Modified ZIF-8 Nanoparticles for Targeted Metabolic Treatment of Acute Spinal Cord Injury

The activation of proinflammatory M1-type macrophages in the injured lesion accelerates the progression of a spinal cord injury (SCI). However, adverse side effects during systemic treatments targeting M1 macrophages have limited their applications. Nanoplatforms are novel carriers of traditional Chinese medicine because of their great efficiency to deliver and accumulation in the lesion. Herein, we synthesized a modified zeolitic imidazolate framework-8 (ZIF-8) nanoplatform for internalization and accumulation in the injured spinal cord and effective administration for SCI. In vitro and in vivo experiments suggested that Prussian blue and Schisandrin B modified ZIF-8 effectively accumulated in M1 macrophages, inhibited reactive oxygen species (ROS), and polarized the macrophage from proinflammatory M1 to anti-inflammatory M2 for rapid tissue infiltration by reprogramming the metabolic macrophages phenotype. This nanoplatform achieves a synergistic therapeutic effect of immunomodulation and neuroprotection, thereby shedding new light on the application of ZIF-8, and provides great potential for SCI.

Enhancing Bone Regeneration through CDC20-Loaded ZIF-8 Nanoparticles Wrapped in Erythrocyte Membranes with Targeting Aptamer

In the context of bone regeneration, nanoparticles harboring osteogenic factors have emerged as pivotal agents for modulating the differentiation fate of stem cells. However, persistent challenges surrounding biocompatibility, loading efficiency, and precise targeting ability warrant innovative solution. In this study, a novel nanoparticle platform founded upon the zeolitic imidazolate framework-8 (ZIF-8) is introduced. This new design, CDC20@ZIF-8@eM-Apt, involves the envelopment of ZIF-8 within an erythrocyte membrane (eM) cloak, and is coupled with a targeting aptamer. ZIF-8, distinguished by its porosity, biocompatibility, and robust cargo transport capabilities, constitutes the core framework. Cell division cycle protein 20 homolog (CDC20) is illuminated as a new target in bone regeneration. The eM plays a dual role in maintaining nanoparticle stability and facilitating fusion with target cell membranes, while the aptamer orchestrates the specific recruitment of bone marrow mesenchymal stem cells (BMSCs) within bone defect sites. Significantly, CDC20@ZIF-8@eM-Apt amplifies osteogenic differentiation of BMSCs via the inhibition of NF-κB p65, and concurrently catalyzes bone regeneration in two bone defect models. Consequently, CDC20@ZIF-8@eM-Apt introduces a pioneering strategy for tackling bone defects and associated maladies, opening novel avenues in therapeutic intervention.

Versatile Bioactive Glass/Zeolitic Imidazolate Framework-8-Based Skin Scaffolds toward High-Performance Wound Healing

Designing a novel biomaterial for wound healing is based on biocompatibility and excellent mechanical strength. In this study, bioactive glass (BG) and zeolitic imidazolate framework-8 (ZIF-8) have been incorporated into poly(ε-caprolactone)/poly(vinyl alcohol) (PCL/PVA) composite skin scaffolds via microfluidic electrospinning. Interestingly, the addition of ZIF-8 further strengthens the BG stability and demonstrates better antibacterial effects. Utilizing the slow release of Zn, Ca, and Si ions, it also significantly promotes growth factor expression and skin regeneration. In addition, it is further demonstrated by in vitro and in vivo studies that the prepared composite skin scaffolds possess excellent biocompatibility, antibacterial capabilities, and mechanical properties. The prepared BG/ZIF-8-loaded scaffold possesses high tensile strength (26 MPa) and excellent antibacterial properties (achieves 89.64 and 78.8% inhibition of E. coli and S. aureus, respectively), and cell viability increased by 51.2%. More importantly, the wound shrinkage of the BG/ZIF-8-loaded scaffold is better than that of an unloaded scaffold, and the shrinkage rates of PCL/PVA@BG/ZIF-8(1 wt %) group is 95% with 2.2 mm granulation growth thickness within 12 days. Thus, the composite skin scaffold loaded with BG/ZIF-8 prepared by microfluidic electrospinning provides a new perspective for accelerating wound healing and is a potential novel therapeutic strategy for efficient wound healing.

Laser Synthesis of Nonprecious Metal-Based Single-Atom Catalysts for Oxygen Reduction Reaction

Development of nonprecious metal-based single-atom catalysts (SACs) has provided opportunities to substitute Pt group metals and offer maximum atom utilization and unique coordination environments. Among these catalysts, Fe-N-C catalysts with atomically dispersed Fe-N4 active sites have emerged as some of the most promising oxygen reduction reaction (ORR) catalysts. However, furnace synthesis of Fe-N-C catalysts with carbon substrate derived from metal-organic framework (MOF) involves a high-temperature procedure, in which nitrogen from the carbonized MOF tends to be removed, subsequently leading to a low density of active sites. In this work, we developed a rapid and simple solid-state route to fabricate SACs through laser-induced thermal activation (LITA) of carbonized zeolitic imidazolate framework-8 (ZIF-8) adsorbed with Fe precursors. The results demonstrate that the laser process effectively avoids the loss of nitrogen in the nitrogen-doped carbon substrate and achieves a loading of Fe single atoms of 2.3 wt %, in comparison with that of 1.2 wt % from the conventional furnace treatment. The Fe-N-C catalyst synthesized in the study presents a half-wave potential of 0.91 V for ORR in alkaline media, which is higher than that of commercial Pt/C (0.87 V). When used as a cathode catalyst in zinc-air batteries (ZABs), the battery exhibits excellent electrochemical performance. This work also demonstrates the versatility of the technique through the successful synthesis of Co-N-C and Ni-N-C single atoms on nitrogen-doped carbon substrates.

