Integration Of Metal-organic Frameworks Research Articles

Measuring Mass Transfer of n-Hexane and 2-Chloroethyl Ethyl Sulfide in Sorbent/Polymer Fiber Composites Using a Volumetric Adsorption Apparatus.

The integration of metal-organic frameworks (MOFs) into composite systems serves as an effective strategy to increase the processability of these materials. Notably, MOF/fiber composites have shown much promise as protective equipment for the capture and remediation of chemical warfare agents. However, the practical application of these composites requires an understanding of their mass transport properties, as both mass transfer resistance at the surface and diffusion within the materials can impact the efficacy of these materials. In this work, we synthesized composite fibers of MOF-808 and amidoxime-functionalized polymers of intrinsic microporosity (PIM-1-AX) and measured the adsorption and mass transport behavior of n-hexane and 2-chloroethyl ethyl sulfide (CEES), a sulfur mustard simulant. We developed a new Fickian diffusion model for cylindrical shapes to fit the dynamic adsorption data obtained from a commercial volumetric adsorption apparatus and found that mass transport behavior in composite fibers closely resembled that in the pure PIM fibers, regardless of MOF loading. Moreover, we found that n-hexane adsorption mirrors that of CEES, indicating that it could be used as a structural mimic for future adsorption studies of the sulfur mustard simulant. These preliminary insights and the new model introduced in this work lay the groundwork for the design of next-generation composite materials for practical applications.

Tailorable metal–organic framework based thin film nanocomposite membrane for lithium recovery from wasted batteries

This paper presents a tailorable method for the preparation of hierarchically structured membranes for efficient lithium recovery. Firstly, a metal–organic framework (MOF), namely MIL-101 (Cr), is grafted with different ionic liquids (ILs) onto its coordinate unsaturated site (CUS). The modified MOF (IL-MOF) is then used as nanoparticles to fabricate the flexible hydrophilic polyvinylidene fluoride (PVDF) based thin film nanocomposite (TFN) membrane. Secondly, comprehensive characterizations of both the nanoparticle and the IL-MOF based TFN membrane are carried out. Thirdly, lithium recovery is performed experimentally using simulated lithium-ion batteries (LIBs) leaching solution with the as-synthesized membrane. The first order ageing test of TFN membrane is conducted by MOF detachment tendency investigation and ILs leaching tendency evaluation. The results show that IL-MOF nanoparticles have a significant effect on lithium recovery. Compared with the original membrane, the IL-MOF-TFN membrane exhibits a fourfold lithium selectivity enhancement for SLi+,Mn2+ (from 1.73 to 8.91), SLi+,Co2+ (from 1.75 to 9.94) and SLi+,Ni2+ (from 1.69 to 10.09), as well as improved regeneration behavior, permeability (up to 45.0 L/(m2·h·bar)) and antifouling performance (flux recovery rate FRR up to 96.39 %). It is found that 98.9 % of the lithium was recovered from the feed solution over five repeated filtration cycles with maintained membrane integrity. This work highlights the advances in the design, modification and integration of MOFs into mechanically and chemically stable membrane technology for lithium recovery.

Low temperature in situ fabrication of NiFe2O4/tetragonal-BiVO4/Bi2MoO6 ternary heterostructure: A conjugated step-scheme multijunction photocatalyst with synergistic charge migration for antibiotic photodegradation and H2 generation

