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A simple colorimetric sensing strategy for Hg2+ ions was developed using silver/copper nanoclusters (Ag/Cu NCs) with excellent selectivity and sensitivity. Bimetallic Ag/Cu NCs were synthesized by using glutathione (GSH) as a template and sodium borohydride as a reducing agent. It was found that the peroxidase-like activity of Ag/Cu NCs was significantly enhanced in the presence of Hg2+. Therefore, a colorimetric method based on catalysis was developed to detect Hg2+ with a linear concentration range of 0.1–700 nM and a detection limit of 0.05 nM (S/N = 3). The common species have no effect on Hg2+ ion detection. Furthermore, this method is applicable to accurately detect Hg2+ in real aqueous samples and is reproducible. Therefore, owing to the merits of sensitivity, selectivity, rapid response and visual read-out, it can be promising in the development of a portable Hg2+ analyzer for on-site detection.

It is important to detect pathogens rapidly, sensitively, and selectively for clinical medicine, homeland security, food safety, and environmental control. We report here a specific and sensitive colorimetric assay that incorporated a bovine serum albumin-templated Co3O4 magnetic nanozyme (Co3O4 MNE) with a novel specific fusion phage protein and magnetophoretic chromatography to detect Staphylococcus aureus. The Co3O4 MNE was conjugated to S. aureus-specific fusion-pVIII (Co3O4 MNE@fusion-pVIII), screened from the S. aureus-specific phage AQTFLGEQD (the phage monoclone is denoted by the peptide sequence). The as-prepared triple-functional Co3O4 MNE@fusion-pVIII particles were capable of capturing S. aureus in sterile milk, which were then isolated from milk magnetically. Assisted by polyethylene glycol, the Co3O4 MNE@fusion-pVIII@S. aureus complex was separated from the free Co3O4 MNE@fusion-pVIII by magnetophoretic chromatography in an external magnetic field. After transferring the isolated Co3O4 MNE@fusion-pVIII@S. aureus complexes into a 96-well plate, diammonium salt of 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) and H2O2 were added to develop color because of the peroxidase mimetics activity of the Co3O4 MNE. A S. aureus concentration within 10-10,000 cfu/mL in milk can be detected (detection limit: 8 cfu/mL). The as-developed method is simple, cost-efficient, and sensitive, which is useful for rapidly diagnosing pathogenic bacteria and helpful to prevent disease outbreaks induced by pathogens in developing countries.

A nanocomposite nanozyme has been fabricated through mineralizing gold-silver bimetals into Hemin (Hem)-coupled melamine (MA) polymer matrix for visual colorimetric analysis of H2O2 and glucose. Catalytic Hem was cross-linked onto MA scaffold for the mineralization of Au–Ag bimetals yielding the rod-like nanocomposite of MA-Hem/Au–Ag. It was discovered that the resulting nanocomposite could present high aqueous stability and especially improved catalysis, which was more than four-fold higher than that of native Hem. Catalytic kinetics studies indicate that the prepared nanocomposite nanozyme could present much higher affinities to the substrates than those of native Hem or even horseradish peroxidase. Herein, the so mineralized Au–Ag bimetals with the “silver effect” would act as “nanowires” for promoting the electron transferring of nanocomposite nanozyme. Moreover, the Hem-coupled MA polymer matrix with high specific surface area could ensure the high adsorption capacity for the reactant substrates and targeting analytes. The application feasibility of the developed nanocomposite nanozyme was demonstrated subsequently by the colorimetric assays for H2O2 and glucose separately in milk and blood samples, with the linear ranges of 0.010–2.50 mM and 0.0050–2.0 mM, respectively. Such a bimetal mineralization-based fabrication route may open a new door toward the design of diverse nanocomposites nanozymes with improved catalysis and adsorption performances.

