Curettage combined with decompression for the treatment of ameloblastoma in children: report of two cases.

BACKGROUND: Ameloblastoma (AM) is the most common benign odontogenic tumor, which is more often detected in the mandible than maxilla, especially the mandibular body and mandibular angle. Pediatric AM is a rare disease, especially in patients aged 10 and younger. Compared with the mainstream osteotomy and reconstructive surgery for adult ameloblastoma, there is more room for discussion in the treatment of pediatric ameloblastoma. The postoperative functional and psychological influence can not be ignored. Especially for children in the period of growth and development, an osteotomy is often challenging to be accepted by their parents. We report two patients with ameloblastoma under 10 years old who are treated with curettage and fenestration, which is a beneficial method for children with ameloblastoma. CASE PRESENTATION: We present two cases of classic ameloblastoma in children. We describe in detail the patients' characteristics, treatment processes, and follow-up result. The bone formation and reconstruction in the lesion area after fenestration decompression and curettage are recorded at every clinic review. The surgical details and principles of curettage and decompression are also described and discussed. The two patients have good bone shape recovery and no recurrence. CONCLUSIONS: Children are in the growth and development period and possess an extremely strong ability of bone formation and reconstruction. Based on the principles of minimally invasive and functional preservation, we believe that curettage combined with decompression can be the first choice for treating AM in children, especially for mandibular lesions.

Yolk shell structured YS-Si@N-doped carbon derived from covalent organic frameworks for enhanced lithium storage.

Silicon (Si) has ultra-high theoretical capacity (4200 mAh g-1) and accordingly is widely studied as anode materials for lithium-ion batteries (LIBs). However, its huge volume expansion during charging/discharging is a fatal challenge. The preparation of Si-based composite materials with yolk shell structure is the key to solving the Si volume expansion. Here, N-doped carbon-coated Si nanoparticles (SiNPs) nanocomposites (YS-Si@NC-60) with yolk shell structure derived from covalent organic frameworks (COFs) was prepared. N-doped carbon shells derived from COFs not only maintain the well-ordered nanosized pores of COFs, which facilitates the transport of Li+ to contact with internal SiNPs, but also provide more extra active sites for Li+ storage. Most importantly, the internal void can effectively alleviate the damage effect of SiNPs volume expansion. The obtained YS-Si@NC-60 as a LIBs anode show high cyclic stability and Li+ storage performances. At 0.1 A g-1, the capacity is 1446 mAh g-1 after 110 cycles, and initial coulomb efficiency is as high as 82.2 %. The excellent performance can be attributed to the unique yolk shell structure. This simple and template-free strategy provides a new idea for preparing Si-C nanocomposites with yolk shell structure.

A "turn-on" fluorescent sensor based on three-component covalent organic framework for trace water detection.

Trace amount of H2O is difficult to eliminate in laboratory environments and chemical industries as impurities. In some chemical reactions, trace amount of H2O can alter final reaction products, yield, and selectivity. So, the detection of trace H2O is very important. Herein, a series of TFPT[X]-BMTH- covalent organic frameworks (COFs) (X = 0, 33, 50, 67, 100 %) with intramolecular charge transfer effect (ICT) and aggregate-induced emission (AIE) characteristics were synthesized by amino-aldehyde condensation reaction between 2,5-bis(2-methoxyethoxy)terephthalohydrazide (BMTH)/ 1,3,5-tris(p-formylphenyl)benzene (TFPB) and 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TFPT). By changing TFPT' content in TFPT[X]-BMTH-COFs, the ICT and AIE of TFPT[X]-BMTH-COFs can be controlled, and accordingly the response to trace H2O can be adjusted. A H2O sensor based on TFPT[67]-BMTH-COF with a wide linear range from 0 wt% to 0.5 wt% was developed and the detection limit was 0.00007 wt%. In addition, a portable fluorescent test paper based on TFPT[67]-BMTH-COF for visual detection of trace H2O in honey samples and salt was constructed. This work has important guiding significance for the development of fluorescent probes for the visual detection of trace water.

