Novel electrochemical sensing strategy for ultrasensitive detection of tetracycline based on porphyrin/metal phthalocyanine-covalent organic framework.

In this work, a novel two-dimensional semiconducting metal covalent organic framework (CuTAPc-TFPP-COF) was synthesized and used as biosensing platform to construct aptasensor for trace detection of tetracycline (TC). The CuTAPc-TFPP-COF integrates the highly conjugated structure, large specific surface area, high porosity, abundant nitrogen functional groups, excellent electrochemical activity, and strong bioaffinity for aptamers, providing abundant active sites to effectively anchor aptamer strands. As a result, the CuTAPc-TFPP-COF-based aptasensor shows high sensitivity for detecting TC via specific recognition between aptamer and TC to form Apt-TC complex. An ultralow detection limit of 59.6 fM is deduced from the electrochemical impedance spectroscopy within a wide linear range of 0.1-100000 pM for TC. The CuTAPc-TFPP-COF-based aptasensor also exhibits good selectivity, reproducibility, stability, regenerability, and excellent applicability for real river water, milk, and pork samples. Therefore, the CuTAPc-TFPP-COF-based aptasensor will be promising for detecting trace harmful antibiotics residues in environmental water and food samples.

TPN-COF@Fe-MIL-100 composite used as an electrochemical aptasensor for detection of trace tetracycline residues.

In this work, a metal-organic framework@covalent organic framework composite (TPN-COF@Fe-MIL-100) was prepared and used as a sensing material to construct an aptasensor for trace detection of tetracycline (TET). The TPN-COF@Fe-MIL-100 integrates a large surface area, porous structure, excellent electrochemical activity, rich chemical functionality, and strong bioaffinity for aptamers, providing abundant active sites to effectively anchor aptamer strands. As a result, the TPN-COF@Fe-MIL-100-based aptasensor shows high sensitivity for detecting TET via specific recognition between aptamer and TET to form G-quadruplex. An ultralow detection limit of 1.227 fg mL-1 is deduced from the electrochemical impedance spectroscopy within a wide linear range of 0.01-10000 pg mL-1 for TET. The TPN-COF@Fe-MIL-100-based aptasensor also exhibits good selectivity, reproducibility, stability, regenerability, and applicability for a real milk sample. Therefore, the TPN-COF@Fe-MIL-100-based aptasensor will be promising for detecting trace harmful antibiotics residues for food safety.

Capillary rise induced salt deterioration on ancient wall paintings at the Mogao Grottoes.

Salt deterioration has been found to be a major threat to wall paintings at culture heritage sites in arid areas along the Silk Road. However, the routes of water migration that cause the efflorescence have not been identified, and consequently, effective preservation measures have not been developed. Our microanalysis, by interrogating 93,727 individual particles collected in a Mogao cave in Dunhuang, China, revealed that capillary rise of water in the earthen plasters drives the deterioration of wall paintings. The vertical distribution of chloride and sulfate particles in the salt efflorescence and their morphologies implied a migration of salts through capillary rise and subsequent crystal growth under environmental conditions exerts sufficient pressure to cause surface decay and loss. These results indicate that blocking the water capillary rise under the porous structures is likely the most effective route to prevent rapid deterioration of the ancient wall paintings. These salt transport and deterioration mechanisms in an arid environment, suggests that a wide range of management strategies and protective measures could be developed to effectively preserve heritage sites in arid regions, especially along the Silk Road.

Construction of MOF@COF composite-based electrochemical aptasensor for detection of Staphylococcus aureus.