Zeolitic Imidazolate Framework-8 Composite-Based Enzyme-Linked Aptamer Assay for the Sensitive Detection of Deoxynivalenol

The mycotoxin deoxynivalenol (DON) is a prevalent contaminant in cereals that threatens the health of both humans and animals and causes economic losses due to crop contamination. The rapid and sensitive detection of DON is essential for food safety. Herein, a colorimetric biosensor based on horseradish peroxidase- and gold nanoparticle-encapsulated zeolitic imidazolate framework-8 (HRP&Au@ZIF-8) was developed for the sensitive screening of DON. The synthesized HRP&Au@ZIF-8 probes not only held great potential for signal amplification but also exhibited stable catalytic activity even under extreme conditions, which endowed the biosensor with both good sensitivity and stability. Under the optimized conditions, qualitative measurement of DON can be achieved through visual inspection, and quantitative evaluation can be performed via absorbance measurements at a characteristic wavelength of 450 nm. The proposed method has demonstrated high sensitivity with a linear detection range of 1-200 ng/mL and a detection limit of 0.5068 ng/mL. It also presented good selectivity and reliability. Furthermore, DON in spiked cereal samples has been quantified successfully using this method. This novel approach demonstrates significant potential for the facile and expeditious detection of DON in cereal products and brings us one step closer to enhancing food safety.

Pomegranate-Bionic Encapsulating Horseradish Peroxidase Using Dopamine Flexible Scaffold-Coated Multishell Porous ZIF-8 To Enhance Immunochromatographic Diagnosis

Nanoparticle-natural enzyme complexes are receiving increasing attention as the promising signal reporters for colorimetric lateral flow immunoassay (LFIA). Nonetheless, it remains a challenge to develop the nanocomplexes with high loading efficiency, catalytic efficiency, and colorimetric signal brightness. Herein, inspired by pomegranate structure, we reported the synthesis of a colorimetric catalytic nanocomplex ((HRP@ZIF-8)³@PDA@HRP), using dopamine flexible scaffold-coated multishell porous zeolitic imidazolate framework-8 (ZIF-8) as a hierarchical scaffold to encapsulate horseradish peroxidase (HRP), and described its potential to promote an ultrasensitive colorimetric LFIA of cardiac troponin I (cTnI). (HRP@ZIF-8)³@PDA@HRP exhibited ultrahigh HRP loading efficiency and catalytic activity due to the epitaxial shell-by-shell overgrowth of porous ZIF-8 scaffold, which provided more cavities for enzyme immobilization and a diffusion path for the catalytic substrate. Furthermore, the polydopamine (PDA) layer on the (HRP@ZIF-8)³ surface both enhanced the colorimetric signal brightness and acted as a flexible scaffold to immobilize HRP, further increasing the amount of enzyme. Following integration with LFIA, the developed platform achieved an ultrasensitive colorimetric test strip assay for cTnI with pre- and postcatalytic naked-eye detection sensitivities of 0.5 ng mL^-1 and 0.01 ng mL^-1, respectively, which were 4/2- and 200/100-fold higher than gold nanoparticles (AuNPs)/PDA-based LFIA and comparable to chemiluminescence immunoassay. Further, the quantitative testing results of the developed colorimetric LFIA on 57 clinical serum samples agreed well with the clinical data. This work provides ideas for the design of natural enzymes-based colorimetric catalytic nanocomplex to encourage applications for the development of ultrasensitive LFIA for early diseases diagnosis.

In Situ Construction of Nitrogen-Doped and Zinc-Confined Microporous Carbon Enabling Efficient Na+-Storage Abilities

Benefiting from the additional active sites for sodium-ion (Na⁺) adsorption and porous architecture for electrolyte accessibility, nitrogen-doped porous carbon has been considered the alternative anode material for Na⁺-storage applications. In this study, nitrogen-doped and zinc-confined microporous carbon (N,Z-MPC) powders are successfully prepared by thermally pyrolyzing the polyhedral ZIF-8 nanoparticles under an argon atmosphere. Following the electrochemical measurements, the N,Z-MPC not only delivers good reversible capacity (423 mAh/g at 0.02 A/g) and comparable rate capability (104 mAh/g at 1.0 A/g) but also achieves a remarkable cyclability (capacity retention: 96.6% after 3000 cycles at 1.0 A/g). Those can be attributed to its intrinsic characteristics: (a) 67% of the disordered structure, (b) 0.38 nm of interplanar distance, (c) a great proportion of sp²-type carbon, (d) abundant microporosity, (e) 16.1% of nitrogen doping, and (f) existence of sodiophilic Zn species, synergistically enhancing the electrochemical performances. Accordingly, the findings observed here support the N,Z-MPC to be a potential anode material enabling exceptional Na⁺-storage abilities.

A Mechanically Reinforced Super Bone Glue Makes a Leap in Hard Tissue Strong Adhesion and Augmented Bone Regeneration

Existing bone tissue engineering strategies aim to achieve minimize surgical trauma, stabilize the injured area, and establish a dynamic osteogenic microenvironment. The cutting-edge bone glue developed in this study satisfies these criteria. Inspired by the excellent adhesive properties of mussels, herein, a super osteogenic glue (L-DPZ) that integrates poly(vinyl alcohol), L-dopa amino acid, and zeolitic imidazolate framework-8 characterized by catechol-metal coordination is used to successfully adhere to hard tissue with a maximum adhesive strength of 10 MPa, which is much higher than those of commercial and previously reported bone glues. The stable hard tissue adhesion also enables it to adhere strongly to luxated or broken teeth, Bio-Oss (a typical bone graft material), and splice fragments from comminuted fractures of the rabbit femur. Then, it is testified that the L-DPZ hydrogels exhibit satisfactory biocompatibility, stable degradability, and osteogenic ability in vitro. Moreover, the ability to anchor Bio-Oss and sustained osteogenesis of L-DPZ result in satisfactory healing in calvarial bone defect models in rabbits, as observed by increased bone thickness and the ingrowth of new bone tissue. These results are expected to demonstrate solutions to clinical dilemmas such as comminuted bone fracture fixation, bone defect reconstruction, and teeth dislocation replantation.

