Boosted Sensor Performance by Surface Modification of Bifunctional rht-Type Metal-Organic Framework with Nanosized Electrochemically Reduced Graphene Oxide

A non-enzymatic hydrogen peroxide biosensor based on cerium metal-organic frameworks, hemin, and graphene oxide composite

This study presents the development of a novel non-enzymatic electrochemical biosensor for the real-time detection of hydrogen peroxide (H2O2) based on a composite of cerium metal-organic frameworks (Ce-MOFs), hemin, and graphene oxide (GO). The Ce-MOFs served as an efficient matrix for hemin encapsulation, while GO enhanced the conductivity of the composite. Characterization techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, UV-vis spectroscopy, and thermogravimetric analysis (TGA) confirmed the successful integration of hemin into the Ce-MOFs. The Ce-MOFs@hemin/GO-modified sensor demonstrated sensitive H2O2 detection due to the exceptional electrocatalytic activity of Ce-MOFs@hemin and the high conductivity of GO. This biosensor exhibited a linear response to H2O2 concentrations from 0.05 to 10 mM with a limit of detection (LOD) of 9.3 μM. The capability of the biosensor to detect H2O2 released from human prostate carcinoma cells was demonstrated, highlighting its potential for real-time monitoring of cellular oxidative stress in complex biological environments. To further assess its practical applicability, the sensor was tested in human serum samples, yielding promising results with recovery values ranging from 94.50 % to 103.29 %. In addition, the sensor showed excellent selectivity against common interfering compounds due to the outstanding peroxidase-like activity of the composite.

Electrochemical and Electrical Biosensors for Wearable and Implantable Electronics Based on Conducting Polymers and Carbon-Based Materials

Bioelectronic devices are designed to translate biological information into electrical signals and vice versa, thereby bridging the gap between the living biological world and electronic systems. Among different types of bioelectronics devices, wearable and implantable biosensors are particularly important as they offer access to the physiological and biochemical activities of tissues and organs, which is significant in diagnosing and researching various medical conditions. Organic conducting and semiconducting materials, including conducting polymers (CPs) and graphene and carbon nanotubes (CNTs), are some of the most promising candidates for wearable and implantable biosensors. Their unique electrical, electrochemical, and mechanical properties bring new possibilities to bioelectronics that could not be realized by utilizing metals- or silicon-based analogues. The use of organic- and carbon-based conductors in the development of wearable and implantable biosensors has emerged as a rapidly growing research field, with remarkable progress being made in recent years. The use of such materials addresses the issue of mismatched properties between biological tissues and electronic devices, as well as the improvement in the accuracy and fidelity of the transferred information. In this review, we highlight the most recent advances in this field and provide insights into organic and carbon-based (semi)conducting materials' properties and relate these to their applications in wearable/implantable biosensors. We also provide a perspective on the promising potential and exciting future developments of wearable/implantable biosensors.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

Recent advances in metal-based nanoporous materials for sensing environmentally-related biomolecules

Highly sensitive, stable, selective, efficient, and short reaction time sensors play a substantial role in daily life/industry and are the need of the day. Due to the rising environmental issues, nanoporous carbon and metal-based materials have attracted significant attention in environmental analysis owing to their intriguing and multifunctional properties and cost-effective and rapid detection of different analytes by sensing applications. Environmental-related issues such as pollution have been a significant threat to the world. Therefore, it is necessary to fabricate highly promising performance-based sensor materials with excellent reliability, selectivity and good sensitivity for monitoring various analytes. In this regard, different methods have been employed to fabricate these sensors comprising metal, metal oxides, metal oxide carbon composites and MOFs leading to the formation of nanoporous metal and carbon composites. These composites have exceptional properties such as large surface area, distinctive porosity, and high conductivity, making them promising candidates for several versatile sensing applications. This review covers recent advances and significant studies in the sensing field of various nanoporous metal and carbon composites. Key challenges and future opportunities in this exciting field are also part of this review.