In this work, a biological metal-organic framework@conductive covalent organic framework composite (bio-MOF@con-COF, denoted as Zn-Glu@PTBD-COF, here, Glu indicates L-glutamic acid, PT indicates 1,10-phenanthroline-2,9-dicarbaldehyde, and BD indicates benzene-1,4-diamine) was prepared and used as sensing material to fabricate aptasensor for trace detection of Staphylococcus aureus (SA). The Zn-Glu@PTBD-COF integrates the mesoporous structure and abundant defects of the MOF framework, the excellent conductivity of the COF framework, and high stability of the composite, providing abundant active sites to effectively anchor aptamers. As a result, the Zn-Glu@PTBD-COF-based aptasensor shows high sensitivity to detect SA via specific recognition between aptamer and SA, as well as the formation of aptamer-SA complex. Low detection limits of 2.0 and 1.0 CFU·mL-1 are deduced from the electrochemical impedance spectroscopy and differential pulse voltammetry within a wide linear range of 10-108 CFU·mL-1 for SA, respectively. The Zn-Glu@PTBD-COF-based aptasensor also shows good selectivity, reproducibility, stability, regenerability, and applicability for real milk and honey samples. Therefore, the Zn-Glu@PTBD-COF-based aptasensor will be promising for fast screening of foodborne bacteria in food service industry. Zn-Glu@PTBD-COF composite was prepared and used as sensing material to fabricate aptasensor for trace detection of Staphylococcus aureus (SA). Low detection limits of 2.0 and 1.0 CFU·mL-1 are deduced from the electrochemical impedance spectroscopy and differential pulse voltammetry within a wide linear range of 10-108 CFU·mL-1 for SA, respectively. The Zn-Glu@PTBD-COF-based aptasensor also shows good selectivity, reproducibility, stability, regenerability, and applicability for real milk and honey samples.

Novel aptasensing strategy for efficiently quantitative analyzing Staphylococcus aureus based on defective copper-based metal-organic framework.

We have proposed a novel electrochemical aptasensing strategy for efficiently detecting staphylococcus aureus (S. aureus) based on copper-based metal-organic framework encapsulated with plenty of Cu2O nanocrystals (represented by ML-Cu2O@Cu-MOF) synthesized using the mixed ligands of diphenylethyne-3,3',5,5'-tetracarboxylic acid, 1,3,5-benzenetricarboxylic acid, and terephthalic acid. The ML-Cu2O@Cu-MOF nanospheres comprised multiple Cu valence states (Cu0/Cu+/Cu2+) and Cu2O nanocrystals, possessed defect-rich crystal structure, high anchoring ability toward aptamer and boosted electrical conductivity. The gained ML-Cu2O@Cu-MOF-based biosensor exhibited lower limit of detection toward S. aureus, as low as 2.0 and 1.6 CFU mL-1 within the S. aureus concentration from 10 to 1 × 108 CFU mL-1 obtained by electrochemical impedance spectroscopy and differential pulse voltammetry techniques, respectively. Additionally, the developed aptasensor also demonstrated high superior stability, excellent reproducibility, acceptable regeneration ability, and wide practicality. The present work can give rise to an alternative aptasensing strategy for analyzing foodborne bacteria or other food containments and ensuring food safety assessment.

Impedimetric aptasensor based on zirconium-cobalt metal-organic framework for detection of carcinoembryonic antigen.

A zirconium-cobalt metal-organic framework (ZrCo-MOF) was prepared and used as sensing material to fabricate an aptasensor for trace detection of carcinoembryonic antigen (CEA). The ZrCo-MOF integrates the 3D porous structure and abundant defects of the MOF framework, the catalytic activity and inherent redox behavior of Co, and high stability of Zr-MOF, providing abundant active sites to effectively anchor aptamers. As a result, the ZrCo-MOF-based aptasensor shows high sensitivity to detect CEA via specific recognition between aptamer and CEA, as well as the formation of aptamer-CEA complex. A detection limit of 0.35 fg·mL-1 was deduced from the electrochemical impedance spectroscopy within a wide linear range of 0.001-100 pg·mL-1 for CEA, which was substantially lower than those of most reported CEA biosensors. The ZrCo-MOF-based aptasensor also shows good selectivity, reproducibility, regenerability, stability, and applicability for human serum sample. Therefore, the developed ZrCo-MOF-based aptasensor will be promising for ultrasensitive detection of biomarkers and the early diagnosis of cancer. This work presents a novel electrochemical aptasensor for the trace detection of carcinoembryonic antigen (CEA) based on a zirconium-cobalt metal-organic framework (ZrCo-MOF), which shows low detection limit of 0.35 fg·mL-1, high selectivity as well as good reproducibility, regenerability, stability, and applicability. The result provides a promising approach to detect the cancer biomarkers in an early age.

Morphology and mineralogical composition of sandblasting dust particles from the Taklimakan Desert.

