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A metal organic framework obtained from cerium(III) and trimesic acid was pyrolyzed to obtain a novel nanostructure referred to as CeO2/C nanowires. The experimental parameters temperature, precursor and gas atmosphere were optimized. The nanowires show good dispersion and a large number of oxygen vacancies, and this leads to excellent peroxidase-like activity. The nanowires are stable at pH values between 2 and 10, and in the 4–80 °C temperature range. The peroxidase-mimicking activity was exploited in a sensitive colorimetric method for determination of H2O2 by using 3,3′,5,5′-tetramethylbenzidine as the chromogenic substrate. The absorbance at 652 nm increases linearly in the 0.5 to 100 μM H2O2 concentration range. If glucose oxidase is added to a solution containing glucose, H2O2 will be enzymatically produced. This was exploited to design a new method for determination of glucose. The optical response is linear in the 1–100 μM glucose concentration range, and the detection limit is 0.69 μM (at S/N = 3). The method was successfully applied to the determination of glucose in serum samples. [ABSTRACT FROM AUTHOR]

Abstract As novel cyclin-dependent kinase (CDK) activators, Speedy/RINGO (hereafter named Speedy) proteins can directly regulate the cell cycle of vertebrates by binding to and activating various CDKs. Previous studies have shown that Speedy genes are highly associated with different types of cancer and other diseases. However, Speedy genes have not been systematically identified in mice, and their function and expression profiles remain elusive, which greatly hinders the functional and mechanistic study of Speedy genes in vivo. Here, we comprehensively identified Speedy genes in the mouse genome. Phylogenetic analysis showed that the Speedy gene family should be divided into three subfamilies, rather than the previously reported two subfamilies. Mice have two of the three subfamilies of Speedy genes, namely, subfamilies A and E. Speedy subfamily C genes have been lost from the mouse genome. By combining experimental and bioinformatics approaches, we found that the genes from subfamilies A and E have different expression profiles, indicating their functional divergence, which was also consistent with the phylogenetic results. The genes belonging to subfamily E showed only slightly different expression profiles, indicating their similar functions. Coexpression network analysis showed that the genes coexpressed with mouse Speedy genes were primarily enriched in reproduction-related mechanisms and there were significant functional differences between genes from subfamilies A and E, further demonstrating functional differentiation. In summary, we provide a comprehensive landscape (from evolution to expression and function) of the Speedy family in mice; we also demonstrate that Speedy genes mainly participate in reproduction-related mechanisms and that they have undergone functional differentiation in mice. Highlights • Genome-wide identification of Speedy/RINGO genes in the mouse genome. • Speedy/RINGO family have three rather than two subfamilies reported previously. • Speedy C subfamily have been lost in mice, while E subfamily have been expanded. • All results in this article demonstrate the functional differentiation of Speedy/RINGO family in mice. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel competitive strategy using oxidase nanozyme for glucose detection was proposed. • The strategy shows high detection efficiency with convenience, rapidness, sensitivity all promised. • The strategy can be applied into human serums with good accuracy. Nanozyme-based sensing strategy for glucose generally involves a two-step H 2 O 2 -bridged cascade reaction. However, this two-step cascade reaction always shows a limited detection efficiency for glucose, which hardly makes simply operation, rapid detection, and sensitivity all promised. Herein, a novel strategy for one-step glucose detection was proposed based on the efficiently competitive relationship between glucose oxidase catalyzed glucose oxidation and oxidase nanozyme catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) colorimetric oxidation. As a proof of concept, Co-Nx sites on porous carbon (Co-Nx/PC) derived from ZIF-67 was selected as the oxidase nanozyme with O 2 -sensitive nature, which can activate O 2 to produce 1O 2 for TMB colorimetric oxidation. In the presence of glucose, the competitive reaction of glucose oxidase catalyzed glucose oxidation occurs, which will obviously inhibit the Co-Nx/PC catalyzed TMB colorimetric oxidation to construct method for glucose detection. The usage of the same reactant O 2 and the production of suppressive H 2 O 2 cause a dual effect to this inhibition. In addition, the available pH range of Co-Nx/PC overlaps with that of glucose oxidase, promising a one pot reaction. The proposed method with Co-Nx/PC as oxidase nanozyme based on one-step competitive strategy for glucose detection possesses high detection efficiency with convenience (one-pot), rapidness (total reaction time of 10 min) and sensitivity (LOD of 0.31 μM) all promised, which is superior among the methods based on two-step one-pot or two-pot cascade strategy. The strategy can be successfully applied into the blood glucose detection in human serums with satisfactory results. Also, the strategy can be scalable to other oxidase nanozyme like Mn 3 O 4. [ABSTRACT FROM AUTHOR]