Rare Occipital Artery Pseudoaneurysm After Radical Neck Dissection.

Pseudoaneurysm formation in the occipital artery, post radical neck dissection, leading to a bulging mass, is a rare but potentially fatal occurrence. The authors treated a patient with pseudoaneurysm of occipital artery, post radical neck dissection, presenting with pain and swelling after 17 days of surgery. A pseudoaneurysm involving occipital artery was revealed by digital subtraction angiography and treated by endovascular micro-coil embolization.

Immunosensing of neuron-specific enolase based on signal amplification strategies via catalysis of ascorbic acid by heteropolysate COF.

In view of the importance of quantification of neuron-specific enolase (NSE), an electrochemical NSE immunosensor was developed. The sandwich voltammetric immunosensor utilized vinyl-functionalized crystalline covalent organic framework (COFTAPT-Dva) modified electrode to load lots of Ab1 via thiol-ene "click" reaction as matrix. A crystalline cationic EB-COF:Br was used to load Au nanoparticles (AuNPs) and H3[PMo12O40] (PMo12) as immunoprobe. The AuNPs with the size of about 30 nm were firstly grown on EB-COF:Br and then a large number of electroactive PMo12 were uniformly assembled on AuNPs/EB-COF:Br via ion exchanging reaction. The AuNPs not only facilitated the bonding of Ab2 based on Au-S bond, but also improved performance of Ab2/AuNPs/EB-COF:PMo12 immunoprobe. The sensitivity of sandwich electrochemical immunosensor could be primarily amplified based on loaded abundant PMo12. Secondary sensitivity amplification of immunosensor could be achieved by using PMo12 to catalyze ascorbic acid. The linear range of sandwich voltammetric immunosensor based on current change of differential pulse voltammetry is 500 ± 36 fg mL-1 - 100 ± 8 ng mL-1. Thanks to the dual sensitivity amplification strategy, the sensitivity is as high as 54.06 ± 3.2 µA cm-2/lg(cNSE/ng mL-1), and the detection limit is as low as 166 ± 10.8 fg mL-1. It proves that it is completely feasible to amplify sensitivity of sandwich voltammetric immunosensors using polyoxometalate-COF and its catalytic substrate.

A fluorescent covalent organic framework for visual detection of p-benzoquinone.

P-benzoquinone (PBQ) is toxic and harmful for health. The development of portable sensor to realize the detection of PBQ is of great significance. Herein, a novel covalent organic framework (COFML-TFPB) with intramolecular charge transfer and aggregation induced emission properties was proposed via condensation reaction of melem (ML) and 1,3,5-tris (4-formylphenyl) benzene (TFPB). COFML-TFPB shows strong fluorescence in both solution and solid state and can be used for the fluorescence detection of PBQ. Due to the internal filtration effect and photoinduced electron transfer effect, PBQ can quench the fluorescence of COFML-TFPB. The developed COFML-TFPB fluorescent sensor displayed a wide linear range for PBQ from 0.138 ng mL-1 - 35 µg mL-1, and the detection limit was 0.046 ng mL-1. In addition, fluorescent test paper for rapid and portable detection of PBQ was also developed by depositing COFML-TFPB on filter paper directly. It reduces the cost and time of detection and realizes the semiquantitative detection of PBQ. Moreover, the fluorescence color was converted into digital RGB value to calculate the concentration of PBQ accurately by a smartphone. This method realizes the portable qualitative and semiquantitative determination of PBQ.

Si@nitrogen-doped porous carbon derived from covalent organic framework for enhanced Li-storage.