Copper-based metal-organic frameworks for biomedical applications

Metal-organic frameworks (MOFs) are a class of important porous, crystalline materials composed of metal ions (clusters) and organic ligands. Owing to the unique redox chemistry, photochemical and electrical property, and catalytic activity of Cu^2+/+, copper-based MOFs (Cu-MOFs) have been recently and extensively explored in various biomedical fields. In this review, we first make a brief introduction to the synthesis of Cu-MOFs and their composites, and highlight the recent synthetic strategies of two most studied representatives, three-dimensional HKUST-1 and two-dimensional Cu-TCPP. The recent advances of Cu-MOFs in the applications of cancer treatment, bacterial inhibition, biosensing, biocatalysis, and wound healing are summarized and discussed. Furthermore, we propose a prospect of the future development of Cu-MOFs in biomedical fields and beyond.

Recent advancements in metal-organic frameworks composites based electrochemical (bio)sensors

Metal-organic frameworks (MOFs) are a novel class of crystalline materials which find widespread applications in the field of microporous conductors, catalysis, separation, biomedical engineering, and electrochemical sensing. With a specific emphasis on the MOF composites for electrochemical sensor applications, this review summarizes the recent construction strategies on the development of conductive MOF composites (post-synthetic modification of MOFs, in situ synthesis of functional materials@MOFs composites, and incorporating electroactive ligands). The developed composites are revealed to have excellent electrochemical sensing activity better than their pristine forms. Notably, the applicable functionalized MOFs to electrochemical sensing/biosensing of various target species are discussed. Finally, we highlight the perspectives and challenges in the field of electrochemical sensors and biosensors for potential directions of future development.

A novel artificial peroxisome candidate based on nanozyme with excellent catalytic performance for biosensing

Artificial peroxisome is of critical importance to supersede natural peroxisome in fabricating protocell system and disease treatment. Nevertheless, developing feasible artificial peroxisome with various stable functions remains a monumental challenge. Nanozyme with multiple enzyme-like activities can mimic natural enzymes in peroxisome, which make it a prospective candidate for artificial peroxisome design. Herein, we prepared a nanozyme with multiple peroxisomal-like activities - Pd nanoparticles functionalized nitrogen-doped porous carbon-reduced graphene oxide (PdNPs/N-PC-rGO). Due to its sandwich-like structure, the incorporation of N heteroatoms and the synergistic effect between PdNPs and N-PC-rGO bi-support, the PdNPs/N-PC-rGO exhibited triple peroxisomal-like activities including oxidase (OXD), peroxidase (POD) and catalase (CAT), leading it a promising alternative for artificial peroxisome exploration. Furthermore, the PdNPs/N-PC-rGO showed high electrocatalytic activity, which could be employed for the detection of electrochemical active substances reduced glutathione (GSH). The PdNPs/N-PC-rGO modified electrode displayed a wide concentration range from 70 nM to 1500 μM, with a very low detection limit of 9.8 nM (S/N = 3). Therefore, PdNPs/N-PC-rGO was a promising nanozyme for various biotechnological applications such as artificial organelles, biosensing, cytoprotection, disease diagnosis and treatment.

Electrochemical Sensor for the Detection of 1-Hydroxypyrene Based on Composites of PAMAM-Regulated Chromium-Centered Metal-Organic Framework Nanoparticles and Graphene Oxide