A metal-free polymer nanozyme has been developed for the first time simply via the one-pot covalent reaction of hyperbranched polyethyleneimine (PEI) and redox dihydroxybenzaldehyde (DHB). The yielded PEI-DHB nanoparticles could display the peroxidase-like catalysis activity, so as to act as the metal-free nanozyme in catalyzing the chromogenic reactions of 3,3′,5,5′-tetramethylbenzidine and H2O2. More interestingly, the catalysis activity of the polymer nanozymes could be specifically inhibited by heparin oppositely charged. A facile visualized colorimetric method was thereby developed for sensing heparin through combining the specific catalysis and electrostatic attraction of PEI-DHB nanozyme. It was found that the developed colorimetric method can enable the detection of heparin in serum over the linear concentration range of 0.050–1.0 μM, promising the wide applications for the detection of heparin in the clinical laboratory for the disease diagnostics and pharmacological monitoring. More importantly, such a green synthesis method may be tailored for fabricating various metal-free polymer nanozymes for the wide catalysis applications.

Polymer prodrug micelles, combining the advantages of prodrugs and polymer micelles, can greatly improve the solubility, permeability and stability of drugs. In this work, amphiphilic block copolymers poly(α-azide caprolactone-co-caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine), P(ACL-co-CL)-b-PMPC, were synthesized, and an antineoplastic drug 7-ethyl-10-hydroxy camptothecin (SN38) was grafted to the amphiphilic copolymers to obtain a prodrug and their micelles. The preparation of P(ACL-co-CL)-b-PMPC was proceeded by ring-opening polymerization of e-caprolactone/α-bromide caprolactone, converting the bromide to an azide, and atom transfer radical polymerization (ATRP). The camptothecin derivative SN38-alkyne was bonded to the polymer to obtain P(CL/CL-g-SN38)-b-PMPC by a “click reaction”. The obtained polymer–drug complex can easily self-assemble to form prodrug micelles with the shell composed of PMPC and the core composed of PCL and SN38. The micelles presented characteristics including improved drug loading efficiency and stabilization of the drug. In vivo, the retention time of the prodrug micelles in blood could be tripled, and the clearance was delayed compared with the SN38 solution. The in vivo anti-tumor experiments demonstrated that the prodrug micelles had a better treatment effect and low toxicity to 4T1-bearing BALB/C mice.

An electroanalysis strategy has been developed for probing glutathione (GSH) separately in hela and yeast cells based on the displacement reaction route using melamine-copper (MA-Cu) nanocomposites. Herein, MA-Cu nanocomposites were initially synthesized by the controlled supermolecular self-assembly process showing various morphological structures depending on the MA-to-Cu ratios used. It was discovered that the electrodes modified with rod-like MA-Cu nanocomposites could achieve the stable electrochemical output of solid-state CuCl at a low potential, which might circumvent the possible interference from co-existing electroactive substances in complicated backgrounds like cells. More importantly, the yielded CuCl signals would decrease selectively induced by GSH through the specific Cu-GSH interaction that would trigger the displacement of CuCl into non-electroactive complex. The MA-Cu nanorods-modified electrodes can allow for the detection of GSH with the concentrations linearly ranging from 0.010 to 300.0 μM. Subsequently, the feasibility of the developed electroanalysis strategy was demonstrated for the evaluation of GSH separately in the extractions of hela and yeast cells, promising the wide applications in the clinical and food analysis fields.

A highly selective and sensitive electroanalysis strategy has been developed for sensing histamine (HTA) and histidine (His) with “turn-on” signal outputs using copper nanocomposites (Cu NCs) of reduced copper metal–organic frameworks (Cu MOFs). It was discovered that the Cu NC-modified electrodes could display the sharp and stable oxidation peaks of solid-state CuCl electrochemistry at a low potential (about −0.10 V). More interestingly, once HTA or His was introduced, the peaking currents of the electrodes would increase due to the specific interaction between Cu2+ and imidazole groups of HTA or His. A highly selective electroanalysis method was thereby developed for the detection of both HTA and His in the concentration range of 0.010–100 μM. Besides, the application feasibility of the developed electroanalysis strategy was demonstrated for the evaluation of HTA and His separately in red wine and urine samples. Such an electroanalysis candidate for HTA and His holds great potential for wide applications in the fields of food analysis and clinical disease diagnosis.