Rational design of novel conjugated step-scheme (S-scheme) multijunction heterostructure with synergistic charge channelization, superior light harvesting efficiency and strong redox ability is a pioneering approach to mimic natural photosynthesis process. Herein, a mild cetyltrimethyl ammoniumbromide (CTAB) assisted one pot reflux synthesis route is designed for in situ integration of metal organic framework (MOF)-derived NiFe2O4 with tetragonal-BiVO4 (t-BiVO4) and γ-Bi2MoO6 to prepare NiFe2O4/t-BiVO4/Bi2MoO6 (NFO/BVO/BMO) ternary composites. Morphologically, fine dispersion of NiFe2O4 (NFO) quantum dots over γ-Bi2MoO6 (BMO) and t-BiVO4 (BVO) nanoplates yielded three types of microscopic heterojunctions among BMO-BVO, BVO-NFO and BMO-NFO phases. The ternary composites displayed important physicochemical attributes including high surface area, strong optical absorption, superior charge mobility and higher excited state lifetime which accounted for its improved photocatalytic activity towards ciprofloxacin degradation (>99% in 90 min) and H2 evolution (1.11 mmolh-1g−1, photon conversion efficiency 18.5%). Kinetics study revealed 12–55 fold higher ciprofloxacin photodegradation activity and 31–41 times higher H2 evolution rate for the ternary composite in comparison to the pure semiconductors. A conjugated S-scheme charge transfer mechanism has been deduced from comprehensive band position analysis and radical trapping study to explain the enhanced photocatalytic activity. This work for the first time demonstrated the rational construction of conjugated S-scheme heterostructures with potential application in water remediation and green H2 production.

Recent Progress in MOF-Based Electrochemical Sensors for Non-Enzymatic Glucose Detection

In recent years, substantial advancements have been made in the development of enzyme-free glucose sensors utilizing pristine metal-organic frameworks (MOFs) and their combinations. This paper provides a comprehensive exploration of various MOF-based glucose sensors, encompassing monometallic MOF sensors as well as multi-metal MOF combinations. These approaches demonstrate improved glucose detection capabilities, facilitated by the augmented surface area and availability of active sites within the MOF structures. Furthermore, the paper delves into the application of MOF complexes and derivatives in enzyme-free glucose sensing. Derivatives incorporating carbon or metal components, such as carbon cloth synthesis, rGO-MOF composites, and core–shell structures incorporating noble metals, exhibit enhanced electrochemical performance. Additionally, the integration of MOFs with foams or biomolecules, such as porphyrins, enhances the electrocatalytic properties for glucose detection. Finally, this paper concludes with an outlook on the future development prospects of enzyme-free glucose MOF sensors.

Tuning the Electrical Conductivity of a Flexible Fabric-Based Cu-HHTP Film through a Novel Redox Interaction between the Guest-Host System.

Integration of metal-organic frameworks (MOFs) and flexible fabrics has been recently considered as a promising strategy applied in wearable electronic devices. We synthesized a flexible fabric-based Cu-HHTP film consisted of Cu2+ ions and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) via a self-sacrificial template method. The obtained Cu-HHTP film displays an outstanding nanostructured surface and uniformity. Iodine molecules are first introduced into the pores of Cu-HHTP to investigate the influence of guest molecules on electrical conductivity in a 2D guest-host system. After doping, the conductivity of the Cu-HHTP film shows an increased dependent on the doping time, and the maximum value is more than 30 times that of the original MOFs. The enhanced electrical conductivity results from an intriguing redox interaction occurred between the confined iodine molecules and the framework. The organic ligands are oxidized by iodine molecules, and generating new ions allows for subsequent participation in the regulation of the mixed valence bands of copper ions in MOFs, changing the ratio of Cu2+/Cu+, promoting the charge transport of the framework, and then synergistically enhancing the electronic conductivity. This study successfully prepared a flexible fabric-based conductive I2@Cu-HHTP film and presented insights into revealing the behavior of iodine molecules after entering the Cu-HHTP pores, expanding the possibilities of Cu-HHTP used in flexible wearable electronics.

