A novel electrochemical sensing strategy for detecting hazardous 4-nitrophenol (4-NP) was constructed based on mesoporous carbon embedded with FeOx and TiO2 nanoparticles (denoted as FeOx/TiO2@mC ...nanocomposites) derived from the bimetallic Fe/Ti-based metal–organic framework at high temperature. The developed electrochemical sensor shows excellent sensitivity, good anti-interference ability, stability, and applicability toward 4-NP determination in environmental water samples.
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•Bimetallic Fe/Ti-based MOF derived mesoporous carbon embedded with FeOx and TiO2 nanoparticles.•A hierarchically micro/mesoporous FeOx/TiO2@mC-based electrochemical sensor was constructed.•Excellent sensitivity, selectivity, stability, and applicability for detecting 4-nitrophenol.
A series of composites comprising FeOx and TiO2 nanoparticles uniformly distributed throughout a mesoporous carbon matrix (hereafter denoted as FeOx/TiO2@mC nanocomposites) was synthesized by the direct pyrolysis of a bimetallic Fe/Ti-based metal–organic framework at high temperatures (500, 700, and 900 °C). It shows that the as-prepared FeOx/TiO2@mC nanocomposites exhibit large specific surface areas and hierarchically micro/mesoporous hybrid structures, further leading to high electron transfer rate. Combining the highly electrocatalytic activity of TiO2 and FeOx and the good charge-transfer capability of mesoporous carbon, the caused synergism enables the construction of novel and platforms for sensitively detecting 4-nitrophenol (4-NP). After the optimization of sensitive layers and detection conditions, FeOx/TiO2@mC700 (calcined at 700 °C) is found to exhibit high detection ability toward 4-NP owing to its excellent electrochemical performance and electrocatalytic activity. The FeOx/TiO2@mC700-based electrochemical sensor shows a low limit of detection of 0.183 μM (S/N = 3) within the linear range of 5–310 μM as determined using amperometry toward 4-NP. The proposed method also displays good anti-interference ability, stability, and applicability toward 4-NP determination in environmental water samples. All these results suggest that the components of the MOF-derived binary metal oxide/mesoporous carbon electrocatalyst can function as a novel electrocatalyst for more endeavors into the development of a promising sensing platform for hazardous compounds in the environment.
The plant height is an important trait in fruit tree. However, the molecular mechanism on dwarfism is still poorly understood. We found that colchicine-induced autotetraploid apple plants (Malus × ...domestica) exhibited a dwarf phenotype. The vertical length of cortical parenchyma cells was shorter in autotetraploids than in diploids, by observing paraffin sections. Hormone levels of indoleacetic acid (IAA) and brassinosteroid (BR) were significantly decreased in 3- and 5-year-old autotetraploid plants. Digital gene expression (DGE) analysis showed that the differentially expressed genes were mainly involved in IAA and BR pathways. microRNA390 was significantly upregulated according to microarray analysis. Exogenous application of IAA and BR promoted stem elongation of both apple plants grown in medium. The results show that dwarfing in autotetraploid apple plants is most likely regulated by IAA and BR. The dwarf phenotype of autotetraploid apple plants could be due to accumulation of miR390 after genome doubling, leading to upregulation of apple trans-acting short-interfering RNA 3 (MdTAS3) expression, which in turn downregulates the expression of MdARF3. Overall, this leads to partial interruption of the IAA and BR signal transduction pathway. Our study provides important insights into the molecular mechanisms underlying dwarfism in autopolyploid apple plants.
•Preparation of nanorod-like nanocomposite of three-dimensional reduced graphene oxide and polyaniline by an in situ chemical oxidative polymerization method (3D-rGO@PANI).•The presence of 3D-rGO ...within the nanocomposite further improves the specific surface area and electrochemical performance.•High sensitivity and selectivity toward Hg2+ within a concentration range from 0.1nM to 100nM with low detection limit of 0.035nM.
Nanorod-like nanocomposite of three-dimensional reduced graphene oxide and polyaniline (3D-rGO@PANI) was synthesized via an in situ chemical oxidative polymerization method and was then used as the sensitive layer of a DNA adsorbent for detecting Hg2+ in aqueous solution. Amino-group-rich 3D-rGO@PANI exhibited high affinity toward the immobilization of T-rich DNA strands, which preferred to bind with Hg2+ to form THg2+T coordination. Electrochemical impedance spectroscopy was applied to determine the difference in the electrochemical performances during Hg2+ detection. The results demonstrated that the electrochemical biosensor based on 3D-rGO@PANI nanocomposite showed high sensitivity and selectivity toward Hg2+ within a concentration range from 0.1nM to 100nM with low detection limit of 0.035nM. The proposed nanosensor could be applied for highly sensitive and selective determination of heavy metal ion in various environmental detections.
