Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

Dose-responsive phytotoxicity and oxidative stress induced by metal-organic framework PCN-224 in Arabidopsis thaliana seedlings

Metal-organic frameworks (MOFs) are advanced porous materials composed of metal ions and organic ligands, known for their unique structures and fascinating physio-chemical properties. To ensure their safe production and applications, it is crucial to thoroughly investigate their toxicity and environmental hazards. However, the potential risks of MOFs, particularly their impact on plants remained underexplored. Herein, we systematically assessed the phytotoxicity of PCN-224 on Arabidopsis thaliana (A. thaliana) due to its commercial availability and widespread use. To achieve this goal, A. thaliana seedlings were subjected to PCN-224 concentrations (10-300 µg/mL) and durations (1-12 days) in agar media, with a control group. PCN-224 slightly accelerated seed germination across all concentrations without altering the total germination rate. Exposure to a higher concentration of PCN-224 (300 µg/mL) significantly impaired A. thaliana development, reducing fresh weight (54.0 %) and root length (82.3 %) compared with control; however, lower exposure (10 µg/mL) showed minimal growth inhibition. Fluorescence microscopy showed that PI-labeled PCN-224 particles adhered to root surfaces and internalized in a concentration- and time-dependent manner, with notable xylem accumulation after 2 h. The net photosynthetic rate, transpiration rate, and stomatal conductance decreased by 54.25 %, 62.37 % and 38.53 %, respectively, compared with control, when the material concentration exceeded 100 µg/mL. Regarding the oxidative damage, higher PCN-224 exposure reduced antioxidant levels and downregulation of antioxidant-related genes resulted in a diminished oxidative stress response. Overall, our study highlights the potential risk of MOFs for plant growth and emphasizes the need to assess their environmental impact for sustainable agricultural practices.

Impact of photoaging on the chemical and cytotoxic properties of nanoscale zeolitic imidazolate framework-8

This study investigated the influence of photoaging on a nanoscale metal-organic framework (MOF), truncated rhombic dodecahedron nano-zeolitic imidazolate framework-8 (nZIF-8), focusing on its oxidative stress, inflammation, and implications for pulmonary diseases. We observed significant photodegradation-induced transformations in nZIF-8, characterized by a reduction in particle size from 200.5 to 101.4 nm and notable structural disintegration after prolonged exposure to simulated solar radiation. This alteration resulted in a marked decrease in oxidative cytotoxicity in BEAS-2B cells, which was attributed to changes in surface properties and reduced reactive oxygen species (ROS) production. Gene expression analysis further revealed a decrease in cytotoxic and inflammatory responses, which potentially lowers the risk of chronic obstructive pulmonary disease (COPD). Aged nZIF-8 also showed diminished capacity to induce pro-inflammatory cytokines and influence COPD-related gene expression, reducing its potential to exacerbate COPD pathogenesis. Our findings highlight the critical need for comprehensive safety evaluations of these materials, while considering their long-term environmental and biological impacts. The diminished cytotoxicity and inflammatory potential of aged nZIF-8 highlighted its enhanced suitability for broader applications, indicating that photoaging may lead to safer and more sustainable material utilization.

Effects of zeolite imidazole frameworks on rice seedlings (Oryza sativa L.): Phytotoxicity, transformation, and bioaccumulation

Zeolite imidazole frameworks (ZIFs), a class of the metal organic framework, have been extensively studied in environmental applications. However, their environmental fate and potential ecological impact on plants remain unknown. Here, we investigated the phytotoxicity, transformation, and bioaccumulation processes of two typical ZIFs (ZIF-8 and ZIF-67) in rice (Oryza sativa L.) under hydroponic conditions. ZIF-8 and ZIF-67 in the concentration of 50 mg/L decreased root and shoot dry weight maximally by 55.2% and 27.5%, 53.5% and 37.5%, respectively. The scanning electron microscopy (SEM) imaging combined with X-ray diffraction (XRD) patterns revealed that ZIFs on the root surface gradually collapsed and transformed into nanosheets with increasing cultivation time. The fluorescein isothiocyanate (FITC) labeled ZIFs were applied to trace the uptake and translocation of ZIFs in rice. The results demonstrated that the transformed ZIFs were mainly distributed in the intercellular spaces of rice root, while they cannot be transported to culms and leaves. Even so, the Co and Zn contents of rice roots and shoots in the ZIFs treated groups were increased by 1145% and 1259%, 145% and 259%, respectively, compared with the control groups. These findings suggested that the phytotoxicity of ZIFs are primarily attributed to the transformed ZIFs and to a less extent, the metal ions and their ligands, and they were internalized by rice root and increased the Co and Zn contents of shoots. This study reported the transformation of ZIFs and their biological effectiveness in rice, highlighting the potential environmental hazards and risks of ZIFs to crop plants.

Metal-Organic Frameworks for Overcoming the Blood-Brain Barrier in the Treatment of Brain Diseases: A Review

The blood-brain barrier (BBB) plays a vital role in safeguarding the central nervous system by selectively controlling the movement of substances between the bloodstream and the brain, presenting a substantial obstacle for the administration of therapeutic agents to the brain. Recent breakthroughs in nanoparticle-based delivery systems, particularly metal-organic frameworks (MOFs), provide promising solutions for addressing the BBB. MOFs have become valuable tools in delivering medications to the brain with their ability to efficiently load drugs, release them over time, and modify their surface properties. This review focuses on the recent advancements in molecular-based approaches for treating brain disorders, such as glioblastoma multiforme, stroke, Parkinson's disease, and Alzheimer's disease. This paper highlights the significant impact of MOFs in overcoming the shortcomings of conventional brain drug delivery techniques and provides valuable insights for future research in the field of neurotherapeutics.