A nanocomposite was formed by combining graphene oxide (GO) with chromium-centered metal-organic framework (Cr-MOF) nanoparticles regulated by the dendrimer polyamidoamine (PAMAM). PAMAM can successfully regulate the synthesis of Cr-MOF; in doing so, the size of Cr-MOF is reduced, its original morphology is maintained, and it has good crystallinity. A simple ultrasonication method was used to make the Cr-MOF/GO hybrid nanocomposite. Various characterization methods confirmed the successful synthesis of PAMAM/Cr-MOF/GO nanocomposites. The PAMAM/Cr-MOF/ERGO modified electrode could be used with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) to study the electrochemical behaviors of 1-hydroxypyrene (1-OHPyr). The results indicated that the constructed PAMAM/Cr-MOF/ERGO electrochemical sensor had a significantly enhanced electrocatalytic effect on the electrochemical reduction of 1-OHPyr compared with the sensors with no PAMAM and the ERGO sensor, which could be ascribed to the synergetic effect from the high porosity of Cr-MOF and the high conductivity of ERGO, as well as the further electron transport action of the nanocomposite. Under the optimal conditions, the reduction peak current and concentration of 1-OHPyr showed a good linear relationship in the range of 0.1-1.0 and 1.0-6.0 μM, and the detection limit of 1-OHPyr was calculated to be 0.075 μM. Moreover, the PAMAM/Cr-MOF/ERGO electrochemical sensor constructed in this paper can be expected to provide some instructions for the construction of electrochemical sensing platforms and wider potential applications.

Review on recent progress in metal-organic framework-based materials for fabricating electrochemical glucose sensors

Diabetes is a type of disease that threatens human health, which can be diagnosed based on the level of glucose in the blood. Recently, various MOF-based materials have been developed as efficient electrochemical glucose sensors because of their tunable pore channels, large specific surface area well dispersed metallic active sites, etc. In this review, the significance of glucose detection and the advantages of MOF-based materials for this application are primarily discussed. Then, the application of MOF-based materials can be categorized into two types of glucose sensors: enzymatic biosensors and non-enzymatic sensors. Finally, insights into the current research challenges and future breakthrough possibilities regarding electrochemical glucose sensors are considered.

Catalytic amplification based on hierarchical heterogeneity bimetal-organic nanostructures with peroxidase-like activity

In this paper, integrating heterometallic units and nanostructures into metal-organic frameworks (MOFs) were applied to improve the sensitivity of detecting hydrogen peroxide (H₂O₂) in neutral solution. The bimetal-MOFs (CuCo-BDC) and GO composite (CuCo-BDC/GO) were first synthesized via an ordinary one-step solvothermal synthesis. The CuCo-BDC/GO with admirable peroxidase-like catalytic activity could be applied to detect H₂O₂. The results have low detection limit of 69 nM (S/N = 3) and a wide linear detection range, from 100 nM to 3.5 mM. This is superior to recently published biosensors based on noble metal nanomaterials, which confirms CuCo-BDC/GO as the MOF electrocatalysts with high performance. The remarkable electroanalytical performance of CuCo-BDC/GO is due to the presence of numerous open metal active sites, the synergistic effect of Cu²⁺ and Co²⁺, hierarchical structure with high-specific surface areas and the marvelous electrochemical properties of GO. Therefore, CuCo-BDC/GO is a powerful candidate for detecting H₂O₂ in electrochemical biosensing fields. Moreover, H₂O₂ detection in real samples can be done with the CuCo-BDC/GO, including human serum samples. Therefore, the novel CuCo-BDC/GO is a promising catalyst that can be applied in biotechnological and environmental applications.

Novel SeS2-loaded Co MOF with Au@PANI comprised electroanalytical molecularly imprinted polymer-based disposable sensor for patulin mycotoxin