Core−shell structured hollow copper sulfide@metal−organic framework for magnetic resonance imaging guided photothermal therapy in second near-infrared biological window

Multifunctional core-shell hybrids formed by integration of metal-organic framework (MOF) and functional materials have attracted extensive attention as promising theranostic nanoplatforms due to their combined novel properties and enhanced therapeutic efficacy. Recently, the second near-infrared (NIR-II, 1000–1700 nm) laser-induced photothermal therapy (PTT) as compared to the NIR-I(700–950 nm) laser-induced PTT has displayed improved therapeutic effects owing to its merits that include deeper tissue penetration and increased maximum permissible exposure. Herein, a novel core-shell hollow copper sulfide@metal−organic framework (HCuS@MIL-100) has been successfully fabricated by a layer-by-layer technique for the first time and their collective theranostic effects are investigated in vitro and in vivo. In this platform, the inner HCuS was applied as the NIR-II photothermal agent with excellent NIR-II absorption feature, leading to impressive photothermal effects under irradiation by 1064 nm light. With MIL-100 as the shell, HCuS@MIL-100 not only displayed optimal biocompatibility but also presented superior T2 magnetic resonance imaging (MRI) ability. In the current study multifunctional hollow core-shell HCuS@MIL-100 are fabricated for the MRI-guided PTT. This study also offers a facile and effective strategy for the development of novel theranostic platforms with high efficiency through the integration of MOFs and functional materials.

Wet-Adhesive On-Skin Sensors Based on Metal-Organic Frameworks for Wireless Monitoring of Metabolites in Sweat.

Metal-organic frameworks (MOFs) with well-defined porous structures and tailored functionalities have been widely used in chemical sensing. However, the integration of MOFs with flexible electronic devices for wearable sensing is challenging because of their low electrical conductivity and fragile mechanical properties. Herein, a wearable sweat sensor for metabolite detection is presented by integrating an electrically conductive Ni-MOF with a flexible nanocellulose substrate. The MOF-based layered film sensor with inherent conductivity, highly porous structure, and active catalytic properties enables the selective and accurate detection of vitamin C and uric acid. More importantly, the lightweight sensor can conformably self-adhere to sweaty skin and exhibits high water-vapor permeability. Furthermore, a wireless epidermal nutrition tracking system for the in situ monitoring of the dynamics of sweat vitamin C is demonstrated, the results of which are comparable to those tested by high-performance liquid chromatography. This study opens a new avenue for integrating MOFs as the active layer in wearable electronic devices and holds promise for the future development of high-performance electronics with enhanced sensing, energy production, and catalytic capabilities through the implementation of multifunctional MOFs.

Enhanced removal of oxytetracycline from wastewater using bimetallic Fe/Ni nanoparticles combined with ZIF-8 nanocomposites.

The integration of metal-organic frameworks with other functional materials has recently emerged as a promising approach for creating innovative materials for environmental remediation. Here, a nano-sized iron/nickel (Fe/Ni) functionalized zeolitic imidazolate framework-8 (ZIF-8-Fe/Ni) was fabricated for oxytetracycline (OTC) removal from wastewater. Cyclic voltammetry and amperometric I-t measurements indicated that OTC was degraded by ZIF-8-Fe/Ni. X-ray diffraction spectroscopy (XRD), transmission electron microscopy mapping (TEM-mapping) and X-ray photoelectron spectroscopy (XPS) indicated that Fe/Ni was evenly dispersed throughout ZIF-8 and partially oxidized after reaction with OTC. OTC adsorption isotherms and kinetics best fitted the Langmuir isotherm (R2>0.982) and pseudo-second-order model (R2>0.997), respectively. Reduction kinetics data followed the pseudo-first-order model (R2>0.905), where the apparent activation energy (Ea) was 22.9kJmol-1, demonstrating that OTC degradation was mainly via a chemical process. The practical removal efficiency of OTC from real wastewater by ZIF-8-Fe/Ni was 92.6%, where even after application of ZIF-8-Fe/Ni for 5 consecutive removal cycles, a high OTC removal of 74.9% was maintained. Thus ZIF-8-Fe/Ni exhibited both high removal efficiency and good recyclability.