[Immobilizing engineered Escherichia coli cells into zeolitic imidazolate framework 8 for efficient biosynthesis of Ala-Gln]

The α-amino acid ester acyltransferase (SAET) from Sphingobacterium siyangensis is one of the enzymes with the highest catalytic ability for the biosynthesis of l-alanyl-l-glutamine (Ala-Gln) with unprotected l-alanine methylester and l-glutamine. To improve the catalytic performance of SAET, a one-step method was used to rapidly prepare the immobilized cells (SAET@ZIF-8) in the aqueous system. The engineered Escherichia coli (E. coli) expressing SAET was encapsulated into the imidazole framework structure of metal organic zeolite (ZIF-8). Subsequently, the obtained SAET@ZIF-8 was characterized, and the catalytic activity, reusability and storage stability were also investigated. Results showed that the morphology of the prepared SAET@ZIF-8 nanoparticles was basically the same as that of the standard ZIF-8 materials reported in literature, and the introduction of cells did not significantly change the morphology of ZIF-8. After repeated use for 7 times, SAET@ZIF-8 could still retain 67% of the initial catalytic activity. Maintained at room temperature for 4 days, 50% of the original catalytic activity of SAET@ZIF-8 could be retained, indicating that SAET@ZIF-8 has good stability for reuse and storage. When used in the biosynthesis of Ala-Gln, the final concentration of Ala-Gln reached 62.83 mmol/L (13.65 g/L) after 30 min, the yield reached 0.455 g/(L·min), and the conversion rate relative to glutamine was 62.83%. All these results suggested that the preparation of SAET@ZIF-8 is an efficient strategy for the biosynthesis of Ala-Gln.

Metolachlor metal-organic framework nanoparticles for reducing leaching, ecotoxicity and improving bioactivity

BACKGROUND

The adverse effects of pesticides has led to a series of ecological, environmental and public health issues. Amide herbicides are an important agrochemical, yet many are prone to leach and pollute the environment, which limits their further application. In this study, metolachlor (METO) was selected as a model pesticide and a controlled released nanoparticle (NP) system was constructed employing a zeolitic imidazolate framework-8 hybrid inorganic-organic porous material (METO@ZIF-8).

RESULTS

The synthesis parameters of METO@ZIF-8 were optimized, and the loading content of METO@ZIF-8 was maximized by a central composite design of response surface test. The NPs were regular dodecahedron with uniform size (mostly 54.3 nm diameter). METO@ZIF-8 had high specific surface area and good dispersal in water. Moreover, it endowed the active ingredient with a pH-responsive release property. The nanocarrier effectively improved the adsorption capacity of METO in soil and reduce the leaching by 10.3-21.7%. Pot experiments suggested that the control effect of METO@ZIF-8 was 16.6 and 48.4% higher than that of METO emulsifiable concentrate (EC) and METO technical concentration (TC) at the recommended dose. Based on the excellent controlled release profiles, METO@ZIF-8 did not affect corn plant growth and significantly reduced the risk of phytotoxicity induced by METO. METO@ZIF-8 effectively reduced acute toxicity in zebrafish compared with METO EC.

CONCLUSION

This study explored the fabrication of a nanocarrier for improving the efficacy and promoting the environmental safety of leachable amide herbicides. © 2022 Society of Chemical Industry.

Nanoporous ZIF-8 Microparticles as Acetylcholinesterase and Alkaline Phosphatase Mimics for the Selective and Sensitive Detection of Ascorbic Acid Oxidase and Copper Ions

In this study, the alkaline phosphatase (ALP)-like activity of zeolitic-imidazolate framework-8 (ZIF-8) is reported for the first time. Then, colorimetric sensors for the ascorbic acid oxidase (AAO) and copper ion (Cu²⁺) detection were developed based on the acetylcholinesterase (AChE)- and ALP-like activities of ZIF-8. The ZIF-8 has good mimetic enzyme activity and exhibits high affinity to the substrates. Its AChE- and ALP-like activities also have good reusability and storage stability. Good linear dependences are obtained in the range of 1.3-250.0 μM (AChE-like activity-based) and 4.5-454.5 μM (ALP-like activity based) for Cu²⁺ detection. Furthermore, good linear dependence is also obtained based on the ALP-like activity of ZIF-8 for AAO detection in the range of 2.3-454.5 U/L. Their limits of detection (LODs) are calculated to be 0.7 µM, 2.8 µM, and 1.8 U/L, respectively. Finally, the sample spiked recoveries of Cu²⁺ in tap water, Cu²⁺, and AAO in human serum and rabbit plasma were measured, and the results are in the range of 80.0-119.3%. In short, the preparation of ZIF-8 is simple, environmentally friendly, and harmless, and can realize highly selective detection of AAO and Cu²⁺ in an efficient and fast process.

Dual-Modal Nanoscavenger for Detoxification of Organophosphorus Compounds

Organophosphorus compounds (OPs) pose great military and civilian hazards. However, therapeutic and prophylactic antidotes against OP poisoning remain challenging. In this study, we first developed a novel nanoscavenger (rOPH/ZIF-8@E-Lipo) against methyl paraoxon (MP) poisoning using enzyme immobilization and erythrocyte-liposome hybrid membrane camouflage techniques. Then, we evaluated the physicochemical characterization, stability, and biocompatibility of the nanoscavengers. Afterward, we examined acetylcholinesterase (AChE) activity, cell viability, and intracellular reactive oxygen species (ROS) to indicate the protective effects of the nanoscavengers in vitro. Following the pharmacokinetic and biodistribution studies, we further evaluated the therapeutic and prophylactic detoxification efficacy of the nanoscavengers against MP in various poisoning settings. Finally, we explored the penetration capacity of the nanoscavengers across the blood-brain barrier (BBB). The present study validated the successful construction of a novel nanoscavenger with excellent stability and biocompatibility. In vitro, the resulting nanoscavenger exhibited a significant protection against MP-induced AChE inactivation, oxidative stress, and cytotoxicity. In vivo, apart from the positive therapeutic effects, the nanoscavengers also exerted significant prophylactic detoxification efficacy against single lethal MP exposure, repeated lethal MP challenges, and sublethal MP poisoning. These excellent detoxification effects of the nanoscavengers against OPs may originate from a dual-mode mechanism of inner recombinant organophosphorus hydrolase (rOPH) and outer erythrocyte membrane-anchored AChE. Finally, in vitro and in vivo studies jointly demonstrated that monosialoganglioside (GM1)-modified rOPH/ZIF-8@E-Lipo could penetrate the BBB with high efficiency. In conclusion, a stable and safe dual-modal nanoscavenger was developed with BBB penetration capability, providing a promising strategy for the treatment and prevention of OP poisoning.