Due to ultra-high theoretical capacity (4200 mAh g-1), silicon (Si) is an excellent candidate for the anode of lithium-ion batteries (LIBs). However, the application of Si is severely limited by its volume expansion of approximately 300% during the charge/discharge process. Herein, nitrogen-doped porous carbon (NC) capped nano-Si particles (Si@NC) composites with a core-shell structure were obtained by calcination of covalent organic frameworks (COFs) encapsulated nano-Si. COFs is a crystalline material with well-ordered structures, adjustable and ordered pores and abundant N atoms. After carbonization, the well-ordered pores and frameworks were kept well. Compared with other Si@NC composites, the well-ordered NC framework shell derived from COFs possesses high elasticity and well-ordered pores, which provides space for the volume expansion of nano-Si, and a channel to transfer Li+. The core-shell Si@NC composite exhibited good performances when applied as the anode of LIBs. At a current density of 100 mA g-1, it exhibited a discharge-specific capacity of 1534.8 mAh g-1 after 100 cycles with a first-coulomb efficiency of 69.7%. The combination of COFs with nano-Si is a better strategy for the preparation of anode materials of LIBs.

S,N-rich luminous covalent organic frameworks for Hg2+ detection and removal.

The challenge for simultaneous detection and removal of Hg2+ is the design of bifunctional materials bearing abundant accessible chelating sites with high affinity. Covalent-organic frameworks (COFs) are attracting more and more attention as potential bifunctional materials for Hg2+ detection due to their large specific surface area, ordered pores, and abundant chelating sites. Here, a new luminous S,N-rich COFBTT-AMPD based on hydrophilic block unit of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AMPD) was constructed, which improved the solubility and affinity for Hg2+ greatly. Another S-rich fused-ring unit of benzotrithiophene tricarbalaldehyde (BTT) enhanced the conjugation of COFBTT-AMPD, and the methyl-rich chains block unit of AMPD effectively suppressed the aggregation-caused quenching. Thus, the COFBTT-AMPD emitted strong fluorescence at 546 nm in liquid and solid as well as different solvent with a wide pH range, which was used for the visual detection and removal of Hg2+ (detection limit: 2.6 nM, linear range: 8.6 × 10-3-20 µM, monolayer adsorption capacity: 476.19 mg g-1) successfully. COFBTT-AMPD-based fabric and light-emitting diode coatings were further constructed to realize the visual detection of Hg2+ vapor. The results reveal the potential of S,N-rich luminous COFBTT-AMPD for Hg2+ detection and remediation in the environment.

A Paper-Based Electrochemical Sensor Based on PtNP/COFTFPB-DHzDS@rGO for Sensitive Detection of Furazolidone.

Herein, a paper-based electrochemical sensor based on PtNP/COFTFPB-DHzDS@rGO was developed for the sensitive detection of furazolidone. A cluster-like covalent organic framework (COFTFPB-DHzDS) was successfully grown on the surface of amino-functional reduced graphene oxide (rGO-NH2) to avoid serious self-aggregation, which was further loaded with platinum nanoparticles (PtNPs) with high catalytic activity as nanozyme to obtain PtNP/COFTFPB-DHzDS@rGO nanocomposites. The morphology of PtNP/COFTFPB-DHzDS@rGO nanocomposites was characterized, and the results showed that the smooth rGO surface became extremely rough after the modification of COFTFPB-DHzDS. Meanwhile, ultra-small PtNPs with sizes of around 1 nm were precisely anchored on COFTFPB-DHzDS to maintain their excellent catalytic activity. The conventional electrodes were used to detect furazolidone and showed a detection limit as low as 5 nM and a linear range from 15 nM to 110 µM. In contrast, the detection limit for the paper-based electrode was 0.23 µM, and the linear range was 0.69-110 µM. The results showed that the paper-based electrode can be used to detect furazolidone. This sensor is a potential candidate for the detection of furazolidone residue in human serum and fish samples.

Biosensor Based on Covalent Organic Framework Immobilized Acetylcholinesterase for Ratiometric Detection of Carbaryl.