Constructing hollow mesoporous nanostructures for dispersing catalytically active sites has attracted growing interest. Here, for the first time, Co 3 O 4 hollow nanocages (Co 3 O 4 HNCs) derived from ZIF-67 were prepared for loading iron nanoparticles (FeNPs), resulting in FeNPs@Co 3 O 4 hollow nanocages (FeNPs@Co 3 O 4 HNCs). FeNPs@Co 3 O 4 HNCs were characterized by SEM, TEM, XRD, XPS and FT-IR. The FeNPs@Co 3 O 4 HNCs composites could catalyze the oxidation of TMB into blue product by H 2 O 2 , showing better peroxidase-like activity than FeNPs and Co 3 O 4 HNCs. Notably, kinetic studies indicated that FeNPs@Co 3 O 4 HNCs behaved an excellent affinity to H 2 O 2 with K m value of 0.019 mM, which was 195 times lower than that of HRP. On this basis, a facile colorimetric biosensing method was established to detect glucose. The linear range was 0.5–30 μM, and the limit of detection was 0.05 μM. The proposed sensor was successfully used to determine glucose in human serum samples. The highly catalytic performance of FeNPs@Co 3 O 4 HNCs is attributed to its porous hollow structure, which is beneficial for dispersion of in situ formed FeNPs and for reducing the agglomeration. Further, the FeNPs@Co 3 O 4 HNCs catalysts with porous character provide an essential way to expose active sites as far as possible to the substrate and increase the catalytic active sites. [ABSTRACT FROM AUTHOR]

Encapsulating metal nanoparticles (NPs) into carbon materials is a promising strategy for the fabrication of nanozymes with high activity. Here, for the first time, the proof-of-concept is demonstrated by fabricating CoNPs embedded in NH 2 -MIL-88(Fe) MOFs-derived magnetic carbon (MC) through in situ reduction of cobalt precursors by NaBH 4 . The obtained CoNPs/MC was characterized by TEM, SEM, XPS, XRD, Raman spectrum, and FT-IR. The CoNPs/MC exhibits much higher peroxidase-like activity than pure CoNPs and magnetic carbon. The high peroxidase-like activity of the CoNPs/MC is attributed to the decomposition of H 2 O 2 to generate OH and O 2 − radicals, resulting in TMB color reaction. Also, CoNPs/MC is robust in a wide range of pH and temperature, indicating a promising peroxidase-like candidate. On this basis, a colorimetric assay was developed by combining glucose oxidase with CoNPs/MC for glucose biosensing. The linear range for glucose detection is from 0.25 to 30 μM with a lower detection limit of 156 nM. The CoNPs/MC-based colorimetric method has been successfully used to assay the content of glucose in real biological samples such as human serums. Our work reveals the high potential of encapsulating metal NPs into carbon materials for the fabrication of nanozymes with stable and high activity. [ABSTRACT FROM AUTHOR]

A facile and rapid post-synthetic strategy was proposed to prepare a glycine functionalized MIL-53(Fe), namely glycine-MIL-53(Fe), by a simple mixing of water dispersible MIL-53(Fe) and glycine. The FT-IR, SEM, XRD and zeta potential were used to characterize the glycine-MIL-53(Fe). The result showed that glycine post-synthetic modification of MIL-53(Fe) did not change in the morphology and crystal structure of MIL-53(Fe). Interestingly, compared with MIL-53(Fe), the glycine-MIL-53(Fe) exhibits an enhanced peroxidase-like activity, which could catalyze the oxidation of TMB by H 2 O 2 to produce an intensive color reaction. Kinetic analysis indicated that the K m of glycine-MIL-53(Fe) for TMB was one-tenth of that of MIL-53(Fe). The glycine-MIL-53(Fe) as peroxidase mimetic displays better stability under alkaline or acidic conditions than MIL-53(Fe). The good performance of glycine-MIL-53(Fe) over MIL-53(Fe) may be attributed to the increase of affinity between TMB and the glycine-MIL-53(Fe). With these characteristics, a simple and sensitive method was developed for the detection of H 2 O 2 and glucose. The linear detection range for H 2 O 2 is 0.10–10 μM with a detection limit of 49 nM, and glucose could be linearly detected in the range from 0.25 to 10 μM with a detection limit of 0.13 μM. The proposed method was successfully used for glucose detection in human serum samples. [ABSTRACT FROM AUTHOR]