Stem Cell Membrane-Encapsulated Zeolitic Imidazolate Framework-8: A Targeted Nano-Platform for Osteogenic Differentiation

Mesenchymal stem cells (MSCs) have been recognized as one of the most promising pharmaceutical multipotent cells, and a key step for their wide application is to safely and efficiently regulate their activities. Various methods have been proposed to regulate the directional differentiation of MSCs during tissue regeneration, such as nanoparticles and metal ions. Herein, nanoscale zeolitic imidazolate framework-8 (ZIF-8), a Zn-based metal-organic framework, is modified to direct MSCs toward an osteoblast lineage. Specifically, ZIF-8 nanoparticles are encapsulated using stem cell membranes (SCMs) to mimic natural molecules and improve the biocompatibility and targeted ability toward MSCs. SCM/ZIF-8 nanoparticles adjust the sustained release of Zn²⁺ , and promote their specific internalization toward MSCs. The internalized SCM/ZIF-8 nanoparticles show excellent biocompatibility, and increase MSCs' osteogenic potentials. Moreover, RNA-sequencing results elucidate that the activated cyclic adenosine 3,5-monophosphate (cAMP)-PKA-CREB signaling pathway can be dominant in accelerating osteogenic differentiation. In vivo, SCM/ZIF-8 nanoparticles greatly promote the formation of new bone tissue in the femoral bone defect detected by 3D micro-CT, hematoxylin and eosin staining, and Masson staining after 4 weeks. Overall, the SCM-derived ZIF-8 nanostructures achieve the superior targeting ability, biocompatibility, and enhanced osteogenesis, providing a constructive design for tissue repair.

Site-Specific Controlled-Release Imidazolate Framework-8 for Dazomet Smart Delivery to Improve the Effective Utilization Rate and Reduce Biotoxicity

An accurate controlled-release strategy of pesticides is considered desirable in sustainable agriculture. A site-specific nanorelease system of dazomet (DZ) was proposed by employing the zeolitic imidazolate framework-8 composite (DZ@ZIF-8) by a one-pot method. The synthetic parameters of DZ@ZIF-8 were optimized, and the loading content of DZ was maximized. ZIF-8 endowed DZ with a pH-sensitive behavior. The collapse of the DZ@ZIF-8 structure and the site-specific release of DZ were triggered by acidic substances produced by Botrytis cinerea. In vitro and pot experiments showed that the fungicidal activity of DZ@ZIF-8 was about 36.3 and 42.7% higher than that of DZ, respectively. DZ is conventionally used before a crop is planted because of its volatility and toxicity. However, DZ@ZIF-8 could avoid phytotoxicity of DZ to plants, which made the application of DZ possible during plant growth. Moreover, the acute toxicity to zebrafish changed from high to moderate levels. This study highlights a potential strategy that improves DZ effective utilization and reduces side effects.

ZIF-8 nanoparticles coated with macrophage-derived microvesicles for sustained, targeted delivery of dexamethasone to arthritic joints

Dexamethasone sodium phosphate (Dex) is widely used in the clinic for the treatment of rheumatoid arthritis. However, it circulates in blood for a short time and it is linked to high risk of severe side effects caused by repeated dosing. Here, we encapsulated Dex onto zeolitic imidazolate framework-8 (ZIF-8) to prepare metal-organic framework nanoparticles with high drug loading efficiency. To prevent clearance by the mononuclear phagocyte system and extend time in circulation, the nanoparticles were also camouflaged with macrophage-derived microvesicles (MV) to obtain the biomimetic drug delivery system MV/Dex/ZIF-8. In vitro and in vivo experiments showed that the nanosystem had high drug loading and encapsulation efficiency, high stability, and long circulation time, and it permitted sustained drug release longer in inflamed joint tissues. Our study provides new insights into designing camouflaged drug carriers to prevent their phagocytosis and prolong their time in circulation.

A High-Luminescence Biomimetic Nanosensor Based on N, S-GQDs-Embedded Zinc-Based Metal-Organic Framework@Molecularly Imprinted Polymer for Sensitive Detection of Octopamine in Fermented Foods

In this study, a novel fluorescent molecularly imprinted nanosensor (N, S-GQDs@ZIF-8@MIP) based on the nitrogen and sulfur co-doped graphene quantum dots decorated zeolitic imidazolate framework-8 was constructed for the detection of octopamine (OA). Herein, ZIF-8 with a large surface area was introduced as a supporter of the sensing system, which effectively shortened the response time of the sensor. Meanwhile, high green luminescent N, S-GQDs and a maximum emission wavelength of 520 nm under 460 nm excitation and a 12.5% quantum yield were modified on the surface of ZIF-8 as a signal tag that can convert the interactions between the sensor and OA into detectable fluorescent signals. Finally, N, S-GQDs@ZIF-8@MIP was acquired through the surface molecular imprinting method. Due to the synergy of N, S-GQDs, ZIF-8, and MIP, the obtained sensor not only demonstrated higher selectivity and sensitivity than N, S-GQDs@ZIF-8@NIP, but also displayed faster fluorescence response than N, S-GQDs@MIP. Under optimal conditions, the developed sensor presented a favorable linear relationship in the range of 0.1-10 mg L-1 with a detection limit of 0.062 mg L-1. Additionally, the proposed N, S-GQDs@ZIF-8@MIP strategy was effectively applied to the detection of OA in fermented samples, and the obtained results had a satisfactory correlation with those of HPLC.