Metal-organic frameworks decorated wood aerogels for efficient particulate matter removal

The severe indoor/outdoor air contamination caused by hazardous particulate matters (PMs) has a devastating impact on the environment and human health. Herein, air filters fabricated from delignified wood aerogels and metal–organic frameworks (MOFs) were used for PM removal. Two specially designed MOFs (i.e. Zn-based ZIF-L and Zr-based UiO-66-NH2) were deposited into a highly porous wood matrix through in situ growth approach. The MOF crystals are attached tightly to the highly available cellulose surface groups and distributed uniformly. The integration of MOFs can regulate the aerogel morphology and surface property, leading to enhanced PM removal performance. Bare wood aerogels beard removal efficiencies of 70.7% and 75.0% for PM2.5 and PM10, with a low-pressure drop of 15 Pa. By contrast, ZIF-L decorated wood aerogels exhibited PM2.5 and PM10 removal efficiencies of 97.6% and 99.5%, respectively, which are ascribed to the increased interception/impaction of PMs with the positively charged ZIF-L layer. While UiO-66-NH2 functionalized wood aerogels demonstrated PM2.5 and PM10 removal efficiencies of 96.4% and 98.9% because of the hierarchical filter matrix and the presence of polar –NH2 groups. Moreover, MOF modified wood aerogels can be easily regenerated and superior reusability can be achieved. This work provides an effective and economic strategy for the preparation of air filters from renewable materials.

Construction of metal-organic framework-nucleic acid composites and their application in fluorescent biomedical sensing

<p indent="0mm"><b/>Metal organic frameworks (MOFs) are a new class of porous materials composed of inorganic metal nodes and organic ligands, and are widely used in biomedical, biosensing fields due to their adjustable structure and function, large specific surface area, and diverse sites. Furthermore, much progress has been made in nucleic acid molecules used for target recognition and molecular detection in recent years due to their unique molecular recognition and flexible editability. Therefore, the integration of MOFs and nucleic acids has considerably expanded the functions and applications of both monomers, and has become a hot research topic in chemistry, biology, and medicine. This review covers current advancements in the construction of nucleic acid-functionalized MOF composites and their applications in fluorescent biological fields. Firstly, different functionalization methods of nucleic acid molecules on the surface of MOFs are introduced to provide a basis for the construction of nucleic acid-functionalized MOFs biosensors. Secondly, according to the varied functions performed by MOFs, the applications of MOF-nucleic acid composites in fluorescent biomedical sensing are defined and outlined as fluorescence quenching MOFs, luminous MOFs, and stimulus responsive MOFs, respectively. Finally, the current limitations of MOF-nucleic acid composites in biosensing applications as well as their future development in this field are discussed.

Sustainable and Efficient Manufacturing of Metal-Organic Framework-Based Polymer Nanocomposites by Reactive Extrusion

Over the past decades, metal–organic frameworks (MOFs) have been considered to be a promising category of materials for gas storage, separation, and catalysis. However, industrial commercialization of MOFs is restricted by their intrinsic operating conditions due to poor processability in powder shape. An integration of MOFs with a polymer matrix has been considered as an efficient way to improve the practical utility of powder MOFs. In contrast to the conventionally discrete bottom-up principle in milligram scale, in this work, a continuously rapid and solvent-free approach is developed to directly manufacture MOF–polymer nanocomposites from solid reagents (polymer matrix, metal irons, and ligands) via reactive extrusion, which can reach a space time yield as high as ∼1.2 × 105 kg/m3/day. To investigate the feasibility of this one-step reactive extrusion method, two types of widely used polymer matrixes, polypropylene and polystyrene, are chosen to manufacture different MOF-based nanocomposites using a Process 11 parallel twin-screw extruder. Specific MOFs, zeolitic imidazolate frameworks (ZIFs), namely, ZIF-8 and ZIF-67, are used herein. The improvements of thermal stability, flammability, and mechanical properties of the polymer matrix are investigated in detail. The catalytic application for activating peroxymonosulfate by ZIF-67 for contaminant degradation is also explored. With a small amount of ZIF-67/polymer nanocomposite films, more than 90% of methylene blue can be catalytically degraded in 25 min. This newly developed manufacturing approach can be extended to other functional polymers in combination with different MOFs to resolve global challenges in carbon neutrality and clean water.