A ratiometric electrochemical biosensor based on a covalent organic framework (COFThi-TFPB) loaded with acetylcholinesterase (AChE) was developed. First, an electroactive COFThi-TFPB with a two-dimensional sheet structure, positive charge and a pair of inert redox peaks was synthesized via a dehydration condensation reaction between positively charged thionine (Thi) and 1,3,5-triformylphenylbenzene (TFPB). The immobilization of AChE on the positively charged electrode surface was beneficial for maintaining its bioactivity and achieving the best catalytic effect; therefore, the positively charged COFThi-TFPB was an appropriate support material for AChE. Furthermore, the COFThi-TFPB provided a stable internal reference signal for the constructed AChE inhibition-based electrochemical biosensor to eliminate various effects which were unrelated to the detection of carbaryl. The sensor had a linear range of 2.2-60 µM with a detection limit of 0.22 µM, and exhibited satisfactory reproducibility, stability and anti-interference ability for the detection of carbaryl. This work offers a possibility for the application of COF-based materials in the detection of low-level pesticide residues.

Benzotrithiophene-based covalent organic frameworks for real-time visual onsite assays of enrofloxacin.

Enrofloxacin (ENR) is a fluoroquinolone antibiotic that has been used to treat bacterial diseases in aquaculture extensively. ENR might accumulate in the body and cause severe liver damage. Therefore, it is necessary to develop a method for rapid detection of ENR. Herein, amine monomers with different numbers of amino groups, charge and length (1,3-diaminoguanidine monohydrochloride: DMGH, triaminoguanidine hydrochloride: TAGH, hydrazine: H) were used to regulate the fluorescence of benzotrithiophene tricar-baldehyde (BTT)-based covalent organic frameworks (COFs) for real-time visual onsite assays of ENR for the first time. The C3 symmetric COFBTT-TAGH only had one emission peak at 540 nm, while C6 symmetric COFBTT-DMGH and COFBTT-H had two emission peaks. COFBTT-TAGH could achieve the color transition from green to blue with increasing ENR. Thus test paper and gel were designed as real-time detection tools, combined with a smartphone APP. The detection limits obtained by RGB analysis were 106.2 nM for test paper and 26.00 nM for test gel, respectively. This method was applied to detect ENR in fish and clam metabolite successfully. This work also provides important reference to regulate fluorescence of COFs according to actual application.

An Immunosensor Using Electroactive COF as Signal Probe for Electrochemical Detection of Carcinoembryonic Antigen.

Two kinds of two-dimensional (2D) covalent-organic frameworks (COF) were used to construct a sandwich-type electrochemical immunosensor for a proof-of-concept study. Vinyl-functionalized COFTab-Dva could be linked with Ab1 by the thiol-ene "click" reaction. Electroactive COFTFPB-Thi was modified with gold nanoparticles (AuNPs) to ensure the successful connection with Ab2 through Au-S bond. Meanwhile, electroactive COFTFPB-Thi was used to as signal probe to realize both the detection of carcinoembryonic antigen (CEA) and the amplification of detection signal. In detection process of the sandwich-type electrochemical immunosensor, glassy carbon electrode (GCE) was modified with 2D COFTab-Dva first then connected with Ab1 by the thiol-ene "click" reaction, next quantitative CEA was captured, followed by specificially capturing signal probe of Ab2/AuNPs/COFTFPB-Thi where AuNPs acted as nanocarriers of Ab2 and COFTFPB-Thi served as the signal producers. As the amount of CEA was increased, the amount of signal probe captured to the electrode was also increased, and the peak signal intensity of the redox reaction of COFTFPB-Thi was enhanced accordingly. Thus, the quantitative detection of CEA could be realized according to the peak signal intensity of electroactive COFTFPB-Thi. The electrochemical immunosensor owned wide detection range of 0.11 ng/mL-80 ng/mL, low detection limit of 0.034 ng/mL and good practicability. This study opens up a new revelation for quantitative detection of CEA using electroactive COF as enhanced signal probe.