The physicochemical characteristics of dust particles from the Taklimakan Desert are the fundamental basis for the assessment of particle variation during their long-distance transport and the subsequent environmental effects. In this study, 43,222 individual sandblasting dust particles, which were mobilised using a chamber with surface soils of sand dunes and Gobi (the two types of surfaces constituting the desert) were analysed to statistically quantify the shape and mineralogical composition of dust particles from the desert. The mode of the number-size distribution of particles from the sand dunes was 0.5-0.7 µm and that of particles from Gobi soils was approximately 1.0 µm. In contrast, the distributions of particle number fractions versus shape factors such as aspect ratio and roundness were similar, despite the irregular shape of the particles. Clay mineral particles were most frequently composed of chlorite and kaolinite, accounting for 66.74 ± 12.08% of the particles from both types of soils. Quartz and feldspar particles accounted for 9.57 ± 4.52% and 2.84 ± 1.28%, respectively. The mineralogical composition of particles smaller than 1.0 µm, in both soil types, was dominated by chlorite (Al-Si-O-Mg), kaolinite (Ai-Si-O), and quartz (SiO). Gypsum (CaS) and halite (NaCl) were the major salt components in particles from both soil types. Gypsum-containing particles existed in a wide size range and occupied 3.42%-8.98% of the particles from Gobi soils and 0.27%-2.18% of the particles from sand dunes. Most gypsum-containing particles were mixed with Si-containing minerals in the form of silicate or aluminosilicate; the remaining gypsum-containing particles were gypsum crystals or mixtures of gypsum and Ca-containing minerals. These results provide a comprehensive statistical profile of dust particles released by the sandblasting process from the Taklimakan Desert to the atmosphere.

Direct growth of two-dimensional phthalocyanine-based COF on Cu-MOF to construct a photoelectrochemical-electrochemical dual-mode biosensing platform for high-efficiency determination of Cr(III).

A photoelectrochemical (PEC)-electrochemical (EC) dual-mode biosensing strategy based on COF@MOF heterostructure was developed for efficiently analyzing Cr(III) ions. A two-dimensional phthalocyanine-based COF (CoPc-PT-COF) was in situ grown on a Cu-based MOF (Cu-MOF) substrate via covalent binding between carboxyl groups in Cu-MOF and amino groups in CoPc-PT-COF (denoted as CoPc-PT-COF@Cu-MOF). The coexistence of both phthalocyanine and bipyridine in CoPc-PT-COF@Cu-MOF affords the outperformed electro- and photo-activities, thus serving as a photoelectric beacon with favorable energy-band configuration and amplified electrochemical response. Due to the high porosity and rich functionality of the obtained heterostructure, the DNA strands can be tightly anchored over CoPc-PT-COF@Cu-MOF via diverse interactions. Thanks to the specific recognition between DNA strands and Cr3+ ions, the CoPc-PT-COF@Cu-MOF-based biosensor can be used to determine Cr3+ ions in an aqueous environment by PEC-EC mode. The gained biosensor shows an extremely low limit of detection (LOD) of 14.5 fM (for PEC) and 22.9 fM (for EC) within the Cr3+ concentration range from 0.1 pM to 100 nM, along with high selectivity, good reproducibility and stability. Moreover, this novel biosensor exhibits acceptable applicability for analyzing the trace Cr3+ from diverse samples (e.g., river and tap water). As a result, this work provides new insights into the construction of a high-efficiency PEC-EC dual-mode biosensor for detecting heavy metal ions from complex environments.

Novel impedimetric sensing strategy for detecting ochratoxin A based on NH2-MIL-101(Fe) metal-organic framework doped with cobalt phthalocyanine nanoparticles.

Iron-based metal-organic framework, NH2-MIL-101(Fe), was doped with different dosages of cobalt phthalocyanine nanoparticles (CoPc) to synthesize a series of NH2-MIL-101(Fe)@CoPc nanocomposites. The NH2-MIL-101(Fe)@CoPc nanocomposites were then employed to construct novel impedimetric aptasensors for the detection of ochratoxin A (OTA). Combining the intrinsic advantages of NH2-MIL-101(Fe) (highly porous structure and excellently electrochemical activity) and CoPc (good physiochemical stability and strong bioaffinity), the NH2-MIL-101(Fe)@CoPc nanocomposites show promising properties, which are beneficial for immobilizing OTA-targeted aptamer strands. Amongst, the developed impedimetric aptasensor based on NH2-MIL-101(Fe)@CoPc6:1, prepared using the mass ratio of NH2-MIL-101(Fe):CoPc of 6:1, exhibits the best amplified electrochemical signal and highest sensitivity for detecting OTA. The detection limitation is 0.063 fg·mL-1 within the OTA concentration of 0.0001-100 pg·mL-1, accompanying with high selectivity, good reproducibility and stability, acceptable regenerability, and wide applicability in diverse real samples. Consequently, the proposed sensing strategy can be applied for detecting OTA to cope with food safety.