Preparation of PEG/ZIF-8@HF drug delivery system for melanoma treatment via oral administration

Melanoma is one of the highly malignant tumors whose incidence and fatality rates have been increased year by year. However, in addition to early surgical resection, there still lacks specific targeted drugs and treatment strategies. In this study, it was discovered that hinokiflavone (HF) encapsulated in zeolitic imidazolate framework-8 (ZIF-8) exhibited a superior anti-melanoma effect in vitro and in vivo. HF was encapsulated in ZIF-8 through a one-step synthesis method, and polyethylene glycol (PEG-2000) was used to optimize the size and dispersion of the drug-loaded complex (PEG/ZIF-8@HF). The results show that the prepared PEG/ZIF-8@HF has a high encapsulation efficiency (92.12%) and can achieve selective drug release in an acidic microenvironment. The results of in vitro anti-melanoma experiments indicate that PEG/ZIF-8@HF shows up-regulation of reactive oxygen species (ROS) levels and can restrain the migration and invasion of B16F10 cells. Moreover, in vivo animal experiments further confirm that PEG/ZIF-8@HF shows anti-tumor effect by up-regulating the pro-apoptotic proteins caspase-3 and caspase-8, and down-regulating the migration-promoting invasion protein MMP-9. This study developed a safe and effective oral administration of HF based on the high-efficiency delivery ZIF-8 system, which provides an effective treatment strategy for melanoma.

Zeolitic imidazolate framework-8 as a dispersive solid phase extraction sorbent for simultaneous determination of 145 pesticide residues in polyphenol-rich plants

Many plants showed higher polyphenol content, which caused the matrix effect and made the analysis of trace pesticide residues highly challenging. A common approach to improving matrix effects is to purify pesticides through the use of sorbents, but this requires a combination of multiple sorbents and extensive use. Zeolitic imidazolate framework-8 is widely used for pesticide analysis due to its high porosity, large specific surface area and versatility. Here, We established and validated a modified quick, easy, cheap, effective, rugged, and safe method based on a zeolitic imidazolate framework-8 that was used to test the removal ability for polyphenols. And 145 pesticide residues in peppermint, perilla, fennel, and mulberry leaves were analyzed by the modified method coupled with LC-MS/MS. The mean recoveries of all pesticide residues were in the range of 74.3%-103.7%, with mean relative standard deviations≤ 9.1% at spiked concentrations of 1, 10, 50, and 100 μg kg^-1 for mulberry leaves. The limits of quantitation of the method ranged from 1 to 50 μg kg^-1 . This study offers a reliable approach for the accurate quantitative analysis of various trace substances in the polyphenol-rich plants. This article is protected by copyright. All rights reserved.

Nitrogen-Doped Carbon Networks with Consecutive Conductive Pathways from a Facile Competitive Carbonization-Etching Strategy for High-Performance Energy Storage

Recently, new carbonization strategies for synthesizing structure-controlled and high-performance carbon electrode materials have attracted great attentions in the field of energy storage and conversion. Here a competitive carbonization-etching strategy to prepare nitrogen-doped carbon polyhedron@carbon nanosheet (NCP@CNS) hybrids derived from zeolitic imidazolate framework-8 is presented. Consecutive conductive networks are constructed in the NCP@CNS hybrids during a unique carbonization-etching pyrolysis, where a competition between the formation of NCPs and CNSs exists. When the NCP@CNS hybrids are employed as supercapacitor electrodes, their hierarchically porous NCPs serve as ion-buffering reservoirs for offering fast ion transport channels, and the CNSs within hybrids not only link the NCPs together to build electron transfer pathways but also restrict the volume fluctuation of electrodes during charging and discharging process. As a result, the as-fabricated NCP@CNS electrode displays excellent electrochemical performances including a superior specific capacitance of 320 F g^-1 , a high energy density of 22.2 W h kg^-1 (5.6 W h kg^-1 for symmetric device), and a long cycle life with capacitance retention of ≈101.8% after 5000 cycles. This study opens an encouraging avenue toward the tailored synthesis of metal-organic frameworks (MOFs)-derived carbon electrodes for renewable energy storage applications and devices.

Bioresponsive Nanoarchitectonics-Integrated Microneedles for Amplified Chemo-Photodynamic Therapy against Acne Vulgaris

The excessive colonization of Propionibacterium acnes (P. acnes) is responsible for the genesis of acne vulgaris, a common inflammatory disease of skin. However, the conventional anti-acne therapies are always limited by various side effects, drug resistance, and poor skin permeability. Microneedles (MNs) are emerging topical drug delivery systems capable of noninvasively breaking through the skin stratum corneum barrier to efficiently enhance the transdermal drug penetration. Herein, MNs loaded with intelligent pH-sensitive nanoplatforms were constructed for amplified chemo-photodynamic therapy against acne vulgaris, jointly exerting antimicrobial and anti-inflammatory effects. The photosensitizer indocyanine green (ICG) was loaded into the zeolitic imidazolate framework-8 (ZIF-8) to improve its photostability, which would be triggered by 808 nm laser irradiation to generate cytotoxic reactive oxygen species (ROS) to result in oxidative damage and disturbed metabolic activities of P. acnes. In addition to the efficient drug delivery, the ZIF-8 carrier could selectively degrade in response to the acidic microenvironment of acne lesions, and the released Zn2+ also exhibited a potent antimicrobial activity. The fabricated ZIF-8-ICG@MNs presented an outstanding synergistic anti-acne efficiency both in vitro and in vivo. This bioresponsive microneedle patch is expected to be readily adapted as a generalized, modular strategy for noninvasive therapeutics delivery against superficial skin diseases.

Site-Selective Deposition of Metal-Organic Frameworks on Gold Nanobipyramids for Surface-Enhanced Raman Scattering

Site-selective deposition of metal-organic frameworks (MOFs) on metal nanocrystals has remained challenging because of the difficult control of the nucleation and growth of MOFs. Herein we report on a facile wet-chemistry approach for the selective deposition of zeolitic imidazolate framework-8 (ZIF-8) on anisotropic Au nanobipyramids (NBPs) and nanorods. ZIF-8 is selectively deposited at the ends and waist and around the entire surface of the elongated Au nanocrystals. The NBP-based nanostructures with end-deposited ZIF-8 exhibit the best surface-enhanced Raman scattering (SERS) performance, implying that molecules can be concentrated by ZIF-8 at the hot spots. In addition, the SERS signal exhibits good selectivity for small molecules because of the molecular sieving effect of ZIF-8. This study opens up a promising route for constructing plasmonic nanostructures with site selectively deposited ZIF-8, which hold enormous potential for molecular sensing, optical switching, and plasmonic catalysis.