Dose-Dependent Effect on Plant Growth of Exposure to Metal-Organic Framework MIL-101(Cr)

With the increasing use of metal-organic frameworks (MOFs), they will inevitably enter the environment intentionally or unintentionally. However, the effects of MOFs on plant growth are poorly understood. Here, we investigated the effects of exposure of the rhizosphere to MOFs on plant growth. MIL-101(Cr) was selected as a research model due to its commercial availability and wide use. Soybean plants at the two-leaf stage were subjected to various durations (1-7 days) and concentrations (0-1000 mg/L) of exposure in hydroculture with a control group treated with ultrapure water. We found that MIL-101(Cr) had a positive effect on soybean growth at a lower dose (i.e., 200 mg/L); however, at higher doses (i.e., 500 and 1000 mg/L), it exhibited significant toxicity to plant growth, which is evidenced by leaf damage. To investigate the mechanism of this effect, we used Cr as an indicator to quantify, track, and image MIL-101(Cr) in the plant with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results indicated that MIL-101(Cr) primarily accumulated in the cortex of roots (up to 40 times higher than that in stems), with limited translocation to stems and negligible presence in leaves and cotyledons. In addition, metabolomic analysis of soybeans indicated that low-dose MIL-101(Cr) could increase the sucrose content of soybean roots to promote plant growth, while a high dose could induce lipid oxidation in roots. This study provides valuable insights into the ecological toxicology of MOFs and underscores the importance of assessing their environmental impact for sustainable agricultural practices.

Targeted cancer treatment using folate-conjugated sponge-like ZIF-8 nanoparticles: a review

ZIF-8 (zeolitic imidazolate framework-8) is a potential drug delivery system because of its unique properties, which include a large surface area, a large pore capacity, a large loading capacity, and outstanding stability under physiological conditions. ZIF-8 nanoparticles may be readily functionalized with targeting ligands for the identification and absorption of particular cancer cells, enhancing the efficacy of chemotherapeutic medicines and reducing adverse effects. ZIF-8 is also pH-responsive, allowing medication release in the acidic milieu of cancer cells. Because of its tunable structure, it can be easily functionalized to design cancer-specific targeted medicines. The delivery of ZIF-8 to cancer cells can be facilitated by folic acid-conjugation. Hence, it can bind to overexpressed folate receptors on the surface of cancer cells, which holds the promise of reducing unwanted deliveries. As a result of its importance in cancer treatment, the folate-conjugated ZIF-8 was the major focus of this review.

Metal-Organic Frameworks-Based Nanoplatforms for the Theranostic Applications of Neurological Diseases

Neurological diseases are the foremost cause of disability and the second leading cause of death worldwide. Owing to the special microenvironment of neural tissues and biological characteristics of neural cells, a considerable number of neurological disorders are currently incurable. In the past few years, the development of nanoplatforms based on metal-organic frameworks (MOFs) has broadened opportunities for offering sensitive diagnosis/monitoring and effective therapy of neurology-related diseases. In this article, the obstacles for neurotherapeutics, including delayed diagnosis and misdiagnosis, the existence of blood brain barrier (BBB), off-target treatment, irrepressible inflammatory storm/oxidative stress, and irreversible nerve cell death are summarized. Correspondingly, MOFs-based diagnostic/monitoring strategies such as neuroimaging and biosensors (electrochemistry, fluorometry, colorimetry, electrochemiluminescence, etc.) and MOFs-based therapeutic strategies including higher BBB permeability, targeting specific lesion sites, attenuation of neuroinflammation/oxidative stress as well as regeneration of nerve cells, are extensively highlighted for the management of neurological diseases. Finally, the challenges of the present research from perspective of clinical translation are discussed, hoping to facilitate interdisciplinary studies at the intersections between MOFs-based nanoplatforms and neurotheranostics.

Nanoscale Zinc-Based Metal-Organic Frameworks Induce Neurotoxicity by Disturbing the Metabolism of Catecholamine Neurotransmitters

As a group of new nanomaterials, nanoscale metal-organic frameworks (MOFs) are widely applied in the biomedical field, exerting unknown risks to the human body, especially the central nervous system. Herein, the impacts of MOF-74-Zn nanoparticles on neurological behaviors and neurotransmitter metabolism are explored in both in vivo and in vitro assays modeled by C57BL/6 mice and PC12 cells, respectively. The mice exhibit increased negative-like behaviors, as demonstrated by the observed decrease in exploring behaviors and increase in despair-like behaviors in the open field test and forced swimming test after exposure to low doses of MOF-74-Zn nanoparticles. Disorders in the catecholamine neurotransmitter metabolism may be responsible for the MOF-74-Zn-induced abnormal behaviors. Part of the reason for this is the inhibition of neurotransmitter synthesis caused by restrained neurite extension. In addition, MOF-74-Zn promotes the translocation of more calcium into the cytoplasm, accelerating the release and uptake and finally resulting in an imbalance between synthesis and catabolism. Taken together, the results from this study indicate the human toxicity risks of nanoscale low-toxicity metal-based MOFs and provide valuable insight into the rational and safe use of MOF nanomaterials.

Exploring the Physicochemical, Electroactive, and Biodelivery Properties of Metal Nanoparticles on Peripheral Nerve Regeneration

Despite the advances in the regeneration/rehabilitation field of damaged tissues, the functional recovery of peripheral nerves (PNs), especially in a long gap injury, is considered a great medical challenge. Recent progress in nanomedicine has provided great hope for PN regeneration through the strategy of controlling cell behavior by metal nanoparticles individually or loaded on scaffolds/conduits. Despite the confirmed toxicity of metal nanoparticles due to long-term accumulation in nontarget tissues, they play a role in the damaged PN regeneration based on the topography modification of scaffolds/conduits, enhancing neurotrophic factor secretion, the ion flow improvement, and the regulation of electrical signals. Determining the fate of neural progenitor cells would be a major achievement in PN regeneration, which seems to be achievable by metal nanoparticles through altering cell vital approaches and controlling their functions. Therefore, in this literature, an attempt was made to provide an overview of the effective activities of metal nanoparticles on the PN regeneration, until the vital clues of the PN regeneration and how they are changed by metal nanoparticles are revealed to the researcher.