An SeS₂-loaded Co MOF and Au@PANI nanocomposite comprising the base matrix of the electrode was developed with electropolymerized molecularly imprinted polymer (MIP) consisting of p-aminobenzoic acid (PABA) and patulin (PT) to detect PT molecules based on the PT imprinted cavities. SeS₂@Co MOF and Au@PANI were synthesized using hydrothermal synthesis and interfacial polymerization strategies, respectively. A suitable functional monomer to fabricate the MIP platform was selected using the density functional theory (DFT/M06-2X method). Higher electrochemical active surface area (0.985 cm² which is 6.99 times higher than the bare SPE) and a lower charge transfer resistance (R_ct = 27.8 Ω) at the MIP/Au@PANI/SeS₂@Co MOF electrode was achieved based on the higher number of adsorptive sites and enhanced conductivity (electron transfer rate constant (k_s = 3.24 × 10^-3 s^-1) of the sensing platform. The fabricated MIP sensor performance was studied in 10 mM PBS (pH = 6.4), where an improved detection limit (0.66 pM) for PT and a broad logarithmic linear dynamic range (0.001-100 nM) were both observed. The sensor possessed higher selectivity (Imprinting factor = 15.4 for PT), excellent reusability (%RSD of 10 cycles = 2.49%), high storage stability (6.7% lost after 35 days), and robust reproducibility (%RSD = 3.22%) The as-prepared MIP-based PT sensor was applied to detect PT in a real-time apple juice sample (10% diluted with PBS) with a recovery % ranging from 94.5 to 106.4%. The proposed sensor possesses great advantages in terms of cost-effectiveness, providing a simple detection strategy for long-term storage stability, and reversible cycle measurements.

A Long-Term Stable Sensor Based on Fe@PCN-224 for Rapid and Quantitative Detection of H2O2 in Fishery Products

Hydrogen peroxide (H2O2) has been reported to be used for the illegal treatment of fishery products in order to obtain "fake" freshness. Residues of H2O2 in food may be of toxicology concern. In this study, a nonenzymatic sensor was developed based on Fe@PCN-224 metal-organic frameworks wrapped by Nafion to detect H2O2 concentration. The hybrid structure of Fe@PCN-224 was fabricated by incorporated free FeIII ions into the center of PCN-224, which was ultra-stable due to the strong interactions between Zr6 and the carboxyl group. Scanning electron spectroscopy images exhibited that Nafion sheets crossed together on the surface of Fe@PCN-224 nanoparticles to form a hierarchical and coherent structure for efficient electron transfer. Electrochemical investigations showed that the Fe@PCN-224/Nafion/GCE possessed good linearity from 2 to 13,000 μM (including four orders of magnitude), low detection limits (0.7 μM), high stability in continuous monitoring (current remained nearly stable over 2300 s) and in long-term measurement (current decreased 3.4% for 30 days). The prepared nanohybrid modified electrode was effectively applied to H2O2 detection in three different fishery products. The results were comparable to those measured using photometrical methods. The developed electrochemical method has a great potential in detecting the illegal management of fishery products with H2O2.

Electrocatalytic Oxidation of Glucose on Boron and Nitrogen Codoped Graphene Quantum Dot Electrodes in Alkali Media

A novel solvothermal technique has been developed in the presence of C/N/B precursor for synthesizing B-N-coped graphene quantum dots (GQDs) as non-metal electrocatalysts towards the catalytic glucose oxidation reaction (GOR). Both N-doped GQD and B-N-codoped GQD particles (~4.0 nm) possess a similar oxidation and amidation level. The B-N-codoped GQD contains a B/C ratio of 3.16 at.%, where the B dopants were formed through different bonding types (i.e., N‒B, C‒B, BC2O, and BCO2) inserted into or decorated on the GQDs. The cyclic voltammetry measurement revealed that the catalytic activity of B-N-codoped GQD catalyst is significantly higher compared to the N-doped GQDs (~20% increase). It was also shown that the GOR activity was substantially enhanced due to the synergistic effect of B and N dopants within the GQD catalysts. Based on the analysis of Tafel plots, the B-N-codoped-GQD catalyst electrode displays an ultra-high exchange current density along with a reduced Tafel slope. The application of B-N-codoped GQD electrodes significantly enhances the catalytic activity and results in facile reaction kinetics towards the glucose oxidation reaction. Accordingly, the novel design of GQD catalyst demonstrated in this work sets the stage for designing inexpensive GQD-based catalysts as an alternative for precious metal catalysts commonly used in bio-sensors, fuel cells, and other electrochemical devices.