Various analytical applications of metal-organic frameworks (MOFs) have been rapidly developed in the past few years. However, the employment of MOFs as catalysts in chemiluminescence (CL) analysis is rare. Here, for the first time, we found that MIL-53(Fe) MOFs could significantly enhance the CL of luminol in the presence of HO in an alkaline medium. The CL intensity in the luminol-HO-MIL-53(Fe) system was about 20 times higher than that in the luminol-HO system. Moreover, the XRD pattern of MIL-53(Fe) after CL reaction was almost the same as that of the original MIL-53(Fe), confirming the catalytic role of MIL-53(Fe) in the luminol-HO-MIL-53(Fe) system. The possible mechanism behind the enhancing phenomenon was discussed based on the results from the CL spectra, FL probe experiments, and active oxygen species measurements. By coupling with the glucose oxidase-based catalytic oxidation reaction, a sensitive and selective CL method was developed for the detection of glucose. There is a linear relationship between the logarithm of CL intensity and the logarithm of glucose concentration in the range from 0.1 to 10 μM, and a detection limit of 0.05 μM (S/N = 3) is obtained. The proposed method has been applied to the determination of glucose in human serum samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Fe-MIM/ZIF-8 with rich biomimetic iron-imidazole groups was prepared and investigated as superior peroxidase mimic for colorimetric analysis of H 2 O 2 and glucose. [Display omitted] • Biomimetic Fe-MIM/ZIF-8 nanoflower was fabricated and firstly explored as nanozyme. • Fe-MIM/ZIF-8 with rich biomimetic Fe-MIM exhibits superior peroxidase-like activity. • Fe-MIM/ZIF-8 owns a strong affinity for H 2 O 2 with a low K m of 0.028 mM. • The colorimetric biosensor for H 2 O 2 and glucose promises high sensitivity. • The biosensor can detect glucose content in biological samples with high accuracy. The active site of natural horseradish peroxidase (HRP) comprises iron coordinated equatorially by a porphyrin ring and axially by the imidazole group of His170. The low water solubility of porphyrin rings inspired us to investigate the potential of the iron-imidazole group as peroxidase mimic. Herein, iron-imidazole (Fe-MIM) was one-pot constructed using ascorbic acid stabilized Fe2+ and 2-methylimidazole in the presence of zinc acetate at room temperature in aqueous medium, along with the formation of ZIF-8 framework around Fe-MIM sites. Fe-MIM/ZIF-8 was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface measurements. Fe-MIM/ZIF-8 exhibits high peroxidase-like activity, efficiently catalyzing the redox reaction between H 2 O 2 and 3, 3′, 5, 5′-tetramethylbenzidine, as made evident by the appearance of a UV–Vis signal at 652 nm. Fe-MIM/ZIF-8 displays higher catalytic activity than the material (Fe + MIM) prepared by ascorbic acid stabilized Fe2+ and MIM, due to its rich biomimetic architecture and large BET surface area. The K m of Fe-MIM/ZIF-8 for H 2 O 2 was 28 μM, which is 132 and 98 times lower than those of HRP and hemin (ironIII porphyrin), respectively. This low K m value indicates the strong affinity of Fe-MIM/ZIF-8 for H 2 O 2 , which proves the superiority of biomimetic Fe-MIM sites and suggests Fe-MIM/ZIF-8′s potential for H 2 O 2 -related biosensing. The highly sensitive colorimetric methods for H 2 O 2 and H 2 O 2 -related glucose detection has been proposed. The applicability of this method to glucose detection in serum samples was tested with satisfactory results. [ABSTRACT FROM AUTHOR]