Nanozymes are artificial enzymes, which can substitute traditional biological enzymes for multifield applications. However, to date, it remains challenging to search novel mimic enzymes or multienzyme mimics. Herein, a facile and green method for preparing monodisperse, homogeneous copper nanoclusters (Cu NCs) with smaller size was developed, which used cysteamine as a template and hydrazine hydrate as a reductant to reduce Cu2+. The as-prepared Cu NCs exhibited excellent tetraenzyme-like activities, including peroxidase (POD)-, catalase (CAT)-, superoxide dismutase (SOD)-, and ascorbic acid oxidase (AAO)-mimic activities. The mechanisms, kinetics, and catalytic performances of Cu NCs were systematically studied. Moreover, based on the POD-like activity of Cu NCs, sensitive and simple colorimetric sensing glutathione (GSH) was explored, with the low limit of detection of 0.89 μM GSH (S/N = 3). Additionally, a novel fluorimetric ascorbic acid (AA) sensor was developed with the linear range of 0.5-30 μM and limit of detection (LOD) of 0.144 μM, on the basis of the principle that AA is oxidized to dehydroascorbic acid (DHAA) specifically catalyzed by the AAO-like activity of Cu NCs, while DHAA can further react with o-phenylenediamine (OPDA) to generate a highly fluorescent quinoxaline (DFQ) derivative. The as-proposed colorimetric GSH sensor and the fluorimetric AA sensor were capable of detecting GSH and AA, respectively, in real samples accurately and reproducibly. Thus, the Cu NCs-based multienzyme mimic is a promising candidate for biocatalysis and biosensing.

A porous hydrogel scaffold was fabricated for the first time to encapsulate chromogenic reaction substrates onto arrayed capillary tubes, resulting in a visual and high-throughput colorimetric method for rapid occult blood tests (OBTs) based on the hemoglobin (Hgb)-catalyzed chromogenic reactions. Gelatin (Gel), a biodegradable and biocompatible polymer, was introduced to couple with p-hydroxyphenyl-propionic acid (HPA) yielding the Gel–HPA hydrogel scaffold. Chromogenic reaction substrates of 3,3,5,5-tetramethylbenzidine and H2O2 were then encapsulated into the Gel–HPA matrix and further attached onto the amine-derivatized capillary tubes by forming porous chromogenic composites through the HPA-mediated bridging of Gel by the oxidization of H2O2. The developed Hgb catalysis-based OBT platform can facilitate the detection of Hgb with the level down to 0.125 μg mL−1 in human excreta (i.e., saliva, urine, and feces) through capillarity-enabled automatic sampling. This simple, sensitive, selective, and high-throughput colorimetric method may be promising for the bedside OBT for point-of-care monitoring and rapid diagnostics of clinical bleeding diseases.

Silver nanoclusters (AgNCs) were first coated with bovine serum albumin (BSA) and then encapsulated into porous metal–organic frameworks of ZIF-8 by the protein-mediated biomineralization process. Unexpectedly, the fluorescence intensities of the yielded AgNCs-BSA@ZIF-8 nanocomposites were discovered to be continuously enhanced during each of the BSA coating and ZIF-8 encapsulation steps. Compared to common AgNCs, greatly improved photostability and storage stability of AgNCs could also be expected. More importantly, having benefited from the ZIF-8 shells, the prepared nanocomposites could possess the specific accumulation and sensitive response to Cu2+ ions, resulting in the rational quenching of their fluorescence intensities. Moreover, AgNCs-BSA@ZIF-8 nanocomposites were coated onto the hydrophobic arraying slides toward a microdots array-based fluorimetric method for the fast and sensitive evaluation of Cu2+ ions. It was discovered that the developed fluorimetric strategy could ensure the high-through...