Nano-spinel cobalt decorated sulphur doped graphene: an efficient and durable electrocatalyst for oxygen evolution reaction and non-enzymatic sensing of H2O2

We report the synthesis of a nano-spinel cobalt decorated sulphur doped reduced graphene oxide (Co@S–rGO) composite exhibiting excellent electrocatalytic performance and electrochemical stability toward oxygen evolution reaction in an alkaline medium.

A novel Fe-hemin-metal organic frameworks supported on chitosan-reduced graphene oxide for real-time monitoring of H2O2 released from living cells

Herein, a kind of novel hemin-based metal organic frameworks (Fe-hemin-MOFs) with unique peroxidase-like bioactivity was developed for the first time. The synthesized Fe-hemin-MOFs exhibited satisfactory catalytic activity toward hydrogen peroxide (H₂O₂). When it was further supported on Chitosan-reduced graphene oxide (CS-rGO), amplified electrochemical signal could be obtained. The Fe-hemin-MOFs/CS-rGO composite was used to construct a novel H₂O₂ electrochemical sensor. The electrocatalytic reduction of H₂O₂ displayed two segments linearity range from 1 to 61 μM and 61-1311 μM, as well as a low detection limit of 0.57 μM. Furthermore, the proposed sensor was successfully used for real-time monitoring of H₂O₂ released from living cells, which extended the practical application of MOFs-based sensors in monitoring the pathological process in living cells.

Polycarbonate Microchip Containing CuBTC-Monopol Monolith for Solid-Phase Extraction of Dyes

In the present study, preparation of CuBTC-monopol monoliths for use within the microchip solid phase extraction was undertaken through a 20-min UV lamp-assisted polymerization for 2,2-dimethoxy-2-phenyl acetophenone (DMPA), butyl methacrylate (BMA), and ethylene dimethacrylate (EDMA) alongside inclusion of the porogenic solvent system (1-propanol and methanol (1 : 1)). The resultant coating underwent coating using CuBTC nanocrystals in ethanolic solution of ethanolic solution of 1,3,5-benzenetricarboxylic acid (H₃BTC, 10 mM) and 10 mM copper(II) acetate Cu(CH₃COO)₂. This paper reports enhanced extraction, characterization, and synthesis studies for porous CuBTC metal organic frameworks that are marked by different methods including SEM/EDAX analysis, atomic force microscopy (AFM), and Fourier-transform infrared spectroscopy (FT-IR). The evaluation of the microchip's performance was undertaken as sorbent through retrieval of six toxic dyes (anionic and cationic dyes). Various parameters (desorption and extraction step flow rates, volume of desorption solvent, volume of sample, and type of desorption solvent) were examined to optimize dye extraction using fabricated microchips. The result indicated that CuBTC-monopol monoliths were permeable with the ability of removing impurities and attained high toxic dye extraction recovery (83.4-99.9%). The assessment of reproducibility for chip-to-chip was undertaken by computing the relative standard deviations (RSDs) of the six dyes in extraction. The interbatch and intrabatch RSDs ranged between 3.8 and 6.9% and 2.3 and 4.8%. Such features showed that fabricated CuBTC-monopol monolithic disk polycarbonate microchips have the potential of extracting toxic dyes that could be utilized for treating wastewater.

Application of MOF-based materials in electrochemical sensing

A summary of the most recent advancements of metal–organic frameworks (MOFs) for electrochemical sensing is listed in this frontier article.