Dexamethasone-loaded zeolitic imidazolate frameworks nanocomposite hydrogel with antibacterial and anti-inflammatory effects for periodontitis treatment

Periodontitis is a bacterial-induced, chronic inflammatory disease characterized by progressive destruction of tooth-supporting structures. Pathogenic bacteria residing in deep periodontal pockets after traditional manual debridement can still lead to local inflammatory microenvironment, which remains a challenging problem and an urgent need for better therapeutic strategies. Here, we integrated the advantages of metal-organic frameworks (MOFs) and hydrogels to prepare an injectable nanocomposite hydrogel by incorporating dexamethasone-loaded zeolitic imidazolate frameworks-8 (DZIF) nanoparticles into the photocrosslinking matrix of methacrylic polyphosphoester (PPEMA) and methacrylic gelatin (GelMA). The injectable hydrogel could be easily injected into deep periodontal pockets, achieving high local concentrations without leading to antibiotic resistance. The nanocomposite hydrogel had high antibacterial activity and constructs with stable microenvironments maintain cell viability, proliferation, spreading, as well as osteogenesis, and down-regulated inflammatory genes expression in vitro. When evaluated on an experimental periodontitis rat model, micro-computed tomography and histological analyses showed that the nanocomposite hydrogel effectively reduced periodontal inflammation and attenuated inflammation-induced bone loss in a rat model of periodontitis. These findings suggest that the nanocomposite hydrogel might be a promising therapeutic candidate for treating periodontal disease.

Low Toxicity of Metal-Organic Framework MOF-74(Co) Nano-Particles In Vitro and In Vivo

With the rapid development of metal-organic frameworks (MOF), the toxicity and environmental safety of MOF materials should be thoroughly investigated. The behaviors and bio-effects of MOF materials after oral exposure are largely unknown. In this study, we performed a pilot toxicity evaluation of MOF-74(Co) nanoparticles (NPs) both in vitro and in vivo. The cell viability and cell cycle were monitored after LO2 cells were incubated with MOF-74(Co). The Co contents, bodyweight, serum biochemistry, histopathological changes, and oxidative stress parameters were measured after oral exposure to MOF-74(Co) NPs in mice. LO2 cells showed viability loss at 100 mg/L. The cell cycle arrest was more sensitive, which was observed even at 12.5 mg/L. MOF-74(Co) NPs led to a significant accumulation of Co in the liver and kidneys. No bodyweight loss was observed and the serum biochemical index was mainly unchanged. Except for slight inflammation, the histopathological images of the liver and kidneys after oral exposure to MOF-74(Co) NPs were normal compared to the control. Meaningful oxidative stress was found in the liver and kidneys. The results collectively indicated the low toxicity of MOF-74(Co) NPs after oral exposure in mice.

Elemental Composition of Pheochromocytoma Resolved on Solid/Adrenal Tissue and Whole Blood Level

Pheochromocytoma (PCC) is an unusual benign adrenal tumor with an unexamined status of the elements. This study delivers the first insight into the levels of microelements (Mn, Co, Cu, Zn, As, Se, Th), toxic elements (Cd, Pb, U), and macroelements (Na, K, Mg, Ca) in both adrenal tissue and whole blood samples collected from PCC patients. The results were strengthened by comparing recorded findings with the patients' healthy adrenal tissue (HAT) and with whole blood samples from the healthy individuals. PCCs had significantly higher levels of Zn, Se, Na, K, and Mg and lower levels of Mn, Co, Pb, and As than that of HATs. Compared to healthy blood samples, the patients' blood exhibited considerably higher levels of Na, K, and Ca but significantly lower levels of Mn, Cu, Zn, Se, and Mg. Females had significantly higher levels of essential Se and toxic Pb and Cd in their PCC tissue samples compared to males. PCC tissue levels of Mn and Cu were significantly elevated in smokers over levels in nonsmokers and in PCC patients with tumor sizes below 5 cm compared to PCC diameters above 5 cm. The data presented in this study provide a new insight into the pathophysiology of PCC. Thus, recorded elements should be considered as initiators/modifiers of PCC and potential inductors of malignant transformation. The findings of this research deepen scientific understanding of this rare adrenal disease, which, in turn, could highlight the pathogenesis of PCC.

Encapsulating quercetin in cyclodextrin metal-organic frameworks improved its solubility and bioavailability

BACKGROUND

Quercetin (Que) has many pharmacological activities, such as anticancer, antioxidant, cardiovascular protection, antihypertensive and lipid-lowering activities. However, its poor water solubility greatly limits its application in medicine and food. γ-Cyclodextrin metal-organic frameworks (γ-CD-MOFs) are novel porous carriers for loading functional products. In this study, Que was successfully loaded into γ-CD-MOFs, and the new compound (Que-CD-MOFs) was characterised by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy.

RESULTS

The apparent solubility of Que-CD-MOFs was enhanced by 100-fold compared with that of pure Que. The free radical scavenging ability of the encapsulated Que was significantly improved. The cytotoxicity of Que-CD-MOFs to HK-2 cells was decreased, and their inhibition on HT-29 tumour cells was maintained, as confirmed by CCK-8 assays. Flow cytometry of HT-29 cells showed that Que-CD-MOFs can inhibit G2 phase cells. Based on molecular modelling, Que molecules were preferentially located inside the cavities of γ-CD pairs in γ-CD-MOFs.

CONCLUSION

γ-CD-MOFs are promising carriers for bioactive agents in food and pharmaceutical applications. © 2021 Society of Chemical Industry.

Cyclodextrin metal-organic frameworks and derivatives: recent developments and applications

While there is a tremendous amount of scientific research on metal organic frameworks (MOFs) for gas storage/separation, catalysis and energy storage, the development and application of biocompatible MOFs still poses major challenges. In general, they can be synthesised from various biocompatible linkers and metal ions but particularly cyclodextrins (CDs) as cyclic oligosaccharides are an astute choice for the former. Although the field of CD-MOF materials is still in the early stages and their design and fabrication comes with many hurdles, the benefits coming from CDs built in a porous framework are exciting. Versatile host-guest complexation abilities, high encapsulation capacity and hydrophilicity are among the valuable properties inherent to CDs and offer extended and novel applications to MOFs. In this review, we provide an overview of the state-of-the-art synthesis, design, properties and applications of these materials. Initially, a rationale for the preparation of CD-based MOFs is provided, based on the chemical and structural properties of CDs and including their advantages and disadvantages. Further on, the review exhaustively surveys CD-MOF based materials by categorising them into three sub-classes, namely (i) CD-MOFs, (ii) CD-MOF hybrids, obtained via combination with external materials, and (iii) CD-MOF-derived materials prepared under pyrolytic conditions. Subsequently, CD-based MOFs in practical applications, such as drug delivery and cancer therapy, sensors, gas storage, (enantiomer) separations, electrical devices, food industry, and agriculture, are discussed. We conclude by summarizing the state of the art in the field and highlighting some promising future developments of CD-MOFs.