Facile Fabrication of Diatomite-Supported ZIF-8 Composite for Solid-Phase Extraction of Benzodiazepines in Urine Samples Prior to High-Performance Liquid Chromatography

A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1–39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2–500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3–0.4 ng/mL and 1.0–1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4–5.2% and 1.5–8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0–29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.

A Light-Triggered pH-Responsive Metal-Organic Framework for Smart Delivery of Fungicide to Control Sclerotinia Diseases of Oilseed Rape

Using a simple one-pot method, we developed a prochloraz (Pro) and pH-jump reagent-loaded zeolitic imidazolate framework-8 (PD@ZIF-8) composite for the smart control of Sclerotinia disease. The pH-jump reagent can induce the acidic degradation of ZIF-8 using UV light to realize the controlled release of Pro. Thus, the physical properties of PD@ZIF-8, such as its release, formulation stability, and adhesion, were investigated in detail. The results showed that the quantity of Pro released by PD@ZIF-8 under UV light irradiation (365 nm) was 63.4 ± 3.5%, whereas under dark conditions, it was only 13.7 ± 0.8%. In vitro activity indicated that the EC₅₀ of PD@ZIF-8 under UV light irradiation was 0.122 ± 0.02 μg/mL, which was not significantly different from that of Pro (0.107 ± 0.01 μg/mL). Pot experiments showed that the efficacy of PD@ZIF-8 under light irradiation was 51.2 ± 5.7% for a fungal infection at 14 days post-spraying, whereas the effectiveness of prochloraz emulsion in water was only 9.3 ± 3.3%. Furthermore, fluorescence tracking of ZIF-8 and biosafety experiments showed that ZIF-8 could be absorbed by plant leaves and transported to various parts of oilseed rape in a short period of time and that PD@ZIF-8 was relatively safe for plants and HepG2 cells. These results highlight the potential of the composite to provide efficient and smart delivery of fungicides into plants for protection against diseases and provide an idea for developing sustainable agriculture.

Accelerated Bone Regeneration by MOF Modified Multifunctional Membranes through Enhancement of Osteogenic and Angiogenic Performance

Owing to the insufficient guidance of new bone formation in orthopedic and craniomaxillofacial surgery, construction of a guided bone regeneration membrane to support vascularized bone regeneration remains a challenge. Herein, an electrospun asymmetric double-layer polycaprolactone/collagen (PCL/Col) membrane modified by metal-organic framework (MOF) crystals is developed. The optimization of the PCL/Col weight ratio (1:1 and 1:1.5) enables the composite membrane with a balanced tensile strength (only fell by 49.9% in wet conditions) and a controlled degradation rate (completely degraded at 12 weeks). The MOF crystals can provide a pH-responsive release of Zn²⁺ ions. In vitro experiments indicate that the barrier layer functions to prevent the infiltration of fibrous connective tissue. The MOF crystal layer functions to enhance osteogenesis and angiogenesis in vitro. Using a rat calvarial defect model, the MOF crystals exhibit a sign of osteoinductivity along with blood vessel formation after 8 weeks post-surgery. Strikingly, when assessed in a chick chorioallantoic membrane model, the MOF modified membrane demonstrates a significant angiogenic response, which can be envisaged as its outstanding merits over the commercially Col membrane. Therefore, the MOF crystals represent an exciting biomaterial option, with neovascularization capacity for bone tissue engineering and regenerative medicine.

Metal-Organic Frameworks for Preserving the Functionality of Plasmonic Nanosensors

Preserving the functionality of nanosensors is critical for their reliable performance under harsh environmental conditions. Biofunctionalized plasmonic nanostructures are an important class of bionanoconjugates for biosensing, bioimaging, and nanotherapeutics. Plasmonic nanostructures and biomolecules exhibit poor thermal stability over time. Here, we report a class of metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8), as a protective coating for preserving plasmonic nanostructures and plasmonic bionanoconjugates at elevated temperature. Gold nanobipyramids (AuNBPs) with sharp tips are attractive plasmonic nanotransducers with high sensitivity but are prone to structural change and loss of sensitivity. This work reports the first observation that ZIF-8 can preserve the structure of AuNBPs and their corresponding strong electromagnetic field enhancement and high refractive index sensitivity. In addition, ZIF-8 coating enables nearly 100% retention of biorecognition capability of antibodies immobilized on the AuNBP surface after exposure to 60 °C for 48 h. The efficacy, versatility, and facile implementation of ZIF-8 coating offer great promise for the preservation of nanosensors.

Cancer Cell-Targeted Photosensitizer and Therapeutic Protein Co-Delivery Nanoplatform Based on a Metal-Organic Framework for Enhanced Synergistic Photodynamic and Protein Therapy

Efficient and cancer cell-targeted delivery of photosensitizer (PS) and therapeutic protein has great potentiality for improving the anticancer effects. Herein, zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, one of the most attractive metal-organic framework materials, were used for coencapsulating the chlorin e6 (Ce6, a potent PS) and cytochrome c (Cyt c, a protein apoptosis inducer); then the nanoparticle was subsequently decorated with the hyaluronic acid (HA) shell to form cancer cell-active targeted nanoplatform (Ce6/Cyt c@ZIF-8/HA). The in vitro and in vivo experiments show the cancer cell targeting capability and pH-responsive decomposition and the release behavior of Ce6/Cyt c@ZIF-8/HA. Upon light irradiation, the released Ce6 produced cytotoxic reactive oxygen species for photodynamic therapy. Meanwhile, the released Cyt c-induced programmed cell death for protein therapy. Furthermore, the Cyt c worked normally under hypoxia conditions and could decompose H₂O₂ to O₂ (with peroxidase-/catalase-like activity), resulting in synergistically improved therapeutic efficiency. These small molecules and protein codelivery nanoplatforms would promote the development of complementary and synergetic modes for biomedical applications.