Two-dimensional triazine-based porous framework as a novel metal-free bifunctional electrocatalyst for zinc-air batty.

A metal-free carbon catalyst, melem-cyanuric acid complex (MCAC), was prepared by hydrogen bonding assembly and further explored as a novel bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The proposed MCAC network presented nanosheet-like structure, nitrogen-rich, and large specific surface area, which are close to the natures of graphitic carbon nitride (g-C3N4) and N-doped reduced graphene oxide (N-rGO), but giving much more defect active sites and regular framework structure. Compared with the g-C3N4, N-rGO and other reported carbon-nitride electrocatalysts, the MCAC nanosheets exhibited a lower overpotential of 1.45 V at a current density of 10 mA cm-2 for OER, along with a higher half-potential of 0.8 V and larger limit current density of -6.0 mA cm-2 for ORR. Density functional theory calculation revealed that the melem N atoms bonded with cyanurate greatly enhanced the OER activity by increasing the interaction between catalysts and intermediates. Furthermore, as a metal-free electrocatalyst, MCAC displayed superior reversible oxygen electrocatalytic activity, giving a small overpotential difference (0.76 V). The rechargeable zinc-air battery with MCAC as the air electrode in a two-electrode configuration showed a high open-circuit potential of 1.383 V and a specific capacity of 613.5 mA h gZn-1 at 10 mA cm-2. This work opens up a new avenue to develop advanced porous solids as metal-free electrocatalysts for the energy storage and conversion applications.

Quantification of EGFR and EGFR-overexpressed cancer cells based on carbon dots@bimetallic CuCo Prussian blue analogue.

A new bimetallic CuCo Prussian blue analogue (CuCo PBA) loaded with carbon dots (CDs) was prepared (represented by CD@CuCoPBA) and developed as a scaffold for anchoring the epidermal growth factor receptor (EGFR) aptamer to detect EGFR and living EGFR-overexpressed cancer cells. The basic characterizations revealed CuCo PBA exhibited nanocube shape and still remained its nanostructure and physical/chemical properties after coupling with large amounts of CDs. As compared with the pristine CuCo PBA, the CD@CuCoPBA displayed good electrochemical activity, strong binding interaction toward aptamer, and high stability of aptamer-EGFR G-quadruplex in aqueous solution. As such, the results of electrochemical impedance spectroscopy measurements indicated that the CD@CuCoPBA-based aptasensor displayed an ultra-low detection limit toward EGFR (0.42 fg mL-1) and living EGFR-overexpressed MCF-7 cancer cells (80 cell per mL), as well as high selectivity, good reproducibility, high stability, repeatability, and acceptable applicability. Consequently, the constructed CD@CuCoPBA-based aptasensor can be extended to be a promising universal method for early diagnosis of cancers.

A γ-cyclodextrin-based metal-organic framework embedded with graphene quantum dots and modified with PEGMA via SI-ATRP for anticancer drug delivery and therapy.

The γ-cyclodextrin-based metal-organic framework (γ-CD-MOF) composite was designed and prepared toward targeted anticancer drug delivery and cancer therapy. Large amounts of graphene quantum dots (GQDs) were embedded in the γ-CD-MOF matrix (denoted as GQDs@γ-CD-MOF) to endow the γ-CD-MOF with strong fluorescence, which was then modified by pH responsive poly(ethyleneglycol)dimethacrylate (PEGMA) through surface initiated atom transfer radical polymerization (SI-ATRP) to fabricate the PEGMA@GQDs@γ-CD-MOF composite. Then, the cancer cell-targeted probe was obtained by immobilizing the AS1411 aptamer over it (denoted as AS1411@PEGMA@GQDs@γ-CD-MOF) and it exhibits pH-responsive release function and excellent targeting ability. Large amounts of antitumour drug, doxorubicin hydrochloride (DOX), could be encapsulated within this composite due to the chemical-rich functionality, and the resultant pH-responsive DOX delivery system (denoted as DOX/AS1411@PEGMA@GQDs@γ-CD-MOF) displayed a higher DOX loading of 89.1% with sustained release than the pristine γ-CD-MOF and GQDs@γ-CD-MOF. The targeting specificity investigation revealed that this DOX delivery system was effectively internalized via receptor mediated endocytosis with high selectivity. The in vivo antitumour study with tumour-bearing mice illustrated that the tumour growth can be effectively suppressed and partially ablated with negligible side effects after treatments. Therefore, the proposed AS1411@PEGMA@GQD@γ-CD-MOF composite is promising for effective DOX delivery and tumour growth inhibition both in vitro and in vivo, showing great potential for anticancer therapy.