A solid-state fluorimetric strategy has been developed using test strips coated with Q-graphene-loaded metal-organic framework nanocomposites featuring water-triggered fluorescence turn-on. It can facilitate the real-time evaluation of trace water in organic solvents, with the level down to about 0.015% in alcohol.

An ultrasensitive and high-throughput visualized colorimetric method has been initially developed with a wettable microwells array for probing guanine base-containing anthrax DNAs in blood based on silver deposition amplified by the synergic TiO2 photocatalysis and guanine photoreduction under visible light. Hydrophilic microwells were first created on the hydrophobic slides to yield the wettable microwells array, on which photocatalytic titanium dioxide (TiO2) nanoparticles were deposited with dopamine (DA) to yield TiO2@DA for anchoring single strand DNA (ssDNA) capture probes without guanine bases. After the hybridization of the targeted anthrax DNAs, exonuclease I (Exo I) was introduced into the microwells to selectively digest the unhybridized ssDNA probes. The silver deposition was further conducted by the synergic photocatalysis of TiO2@DA and photoreduction of guanine bases of anthrax DNAs, thus achieving the amplified silver signals for the visualized colorimetric assays. Moreover, benefitting from the wettability feature of the hydrophilic–hydrophobic interfaces of the microwells array so fabricated, DNA analytes could be accumulated from the sample droplets through the condensing enrichment process to realize the ultrasensitive detection, in addition to circumventing any crossover contaminants between the sample droplets. The developed visualized colorimetric method with the microwells array was subsequently applied for probing anthrax DNAs in blood with levels down to 1.0 fM. DNAs with single-base and double-base mutations could also be identified accurately. Importantly, such a biosensing design route of a wettable microwells array, in combination with the photocatalytic silver deposition and specific Exo I-catalytic probe digestion, may promise extensive applications for the high-throughput, ultrasensitive, and selective detection of guanine-containing DNA targets with ultra-trace levels in complicated samples like blood.

Nanozymes are artificial enzymes, which can substitute natural enzymes for wide range of catalysis-based applications. However, it is challenging to explore novel mimic enzymes or multi-enzyme mimics. Herein we report the facile preparation of uniform CuS nanoclusters (NCs), which possessed outstanding tetra-enzyme mimetic catalytic activities, including peroxidase (POD)-mimics, catalase (CAT)-mimics, ascorbic acid oxidase (AAO)-mimics and superoxide dismutase (SOD)-mimics. The catalytic mechanism of POD-like was coming from the oxygen vacancies of CuS. Furthermore, the steady-state kinetics of POD-, CAT- and AAO mimics of CuS NCs were systematically explored. On basis of the enzymatic cascade reaction that acid phosphatase (ACP) involved in a weak acidic environment, in the presence of O-phenylenediamine, quinoxaline fluorescent substance will be generated. Thus, a fluorescent biosensor platform was proposed for detection of ACP with the linear range of 0.05–25 U L−1 and limit of detection of 0.01 U L−1. The as-proposed method was applicable to real serum sample detection accurately and reproducibly. Considering the simple preparation, good stability, excellent multi-enzyme activities and controllable experimental operation, CuS NCs would provide a basis for expanding to other biocatalytic and biomedical applications.