Multilayer microcapsules showing unique charge-controlled permeability have been successfully fabricated by employing poly(styrene sulfonate) (PSS)-doped CaCO3 particles as templates. Encapsulation of the PSS molecules is thus achieved after core removal. Scanning force microscopy (SFM), UV−vis, Raman spectroscopy, and ζ-potential confirm the existence of the PSS molecules in the CaCO3 particles and the resultant microcapsules, which are initially incorporated during the core fabrication process. A part of these additionally introduced PSS molecules interacts with PAH molecules residing on the inner surface of the multilayer wall to form a stable complex, while the other part is intertwined in the capsule wall or in a free state. Capsules with this structure possess many special features, such as highly sensitive permeability tuned by probe charge and environmentally controlled gating. They can completely reject negatively charged probes, but attract positively charged species to form a higher concentration in the capsule interior, as evidenced by confocal microscopy. For example, the capsules completely exclude dextran labeled with fluorescein isothiocyanate (FITC−dextran), but are permeable for dextran labeled with tetramethylrhodamine isothiocyanate (TRITC−dextran) having similar molecular mass (from 4 to 70 kDa), although there are only few charged dyes in a dextran chain. By reversing the charge of the probes through pH change, or by suppressing charge repulsion through salt addition, the permeation can be readily switched for proteins such as albumin or small dyes such as fluorescein sodium salt. [ABSTRACT FROM AUTHOR]

Lanthanum-modified mesoporous graphite nitride carbon composites (La-g-C3N4) were synthesized using a thermal shrinkage polymerization method. The samples underwent characterization through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmet–Teller (BET) analysis. The results revealed that the La30-g-C3N4 sample displayed a more porous layered morphology with a uniform pore structure. The BET surface area of the sample was found to be 38.6 m2 g−1, which is 5.8 times higher than that of the undoped sample g-C3N4. The sample exhibited a type IV isotherm, indicating its mesoporous nature with a pore size distribution ranging from 3 to 20 nm. The application of these materials was investigated for the degradation of tetracycline (TC) and acidic fuchsin (AF) in simulated wastewater. The results demonstrated that the La30-g-C3N4 sample exhibited rapid and efficient degradation, along with excellent adsorption capacity for both TC and AF. Within 5 minutes, the degradation efficiency of the La30-g-C3N4 sample for TC and AF was measured to be 83.1% and 74.1%, respectively, with corresponding adsorption capacities of 63.9 mg g−1 and 129.4 mg g−1. The kinetic and thermodynamic analysis of the adsorption process revealed that the adsorption of TC and AF by La30-g-C3N4 followed the quasi-second-order kinetics and Langmuir adsorption isotherm model, indicating a predominantly single-layer chemical adsorption process. Furthermore, the composite material exhibited good cycling stability and maintained excellent adsorption performance even after six repeated uses. [ABSTRACT FROM AUTHOR]

MoS 2 -MIL-101(Fe) was prepared and investigated for colorimetric analysis of H 2 O 2 and glucose with high selectivity based on a superior peroxidase-like activity. • MoS 2 -MIL-101(Fe) was developed and explored as nanozyme for the first time. • Synergistic interaction in MoS 2 -MIL-101(Fe) leads to superior catalytic activity. • Strong affinity of MoS 2 -MIL-101(Fe) for H 2 O 2 due to the low K m of 0.008 mM. • MoS 2 -MIL-101(Fe) could be used for highly sensitive H 2 O 2 and glucose detection. A novel nanostructure MoS 2 nanoflowers anchoring iron(III)-based metal-organic framework MIL-101(Fe) [Fe 3 O(H 2 O) 2 Cl(O 2 C–C 6 H 4 −CO 2) 3 ], named MoS 2 -MIL-101(Fe), was prepared by growing MIL-101(Fe) crystals with as-prepared MoS 2. Then, MoS 2 -MIL-101(Fe) was characterized through SEM, TEM, BET, XRD, DLS, and XPS. MoS 2 -MIL-101(Fe) possesses synergetic peroxidase-mimicking activity over individual MIL-101(Fe) and MoS 2 , which can catalyze the oxidation of TMB by H 2 O 2 with a much stronger Vis-absorption. MIL-101(Fe) has a high porosity and large specific surface area for MoS 2 to absorb H 2 O 2 and TMB. Hydrophilic MIL-101(Fe) could prevent the aggregation of hydrophobic MoS 2 in aqueous solution, which is beneficial for catalysis. In addition, anchored MoS 2 brings mesopore and abundant exposed active units to the MIL-101(Fe) surface. The synergetic effects result in a highly enhanced catalytic performance. The Michaelis constant (0.008 mmol/L) of MoS 2 -MIL-101(Fe) for H 2 O 2 is 462 times lower than that of HRP, showing its strong affinity with H 2 O 2. On the basis, a sensitive method for H 2 O 2 detection was proposed with a linear range of 0.01−20 μmol/L and a detection limit of 10 nmol/L. Considering H 2 O 2 as product in the reaction of glucose catalyzed by glucose oxidase, a sensitive and selective method for glucose detection was proposed. The method can be used in blood glucose detection with good accuracy. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide quantum dots (MoS2 QDs) are used in a fluorometric method for the determination of folic acid (FA) based on fluorescence quenching. The MoS2 QDs synthesized by a hydrothermal method possess bright blue fluorescence (with excitation/emission maxima of 325/415 nm), quantum yield of 3.7%, and excellent storage stability in solution (30 days in the refrigerator). Their fluorescence is quenched by FA, and intensity decreases linearly in the 0.1 to 125 μM FA concentration range. The detection limit is 0.1 μM (at S/N = 3), and the relative standard deviation (for n = 5) is 2.8% for 25 μM concentrations of FA. Studies on the quenching mechanism suggest that the effect is due to static quenching. The FA in commercial FA tablets was successfully determined. [ABSTRACT FROM AUTHOR]