Construction of Tb-MOF-on-Fe-MOF conjugate as a novel platform for ultrasensitive detection of carbohydrate antigen 125 and living cancer cells.

Combining different metal-organic frameworks (MOFs) into a conjugate material can integrate the properties of each MOF component and further lead to emergent properties from the synergistic heterostructured units. In this work, two kinds of bimetallic TbFe-MOFs have been designed by MOF-on-MOF strategy and utilized as a platform for anchoring carbohydrate antigen 125 (CA125) aptamer to detect CA125 and living michigan cancer foundation-7 (MCF-7) cells. Although the integrated MOF-on-MOF architectures show similar chemical and structural features to that of the top layer, the Fe-MOF-on-Tb-MOF and Tb-MOF-on-Fe-MOF have different surface nanostructures to their parent MOFs. The developed aptasensor based on Tb-MOF-on-Fe-MOF displays higher stability of the formed G-quadruplex between aptamer and CA125 than that based on Fe-MOF-on-Tb-MOF, owing to stronger immobilization behavior of the aptamer for the Tb-MOF-on-Fe-MOF composite. The developed aptasensor provides an extremely low detection limit of 58 µU·mL-1 towards CA125 within a wide linear range from 100 µU·mL-1 to 200 U·mL-1, which is significantly lower than those of all reported sensors. This aptasensor also has high selectivity, good stability, acceptable reproducibility, and excellent applicability in human serum. Moreover, the Tb-MOF-on-Fe-MOF nanoarchitecture demonstrates superior biocompatibility and good endocytosis. As a result, the developed aptasensor illustrates high sensitivity for detection of MCF-7 cells with an extremely low detection limit of 19 cell·mL-1. Therefore, the proposed aptasensor based on Tb-MOF-on-Fe-MOF exhibits great potentials for early diagnosis of tumors.

Bimetallic cerium and ferric oxides nanoparticles embedded within mesoporous carbon matrix: Electrochemical immunosensor for sensitive detection of carbohydrate antigen 19-9.

A label-free electrochemical immunosensor was successfully developed for sensitively detecting carbohydrate antigen 19-9 (CA19-9) as a cancer marker. To achieve this, a series of bimetallic cerium and ferric oxide nanoparticles embedded within the mesoporous carbon matrix (represented by CeO2/FeOx@mC) was obtained from the bimetallic CeFe-based metal organic framework (CeFe-MOF) by calcination at different high temperatures. The formed CeO2 or FeOx nanoparticles were uniformly distributed within the highly graphitized mesoporous carbon matrix at the calcination temperature of 500 °C (represented by CeO2/FeOx@mC500). However, the obtained nanoparticles were aggregated into large size when calcined at the temperatures of 700 and 900 °C. The CA 19-9 antibody can be anchored to the CeO2/FeOx@mC network through chemical absorption between carboxylic groups of antibody and CeO2 or FeOx by ester-like bridging. The CeO2/FeOx@mC500-based immunosensor displayed superior sensing performance to the pristine CeFe-MOF, CeO2/FeOx@mC700- and CeO2/FeOx@mC900-based ones. Electrochemical impedance spectroscopy results showed that the developed immunosensor exhibited an extremely low detection limit of 10 µU·mL-1 (S/N = 3) within a wide range from 0.1 mU·mL-1 to 10 U·mL-1 toward CA 19-9. It also illustrated excellent specificity, good reproducibility and stability, and acceptable application analysis in the human serum solution which was diluted 100-fold with 0.01 M PBS solution (pH 7.4) and spiked with different amounts of CA19-9. Consequently, the proposed electrochemical immunosensor is capable enough of determining CA 19-9 in clinical diagnostics.

Novel nanoarchitecture of Co-MOF-on-TPN-COF hybrid: Ultralowly sensitive bioplatform of electrochemical aptasensor toward ampicillin.