Fluorescent dendrimer-based probes for cell membrane imaging: Zebrafish epidermal labeling-based toxicity evaluation

Visualizing the plasma membrane of living mammalian cells both in vitro and in vivo is crucial for tracking their cellular activities. However, due to the complex and dynamic nature of the plasma membrane, most commercial dyes for membrane staining can only realize very limited imaging performance. Thus, precise and stable plasma membrane imaging remains technically challenging. Here, by taking advantage of the small, well-defined, and amine-rich dendrimers, we prepared poly(ethylene glycol)-cholesterol (PEG-Chol)-conjugated and cyanine dye (e.g., cyanine2, cyanine3, and cyanine5)-labeled dendrimer nanoprobes (termed DPC-Cy2, DPC-Cy3, and DPC-Cy5 NPs). It was revealed that these probes enabled universal, wash-free, long-term (at least 8 h), and multicolor (green, yellow, and red) plasma membrane labeling of a variety of live mammalian cells. Further, we confirmed that the nanoprobes (using DPC-Cy5 as a representative) could achieve high-quality, wash-free, and stable cell surface labeling of live zebrafish embryos. More importantly, we demonstrated that our probes could act as biosensors to visualize the toxicity of metal-organic frameworks (MOFs) toward the epidermal cells of zebrafish embryos, and thus they hold great potential for identifying the toxic effect of drugs/materials at the single-cell scale or in live animals. The present work highlights the advantages of utilizing dendrimers for constructing functional imaging materials, and it is also believed that the fluorescent dendrimer nanoprobes developed in this work may find wide applications like cell imaging, drug toxicity evaluation, and cellular state monitoring.

Advances and Applications of Metal-Organic Framework Nanomaterials as Oral Delivery Carriers: A Review

Oral administration is a commonly used, safe, and patient-compliant method of drug delivery. However, due to the multiple absorption barriers in the gastrointestinal tract (GIT), the oral bioavailability of many drugs is low, resulting in a limited range of applications for oral drug delivery. Nanodrug delivery systems have unique advantages in overcoming the multiple barriers to oral absorption and improving the oral bioavailability of encapsulated drugs. Metal-organic frameworks (MOFs) are composed of metal ions and organic linkers assembled by coordination chemistry. Unlike other nanomaterials, nanoscale metal-organic frameworks (nano-MOFs, NMOFs) are increasingly popular for drug delivery systems (DDSs) due to their tunable pore size and easily modified surfaces. This paper summarizes the literature on MOFs in pharmaceutics included in SCI for the past ten years. Then, the GIT structure and oral drug delivery systems are reviewed, and the advantages, challenges, and solution strategies possessed by oral drug delivery systems are discussed. Importantly, two major classes of MOFs suitable for oral drug delivery systems are summarized, and various representative MOFs as oral drug carriers are evaluated in the context of oral drug delivery systems. Finally, the challenges faced by DDSs in the development of MOFs, such as biostability, biosafety, and toxicity, are examined.

Life-Related Hazards of Materials Applied to Mg–S Batteries

Nowadays, rechargeable batteries utilizing an S cathode together with an Mg anode are under substantial interest and development. The review is made from the point of view of materials engaged during the development of the Mg–S batteries, their sulfur cathodes, magnesium anodes, electrolyte systems, current collectors, and separators. Simultaneously, various hazards related to the use of such materials are discussed. It was found that the most numerous groups of hazards are posed by the material groups of cathodes and electrolytes. Such hazards vary widely in type and degree of danger and are related to human bodies, aquatic life, flammability of materials, or the release of flammable or toxic gases by the latter.

Advances in antitumor nanomedicine based on functional metal-organic frameworks beyond drug carriers

Nanoscale metal-organic frameworks (MOFs) have attracted widespread interest due to their unique properties including a tunable porous structure, high drug loading capacity, structural diversity, and outstanding biocompatibility. MOFs have been extensively explored as drug nanocarriers in biotherapeutics. However, by harnessing the functionality of ligands and metal ions or clusters in MOFs, the applications of MOFs can be extended beyond drug delivery vehicles. Based on the intrinsic properties of the components of MOFs (e.g. magnetic moments of metal ions and fluorescence of ligands), different imaging modes can be achieved with varied MOFs. With careful design of the composition of MOFs (e.g. modification of organic linkers), they can respond to tumor microenvironments to realize on-demand treatment. By incorporating porphyrin-based ligands (photosensitizers for photodynamic therapy) or high-Z metal ions (radiosensitizers for radiotherapy) into the scaffold of MOFs, MOFs themselves can act as anticancer therapeutic agents. In this review, we highlight the application of MOFs from the above-mentioned aspects and discuss the prospects and challenges for using MOFs in stimuli-responsive imaging-guided antitumor therapy.