Nowadays, bacterial infections are attracting great attention for the research and development of new antimicrobial agents. As one of the quinolones, ciprofloxacin (CI) has a broad-spectrum, strong antibacterial effect. However, the clinical use of ciprofloxacin is limited by drug resistance. Ciprofloxacin carbon dots (CCDs) with enhanced antibacterial activity and copper-doped ciprofloxacin carbon dots (Cu-CCDs) were synthesized by a simple hydrothermal method. The results of structural analysis and antibacterial experiments show that CCDs and Cu-CCDs have effective antibacterial properties by retaining the active groups of ciprofloxacin (-COOH, C-N, and C-F), and Cu-CCDs doped with copper have a better antibacterial effect. In addition, experiments have shown that Cu-CCDs show excellent antibacterial activity against E. coli and S. aureus and have good biocompatibility, which indicates that they have great prospects in clinical applications. Therefore, novel modified copper CCDs with broad-spectrum antibacterial activity, which can be used as antibacterial nanomaterials for potential applications in the field of antibacterial drugs, were synthesized in this study. [ABSTRACT FROM AUTHOR]

Exosomes derived from cancer cells have been recognized as a promising biomarker for minimally invasive liquid biopsy. Herein, a novel sandwich-type biosensor was fabricated for highly sensitive detection of exosomes. Amino-functionalized Fe3O4 nanoparticles were synthesized as a sensing interface with a large surface area and rapid enrichment capacity, while two-dimensional MXene nanosheets were used as signal amplifiers with excellent electrical properties. Specifically, CD63 aptamer attached Fe3O4 nanoprobes capture the target exosomes. MXene nanosheets modified with epithelial cell adhesion molecule (EpCAM) aptamer were tethered on the electrode surface to enhance the quantification of exosomes captured with the detection of remaining protein sites. With such a design, the proposed biosensor showed a wide linear range from 102 particles μL−1 to 107 particles μL−1 for sensing 4T1 exosomes, with a low detection limit of 43 particles μL−1. In addition, this sensing platform can determine four different tumor cell types (4T1, Hela, HepG2, and A549) using surface proteins corresponding to aptamers 1 and 2 (CD63 and EpCAM) and showcases good specificity in serum samples. These preliminary results demonstrate the feasibility of establishing a sensitive, accurate, and inexpensive electrochemical sensor for detecting exosome concentrations and species. Moreover, they provide a significant reference for exosome applications in clinical settings, such as liquid biopsy and early cancer diagnosis. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescent (RTP) carbon dots (CDs) have promising applications in bioimaging, anticounterfeiting, and information encryption owing to their long lifetimes and wide Stokes shifts. Numerous researchers are interested in developing highly bright RTP CDs using environmentally friendly and safe synthesis processes (e.g., natural raw materials and zero-pollution production pathways). In this study, we successfully synthesized RTP CDs using a hydrothermal process employing natural vitamins as a raw material, ethylenediamine as a passivator, and boric acid as a phosphorescent enhancer, which is referred to as phosphorescent CD (PCD). The PCDs exhibit both bright blue fluorescence emission and green RTP emission, with a phosphorescence lifetime as long as 293 ms and an excellent green afterglow visible to the naked eye for up to 7.0 s. The total quantum yield is 12.69%. The phosphorescence quantum yield (PQY) is up to 5.15%. Based on the RTP performance, PCDs have been successfully employed for anticounterfeiting and information protection applications. The results of this study provide a green strategy for the scalable synthesis of RTP materials, which is a practical method for the fabrication of RTP materials with high efficiency and long afterglow lifetimes. [ABSTRACT FROM AUTHOR]