Micelles with phosphatidylcholine surfaces have numerous advantages, such as good biocompatibility and high enrichment of drug in tumor tissue. In this study, we developed hyaluronic acid-coated phosphatidylcholine micelles, prepared via electrostatic attraction, for targeting the delivery of doxorubicin (DOX) to tumors. An amphiphilic copolymer poly(caprolactone)-poly(N,N-diethylaminoethyl methacrylate)-r-poly(2-(methacryloyloxy) ethyl phosphoryl choline) (PCL-PDEAMPC) was designed and synthesized successfully. PCL-PDEAMPC micelles and their DOX-loaded micelles were prepared by the dialysis method and were coated with hyaluronic acid (HA). The results showed that the micelle diameters increased a little and the zeta potential changed from positive to negative after coating with HA. The in vitro DOX release from phosphatidylcholine micelles could be triggered by pH, and the release from HA-coated PCL-PDEAMPC micelles was slower than that from PCL-PDEAMPC micelles. The in vitro cytotoxicity of the micelles was investigated using the MTT method in 4T1 cells. The results showed that the half maximal inhibitory concentration (IC50) of PCL-PDEAMPC-HA/DOX micelles was lower than that of PCL-PDEAMPC/DOX micelles. The CLSM images of cellular uptake indicated the ability of these micelles to enter into 4T1 cells. The experiments of in vivo antitumor effect and safety evaluation of DOX-loaded micelles demonstrated that the HA-coated DOX micelles had a better treatment effect and lower toxicity to 4T1-bearing Kunming mice. HA-decorated PCL-PDEAMPC micelles are therefore potential carriers for 4T1 tumor treatment.

Phosphorylcholine micelles based on pH/reduction responsive copolymers, poly(e-caprolactone)-ss-b-poly((N,N-diethylaminoethyl methacrylate)-r-poly(2-methacryloyloxyethyl phosphorylcholine)) (PCL-ss-PDEAPMPC) were developed for the intracellular delivery of doxorubicin. The micelles were spherical (less than 90 nm in diameter) and demonstrated pH/reduction sensitivity. The DOX loaded micelles presented the fastest drug release under simultaneously acidic and reductive conditions. Although PCL20-ss-PDEA5PMPC10 had lower pH sensitivity than PCL20-ss-PDEA15PMPC10, the DOX loaded micelles of the former released the drug faster than the latter at pH 5.0 and in the presence of a reductant. The cytotoxicities of the blank micelles and the drug-loaded micelles were investigated using the human cervical cancer cell line (HeLa). The IC50 (half maximal inhibitory concentration) of PCL20-ss-PDEA5PMPC10 micelles was the lowest among PCL-ss-PDEAPMPC micelles. The results of CLSM and flow cytometry showed that the micelles effectively delivered the drug cargo into cancer cells. The cellular uptake pathways of PCL-ss-PDEAPMPC micelles were mainly clathrin-mediated endocytosis, and accompanied by a certain degree of giant pinocytosis.

A wettable well was fabricated on an electrode, which was further modified with carbon quantum dot-scaffolded nanocomposites of melamine and copper for probing histidine through a unique displacement reaction route. The developed electrode with wettable well enables the condensing enrichment of analytes from the sample droplets, improving the electroanalytical sensitivity.

It is challenging to explore specific, stable and cost-effective biorecognizing elements for a wide range of applications including biosensing and nanomedicine. As the primary pro-angiogenic factor, vascular endothelial growth factor (VEGF) plays crucial roles in tumor metastasis. It holds great significance to detect VEGF in clinical diagnostics. Especially, the level of the isoform VEGF165 is usually called as the key index of many malignant tumors. Herein, phage monoclones bound to VEGF165 were selected from the pIII phage display library. Based on the phage capture assay, the phage monoclone expressing peptide LSTSPHT exhibited the best affinity and specificity against VEGF165. Then, peptide V (with the peptide sequence of LSTSPHTGGGSC) was synthesized as VEGF165 capturer to develop an enzyme-linked chemiluminescence immunoassay (ELCLIA). Under the optimal conditions, the proposed ELCLIA method showed wide linear range (10–1000 pg mL−1) and lower limit of detection (5.7 pg mL−1). Moreover, the as-developed ELCLIA was capable of detecting VEGF165 in human serum samples accurately and reproducibly. Due to its good selectivity, stability and cost-effectiveness, the VEGF165-specific peptide is prospected as a novel biointerface in sensing and tumor metastasis related diagnosis and therapy.