Magnetic CuFe2O4 with intrinsic protease-like activity inhibited cancer cell proliferation and migration through mediating intracellular proteins

Protease has been widely used in biological and industrial fields. Developing efficient artificial enzyme mimics remains a major technical challenge due to the high stability of peptide bonds. Nanoenzymes with high stability, high activity and low cost, provided new opportunities to break through natural enzyme inherent limitations. However, compared with many nanomaterials with inherent peroxidase activity, the intrinsic mimic proteases properties of magnetic nanomaterials were seldom explored, let alone the interaction between magnetic nanomaterials and cellular proteins. Herein, we reported for the first time that magnetic CuFe₂O₄ possesses inherent protease activity to hydrolyze bovine serum albumin (BSA) and casein under physiological conditions, and the CuFe₂O₄ is more resistant to high temperature than the natural trypsin. It also exhibited significantly higher catalytic efficiency than other copper nanomaterials and can be recycled for many times. Protease participated in pathophysiological processes and all stages of tumor progression. Interesting, CuFe₂O₄ exhibited anti-proliferative effect on A549, SKOV3, HT-29, BABL-3T3 and HUVEC cells, as well as it was particularly sensitive against SKOV3 cells. CuFe₂O₄ was about 30 times more effective than conventional chemotherapy drugs oxaliplatin and artesunate against SKOV3 cells. In addition, CuFe₂O₄ also mediated the expression of intracellular proteins, such as MMP-2, MMP-9, F-actin, and NF-kB, which may be associated with global protein hydrolysis by CuFe₂O₄, leading to inhibition of cell migration. The merits of the high magnetic properties, good protease-mimic and antitumor activities make CuFe₂O₄ nanoparticles very prospective candidates for many applications such as proteomics and biotechnology.

Heavy metals in soil from gangue stacking areas increases children health risk and causes developmental neurotoxicity in zebrafish larvae

Coal is the main energy source in China, with 4.5 billion metric tons of coal gangue accumulating near the mining areas in the process of coal mining. The objectives of the present study were to identify the health risks to children from soil pollution caused by coal gangue accumulation and to clarify the possible developmental neurotoxicity caused by this accumulation using zebrafish (Danio rerio) as a model. The results reveal that As and seven other heavy metals in soil samples from the gangue dumping area to the downstream villages exhibited distance-dependent concentration variations and posed substantial potential non-carcinogenic risks to local children. Additionally, soil leachate could affect the key processes of early neurodevelopment in zebrafish at critical windows, mainly including the alterations of cytoskeleton regulation (α1-tubulin), axon growth (gap43), neuronal myelination (mbp) and synapse formation (sypa, sypb, and psd95), eventually leading to hypoactivity in the zebrafish larvae. These findings suggest the possible health risks of soil pollution in the coal gangue stacking areas to children, particularly affecting their early neurodevelopment.

Recent Advances in the Application of Two-Dimensional Nanomaterials for Neural Tissue Engineering and Regeneration

The complexity of the nervous system structure and function, and its slow regeneration rate, makes it more difficult to treat compared to other tissues in the human body when an injury occurs. Moreover, the current therapeutic approaches including the use of autografts, allografts, and pharmacological agents have several drawbacks and can not fully restore nervous system injuries. Recently, nanotechnology and tissue engineering approaches have attracted many researchers to guide tissue regeneration in an effective manner. Owing to their remarkable physicochemical and biological properties, two-dimensional (2D) nanomaterials have been extensively studied in the tissue engineering and regenerative medicine field. The great conductivity of these materials makes them a promising candidate for the development of novel scaffolds for neural tissue engineering application. Moreover, the high loading capacity of 2D nanomaterials also has attracted many researchers to utilize them as a drug/gene delivery method to treat various devastating nervous system disorders. This review will first introduce the fundamental physicochemical properties of 2D nanomaterials used in biomedicine and the supporting biological properties of 2D nanomaterials for inducing neuroregeneration, including their biocompatibility on neural cells, the ability to promote the neural differentiation of stem cells, and their immunomodulatory properties which are beneficial for alleviating chronic inflammation at the site of the nervous system injury. It also discusses various types of 2D nanomaterials-based scaffolds for neural tissue engineering applications. Then, the latest progress on the use of 2D nanomaterials for nervous system disorder treatment is summarized. Finally, a discussion of the challenges and prospects of 2D nanomaterials-based applications in neural tissue engineering is provided.

Nanoscale cobalt-based metal-organic framework impairs learning and memory ability without noticeable general toxicity: First in vivo evidence

Metal-organic frameworks (MOFs) exhibit broad potential applications in the environmental, biomedical, catalyst, and energy fields. However, the currently existing data hardly shed light on their health risks before the MOFs' large-scale usage. In this context, we exploratively investigated the in vivo fate and effect of one representative cobalt-based zeolitic imidazolate framework (ZIF-67) at the nano- (60 nm) and submicron- (890 nm) scales. Different from submicron-scale ZIF-67 showing better biosafety, nanoscale particles manifested a neurodegenerative risk at the dose of no general toxicity, evidenced by the impairment of learning and memory ability and disordered function of the neuropeptide signaling pathway in a rat model. The involvement of oxidative damage and inflammatory processes in the neurotoxicity induced by ZIF-67 was discussed as well. These findings not only provide a wake-up call for the prudent applications of MOFs but also provide insight into the better design and safer use of MOFs for broader applications.

Acute Toxicity of Cu-MOF Nanoparticles (nanoHKUST-1) towards Embryos and Adult Zebrafish

Metal-organic frameworks (MOFs) demonstrate unique properties, which are prospective for drug delivery, catalysis, and gas separation, but their biomedical applications might be limited due to their obscure interactions with the environment and humans. It is important to understand their toxic effect on nature before their wide practical application. In this study, HKUST-1 nanoparticles (Cu-nanoMOF, Cu₃(btc)₂, btc = benzene-1,3,5-tricarboxylate) were synthesized by the microwave (MW)-assisted ionothermal method and characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) techniques. The embryotoxicity and acute toxicity of HKUST-1 towards embryos and adult zebrafish were investigated. To gain a better understanding of the effects of Cu-MOF particles towards Danio rerio (D. rerio) embryos were exposed to HKUST-1 nanoparticles (NPs) and Cu²⁺ ions (CuSO₄). Cu²⁺ ions showed a higher toxic effect towards fish compared with Cu-MOF NPs for D. rerio. Both forms of fish were sensitive to the presence of HKUST-1 NPs. Estimated LC₅₀ values were 2.132 mg/L and 1.500 mg/L for zebrafish embryos and adults, respectively. During 96 h of exposure, the release of copper ions in a stock solution and accumulation of copper after 96 h were measured in the internal organs of adult fishes. Uptake examination of the major internal organs did not show any concentration dependency. An increase in the number of copper ions in the test medium was found on the first day of exposure. Toxicity was largely restricted to copper release from HKUST-1 nanomaterials structure into solution.