Double signal ratiometric electrochemical riboflavin sensor based on macroporous carbon/electroactive thionine-contained covalent organic framework.

Riboflavin (RF) is one of the necessary vitamins. If human body lacks RF, it will lead to inflammation and dysfunction of mouth, lips and skin. Thus sensitive and accurate determination of RF is necessary. Here, an electroactive covalent-organic framework nanobelt (COFTFPB-Thi) with thickness of 1.4 nm was prepared by amine-aldehyde condensation reaction between thionine and 1, 3, 5-tris (p-formylphenyl) benzene, which was then grown vertically on three-dimensional porous carbon derived from kenaf stem (3D-KSC) for double signal ratiometric electrochemical detection of RF. The resulted 3D-KSC/COFTFPB-Thi showed two reduction peaks at -0.08 V and -0.23 V, which came from the reduction of COFTFPB-Thi and the conjugated structure of COFTFPB-Thi, respectively. In the presence of RF, those RF molecules near the electrode surface were oxidized at 0.6 V. Then some oxidized RF (RFox) adsorbed on COFTFPB-Thi would oxidize COFTFPB-Thi into COFTFPB-Thi(ox) while other RFox adsorbed on 3D-KSC kept unchanged. When the potential was scanned from 0.6 V to -0.6 V, both COFTFPB-Thi(ox) and RFox adsorbed on 3D-KSC were reduced at -0.08 V and -0.45 V accordingly, while the reduction peak of -0.23 V of the conjugated structure of COFTFPB-Thi kept constant. When j-0.45/j-0.23 was used as the response signal, the detection limit was 44 nM and the linear range was 0.13 µM -0.23 mM. By using j-0.08/j-0.23 as the response signal, a detection limit of 90 nM and a linear range of 0.30 µM-0.23 mM (S/N = 3) were obtained. By using double signals, the measurement results can be corrected to make the results more accurate and reliable. The sensor also showed good selectivity, reproducibility and stability, which provided a good application prospects.

Simultaneous electrochemical sensing of heavy metal ions based on a g-C3N4/CNT/NH2-MIL-88(Fe) nanocomposite.

The presence of Cd2+, Pb2+, Cu2+ and Hg2+ in drinking-water can be harmful to human health, even if their concentration is fairly low. Hence, it is significant to detect these heavy metal ions in sewage to evaluate the quality of water. Herein, amino-functionalized metal-organic frameworks (NH2-MIL-88(Fe)) embedded with graphitic carbon nitride (g-C3N4) nanosheets and acid-functionalized carbon nanotubes were prepared via a one-pot synthesis. The composite can be directly modified on the surface of glass carbon electrodes without the assistance of Nafion or other binders. The modified glass carbon electrodes can be used to simultaneously detect Cd2+, Pb2+, Cu2+ and Hg2+ in water via square wave stripping voltammetry. The doping of g-C3N4 in the composite, rich in N-containing functional groups, participates in the adsorption of metal ions on the surface of the electrodes. The porous composite provides accommodation room for metals generated by electro-reduction. The detection limit for Cd2+, Pb2+, Cu2+ and Hg2+ is 39.6 nM, 7.6 nM, 11.9 nM, and 9.6 nM, respectively. And the sensitivity for Cd2+, Pb2+, Cu2+ and Hg2+ is 0.0789 mA µM-1 cm-2, 0.4122 mA µM-1 cm-2, 0.2616 mA µM-1 cm-2, and 0.3251 mA µM-1 cm-2, respectively. This work not only enriches the functional design of Fe-MOF materials, but also develops a method for the determination of metal ions using the adsorption sites in g-C3N4.

A novel biosensor based on multienzyme microcapsules constructed from covalent-organic framework.