Recent Advances in the Application and Mechanism of Carbon Dots/Metal-Organic Frameworks Hybrids in Photocatalysis and the Detection of Environmental Pollutants.

Metal-organic frameworks (MOFs) are a class of crystalline porous materials with simple synthesis conditions, large specific surface area, structural diversity, and a wide range of interesting properties. The integration of MOFs with other materials can provide new multifunctional composites that exhibit both component properties and new characteristics. In recent years, the integration of carbon dots (CDs) into MOFs to form composites has shown improved optical properties and fascinating new characteristics. This review focuses on the design and synthesis strategies of CDs@MOFs composites (including pore-confined synthesis, in situ encapsulation, post-synthesis modification and impregnation method) and their recent research progress in photocatalysis and detection of environmental pollutants. Both the achievements and problems are evaluated and proposed, and the opportunities and challenges of CDs@MOF composite are discussed.

Integration of Metal-Organic Frameworks with Bi-Nanoprobes as Dual-Emissive Ratiometric Sensors for Fast and Highly Sensitive Determination of Food Hazards.

Functional nanoprobes which detect specific food hazards quickly and simply are still in high demand in the field of food-safety inspection research. In the present work, a dual-emission metal-organic framework-based ratiometric fluorescence probe was integrated to detect Cu2+ and Pb2+ with rapidness and ease. Specifically, quantum dots (QDs) and carbon quantum dots (CQDs) were successfully embedded into zeolitic imidazolate framework-67 (ZIF-67) to function as a novel ratiometric fluorescent sensing composite. The ratiometric fluorescence signal of CQDs/QDs@ZIF-67 was significantly aligned with the concentration of metal ions to give an extremely low detection limit of 0.3324 nM. The highly sensitive and selective CQDs/QDs@ZIF-67 composite showed potential for the rapid and cost-effective detection of two metal ions.

Improvement of aqueous stability and anti-osteoporosis properties of Zn-MOF coatings on titanium implants by hydrophobic raloxifene

Endowed with superior tailorability and functionality, metal–organic frameworks (MOFs) have been exploited for their diverse applications in biomedicine. However, the instability of MOFs under an aqueous environment causes an accelerated degradation preventing their clinical applications and commercialization. To address this issue, studies have reported the incorporation of hydrophobic functional groups into MOF to enhance its stability. In this study, we aimed to fabricate a multifunctional coating on titanium implants by exploiting the synergy between Zn-based MOFs and raloxifene (Ral). We theorized that the integration of MOF and Ral will not only locally deliver the drug, but also take advantage of the hydrophobic functional group of Ral to enhance the stability of MOF in an aqueous environment. The release studies showed a sustained release of both Zn2+ and Ral for more than 14 d. In-depth in vitro investigations also verified that MOF/Ral coatings significantly enhanced the cell viability and osteogenic differentiation of osteoblasts, as well as decreasing the tartrate-resistant acid phosphatase activity and osteoclastic biomarker expressions. In addition, both micro-computed tomography and immunohistochemical analysis further confirmed the efficacy of MOF/Ral coatings in the formation of new bone within the femurs of osteoporotic rats. The feasibility of MOF/Ral coated titanium implants in inhibiting osteolysis and promoting osteogenesis has undoubtedly proved their clinical prospects in the treatment of osteoporotic bone injury.