A comparison of electrochemical performance between LiFe0.4Mn0.595Cr0.005PO4/C and LiMnPO4/C cathode materials was conducted in this paper. The cathode samples were synthesized by a nano-milling-assisted solid-state process using caramel as carbon sources. The prepared samples were investigated by XRD, SEM, TEM, energy-dispersive X-ray spectroscopy (EDAX), powder conductivity test (PCT), carbon-sulfur analysis, electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge cycling. The results showed that LiFe0.4Mn0.595Cr0.005PO4/C exhibited high specific capacity and high energy density. The initial discharge capacity of LiFe0.4Mn0.595Cr0.005PO4/C was 163.6 mAh g−1 at 0.1C (1C = 160 mA g−1), compared to 112.3 mAh g−1 for LiMnPO4/C. Moreover, the Fe/Cr-substituted sample showed good cycle stability and rate performance. The capacity retention of LiFe0.4Mn0.595Cr0.005PO4/C was 98.84 % over 100 charge-discharge cycles, while it was only 86.64 % for the pristine LiMnPO4/C. These results indicated that Fe/Cr substitution enhanced the electronic conductivity for the prepared sample and facilitated the Li+ diffusion in the structure. Furthermore, LiFe0.4Mn0.595Cr0.005PO4/C composite presented high energy density (606 Wh kg−1) and high power density (574 W kg−1), thus suggested great potential application in lithium ion batteries (LIBs).

Magnetic hierarchical flower-like Co3O4 spheres (Co3O4 nanoflowers) were facilely prepared via one-step surfactant-free and template-free wet chemical route at room temperature. The formation mechanism of Co3O4 nanoflowers was explored. The as-prepared Co3O4 nanoflowers exhibited excellent tetra-enzyme mimetic activities, including oxidase-like, peroxidase-like, catalase-like and superoxide dismutase (SOD)-like activity. The catalytic mechanism of the Co3O4 nanoflowers was studied in detail. The oxidase-like catalytic activity of Co3O4 nanoflowers was derived from the inherent oxygen vacancies of Co3O4, while the peroxidase-like catalytic activity originated from the •OH radical generated by hydrogen peroxide (H2O2). Only one specific enzyme mimics reaction with Co3O4 nanoflowers can be obtained by inhibiting specifically other nanozymes via varying pH, adding appropriate scavengers or selecting its specific substrate. Further, the steady-state kinetic and catalytic performance of the oxidase-, peroxidase- and catalase mimics of Co3O4 nanoflowers were studied. Based on the oxidase-like and peroxidase-like activities of Co3O4 nanoflowers, bifunctional colorimetric sensing platforms were constructed for the sensitive detection of acid phosphatase (ACP) with the linear range of 0.1–25 U L-1 and H2O2 with the linear range of 4–400 μM. Further, it is capable of detecting ACP in serum samples and H2O2 in water samples, respectively. Thus, the tetra-enzyme mimetic Co3O4 nanoflowers show broad prospects in the fields of biosensors, tumor therapy, environmental monitoring and biocatalysis.

The hierarchical porous carbon with high specific surface area was facilely synthesized by calcination of Enteromorpha prolifera (EP), a renewable ocean waste biomass. The resultant carbon exhibited bienzyme mimetic properties including oxidase-like and peroxidase-like activities, which can be regulated by varying carbonized temperature. The reaction mechanism of the oxidase-like activity of EP-based hierarchical porous carbon (EPC) contributes to singlet oxygen and superoxide anions generated during the reaction, while the peroxidase-like activity arises from hydroxyl radicals. Finally, a sensitive colorimetric biosensor for acid phosphatase was explored based on the oxidase-like activity, demonstrating a linear range of 0.5–15 U/L and the limit of detection (LOD) of 0.1 U/L (S/N = 3). A fluorescent biosensor for H2O2 was also developed with the linear range of 0.05–80 μM and a LOD of 0.017 μM (S/N = 3), based on OH produced with the peroxidase-like activity, which react with terephthalic acid to form 2-hydroxyterephthalic acid. Further, incorporated with glucose oxidase, fluorometric sensing of glucose was realized with the linear range of 0.05–10 mM and a LOD of 30 μM. The bi-enzyme mimics also exhibited high reproducibility and stability. Thus, this EPC can be promising candidates for broad applications in sensing, nanomedicine, industrial catalysis and environmental engineering.