Copper nanoclusters (Cu NCs) have attracted a surge of interest in fluorescent sensors as their outstanding physicochemical and optical properties. However, most of the reports have focused on single-signal fluorescent sensors, which are susceptible to background interferences and affect accuracy of the results. Herein, we constructed a facile ratiometric fluorescent sensor for monitoring ethanol based on Cu NCs with tunable dual emission. Polyvinylpyrrolidone (PVP)-modified Cu NCs were simply prepared in water, which exhibit ratiometric dual emission, including a strong green emission at 520 nm and a weak blue emission at 450 nm. The PVP-Cu NCs in water with strong green emission display monodisperse state due to the formation of hydration shell around Cu NCs. In ethanol where the hydration shell is destructed, Cu NCs tend to aggregate and show strong blue emission. This emission shift might attribute to the enhancement of Cu–Cu metallophilic interaction with the aggregation of Cu NCs, which induces the excited-state level increasing. Thus, a ratiometric fluorescent probe for ethanol based on the PVP-Cu NCs is fabricated, which possesses rapid response (<1 min), and realize full-range detection from 0 to 100%. In addition, this ratiometric probe is successfully applied to determine the alcohol strength of alcohol beverages, demonstrating the great potential in practical application. A facile and label-free ratiometric fluorescent probe for sensing ethanol contents in water was proposed based on the PVP-Cu NCs with unique ethanol-induced blue shift of emission property. [Display omitted] • The PVP-Cu NCs were prepared with ratiometric dual emission. • A facile ratiometric fluorescent probe was designed for sensing ethanol in water. • This probe has rapid response rate (<1 min) and full detection range from 0 to 100%. • This probe has great anti-interference capacity, and was successfully used in real sample. [ABSTRACT FROM AUTHOR]

The development of immobilization method of a chemoprobe on solid support without sacrificing its good original performance in homogeneous solution is a tricky problem. Herein, we make use of the transparent agarose hydrogel with semi-wet property which provided appropriate microenvironment to immobilize the chemoprobe and maintained its original performance to develop an excellent smartphone-enabled colorimetric platform. As a proof of concept, the sensing platform was fabricated with agarose hydrogel that captured diethylaminoethyldextran chloride (DEAE-dextran) and dithiothreitol modified copper nanoclusters (Cu NCs) as a fluorescence probe. Benefiting from the aggregation-induced emission (AIE) effect and confinement effect of hydrogel, the fluorescence quantum yield (QY) of Cu NCs hydrogel is three times higher than that of Cu NCs. Moreover, sensitively detection of Cr(VI) can be realized in the concentration range of 0.07–38.00 μM based on the amplified fluorescence probe. The outstanding analysis performance for Cr(VI) is also achieved when Cu NCs hydrogel was directly immobilized on paper as a smartphone-enabled colorimetric platform, indicating that our strategy can promote the further development of the application of hydrogel materials. [Display omitted] • An AIE-active copper nanoclusters (Cu NCs) functionalized hydrogel was prepared. • The amplified fluorescent detection of Cr(VI) by Cu NCs hydrogel was achieved. • Cu NCs hydrogel as a smartphone-enabled colorimetric platform showed an outstanding performance of detecting Cr(VI). • Smartphone-enabled colorimetric platform can realize instrument-free, portable and on-site detection of Cr(VI). [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-in-one signal sensing probe is designed for the determination of PMS. • The multisignal output guarantees more accurate monitoring of the PMS. • A conventional chromogenic substrate realizes the output of multiple signals. • Such a strategy improves the probe's reliability, sensitivity and adaptability. The extensive applications of peroxymonosulfate (PMS) in the field of environmental pollutant treatment based on advanced oxidation processes (AOPs) have prompted a high demand for advances in the probe ranging from improving their performances to strengthening their practicalities. Here, a multisignal-output probe of PMS was achieved by the unconventional application of traditional chromogenic system, 3,3′,5,5′-tetramethylbenzidine with Co2+ ions (Co2+-TMB). It works on the trace Co2+-catalyzed specific conversion of a colorless TMB into a blue oxidation product (oxTMB) with PMS as the oxidizing agent, accompanied by the enhanced absorption value of oxTMB at 652 nm and decreased fluorescence intensity of TMB at 405 nm. The change of color was directly observed. The combination of a hydrogel with a colorimetric platform favors the real-time and convenient sensing of PMS in the concentration range of 0.98 to 130.29 μM. A good linear relationship between the PMS concentration and both the absorption and fluorescence intensity was obtained with an r 2 value of 0.999, and a detection limit of 0.03 μM for fluorescence and 0.11 μM for spectrometry. Such a multisignal output probe with the advantages of simplicity, convenience, high sensitivity and stability improves the reliability and practical adaptability. This study successfully applied a valuable strategy for sensing PMS, and verified its availability in detecting the residual quantity of PMS in pollutant water treated by AOPs and PMS concentrations in actual water samples with peroxydisulfate (PDS). [ABSTRACT FROM AUTHOR]