Electrochemical biosensors based on enzymes modified electrode are attracting special attention due to their broad applications. However, the immobilization of enzymes on electrode is always an important challenge because it's not conducive to conformational expansion of enzymes and affects the bioactivity of enzymes accordingly. Although the imobilization of enzymes in micropores of crystalline covalent-organic framework (COF) and metal-organic framework (MOF) to construct electrochemical biosensors based on pore embedding can achive good reuslts, their micropores can still not guarantee that the enzyme's conformation is well extended. Herein, a multienzyme microcapsules (enzymes@COF) containing glucose oxidase, horseradish peroxidase and acetylcholinesterase with a 600 nm-sized cavity and a shell of COF was used to construct electrochemical biosensors. The 600 nm-sized cavity ensures free conformation expansion of encapsulated enzymes and the shell of COF with good chemical stablity protects encapsulated enzymes against external harsh environments. And the specific catalytic substrates of the enzymes can infiltrated into the microcapsule through the pores of COF shell. So, the biosensor based on enzymes@COF microcapsules demonstrated preeminent performances as compared with those of enzymes assembled on electrode. The detection limits were 0.85 µM, 2.81 nM, 3.0×10-13 g/L, and the detection range were 2.83 µM-8.0 mM, 9.53 nM-7.0 µM, 10-12 g/L-10-8 g/L for glucose, H2O2 and malathion detection. This work shows that it is feasible to fabricate electrochemical sensors using enzymes@COF microcapsules.

A g-C3N4 self-templated preparation of N-doped carbon nanosheets@Co-Co3O4/Carbon nanotubes as high-rate lithium-ion batteries' anode materials.

A novel N-doped graphene-like carbon nanosheets (CNs) and carbon nanotubes (CNTs)-encapsulated Co-Co3O4 nanoparticles (NPs) (CN@Co-Co3O4/CNTs) were synthesized successfully by a simple hydrothermal and annealing method with graphite carbon nitride (g-C3N4) as self-template. By annealing Co2+/g-C3N4 under N2 atmosphere, g-C3N4 was transformed into CN/CNTs, and Co2+ was reduced into CoNPs which were embedded in CNs. Further annealing in air, a shell of Co3O4 was formed around CoNPs. The amount of CNs, CNTs, and CoNPs can be adjusted by changing the ratio of Co2+ in Co2+/g-C3N4. The graphene-like CNs provided a large number of active sites and a large specific surface area for loading lots of small CoNPs uniformly. The CNTs with a diameter of 100 nm could not only improve the conductivity but also provide a buffer space for the aggregation and volume expansion of Co3O4. CNTs also enlarged the interlayer distance of CNs, which prevented the re-stacking of CNs and provided great convince for the intercalation and de-intercalation of Li+. When applied for anode material of lithium-ion batteries, CN@Co-Co3O4/CNTs exhibited a high discharge capacity of 460.0 mAh g-1 at 5000 mA g-1 after 300 cycles with a Coulombic efficiency of 98% and excellent higher-rate capacity (401.0 mAh g-1 at 2000 mA g-1 and 329.0 mAh g-1 at 5000 mA g-1).

A novel N,S-rich COF and its derived hollow N,S-doped carbon@Pd nanorods for electrochemical detection of Hg2+ and paracetamol.

Covalent-organic frameworks (COFs) are conjugate crystalline polymers with high porosity, controllable pores and structure as well as large specific surface area, showing great potential for electrochemical sensors. Here, a new N,S-rich COFBTT-TZT is proposed by direct amine-aldehyde dehydration condensation between 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline (TZT) and benzo [1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde (BTT). The COFBTT-TZT has a hexagonal hcb structure with theoretical pore of 2.2 nm and presents rod-like morphology with many small flakes on its surface. Particularly, there are lots of S and N atoms in COFBTT-TZT, which provides abundant adsorption sites for Hg2+ so that it can be used to detect Hg2+. The proposed Hg2+ sensor has a linear range of 0.54 nM-5.0 µM and a detection limit of 0.18 nM. Besides, using COFBTT-TZT as precursor and template, the hollow N,S-doped C@Pd nanorods which possesses many tiny Pd nanoparticles embedded in rods-like hollow structure are obtained. An electrochemical paracetamol sensor is also proposed based on the N,S-doped C@Pd nanorods, showing low detection limit of 11 nM and wide linear range of 33 nM-120 µM. The good results provide an important guidance for the application of COF in electrochemical sensors.