There are opportunities for improvements to the efficiency and toxicity of widely used cancer chemotherapy agents such as doxorubicin (DOX·HCl) and 7-Ethyl-10-hydroxycamptothecin (SN38). We developed a safe and effective combination therapy by encapsulating DOX into micelles of a zwitterionic polymer prodrug, SN38 conjugate of poly (α-azide caprolactone-co-caprolactone)-b-poly (2-methacryloyloxyethyl phosphorylcholine [P(CL/CL-g-SN38)-b-PMPC)] which was described in our previous work. The polymer prodrug micelles displayed a higher loading capacity of DOX due to the π-π stacking effect between DOX and SN38 in comparison with the micelles self-assembled by prodrug's precursor, poly(α-azide caprolactone-co-caprolactone)-b-poly(2-methacryloyloxyethyl phosphorylcholine (P(ACL/CL)-b-PMPC). The DOX loaded prodrug micelles decelerated the release of DOX, and also prolonged its circulation. The micelles showed favorable cellular internalization by 4T1 cells. DOX loaded SN38 prodrug micelles displayed good in vitro anticancer effects owing to the synergistic action of doxorubicin and SN38 and were as effective as DOX·HCl, but with lower toxicity than DOX·HCl. Given the synergetic effects of free drug and polymer prodrug, this nanomedicine may offer a safe and effective drug delivery methodology for conventional drug formations.

A fluorimetric test strips-based strategy has been initially developed for probing trace cysteine (Cys) in hela cells using gold-silver (Au-Ag) nanospheres and metal-organic frameworks of ZIF-8. Bimetallic Au-Ag nanoclusters were first synthesized by the protein-templated biominerization and then harvested by a desolvation route to form Au-Ag nanospheres showing strong fluorescence that could be specifically quenched by Cys. The as-prepared nanospheres were coated onto test strips to be further shelled with ZIF-8 by using a vacuum-aided fast drying route with super-hydrophobic patterns. It was discovered that the so fabricated test strips could not only achieve uniform coatings of fluorescent nano-probes, but also the ZIF-8 shell-enabled improvement of fluorescence, environmental and storage stabilities. In addition to the evaluation of Cys in serum samples, the developed fluorimetric test strips can facilitate the direct detection of Cys in hela cells with the linear concentrations ranging from 0.0032 to 32.0 μM, thus promising for the point-of-care monitoring of low-level Cys for the clinical early diagnosis of some diseases like cancers. Besides, such a proposed protocol forthe fabrication of stable and uniform test strips using MOFs coatings and super-hydrophobic patterns may be tailored for designing various solid-state testing platforms for the extensive analysis applications.

Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010–10.0 μM (limit of detection of 0.50 nM) and 0.0032–32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability.