Rod-like Co based metal-organic framework embedded into mesoporous carbon composite modified glassy carbon electrode for effective detection of pyrazinamide and isonicotinyl hydrazide in biological samples

Herein, we report a novel composite fabricated via embedding rod-like Co based metal-organic framework (Co-MOF-74) crystals into MC matrix for the first time. The introduction of MC astricts the size of Co-MOF-74 crystals, enlarges the pore size and improves the electrical conductivity, which lead to the good electrochemical properties of the composite. The fabricated sensor based on Co-MOF-74@MC exhibits superior electrocatalytic activity toward the reduction of pyrazinamide (PZA) and the oxidation of isonicotinyl hydrazide (INZ). Under optimized conditions, the sensor shows two linear ranges from 0.3 to 46.5 μM and 46.5-166.5 μM with a high sensitivity of 7.2 μA μM^-1 cm^-2 and a detection limit of 0.21 μM for the determination of PZA. The electroanalytical sensing of INZ also gives two linear ranges of 0.15-1.55 μM and 1.55-592.55 μM with a detection limit of 0.094 μM. The mechanism involved was also discussed, briefly. The sensor is assessed toward the detection of PZA and INZ in human serum and urine samples. Recovery values varied from 97.08 to 103.20% for PZA sensing and 96.67-102.90% for INZ sensing, revealing the promising practicality of sensor for PZA and INZ detection.

Covalent Functionalization of Graphene Oxide with a Presynthesized Metal-Organic Framework Enables a Highly Stable Electrochemical Sensing

This paper reports the covalent functionalization of graphene oxide (GO) by a presynthesized metal-organic framework NH₂-MIL-101(Fe) via ultrasonication of the two components. The formation of Fe-O covalent bonding in the NH₂-MIL-101(Fe)-GO nanohybrid is clearly evidenced, and the covalent bonding still remains after electrochemical reduction. The morphology and structure of the nanohybrid are characterized via scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. The electrode based on electrochemically reduced NH₂-MIL-101(Fe)-GO shows ultrastable and high-sensitive performance in simultaneous electrochemical sensing of three purine metabolic derivatives (uric acid, xanthine, and hypoxanthine); in particular, no signal fading is seen even after running for 120 times. The covalent bonding within the nanohybrid is obviously the key to maintain such a stability.

Synergistic Photodynamic and Photothermal Antibacterial Nanocomposite Membrane Triggered by Single NIR Light Source

Herein, we developed a nanocomposite membrane with synergistic photodynamic therapy and photothermal therapy antibacterial effects, triggered by a single near-infrared (NIR) light illumination. First, upconversion nanoparticles (UCNPs) with a hierarchical structure (UCNPs@TiO₂) were synthesized, which use NaYF₄:Yb,Tm nanorods as the core and TiO₂ nanoparticles as the outer shell. Then, nanosized graphene oxide (GO), as a photothermal agent, was doped into UCNPs@TiO₂ core-shell nanoparticles to obtain UCNPs@TiO₂@GO. Afterward, the mixture of UCNPs@TiO₂@GO in poly(vinylidene) fluoride (PVDF) was applied for electrospinning to generate the nanocomposite membrane (UTG-PVDF). Generation of reactive oxygen species (ROS) and changes of temperature triggered by NIR action were both investigated to evaluate the photodynamic and photothermal properties. Upon a single NIR light (980 nm) irradiation for 5 min, the nanocomposite membrane could simultaneously generate ROS and moderate temperature rise, triggering synergistic antibacterial effects against both Gram-positive and -negative bacteria, which are hard to be achieved by an individual photodynamic or photothermal nanocomposite membrane. Additionally, the as-prepared membrane can effectively restrain the inflammatory reaction and accelerate wound healing, thus exhibiting great potentials in treating infectious complications in wound healing progress.

Metal–Organic Frameworks Toward Electrocatalytic Applications

Metal–organic frameworks (MOFs) are a class of porous materials constructed from metal-rich inorganic nodes and organic linkers. Because of their regular porosity in microporous or mesoporous scale and periodic intra-framework functionality, three-dimensional array of high-density and well-separated active sites can be built in various MOFs; such characteristics render MOFs attractive porous supports for a range of catalytic applications. Furthermore, the electrochemically addressable thin films of such MOF materials are reasonably considered as attractive candidates for electrocatalysis and relevant applications. Although it still constitutes an emerging subfield, the use of MOFs and relevant materials for electrocatalytic applications has attracted much attention in recent years. In this review, we aim to focus on the limitations and commonly seen issues for utilizing MOFs in electrocatalysis and the strategies to overcome these challenges. The research efforts on utilizing MOFs in a range of electrocatalytic applications are also highlighted.