Owning to the misuse of the antibiotics in animal husbandry and agriculture, it is highly urgent to determine the quantification of antibiotics in biological systems by the simple, sensitive, and fast method. In this work, a novel nanoarchitecture of Co-based metal-organic frameworks (Co-MOF) and terephthalonitrile-based covalent organic framework (TPN-COF) was synthesized (represented by Co-MOF@TPN-COF), followed by the exploitation as the bioplatform of non-label aptasensor for detecting the most frequently used ß-lactam antibiotics, ampicillin (AMP). The new porous hybrid material of Co-MOF@TPN-COF was synthesized by adding the as-prepared TPN-COF into the Co-MOF preparation system. The multilayered Co-MOF@TPN-COF nanosheets exhibit a high specific surface area (52.64 m2 g-1), nitrogen-rich groups and excellent electrochemical activity. As a result, large amounts of aptamer strands can be bound over the Co-MOF@TPN-COF nanosheets owning to the strong π-π stacking and hydrogen bonds. When detecting AMP by the electrochemical impedance spectroscopy, the fabricated Co-MOF@TPN-COF-based aptasensor exhibits an ultra-low detection limit of 0.217 fg mL-1 within the AMP concentration from 1.0 fg mL-1 to 2.0 ng mL-1, which was superior to those previously reported in literatures. In addition, this proposed aptasensor also shows high selectivity, good reproducibility and stability, acceptable regenerability, and favorable applicability in human serum, river water and milk. Therefore, the proposed Co-MOF@TPN-COF-based aptasensor has a great promise to be applied as a powerful tool in the fields of food safety.

Two-dimensional porphyrin-based covalent organic framework: A novel platform for sensitive epidermal growth factor receptor and living cancer cell detection.

A porphyrin-based covalent organic framework (denoted as p-COF) was synthesized by a simple oil-bath method and exploited as a novel sensing layer for immobilizing epidermal growth factor receptor (EGFR)-targeting aptamer strands to detect trace EGFR and living michigan cancer foundation-7 (MCF-7) cells for the first time. p-COF presented a nanosheet-like structure, large cavities, rich nitrogen-bearing groups, high electrochemical activity, excellent bioaffinity, low toxicity, and good stability in aqueous solution; the microstructural features of this material enabled strong immobilization of the aptamer strands. Interactions between the aptamer strands and EGFR significantly changed the electrochemical signals of the modified electrode due to the formation of an aptamer-EGFR complex. The p-COF-based aptasensor exhibited an extremely low detection limit (LOD) of 5.64 fg·mL-1 obtained from differential pulse voltammetry and 7.54 fg·mL-1 originated from electrochemical impedance spectroscopy with a broad linear detection range of 0.05-100 pg·mL-1 of the EGFR concentration. When detecting living MCF-7 cells, the p-COF-based aptasensor showed an LOD of 61 cell·mL-1 with a linear detection range of 500 × 105 cell·mL-1. The fabricated aptasensor exhibited high selectivity, good stability, reproducibility, acceptable recyclability, and favorable applicability in human serum samples. We believe that the developed p-COF-based aptasensor is a potential candidate for the sensitive detection of target cancer markers or living cells.

Tailoring the dimensionality of carbon nanostructures as highly electrochemical supports for detection of carcinoembryonic antigens.

Partially- and fully-unzipped nitrogen-doped carbon nanotubes (NCNTs) were prepared by unzipping pristine NCNTs and three carbon nanostructures were applied to support Au nanoparticles (AuNPs) to form nanocomposites (Au/NCNTs, Au/PU-NCNTs, and Au/FU-NCNTs). The electrochemical behavior and the electrocatalytic activities of the nanocomposite-modified electrodes were examined. The oxygen functional groups, doped N content, and AuNP loaded concentrations are dependent on the unzipping-degree and then affect the electrochemical response and electrocatalytic performance of the electrodes. Besides, the three nanocomposites were also used for the immobilization of carcinoembryonic antigen (CEA) aptamer strands and applied for the detection of CEA. The Au/FU-NCNTs possess the optimal electrocatalytic activity and biosensing performance for the biomolecules and CEA, which is attributed to the maximum loaded AuNPs, the largest specific surface areas and the most active sites. The Au/FU-NCNT-based electrochemical aptasensor exhibits high sensitivity with a low detection limit of 6.84 pg mL-1 within a broad linear range of CEA concentration from 0.01 to 10 ng mL-1. All of these results indicate that the Au/FU-NCNTs may be a potential support for construction of aptasensors with high electrochemical effect and can be employed in the fields of biosensing or biomedical diagnosis.