Glucose oxidase@Cu-hemin metal-organic framework for colorimetric analysis of glucose.

The work presents a novel glucose oxidase@Cu-hemin metal-organic frameworks (GOD@ Cu-hemin MOFs) with a ball-flower structure as bienzymatic catalysts for detection of glucose. The GOD@Cu-hemin MOFs exhibits great stability as compared with free horseradish peroxidase and GOD toward harsh conditions because the ball-flower-like shell of Cu-hemin MOF effectively protects from GOD. Thus, the GOD@Cu-Hemin MOFs can be used in external harsh conditions such as high temperature and acid/base. The GOD@Cu-hemin MOFs is capable of sensitive and selective detection of glucose via peroxidase-like of Cu-hemin MOFs and GOD by using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. Under the existence of glucose, O2 is reduced into H2O2 via GOD@Cu-hemin MOFs. The produced H2O2 as well as Cu-hemin MOFs oxidize TMB into blue oxTMB which shows UV-Vis absorbance at 652. The absorption intensity of oxTMB linearly increases with the increasing concentration of glucose from 0.01 to 1.0 mM with detection limit of 2.8 µM. An integrated agarose hydrogel film (Aga/GOD@Cu-hemin MOF/TMB) sensor is rationally designed for colorimetric detection of glucose. The sensor displays a response range of 30 µM-0.8 mM with a detection limit of 0.01 mM. The result indicates that the Cu-hemin MOFs are an ideal carrier for the encapsulation of enzymes.

Dual emission N-doped carbon dot@benzotrithiophene tricarbaldehyde-terephthalic dihydrazide covalent organic framework.

N-doped carbon dot (NCD)@COFBTT-Th nanosheets with strong dual-emission fluorescence are prepared by encapsulating NCDs into COFBTT-Th through amine-aldehyde dehydration condensation between benzotrithiophene tricarbaldehyde and terephthalic dihydrazide. The fluorescence of COFBTT-Th is enhanced because of fluorescence resonance energy transfer and the decrease of interlaminar accumulation and intramolecular rotation.

Fluorescent metal-organic frameworks MIL-101(Al)-NH2 for rapid and sensitive detection of ellagic acid.

Ellagic acid (EA) is a symmetric natural phenol bioactive compound present in fruits and nuts, and has attracted substantial interest worldwide owing to its beneficial health effects. Here, the exploration of luminescent metal-organic frameworks (MOFs) of MIL-101(Al)-NH2 (MIL = Materials of Institute Lavoisier) for rapid and sensitive sensing of EA in aqueous solution was reported initially. The porous MIL-101(Al)-NH2 MOFs was synthesized by solvent-thermal method with inexpensive 2-aminoterephthalic acid and aluminum salt, which exhibited uniform spherical crystals (~340 nm) and specific mesoporous structure (3.2 nm). The fluorescence intensity of MIL-101(Al)-NH2 at 425 nm showed a good linear relationship with EA concentration in the range of 0.15-100 µM. The detection limit was as low as 43.8 nM, the rapid response time was within 2 min, and the cost of detection was low. In addition, the "turn off" fluorescence probe could be utilized for visual detection of EA according to the color change under the UV lamp. Based on the Stern-Volmer equation, the quenching constants was decreased with the rise of temperature, which indicated that the probable quenching mechanism was static quenching. The nanoprobe was successfully used to detect EA in the cherry and serum samples. MIL-101(Al)-NH2 represents the first instance of MOFs-based fluorescent probe in EA detection. This work not only enriches the detection method of EA, but also expands the potential application of MIL MOFs in small molecules.