Energy-Transfer Metal-Organic Nanoprobe for Ratiometric Sensing with Dual Response to Peroxynitrite and Hypochlorite

An energy-transfer metal-organic nanoprobe is designed for ratiometric sensing with dual response to both peroxynitrite (ONOO-) and hypochlorite (ClO-). Here, a nanoscale metal-organic framework (NMOF) acts as the energy donor and molecular probe as the acceptor to construct a Förster resonance energy transfer (FRET) nanosystem. Biocompatible dextran conveniently binds to the NMOF surface through multiple weak coordination interactions to improve water dispersibility and cell uptake. Dextran can also coordinate with the molecular probe with arylboronic acid group, which enables the convenient grafting of molecular probes to the NMOF surface to construct energy-transfer nanoprobes. Because of efficient FRET, the bright blue fluorescence of NMOF is quenched, whereas red emission from the acceptor is enhanced. Upon reacting with ONOO-, the probe departs from NMOF and the fluorescence of NMOF is recovered because of the interruption of FRET. When reacting with ClO-, the phenothiazine moiety in the molecular probe is oxidized into phenothiazine-5-oxide, which leads to more efficient energy transfer and the fluorescence shifts from red to orange. The nanoprobes are also successfully applied to the detection of ONOO- and ClO- in living cells.

Noncovalently copper-porphyrin functionalized reduced graphene oxide for sensitive electrochemical detection of dopamine

The nanocomposite of an electron-deficient flat tetrakis-(ethoxycarbonyl) porphyrin copper(II) (Cu-TECP) and reduced grapheme oxide (RGO) was prepared and used for electrochemical detection of dopamine (DA). The prepared nanocomposite was characterized by scanning electron microscopy, Raman spectroscopy, FT-IR spectroscopy, ultraviolet-visible spectroscopy and electrochemical impedance spectroscopy. Electrochemical studies of the modified glass carbon electrode (GCE) were carried out by the cyclic voltammetry and differential pulse voltammograms (DPV) methods. The RGO/Cu-TECP/GCE exhibited enhanced electrocatalytic activity towards the detection of dopamine (DA). The detection limit was 0.58 μM, while the linear range was from 2 to 200 μM ([Formula: see text] 0.997).

Simulations of hydrogen, carbon dioxide, and small hydrocarbon sorption in a nitrogen-rich rht-metal–organic framework

Detailed theoretical insights into the gas-sorption mechanism of Cu-TDPAH are presented for the first time.

Pyrolysis of metal–organic framework (CuBTC) decorated filter paper as a low-cost and highly active catalyst for the reduction of 4-nitrophenol

The fabrication of noble metal free catalysts with excellent performance and high stability by a simple, efficient, general and low-cost approach remains an urgent task for solving the problem of resource shortage.

Modifying Commercial Carbon with Trace Amounts of ZIF to Prepare Derivatives with Superior ORR Activities

Reducing costs while maintaining high activities and stabilities of oxygen reduction reaction (ORR) catalysts has long been pursued for applications to membrane fuel cells. Here, an absorption-reaction method is used to prepare a zeolitic imidazolate framework coated commercial carbon, and the pyrolysis of such material brings about impressive ORR activities and stabilities with large diffusion-limited current density, half-wave potential, and no obvious decay after 10 000 cyclic voltammetry cycles, which is even better than that of the commercial Pt/C catalysts. The absorption-reaction method is realized by simply soaking the commercial carbon black sequentially in Co(NO₃ )₂ and 2-methylimidazole solutions at ambient conditions. The detailed analysis on such carbon materials reveals that both Co and N are essential to activities, even the amount of N and Co species is very low. The reduction of raw materials and simplified handling procedures result in well-controlled costs in applications.