Core-Shell Heterostructured CuFe@FeFe Prussian Blue Analogue Coupling with Silver Nanoclusters via a One-Step Bioinspired Approach: Efficiently Nonlabeled Aptasensor for Detection of Bleomycin in Various Aqueous Environments.

We synthesized novel core-shell heterostructured Prussian blue analogue (PBA) nanospheres coupled with silver nanoclusters (AgNCs) via a one-step bioinspired approach and further exploited these as aptasensors for the detection of a trace antibiotic, bleomycin (BLM). Using FeFe Prussian blue (FeFe PB) as the core, a bimetallic CuFe@FeFe PBA layer was prepared by coupling with AgNCs synthesized by taking the BLM-targeted aptamer as a template (denoted by AgNCs/Apt@CuFe@FeFe). The coupling of AgNCs/Apt via a one-step bioinspired approach not only can improve the sensing performance of CuFe@FeFe-based aptasensors but also can shorten the aptasensor fabrication procedure. Due to the strong coordination interaction between abundant Fe(II) ions contained in CuFe@FeFe PBA nanospheres and BLM (represented by Fe(II)·BLM), the Fe(II)·BLM complex formed enables aptamer strands to undergo an irreversible cleavage event that can result in a significant change in electrochemical activity. Electrochemical results displayed that both CuFe@FeFe- and AgNCs/Apt@CuFe@FeFe-based aptasensors exhibited high sensitivity and selectivity, good stability and reproducibility, and acceptable applicability toward BLM. In comparison with the pristine CuFe@FeFe-based aptasensor (limit of detection (LOD) = 0.49 fg mL-1 within the BLM concentration from 1.0 to 2.0 ng mL-1), the as-prepared AgNCs/Apt@CuFe@FeFe-based aptasensor gave a extremely lower LOD value of 0.0082 fg mL-1 within a relatively narrow BLM concentration range (0.01 fg mL-1 to 0.1 pg mL-1). The proposed method can broaden the application of PBA nanomaterials in food safety and biosensing fields and provides a potential determination method for rapidly detecting BLM in various aqueous environments.

Solution-Plasma-Assisted Bimetallic Oxide Alloy Nanoparticles of Pt and Pd Embedded within Two-Dimensional Ti3C2T x Nanosheets as Highly Active Electrocatalysts for Overall Water Splitting.

Exploiting high-efficiency and low-cost bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has been actively encouraged because of their potential applications in the field of clean energy. In this paper, we reported a novel electrocatalyst based on an exfoliated two-dimensional (2D) MXene (Ti3C2T x) loaded with bimetallic oxide alloy nanoparticles (NPs) of Pt and Pd (represented by PtO aPdO bNPs@Ti3C2T x), which was synthesized via solution plasma (SP) modification. The prepared materials were then utilized as highly efficient bifunctional electrocatalysts toward the HER and OER in alkaline solution. At a high plasma input power (200 W), bimetallic oxide alloy nanoparticles of Pt and Pd or nanoclusters with different metallic valence states were deposited onto the Ti3C2T x nanosheets. Because of the synergism of the noble-metal NPs and the Ti3C2T x nanosheets, the electrocatalytic results revealed that the as-prepared PtO aPdO bNPs@Ti3C2T x nanosheets under the plasma input power of 200 W for 3 min only required a low overpotential to attain 10 mA cm-2 for the HER (-26.5 mV) in 0.5 M H2SO4 solution and OER (1.54 V) in 0.1 M KOH solution. Moreover, water electrolysis using this catalyst achieved a water splitting current density of 10 mA cm-2 at a low cell voltage of 1.53 V in 1.0 M KOH solution. These results suggested that the hybridization of the extremely low usage of PtO a/PdO b NPs (1.07 µg cm-2) and Ti3C2T x nanosheets by SP will expand the applications of other clean energy reactions to achieve sustainable energy.

Chemical structure of hollow carbon spheres and polyaniline nanocomposite.

In this data article, the chemical data of hollow carbon spheres and polyaniline (HCS@PANI) nanocomposite are presented for the research article entitled "Novel electrochemical biosensor based on core-shell nanostructured composite of hollow carbon spheres and polyaniline for sensitively detecting malathion" (He et al., 2018) [1]. The data includes chemical structure and components obtained by Raman spectra, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption and desorption isotherms.