ZIF-8-Modified Multifunctional Bone-Adhesive Hydrogels Promoting Angiogenesis and Osteogenesis for Bone Regeneration

Designing bone adhesives with adhesiveness, antideformation, biocompatibility, and biofunctional effects has great practical significance for bone defect reconstructive treatment, especially for bone graft repair surgery. Here, we designed zeolitic imidazolate framework-8 nanoparticle (ZIF-8 NP)-modified catechol-chitosan (CA-CS) multifunctional hydrogels (CA-CS/Z) to stabilize the bone graft environment, ensure blood supply, promote osteogenic differentiation, and accelerate bone reconstruction. Characterizations confirmed the successful synthesis of CA-CS/Z hydrogels. Hydrogels exhibited advanced rheological properties, reliable mechanical strength, and excellent adhesion for clinical applications. Based on excellent biocompatibility, it could enhance paracrine of the vascular endothelial growth factor (VEGF) in rat bone marrow mesenchymal stem cells (rBMSCs) to ensure blood supply reconstruction in bone defect areas. Furthermore, the ZIF-8 NPs released from the hydrogels could also up-regulate the production and secretion of alkaline phosphatase, collagen 1, and osteocalcin, promoting the osteogenic differentiation of rBMSCs. In addition, the antibacterial properties of CA-CS/Z could also be observed. In vivo experiments further provided a powerful proof that CA-CS/Z promoted vascularized osteogenesis in wound areas by stabilizing bone graft materials and greatly accelerated the speed and healing of bone reconstruction. These results indicate the promising potential of CA-CS/Z hydrogels with promoting implantation stability, angiogenesis, and osteogenesis for bone regeneration applications.

Molecular Sieve Based on a PMMA/ZIF-8 Bilayer for a CO-Tolerable H2 Sensor with Superior Sensing Performance

Semiconductor sensors equipped with Pd catalysts are promising candidates as low-powered and miniaturized surveillance devices that are used to detect flammable hydrogen (H₂) gas. However, the following issues remain unresolved: (i) a sluggish sensing speed at room temperature and (ii) deterioration of sensing performance caused by interfering gases, particularly, carbon monoxide (CO). Herein, a bilayer comprising poly(methyl methacrylate) (PMMA) and zeolitic imidazolate framework-8 (ZIF-8) is utilized as a molecular sieve for diode-type H₂ sensors based on a Pd-decorated indium-gallium-zinc oxide film on a p-type silicon substrate. While the PMMA effectively blocks the penetration of CO gas molecules into the sensing entity, the ZIF-8 improves sensing performances by modifying the catalytic activity of Pd, which is preferable for splitting H₂ and O₂ molecules. Consequently, the bilayer-covered sensor achieves outstanding CO tolerance with superior sensing figures of merit (response/recovery times of <10 s and sensing response of >5000% at 1% H₂).

Surface Engineering of Metal-Organic Framework as pH-/NIR-Responsive Nanocarrier for Imaging-Guided Chemo-Photothermal Therapy

BACKGROUND

Metal-organic frameworks (MOFs) have attracted intensive research interest in the biomedical field because of their unique properties. However, in order to realize the high loading capacity and therapeutic efficacy, it is still urgent to develop a multifunctional MOFs-based nanoplatform.

MATERIALS AND METHODS

Herein, a pH/near-infrared (NIR) dual-responsive drug delivery system based on zeolitic imidazolate framework-8 (ZIF-8) is constructed for synergistic chemo-photothermal therapy and dual-modal magnetic resonance (MR)/photoacoustic (PA) imaging. The doxorubicin hydrochloride (DOX) is embedded into ZIF-8 through one-pot method, and the resultant ZIF-8/DOX is then successively modified with polydopamine, Mn ions and poly(ethylene glycol). The obtained ZIF-8/DMPP is systematically characterized, and both its in vitro and in vivo biological effects are evaluated in detail.

RESULTS

The ZIF-8/DMPP possesses a high drug-loading content of 18.9% and displays appropriate size and morphology. The pH-dependent degradation and drug release behavior of prepared ZIF-8/DMPP are confirmed. Importantly, the results demonstrate that the photothermal effect of ZIF-8/DMPP under NIR laser irradiation can significantly accelerate its drug releasing rate, further improving the intracellular drug concentrations. Thereafter, the augmented chemotherapeutic efficiency by photothermal effect against cancer cells is verified both in vitro and in vivo. Besides, the favorable MR and PA imaging capacity of ZIF-8/DMPP is also evidenced on the tumor model.

CONCLUSION

Taken together, the surface engineering of ZIF-8-based nanocarrier in this work offers a promising strategy for the multifunctional MOFs-based drug delivery system.

Applications of Functional Metal-Organic Frameworks in Biosensors

In recent decades, fast advancements in the fields of metal-organic frameworks (MOFs) are providing unprecedented opportunities for the development of novel functional MOFs for various biosensing applications. Exciting progress is achieved due to the combination of MOFs with various functional components, which introduces novel structures and new features to the MOFs-based biosensing applications, such as higher stability, higher sensitivity, higher flexibility, and higher specificity. This review aims to be a comprehensive summary of the most recent advances in the development of functional MOFs for various biosensing applications, placing special attention on important contributions in recent 3 years. In this review, the most recent developments in design and synthesis of functional MOFs for biosensing applications are summarized. MOFs-based biosensing applications are outlined according to the central roles of MOFs in biosensors, which include carriers of sensitive elements, enzyme-mimic elements, electrochemical signaling, optical signaling, and gas sensing. Finally, the current challenges and future development trends of functional MOFs for biosensing applications are proposed and discussed.

Zeolitic Imidazolate Framework-8 Encapsulating Risedronate Synergistically Enhances Osteogenic and Antiresorptive Properties for Bone Regeneration

Bisphosphonates (BPs) are routinely administered for the treatment of turnover bone diseases. To avoid the undesirable adverse effects of long-term usage of bisphosphonates and improve their bioavailability in the bone microenvironment, we initially encapsulated risedronate (RIS) molecules inside nanoscale zeolitic imidazolate framework-8 particles (nZIF-8) by a one-step synthesis method to generate RIS@ZIF-8 nanoparticles. RIS@ZIF-8 nanoparticles displayed high loading encapsulation efficiency (64.21 ± 2.48%), good biocompatibility, controlled drug release capacity, and dual effects for bone regeneration. This work explored the potential of RIS@ZIF-8 nanoparticles, which could not only enhance ATP production, induce extracellular matrix (ECM) mineralization, and upregulate the expression levels of osteogenic genes but also effectively inhibit the formation of multinucleated giant osteocasts and decrease the Rankl/Opg ratio. Overall, RIS@ZIF-8 nanoparticles could be a very promising approach to synergistically enhance osteogenic and antiresorptive properties for bone regeneration, which could be utilized for the local treatment of bone defects.