The paper describes a voltammetric method for the quantitation of the activity of telomerase extracted from cancer cells. A thiolated single-stranded telomerase substrate primer was firstly immobilized on a gold electrode. In the presence of a mixture of telomerase and deoxynucleotide triphosphates, the primer becomes elongated and contains repetitive nucleotide sequences (TTAGGG)n. After hybridization with blocker DNA, gold nanoparticles are added and captured by the elongated single-stranded DNA. This reduces the charge transfer resistance of the gold electrode. The telomerase activity is then quantified via differential pulse voltammetry, typically at 0.12 V (vs. SCE). The method is PCR-free, rapid, and convenient. It was applied to the detection of HeLa cells via the telomerase activity of lysed cells. The detection range was from 500 to 50,000 cells/mL and the detection limit was as low as 500 cells/mL.A telomerase substrate (TS) primer is immobilized on a gold electrode as the sensing interface to detect the activity of telomerase extracted from cancer cells. Unmodified gold nanoparticles (AuNPs) are utilized which change the electrochemical responses. [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate an uncooled, sensitivity-enhanced infrared (IR) detector based on a Lamb wave sensor coated with polydopamine (PDA). The real-time resonant frequency responses of the sensors with and without PDA coating were measured as functions of IR intensity. Compared to the traditional Lamb wave sensor, the PDA-coated Lamb sensor exhibits a highly linear relationship between resonance frequency and IR intensity, and the slope representing the sensitivity of IR detection is nearly one order of magnitude higher. The enhanced sensitivity is mainly attributed to the optical-thermal transition of PDA nanoparticles rather than the modulation of the thermal-acoustic effect. This mechanism for achieving highly sensitive uncooled IR detectors holds great promise for application in photo-thermal therapy along with other military and civilian fields. [ABSTRACT FROM AUTHOR]

In the digital polymerase chain reaction (dPCR) detection process, discriminating positive droplets from negative ones directly affects the final concentration and is one of the most important factors affecting accuracy. Current automated classification methods usually discuss single-channel detections, whereas duplex detection experiments are less discussed. In this paper, we designed a classification method by estimating the upper limit of the negative droplets. The right tail of the negative droplets is approximated using a generalized Pareto distribution. Furthermore, our method takes fluorescence compensation in duplex assays into account. We also demonstrate the method on Bio-Rad’s mutant detection dataset. Experimental results show that the method provides similar or better accuracy than other algorithms reported over a wider dynamic range. [ABSTRACT FROM AUTHOR]