► Human PHYHD1A has the double-stranded β-helix fold and Fe(II) and cosubstrate binding residues characteristic of the 2-oxoglutarate dependent oxygenases. ► Human PHYHD1A catalyzes the conversion of ...2-oxoglutarate to succinate and CO2 in an iron-dependent manner. ► The PHYHD1 B and C isoforms are likely not active as 2OG oxygenases. ► PHYHD1 does not catalyze the hydroxylation of phytanoyl-CoA unlike its closest homologue PAHX.
Phytanoyl-CoA hydroxylase (PAHX) catalyzes an important step in the metabolism of the fatty acid side chain of chlorophyll. PHYHD1 exists in three isoforms and is the closest human homologue of PAHX. We show that like PAHX, the PHYHD1A but likely not the PHYHD1B/C isoforms, is a functional Fe(II) and 2-oxoglutarate (2OG) dependent oxygenase. Crystallographic and biochemical analyses reveal that PHYHD1A has the double-stranded β-helix fold and Fe(II) and cosubstrate binding residues characteristic of the 2-oxoglutarate dependent oxygenases and catalyzes the conversion of 2-oxoglutarate to succinate and CO2 in an iron-dependent manner. However, PHYHD1A did not couple 2OG turnover to the hydroxylation of acyl-coenzyme A derivatives that are substrates for PAHX, implying that it is not directly involved in phytanoyl coenzyme-A metabolism.
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•Single atomic Fe-N-C and Fe4N active sites embedded carbon nitride network.•High-efficiency adsorption and photocatalytic degradation of malachite green.•Active species of •O2− and ...•OH participated photocatalytic MG degradation.
A series of Fe-N-C single atom catalysts embedded within the carbon nitride network (Fe-N-C/CNx) were developed to effectively degrade a commonly used organic dye, Malachite green (MG). Fe-N-C/CNx catalysts were achieved by pyrolyzing the hybrid of polypyrrole (PPy) and Melamine–cyanuric acid complex (MCA) containing trace Fe3+ (Fe/PPy@MCA) at different temperatures. Given the structural change of polymeric networks and nitridation of Fe3+, the mesoporous Fe-N-C/CNx hybrids comprise multiple components, including Fe-N-C, Fe4N, and CNx species, which show enhanced photocatalytic performance toward MG by integrating the high catalytic ability of Fe components and efficient visible-light harvest of CNx network. Notably, the Fe-N-C/CNx-700 hybrid obtained at 700 °C exhibits the high removal efficiency of 92.1% toward MG under visible light, with good reproducibility and stability. The biotoxicity of degraded products was further investigated by antibacterial experiment and plant growth effect. This work provides new insights into the development of efficient photocatalysts of nanohybrids for treating organic dyes.
Cisplatin (CDDP) has been considered as one of the most effective anticancer drugs against cervical cancer, but the lack of selectivity of CDDP to tumor tissues often leads to serious toxic side ...effects. In this study, CDDP-incorporated Cy5.5-PEG-g-A-HA nanoparticles were prepared to endue CDDP the ability to selectively target tumors and fluorescence imaging in vivo. The nanoparticles exhibited a spherical shape with particle sizes between 216.4 and 281.5 nm and had a pH and Cl– concentration dependence on controlled and sustained CDDP release, which was favorable for nanoparticles to release more drugs at acidic tumor microenvironment. Cell biology experiments demonstrated that the nanoparticles had good biocompatibility and tumor targeting; the nanoparticles could selectively bind and internalize into HeLa cells and induce apoptosis, but lead to less cytotoxicity on NIH3T3 cells. What is more, the nanoparticles could be clearly fluorescent-imaged in vivo and showed an effective accumulation at the tumor site. Antitumor test in vivo displayed that the nanoparticles had good antitumor efficiency and low systemic toxicity which improved the life quality of mice. Hence, the CDDP-incorporated Cy5.5-PEG-g-A-HA nanoparticles were a potential delivery system for targeting delivery of CDDP against cervical cancer.
A novel bifunctional electrochemical aptasensor based on bimetallic NiCo Prussian blue analogue (NiCoPBA) nanocubes has been constructed for detecting carcino-embryonic antigen (CEA) and ...corresponding living cancer cells.
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•Novel bimetallic NiCoPBA with rich functionality, good biocompatibility and strong binding affinity toward aptamer.•Highly sensitive detection of carcino-embryonic antigen and H460 cancer cells.•NiCoPBA-based aptasensor exhibit high sensitivity and selectivity, good stability, and reproducibility.