O2-Generating Metal-Organic Framework-Based Hydrophobic Photosensitizer Delivery System for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) has been introduced as a photochemical process for treatment by causing cancer cell death and necrosis, with higher accuracy and few side effects. However, the hydrophobicity of most photosensitizers and hypoxia at the tumor sites are two crucial problems to be solved to achieve a successful PDT. Herein, we designed and constructed a novel metal-organic framework-based drug delivery system (BSA-MnO₂/Ce6@ZIF-8) with tumor microenvironment controllability. In our system, the hydrophobic photosensitizer chlorin e6 (Ce6) was one-pot incorporated into the matrix of zeolitic imidazolate framework 8 (ZIF-8) to form the Ce6@ZIF-8 compound, which can efficiently keep the Ce6 molecules isolated and avoid them self-aggregate, and the loading rate of Ce6 was high up to 28.3 wt %. The bovine serum albumin (BSA)-MnO₂ nanoparticles (NPs) with catalase-like activity were loaded onto the surface of ZIF-8, having the capacity for self-sufficiency of O₂ under the circumstance of H₂O₂ in acid solution, relieving hypoxia in cancer cells and thereby improving the PDT efficiency greatly when irradiated by low power density (230 mW/cm²) 650 nm light. Moreover, the MnO₂ NPs react with H₂O₂ in acid solution to produce Mn²⁺, granting the system the qualification of a contrast agent for magnetic resonance imaging. Therefore, our nanoplatform would further contribute to the treatment of hypoxic tumors in clinical practice.

Metal-Organic Framework Encapsulation Preserves the Bioactivity of Protein Therapeutics

Protein therapeutics are prone to lose their structure and bioactivity under various environmental stressors. This study reports a facile approach using a nanoporous material, zeolitic imidazolate framework-8 (ZIF-8), as an encapsulant for preserving the prototypic protein therapeutic, insulin, against different harsh conditions that may be encountered during storage, formulation, and transport, including elevated temperatures, mechanical agitation, and organic solvent. Both immunoassay and spectroscopy analyses demonstrate the preserved chemical stability and structural integrity of insulin offered by the ZIF-8 encapsulation. Biological activity of ZIF-8-preserved insulin after storage under accelerated degradation conditions (i.e., 40 °C) is evaluated in vivo using a diabetic mouse model, and shows comparable bioactivity to refrigeration-stored insulin (-20 °C). It is also demonstrated that ZIF-8-preserved insulin has low cytotoxicity in vitro and does not cause side effects in vivo. Furthermore, ZIF-8 residue can be completely removed by a simple purification step before insulin administration. This biopreservation approach is potentially applicable to diverse protein therapeutics, thus extending the benefits of advanced biologics to resource-limited settings and underserved populations/regions.

Disassembly of Hydrophobic Photosensitizer by Biodegradable Zeolitic Imidazolate Framework-8 for Photodynamic Cancer Therapy

Photodynamic therapy (PDT), an alternative to conventional cancer therapeutics, has gained increasing attention for its noninvasive advantage and simultaneous fluorescence imaging property. PDT is a tripartite process that functions in the simultaneous presence of a photosensitizer (PS), light, and available oxygen molecules. However, many highly efficient PSs are hydrophobic and highly tend to self-aggregate in aqueous solution, leading to quick quenching of the PDT effect. Here we construct zeolitic imidazolate framework-8 (ZIF-8) containing water-insoluble photosensitizer zinc(II) phthalocyanine (ZnPc), a typical hydrophobic PS, by one-step coprecipitation process, named as ZnPc@ZIF-8. The micropores of ZIF-8 act as molecular cages to separate and maintain hydrophobic ZnPc in the monomeric state and protect it against self-aggregation, which enables the encapsulated ZnPc to generate cytotoxic singlet oxygen (¹O₂) under light irradiation (650 nm) in aqueous condition. The formed nanosystem of ZnPc@ZIF-8 can be endocytosed by cancer cells and exhibits red fluorescent emission with excellent photodynamic activity for cancer treatment in vitro. In addition, ZnPc@ZIF-8 is acid-sensitive and would completely degrade after PDT, which can be monitored by the self-quenching of fluorescence emission of ZnPc. This work paves a facile way for resolving the problem of solubility and bioavailability of hydrophobic PS by utilizing metal-organic frameworks as nanocarriers.

Nanoscale Zeolitic Imidazolate Framework-8 as Efficient Vehicles for Enhanced Delivery of CpG Oligodeoxynucleotides

CpG oligodeoxynucleotides (ODNs) activate the immune system and induce Th 1 responses by stimulation of Toll-like receptor 9 (TLR9). Thus, CpG ODNs have become immunotherapeutics against various diseases including cancers, allergies, and infection. However, applications of CpG ODNs are largely limited because of their easy degradation by DNase as well as inefficient cellular uptake. Development of efficient delivery systems capable of transferring CpG ODNs into immune cells is important to enhance their therapeutic efficacy. Herein, for the first time, we demonstrated the construction of a novel CpG ODNs delivery system by encapsulating CpG ODNs into zeolitic imidazolate framework-8 (ZIF-8) nanoparticles. ZIF-8 possessed high CpG ODNs loading capacity due to its porous structure. ZIF-8/CpG ODNs complexes exhibited good stability in a physiological environment but effectively released CpG ODNs in acid conditions corresponding to the TLR 9-localized endolysosomes. ZIF-8/CpG ODNs complexes had no cytotoxicity in contrast to ZIF-8. ZIF-8 significantly increased the intracellular uptake of CpG ODNs in RAW264.7 cells, which further enhanced the secretion of immune cytokines both in vitro and in vivo. Our results suggest that nanoscale metal-organic frameworks (MOFs) can serve as ideal vehicles for the delivery of CpG ODNs.