Efficiently Regulating the Electrical Properties of Flexible Fabric‐Based Cu3(BTC)2 Thin Film by Introducing Various Guest Molecules

AbstractRecently, the flexibility of 2D conductive metal–organic frameworks (MOFs) is an important precondition for manufacturing high‐performance smart electronic devices. Preparation of MOFs thin film has drawn much attention, and increasingly more MOF thin films have been deposited on different rigid substrates like glass, silicon, and metal electrodes. However, they do not meet the requirements for flexible materials, such as wearable electronic devices. Here, the fabric‐based composites (the integration of MOFs and fabric materials) can solve this problem. Insulating polyester fabric is chosen as a flexible substrate and atom layer deposition (ALD) and the layer‐by‐layer (LBL) method (also called the liquid phase epitaxy method) are combined to synthesize Cu3(BTC)2 thin film. 7,7,8,8‐tetracyanoquinodimethane (TCNQ) and polypyrrole (PPy) are chosen to improve the conductivity of the MOF thin films. The conductivity of Cu3(BTC)2 thin film is improved by more than four orders of magnitude compared to that of the original sample. This research shows that the large‐area lightweight fabric‐based Cu3(BTC)2 thin films, which possess excellent uniformity and flexibility and controllable thickness, can be prepared at room temperature; this allows MOFs to be applied in more areas, such as large‐area electronic devices and smart wearable sensing equipment.

Tunable arrangement of hydrogel and cyclodextrin-based metal organic frameworks suitable for drug encapsulation and release

The present study focused on the integration of beta-cyclodextrin based metal-organic frameworks (β-CDMOF) with polymer to obtain hybrid materials with advantageous properties compared to traditional single-component polymers or metal-organic frameworks (MOF) matrixes. We fabricated two complexes with different morphology and structure. During the in situ growth of β-CDMOF around the hydrogel, potassium ions on polysaccharides gradually dissociated to participate in the growth of crystals, while other potassium ions on the carboxylic acid groups provided bridges between crystals and hydrogel, forming a necklace-shaped complex (SHPs@β-CDMOF). Hydrogen bonding and coordination interactions between β-CDMOF and hydrogel are present in a dendritic sandwich-shaped complex (β-CDMOF@SHPs). Furthermore, using the hydrophobic molecule curcumin as a model drug, we have demonstrated that SHPs@β-CDMOF and β-CDMOF@SHPs hybrid materials stabilize the included drug and have potential for controlled drug release. Collectively, the integration of MOF with polymer holds a great promise for drug delivery applications.

Surface-Mounted Metal-Organic Frameworks: Past, Present, and Future Perspectives.

Metal-organic frameworks (MOFs) are an emerging class of porous materials composed of organic linkers and metal centers/clusters. The integration of MOFs onto the solid surface as thin films/coatings has spurred great interest, thanks to leveraging control over their morphology (such as size- and shape-regulated crystals) and orientation, flexible processability, and easy recyclability. These aspects, in synergy, promise a wide range of applications, including but not limited to gas/liquid separations, chemical sensing, and electronics. Dozens of innovative methods have been developed to manipulate MOFs on various solid substrates for academic studies and potential industrial applications. Among the developed deposition methods, the liquid-phase epitaxial layer-by-layer (LPE-LbL) method has demonstrated its merits over precise control of the thickness, roughness, homogeneity, and orientations, among others. Herein, we discuss the major developments of surface-mounted MOFs (SURMOFs) in LbL process optimization, summarizing the SURMOFs' performance in different applications, and put forward our perspective on the future of SURMOFs in terms of advances in the formulation, applications, and challenges. Finally, future prospects and challenges with respect to SURMOFs growth will be discussed, keeping the focus on their widening applications.