Toxicity and photosynthetic inhibition of metal-organic framework MOF-199 to pea seedlings

Metal-organic framework (MOF) materials are star materials with unique structures and properties. To ensure safe production and applications, the toxicity and environmental hazards of MOF materials should be thoroughly investigated. However, the environmental impact of MOF materials on plants is completely unknown. Herein, we reported the toxicity and photosynthetic inhibitory properties of MOF-199 to pea plants (Pisum sativum L.). MOF-199 was synthesized by hydrothermal method. MOF-199 was copper containing double-pyramid of high surface area (668 m2/g). MOF-199 accelerated the germination of pea seeds, but the total germination rates were unchanged. MOF-199 inhibited the seedling growth at high concentrations. The net photosynthetic rate increased, while the total photosynthesis capability decreased. Damage to the acceptor side of photosystem II was evidenced by chlorophyll fluorescence. Mechanistically, MOF-199 released Cu2+ in the nutrient solution, led to Cu2+ accumulations in seedlings, and promoted oxidative stress. In addition, the photosynthetic inhibitions of MOF-199 were stronger than equivalent concentrations of Cu(NO3)2, implying that MOF-199 particles also contributed to the environmental hazards. Our results highlighted the potential threat of MOF materials to plant growth and photosynthesis.

Selective mediation of ovarian cancer SKOV3 cells death by pristine carbon quantum dots/Cu2O composite through targeting matrix metalloproteinases, angiogenic cytokines and cytoskeleton

It was shown that some nanomaterials may have anticancer properties, but lack of selectivity is one of challenges, let alone selective suppression of cancer growth by regulating the cellular microenvironment. Herein, we demonstrated for the first time that carbon quantum dots/Cu2O composite (CQDs/Cu2O) selectively inhibited ovarian cancer SKOV3 cells by targeting cellular microenvironment, such as matrix metalloproteinases, angiogenic cytokines and cytoskeleton. The result was showed CQDs/Cu2O possessed anticancer properties against SKOV3 cells with IC50 = 0.85 μg mL-1, which was approximately threefold lower than other tested cancer cells and approximately 12-fold lower than normal cells. Compared with popular anticancer drugs, the IC50 of CQDs/Cu2O was approximately 114-fold and 75-fold lower than the IC50 of commercial artesunate (ART) and oxaliplatin (OXA). Furthermore, CQDs/Cu2O possessed the ability to decrease the expression of MMP-2/9 and induced alterations in the cytoskeleton of SKOV3 cells by disruption of F-actin. It also exhibited stronger antiangiogenic effects than commercial antiangiogenic inhibitor (SU5416) through down-regulating the expression of VEGFR2. In addition, CQDs/Cu2O has a vital function on transcriptional regulation of multiple genes in SKOV3 cells, where 495 genes were up-regulated and 756 genes were down-regulated. It is worth noting that CQDs/Cu2O also regulated angiogenesis-related genes in SKOV3 cells, such as Maspin and TSP1 gene, to suppress angiogenesis. Therefore, CQDs/Cu2O selectively mediated of ovarian cancer SKOV3 cells death mainly through decreasing the expression of MMP-2, MMP-9, F-actin, and VEGFR2, meanwhile CQDs/Cu2O caused apoptosis of SKOV3 via S phase cell cycle arrest. These findings reveal a new application for the use of CQDs/Cu2O composite as potential therapeutic interventions in ovarian cancer SKOV3 cells.

A Simple in vivo Assay Using Amphipods for the Evaluation of Potential Biocompatible Metal-Organic Frameworks

In this study, the application of amphipods in vivo assays was evaluated. The main aim of this work was to check the potential use of this model in biocompatibility assessments of metal-organic frameworks (MOFs). Hence, six different MOFs were synthesized and the in vitro and ex vivo cytotoxicity was first assessed using a colorimetric assay and a macrophage cell line. Obtained results were compared to validate the in vivo toxicity tests carried out using amphipods and increasing concentrations of the different MOFs. Amphipods do not require the need of ethics approval and also are less expensive to keep than conventional in vivo models, showing its potential as a fast and reliable platform in toxicity studies. The obtained results showed that the amphipods based-assay was simple, easy to replicate and yielded toxicity data corresponding to the type of MOFs tested. In addition, it was observed that only CIM-80(Al) and CIM-84(Zr) did not show any toxicity to the animals at the different tested concentrations. Therefore, the developed in vivo model could be applied as a high-throughput toxicity screening method to evaluate the toxicity of numerous materials, chemicals and therapeutic agents among others.

In vitro renal toxicity evaluation of copper-based metal-organic framework HKUST-1 on human embryonic kidney cells

HKUST-1 is currently studied for a very diverse range of applications. Despite its exciting potential, significant concerns remain regarding the safety of HKUST-1. Therefore, human embryonic kidney 293 (HEK293) cells were used to verify the renal toxicity of HKUST-1. In this study, HKUST-1 induced concentration-dependent cytotoxic effects in HEK293 cells. The depolarization of mitochondrial membrane potential and formation of apoptotic bodies and autophagic vesicles were observed in HKUST-1-treated HEK293 cells. Oxidative (oxidative stress and haem oxygenase-1 activation) and inflammatory responses (NF-κB and NLRP3 activation) in HEK293 cells were induced by HKUST-1 exposure. In addition, the observed reduction in NAD(P)H levels in HKUST-1-treated HEK293 cells may be attributable to PARP-1 activation following DNA single- and double-strand breaks. The HKUST-1-induced depletion of zonula occludens proteins in HEK293 cells might lead to altered renal barrier integrity. The variations of α1-antitrypsin, oxidised α1-antitrypsin and NLRP3 protein expression in HEK293 cells suggested that HKUST-1 increases the risk of chronic kidney diseases. However, most of these adverse effects were significantly induced only by high HKUST-1 concentration (100 μg/mL), which do not reflect the actual exposure. Thus, the toxic risk of HKUST-1 appears to be negligible.