A novel bifunctional electrochemical aptasensor based on bimetallic NiCo Prussian blue analogue (NiCoPBA) nanocubes has been constructed for detecting carcino-embryonic antigen (CEA) and corresponding living cancer cells. The NiCoPBA exhibits a regular cubic shape of 100 nm size, with fluorescence and excellent biocompatibility. In view of the intrinsic cavities, metallic coordination centers, rich CN groups, and π-π* interactions of NiCoPBA, the CEA-targeted aptamer strands can be strongly anchored on the surface of nanocubes. Given that the CEA cancer marker is overexpressed on the H460 cell surface of carcinomas, the developed NiCoPBA-based aptasensor not only can be employed to determine CEA in human serum via the formation of stable G-quadruplex between aptamer strands and CEA, but also can be utilized to directly detect cancer cells due to the strong binding force between CEA aptamer and cancer cell. The fabricated sensor shows superior sensing performance toward CEA compared with other reported CEA aptasensors, providing an extremely low limit of detection (LOD) of 0.74 fg mL−1 (1.62 fM) (S/N = 3) in a wide linear range of 1.0 fg mL−1 to 5.0 ng mL−1, as well as an LOD of 47 cells mL–1 for H460 cells. Thereby, the proposed aptasensor may be further used as a promising platform for detecting other cancer markers when anchoring different kinds of aptamers, with potential bifunctional applications in early diagnosis of tumor markers and cancer cells.
Nanomedicines are being developed to treat diverse diseases; however, inadvertent or unintended health effects have to be considered, especially for those targeting cancers. For cancers, occurrence ...of metastasis hints an advanced phase of cancer progression, and nanomedicines per se should be evaluated for their effects on existing metastatic tumors and triggering metastases. Graphene-based 2D nanomaterials, such as graphene oxide (GO), due to its unique characteristics, have been extensively studied for biomedical applications including cancer therapy. However, the potential effect of GO on metastasis has not been determined yet. Herein, we found that low-dose GO could induce significant morphological and structural changes of the cellular membrane within cancer cells, suggesting an epithelial–mesenchymal transition (EMT), with enhanced invasion/migration and the alterations of representative EMT indicators in GO-treated cells. These changes resulted in enhanced lung metastasis of cancer cells in various metastasis models. The mechanistic investigations unveiled that GO increased the protein levels of the TGF-β receptor, leading to a constitutively activated TGF-β-Smad2/3 signaling pathway that drives the EMT. Collectively, our findings enhance the understanding of the unintended side and detrimental effects of GO nanosheets in increasing the progression of metastatic tumors. Thus, the likelihood of pro-EMT effects upon low-dose GO exposure should be considered when developing GO nanomedicines.
•Ti3C2Tx@FePcQDs nanohybrid with mixed-valence states, multicomponent, extended π-systems for immobilization of cDNA.•Sensitively detecting miRNA-155.•High selectivity, good stability, excellent ...reproducibility, and practical applicability of Ti3C2Tx@FePcQDs-based aptasensor.
A promising nanocarrier of the complementary DNA (cDNA) toward miRNA-155 was synthesized on the basis of the nanohybrid type of Ti3C2Tx MXene nanosheets decorated using iron phthalocyanine quantum dots (FePc QDs) (denoted as Ti3C2Tx@FePcQDs) to construct a novel ultrasensitive impedimetric aptasensing system for microRNA-155 (miRNA-155). Owing to π–π* stacking interaction between Ti3C2Tx nanosheets and FePc QDs, the homogeneous nanostructure of the Ti3C2Tx@FePcQD nanohybrid that comprises mixed-valence states (Ti2+/Ti3+ and Fe2+/Fe3+), multicomponent (Ti-O and Ti-C), and various N-related groups was achieved. The constructed Ti3C2Tx@FePcQDs-based aptasensor displayed an ultrahigh sensitivity for detecting miRNA-155 with a low detection limit of 4.3 aM (S/N = 3) within the miRNA-155 concentration ranging from 0.01 fM to 10 pM. Compared with the individual component-based aptasensors and other reported miRNA-155 aptasensors, the proposed impedimetric aptasensing system exhibited substantial merits of a feasible preparation process, non-use of labels or electrochemical indicators, fast response time, and comprehensive sensing performances for detecting miRNA-155. This strategy for determining miRNAs can extensively be applied as the platform for anchoring other kinds of aptamers in detecting diverse targets, thus indicating its great potential application for the early diagnosis of cancer biomarkers.
Primary malignant melanoma of the duodenum is an unusual oncologic entity. Patients usually present the similar clinical symptoms like other common tumors in this site. And there are no specific ...radiological features either. The cases with only little melanin pigment or without notable melanin pigment are very misleading, especially in small biopsies or frozen sections. Definite diagnosis depends on both careful histologic examination and the use of proper immunohistochemical stains. Moreover, detailed history and thorough investigation should be made to exclude the preexistence or coexistence of a primary lesion elsewhere. Herein we report the case of a 60-year-old male patient with primary malignant melanoma of the duodenum, which was misdiagnosed as lymphoma or undifferentiated carcinoma in frozen consultation. The patient had achieved disease-free survival for more than 46 months without any evidence of recurrence after surgery.
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