Fibre-based composites from the integration of metal–organic frameworks and polymers

The integration of metal–organic frameworks (MOFs) with polymer fibres enables the formation of fibrous composite materials with advantages over traditional single-component polymer films and mixed-matrix membranes. In comparison with mixed-matrix membranes, MOF–polymer fibrous composites offer improved molecular transport through the material and easier access to the active sites of MOFs. These attributes make fibrous composites appealing for clothing, personal protective equipment, air purification and filtration, biomedical equipment and delivery of therapeutics, along with detection and sensing applications. In this Review, we outline approaches for the incorporation of MOFs into, or onto, polymer fibres and present some applications for MOF–polymer fabrics. The integration of MOFs and polymers can either occur prior to fibre formation (namely, MOF-first), via particle deposition (resulting in either covalent or non-covalent attachment) of MOFs to the fibre or by in situ MOF growth after fibre formation (namely, fibre-first). We focus on the structure–processing–activity relationships — for example, MOF loading, MOF crystal size, polymer concentration and processing parameters — that impact the behaviour of fibrous composites. We conclude with a discussion of research avenues that can advance this burgeoning field. Composites made from metal–organic frameworks and polymer fibres are gaining popularity in many applications because of their tailorable morphologies and properties. This Review summarizes various methods for fabricating these composites, explores structure–processing–activity relationships and discusses future research opportunities.

Epoxy Functional Composites Based on Lanthanide Metal–Organic Frameworks for Luminescent Polymer Materials

The integration of metal-organic frameworks (MOF) into organic polymers represents a direct and effective strategy for developing innovative composite materials that combine the exceptional properties of MOFs with the robustness of organic polymers. However, the preparation of MOF@polymer hybrid composites requires an efficient dispersion and interaction of MOF particles with polymer matrices, which remains a significant challenge. In this work, a new simple and direct approach was applied for the development of Ln-MOF@polymer materials. A series of Ln-MOF@TGIC composites {Ln-MOF = [Ln(μ3-BTC)(H2O)6]n (Ln-BTC), where Ln = Eu, Tb, Eu0.05Tb0.95; H3BTC = 1,3,5-benzenetricarboxylic acid; TGIC = triglycidyl isocyanurate} were successfully obtained by applying a grinding method via the chemical bonding between uncoordinated carboxylate groups in Ln-BTC and epoxy groups in TGIC. The Ln-BTC@TGIC materials possess significant fluorescence characteristics with superior emission lifetimes and quantum yields if compared to parent Ln-MOFs. Interestingly, under the UV irradiation, a considerable color change from yellow in Eu0.05Tb0.95-BTC to red in Eu0.05Tb0.95-BTC@TGIC was observed. The energy-transfer mechanism was also rationalized by the density functional theory (DFT) calculations. The developed Ln-BTC@TGIC composites were further applied as functional fluorescent coatings for the fabrication, via a simple spraying method, of the flexible polyimide (PI) films, Ln-BTC@TGIC@PI. Thus, the present work unveils a new methodology and expands its applicability for the design and assembly of stable, multicomponent, and soft polymer materials with remarkable fluorescence properties.

Aptamer-functionalized metal-organic frameworks (MOFs) for biosensing

As a class of crystalline porous materials, metal-organic frameworks (MOFs) have attracted increasing attention. Due to the nanoscale framework structure, adjustable pore size, large specific surface area, and good chemical stability, MOFs have been applied widely in many fields such as biosensors, biomedicine, electrocatalysis, energy storage and conversions. Especially when they are combined with aptamer functionalization, MOFs can be utilized to construct high-performance biosensors for numerous applications ranging from medical diagnostics and food safety inspection, to environmental surveillance. Herein, this article reviews recent innovations of aptamer-functionalized MOFs-based biosensors and their bio-applications. We first briefly introduce different functionalization methods of MOFs with aptamers, which provide a foundation for the construction of MOFs-based aptasensors. Then, we comprehensively summarize different types of MOFs-based aptasensors and their applications, in which MOFs serve as either signal probes or signal probe carriers for optical, electrochemical, and photoelectrochemical detection, with an emphasis on the former. Given recent substantial research interests in stimuli-responsive materials and the microfluidic lab-on-a-chip technology, we also present the stimuli-responsive aptamer-functionalized MOFs for sensing, followed by a brief overview on the integration of MOFs on microfluidic devices. Current limitations and prospective trends of MOFs-based biosensors are discussed at the end.