Cellular evaluation of the metal-organic framework PCN-224 associated with inflammation and autophagy

Metal-organic frameworks (MOFs) are innovative porous structures consisting of metal ions and organic ligands, which have been verified for extraordinary applications in nanomedicine and pharmaceuticals. PCN-224 is a type of Zr-based MOFs, which has recently emerged as one of the most attractive nanomaterials for various applications, such as drug delivery, bioimaging and cancer therapy due to its favorable and fascinating physical-chemical properties. However, the safety evaluation and the potential toxicological properties remain unclear. In this study, the general cytotoxicity of PCN-224 were examined in both human hepatocytes L-02 cells and mouse macrophages RAW264.7. Furthermore, the effect of inflammation and autophagy were measured in L-02 cells. The results indicated that PCN-224 was engulfed in L-02 cells and subsequently resulted in morphological changes, cell membrane destruction, and oxidative stress in L-02 cells. PCN-224 might trigger inflammation by promoting the secretion of inflammatory factors such as Tumor necrosis factors (TNF-α) and Interleukin (IL-6). PCN-224 might induce autophagosome accumulation and subsequently autophagic dysfunction. Additionally, PCN-224 induced cytotoxicity in RAW264.7 cells and increased the protein levels of the inflammasome component NLR Family Pyrin Domain Containing 3 (NLRP3) molecular, which indicated its cellular effects in different cell types. All of these results will support the reasonable use of PCN-224.

The Toxicity of Secondary Lithium-Sulfur Batteries Components

Currently, apart from the widely known lithium-ion batteries, there are competitive solutions in the form of, for example, Li-S batteries. While the results of studies on the toxicity of Li-ion battery components are published, such studies on the components of Li-S cells are just beginning. The purpose of the current review was to identify materials used in the production of Li-S batteries and their toxicity, especially for humans. The review showed many kinds of materials with different levels of toxicity utilized for manufacturing of these cells. Some materials are of low toxicity, while some others are of the high one. A lot of materials have assigned different hazard statements. For some of the materials, no hazard statements were assigned, although such materials are toxic. No data related to the toxicity of some materials were found in the literature. This points out the need to further studies on their toxicity and legal actions to assign appropriate hazard statements.

Pristine Cu-MOF Induces Mitotic Catastrophe and Alterations of Gene Expression and Cytoskeleton in Ovarian Cancer Cells

Metals-organic frameworks (MOFs) have been widely explored in biomedicine, mostly in drug delivery, biosensing, and bioimaging due to their large surface area, tunable porosity, readily chemical functionalization, and good biocompatibility. However, the underlining cellular mechanisms controlling the process for MOF cytotoxicity remains almost completely unknown. Here, we demonstrate that pristine Cu-MOF without any loaded drug selectively inhibited ovarian cancer mainly through promoting tubulin polymerization and destroying the cell actin cytoskeleton (F-actin) to trigger the mitotic catastrophe, accompanying by conventional programmed cell death. To our knowledge, this is the first report claiming that mitotic catastrophe may be an explaining mechanism of MOF cytotoxicity. Cu-MOF with an intrinsic protease-like activity also hydrolyzed cellular cytoskeleton proteins (F-actin). The RNA sequencing data indicated the differential expressional mRNA of cell proliferation and actin cytoskeleton (ACTA2, ACTN3, FSCN2, and SCIN) and mitotic spindles (PLK1 and TPX2) related genes. We found that Cu-MOF as a promising candidate in the disruption of cellular cytoskeleton and the change of the gene expression could be actin altering and antimitotic agents against cancer cells, allowing for fundamental biological and biophysical studies of MOFs.

Comparison of different zinc precursors for the construction of zeolitic imidazolate framework-8 artificial shells on living cells

The robust cell-in-shell structure is highly desirable for endowing living cells with an artificial exoskeleton to defend them from many environmental factors such as osmotic pressure, shear force, heat, UV radiation, and enzymes. Cell encapsulation has shown potential applications in many fields and attracted increasing interest. However, the influences of the precursors on the cell viability during the shell formation process are not clear and seldom investigated. Here, zinc nitrite, zinc acetate and zinc sulfate were applied individually to synthesize zeolitic imidazolate framework-8 (ZIF-8) shells on living cells. All the zinc salt precursors could convert to a ZIF-8 layer on the living cell surface. The zinc salts and organic ligand did not exhibit obvious toxicity to yeast cells when applied individually. However, dead cells were observed during the living cell encapsulation process using different zinc precursors. Compared with zinc nitrate and zinc acetate, ZIF-8 formed by zinc sulfate led to a higher percentage of cell death, especially under high concentrations of zinc sulfate. Cell division was suppressed by the ZIF-8 shell but restored fully upon shell removal by EDTA solution or pH 4.0 buffer. Escherichia coli (E. coli) cells showed a lower percentage of cell death, indicating excellent tolerance to the ZIF-8 encapsulation process. This work illustrates the cell toxicity during the formation of ZIF-8 cell shells by different zinc salts and engineering of the cell growth by MOF coating, which could provide a foundation for further quantitative analysis and potential applications in biomedicine and bioengineering.

Multifunctional Fe3O4@C-based nanoparticles coupling optical/MRI imaging and pH/photothermal controllable drug release as efficient anti-cancer drug delivery platforms

Multifunctional nanomedicines featuring high drug loading capacity, controllable drug release and real-time self-monitoring are attracting increasing attention due to their potential to improve cancer therapeutic efficacy. Herein, a new kind of Fe₃O₄@C-based nanoparticles modified with isoreticular metal organic frameworks (IRMOF-3), folic acid (FA) and detachable polyethylene glycol (PEG) under tumor microenvironment was developed. The core-shell structured Fe₃O₄@C was synthesized via the one-pot solvothermal reaction and the IRMOF-3 layers were coated on the outer shell of Fe₃O₄@C through layer-by-layer coating method. The FA and PEG were conjugated on the surface of nanoparticles by reacting with the amine groups provided by IRMOF-3. The as-synthesized nanoparticles showed stable photothermal effect, superparamagnetic properties and blue fluorescence characteristic under 360 nm irradiation. The in vitro experiments showed that the drug loaded nanoparticles exhibit pH-dependent drug release property, and PEGylation was proved effective in suppressing burst drug release (only 8.0% of drugs were released within 95 h). The confocal laser scanning microscopy study revealed that the as-synthesized nanoparticles could serve as a cell imaging agent and the cell internalization can be significantly enhanced after FA modified. The IRMOF-3 modified nanoparticles showed negligible cytotoxicity and the drug loaded nanoparticles showed pH/photothermal-stimuli enhanced cytotoxicity in vitro. It is believed that the present smart drug delivery platforms will hold great potential in imaging guided drug delivery and cancer therapy.