Different manganese oxides materials with various crystalline structures were prepared from KMnO 4 by using a cationic polymer branched polyethyleneimine (BPEI) as the reducing agent and structure directing agent through a hydrothermal process. By varying BPEI concentration, wire-like MnO 2 , rod-like MnOOH/Mn 3 O 4 and octahedral-like Mn 3 O 4 nanoparticles were controllably synthesized, respectively. The as-prepared manganese oxides were characterized by XRD, FT-IR, TEM, SEM and nitrogen adsorption-desorption measurements. The intrinsic enzyme-like activity of the synthesized manganese oxides was evaluated by using 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate in the absence of H 2 O 2 . It was shown that the mesoporous wire-like MnO 2 was best-performing with a highly oxidase-like catalytic activity in the model reaction. The effect of synthetic conditions of mesoporous wire-like MnO 2 on its oxidase-like activity was further investigated. Based on the selective inhibition of glutathione (GSH) on the high oxidase-like activity of as-prepared MnO 2 , a selective and sensitive colorimetric assay for GSH has been established. The limit of detection (LOD) for GSH was as low as 0.11 μM and the developed method was successfully applied to the detection of GSH in human serum samples. [ABSTRACT FROM AUTHOR]

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

Here we proposed a model that describesthe nucleation of cavitationbubbles on nano/microparticle surfaces, which is of significance forthe yet unsolved problem of particle-cavitation interaction. The modelwas verified through rational experimental design varying parametersincluding particle size, their shapes and additives. The surface morphologyevolution of particles under high intensity ultrasonic irradiationin aqueous solution can be tailored by changing the nucleation energybarrier of cavitation bubbles on particle surfaces. Cavitation-inducedbreakage of particles under sonication has also been addressed, whichpredicts the critical effect of the initial size of solid particlesin affecting ultrasound-driven intraparticle fracture. These resultsshed light on the effect of commonly used sonication treatments onnanostructured materials and sonochemical surface modification inparticle science and technology. [ABSTRACT FROM AUTHOR]

• Carbon dots were made from nitrogen-rich adenine via simple hydrothermal strategy. • The sensing mechanism of carbon dots was based on aggregation-induced enhanced emission (AIEE). • Carbon dots can efficiently detect and quantify ClO− in real water samples. A novel fluorescent chemosensing strategy on the detection and determination of hypochlorite (ClO−) based on fluorescence enhancement was reported. In this work, nitrogen-doped carbon dots (N-CDs) were prepared via one-step hydrothermal conversion of nitrogen-rich adenine and ethylenediamine. The N-CDs solution showed excitation-dependent characteristic and displayed green fluorescence (535 nm) when excited by blue light (480 nm). The fluorescence intensity was linearly enhanced with the concentration of ClO− increasing in the range of 0.01–1 mM, and the limit of detection was calculated to be 0.82 μM. Other than the common oxidation of the N-CDs surface by ClO−, spectra change stemmed mainly from aggregation-induced enhanced emission (AIEE), including π-π staking and J-aggregation, which together induced red-shift absorption band and effective fluorescence enhancement. Based on the good sensitivity to ClO−, the N-CDs probe also underwent real sample assay and gave relatively reliable recoveries of ClO− contained in various water samples. In addition, the N-CDs showed excellent anti-interference in the selectivity test and exhibited good stability in complex solution environment with different pH values or ion strengths. In view of the results, the N-CDs sensing probe has impressive sensitivity and selectivity on ClO− determination and possesses good potential on bioimaging applications. [ABSTRACT FROM AUTHOR]

We introduce a novel paradigm to unobtrusively and optically measure blood pressure (BP) without calibration. The algorithm combines photoplethysmography (PPG) waveform analysis and biometrics to estimate BP, and was evaluated in subjects with various age, height, weight and BP levels (n = 1249). In the young population (<50 years old) with low, medium and high systolic blood pressures (SBP, <120 mmHg; 120–139 mmHg; ≥140 mmHg), the fitting errors are 6.3 ± 7.2, −3.9 ± 7.2 and −20.2 ± 14.2 mmHg for SBP respectively; In the older population (>50 years old) with the same categories, the fitting errors are 12.8 ± 9.0, 0.5 ± 8.2 and −14.6 ± 11.5 mmHg for SBP respectively. A simple personalized calibration reduces fitting errors significantly (n = 147), and good peripheral perfusion helps to improve the fitting accuracy. In conclusion, PPG may be used to calculate BP without calibration in certain populations. When calibrated, it shows great potential to serially monitor BP fluctuation, which can bring tremendous economic and health benefits. [ABSTRACT FROM AUTHOR]