A high-throughput and sensitive fluorimetric analysis method has been developed with wettable microwells array for probing short-chain microRNAs (miRNAs) in blood using silver nanoclusters (AgNCs) with red fluorescence amplified and stabilized by metal organic frameworks (MOFs). Glass slides were first spotted with polyacrylic acid to form hydrophilic microdots and then patterned with hydrophobic hexadecyltrimethoxysilane, followed by etching the microdots to yield the microwells array. Furthermore, the DNA capture probes with silver-binding G sequences were covalently bound onto the functionalized microwells to hybridize with targeting miRNAs. Exonuclease I catalytic digestion was then conducted to remove any single-strand DNA probes unhybridized. Eventually, AgNCs were applied to specifically recognize the G sequences of DNA probes survived to be further coated with MOFs of zeolitic imidazolate framework (ZIF-8). Unexpectedly, the red fluorescence of AgNCs probes could be dramatically enhanced due to the "electron-donor effect" of nitrogen-containing ligands of ZIF-8 coatings, together with improved sensing stability. High detection sensitivity and reproducibility could thereby be expected for detecting miRNAs in the blood with the concentrations linearly ranging from 0.175 to 500 pM. Markedly different from the common sandwiched DNA detection methods, the developed fluorimetric strategy using AgNCs coated with MOFs and DNA probes designed with silver-recognizing sequences would be tailored for quantifying various kinds of short-chain miRNAs with low levels in the complicated blood media.

The power lithium ion battery has been widely used for its excellent performance, with the waste batteries increased yearly and causing environmental pollution and resource waste. The problem must be solved immediately. In this paper, through the “alkaline separation-roasting-acid leaching” process, spent lithium ion battery anode is handled so that to achieve the extraction of valuable metals in the anode. The results show positive active material can separate from the aluminum foil by means of the using of NaOH solution. Under the process of 700 ℃ high-temperature roasting for 2 h, active substances Li (NixCo1-x) O2 transform into NiO, CoO, etc., and it is conducive to subsequent acid leaching. After roasting, the acid leaching of active substance is conducted through respectively using hydrochloric acid and sulfuric acid. The leaching rate of Li, Ni, Co are 99.9, 99.5, 99.2% under the optimum conditions in hydrochloric acid system respectively: the concentration of the acid 2 mol/L, the ratio of solid-liquid 60 mg/ml, leaching temperature 90 ℃ and leaching time 50 min. In sulfuric acid system, the leaching rate of Li, Ni, Co are all closer to 100% under the optimum conditions: the concentration of the acid 2 mol/L, the S/L 75 mg/ml, leaching temperature 85 ℃ leaching time 50 min and volume ratio of hydrogen peroxide is 5%. Through the fitting calculation, acid leaching is applied to the nuclear reaction model and leaching of lithium nickel and cobalt are controlled by chemical reaction. Two kinds of acid system all have good results for metal extraction from waste lithium ion battery cathode material. Considering recycling cost and environmental impact, sulfuric acid system is better.

C22H43.33N2O3.67S, monoclinic, P21/c, a = 9.5273(1) Å, b = 14.8850(2) Å, c = 17.5820(2) Å, V = 2492.84(5) Å3, Z = 4, R gt(F) = 0.0526, wR ref(F2 ) = 0.1459, T = 296.

Alcohol solvents especially isopropanol were demonstrated for the first time to endow silver nanoclusters (AgNCs) in water with dramatically enhanced red fluorescence. More importantly, the specific iodide recognition capability of the AgNCs could thus be obtained towards a highly selective fluorimetric assay for detecting iodide ions in urine.

Based on organic semiconductor polymer MEH-PPV ridge waveguide, a new type of 1-D organic edge-emitting photonic crystal laser is proposed, which consists two perfect photonic crystal structures as a resonator to apply feedback and a defective photonic crystal as a mode selection component to suppress the multi-mode competition. It realized lasing at a wavelength of 618nm.

We experimentally demonstrate the lasing action of electrically pumped octagonal quasi-crystal microcavities formed in a layer of conjugated polymer poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) sandwiched between two electrodes. Lasing from a point-defect microcavity is observed at a wavelength of 606 nm with a narrow linewidth of 0.5 nm, limited by the spectrometer resolution. Due to the properties of the photonic bandgap and localization in photonic crystals, the threshold current for lasing is low at 0.8 mA. The ion injection in the luminescent polymer layer by focused ion beam (FIB) etching technology also contributes to enhancement of the carrier density as well as the mobility, resulting in an increase of MEH-PPV conductivity and a decrease of turn-on voltage.