtain significantly enhanced fluorescence in H 2 S over-expressed cancer cells. • BDD-SN38 can achieve enhanced toxicity towards H 2 S over-expressed cancer cells. • BDD-SN38 can reduce toxicity towards normal cells. [ABSTRACT FROM AUTHOR]

Since adenosine triphosphate (ATP) and reactive oxygen species (ROS) are closely related to neuron functions and the pathogenesis of Alzheimer's disease, herein, the first example of using a dual-responsive zeolitic imidazolate framework-90 (ZIF-90) to fabricate a single fluorescent probe, CuNCs/ZIF@P1-P2/ZIF, was reported, which specifically and sensitively responded to intracellular level fluctuations of ATP and ROS both in neuronal and tumor cells without obvious cross-talking. Through a stepwise in situ growth method, ROS-responsive glutathione-stabilized copper nanoclusters (GSH-CuNCs) and double tagged ATP aptamer hybrid chain (P1-P2) were prepared and respectively encapsulated into the inner and outer ZIF-90. The obtained CuNCs/ZIF@P1-P2/ZIF probe as a tandem system could firstly respond to ATP in an "off-to-on" mode, in which, the quenched fluorescence of FAM by BHQ1 attached on P2 was recovered through the competitive displacement between ATP and ZIF-90, leading to the release of FAM from ZIF-90. Upon collapse of the outer ZIF-90, the strong emission of CuNCs enclosed in the inner ZIF-90 was subsequently quenched in the presence of ROS. Accompanied with high sensitivity, selectivity and accuracy, the resultant fluorescent probe exhibited good performance and properties for tracking the level variations of ATP and ROS in SH-SY5Y and Hela cells under different stimulations. This strategy highlighted the potential of the ZIF-90 based nanocomposite for multi-targets detection, and also provided a value tool for the early diagnosis of diseases. • A dual-responsive ZIF-90 based nanocomposite was prepared. • An effective strategy for ATP and ROS combined detection was developed. • The composite selectively responded to ATP and ROS without cross-talking. • Imaging in living SH-SY5Y cells under different stimulations was realized. [ABSTRACT FROM AUTHOR]