Toxicity screening of two prevalent metal organic frameworks for therapeutic use in human lung epithelial cells

INTRODUCTION

The flexibility and tunability of metal organic frameworks (MOFs), crystalline porous materials composed of a network of metal ions coordinated by organic ligands, confer their variety of applications as drug delivery systems or as sensing and imaging agents. However, such properties also add to the difficulty in ensuring their safe implementation when interaction with biological systems is considered.

METHODS

In the current study, we used real-time sensorial strategies and cellular-based approaches to allow for fast and effective screening of two MOFs of prevalent use, namely, MIL-160 representative of a hydrophilic and ZIF-8 representative of a hydrophobic framework. The two MOFs were synthesized "in house" and exposed to human bronchial epithelial (BEAS-2B) cells, a pertinent toxicological screening model.

RESULTS

Analysis allowed evaluation and differentiation of particle-induced cellular effects as well identification of different degrees and routes of toxicity, all in a high-throughput manner. Our results show the importance of performing screening toxicity assessments before introducing MOFs to biomedical applications.

DISCUSSION

Our proposed screening assays could be extended to a wider variety of cell lines to allow for identification of any deleterious effects of MOFs, with the range of toxic mechanisms to be differentiated based on cell viability, morphology and cell-substrate interactions, respectively.

CONCLUSION

Our analysis highlights the importance of considering the physicochemical properties of MOFs when recommending a MOF-based therapeutic option or MOFs implementation in biomedical applications.

Zinc-based metal-organic frameworks as nontoxic and biodegradable platforms for biomedical applications: review study

Development of biomedical systems for controllable drug delivery systems and construction of biosensors is imperative to reduce side effects of common treatment techniques and enhance the therapeutic efficacy. To address this issue, metal-organic frameworks (MOFs) as hybrid porous polymeric structures have attracted worldwide attention due to their unprecedented opportunities in vast range of applications in diverse fields including chemistry, biological, and medicinal science as gas storage/separation, sensing, and drug delivery systems. Recently, biomedical application has become an interesting and promising issue for development and usage of multi-functional MOFs. Flexible chemical composition and versatile porous structure of MOFs enable the engineering and enhancement of their medical formulation and functionality as practical carriers for whether therapeutic or imaging agents. One important point in this domain is the efficient delivery of drugs in the body using nontoxic and biodegradable carriers. This review brings together the literatures that addressing the biomedical applications of Zinc-based MOFs (i.e. as drug delivery systems or nontoxic agent in matter of therapeutic applications) to present recent achievements in this interesting field.

Bottom-Up Formation of Carbon-Based Magnetic Honeycomb Material from Metal-Organic Framework-Guest Polyhedra for the Capture of Rhodamine B

Three-dimensional carbon-based porous materials have proven to be quite useful for tailoring material properties in the energy conservation and environmental protection applications. In view of the three-dimensional and well-defined structure of metal-organic frameworks (MOFs), a novel carbon-based magnetic porous material (HKUST-Fe₃O₄) has been designed and constructed by MOF-guest interactions of high-temperature pyrolysis. The obtained HKUST-Fe₃O₄ exhibited the unique features of superparamagnetism, a macro/mesoporous structure, environmental protection (inexistence of toxic heavy metal ions), and physicochemical stability and has shown high adsorption capacity and rapid adsorption for carcinogenic organic pollutants (for example, rhodamine B) with an environmentally friendly character and excellent reusability. We demonstrate that the unique/superior advantages of HKUST-Fe₃O₄ could meet the requirements of environment cleaning, especially for removing the targeted organic pollutant from water. Moreover, the specific HKUST-Fe₃O₄ and organic pollutant interaction mechanism has been analyzed in detail via parameter-free calculations. This study proposes a promising strategy for constructing novel carbon-based magnetic nanomaterials for various applications, not limitated to pollutant removal.

Drug nanoclusters formed in confined nano-cages of CD-MOF: dramatic enhancement of solubility and bioavailability of azilsartan

Tremendous efforts have been devoted to the enhancement of drug solubility using nanotechnologies, but few of them are capable to produce drug particles with sizes less than a few nanometers. This challenge has been addressed here by using biocompatible versatile γ-cyclodextrin (γ-CD) metal-organic framework (CD-MOF) large molecular cages in which azilsartan (AZL) was successfully confined producing clusters in the nanometer range. This strategy allowed to improve the bioavailability of AZL in Sprague-Dawley rats by 9.7-fold after loading into CD-MOF. The apparent solubility of AZL/CD-MOF was enhanced by 340-fold when compared to the pure drug. Based on molecular modeling, a dual molecular mechanism of nanoclusterization and complexation of AZL inside the CD-MOF cages was proposed, which was confirmed by small angle X-ray scattering (SAXS) and synchrotron radiation-Fourier transform infrared spectroscopy (SR-FTIR) techniques. In a typical cage-like unit of CD-MOF, three molecules of AZL were included by the γ-CD pairs, whilst other three AZL molecules formed a nanocluster inside the 1.7 nm sized cavity surrounded by six γ-CDs. This research demonstrates a dual molecular mechanism of complexation and nanoclusterization in CD-MOF leading to significant improvement in the bioavailability of insoluble drugs.

Novel nanoparticles of cerium-doped zeolitic imidazolate frameworks with dual benefits of antibacterial and anti-inflammatory functions against periodontitis

Novel ZIF-8:Ce nanoparticles provide a unique insight into effective anti-inflammatory and antibacterial platforms for periodontitis treatment.

Technological innovation strategies for the specific treatment of Chagas disease based on Benznidazole

Caused by Trypanosoma cruzi, Chagas disease is responsible for public health problems greater in magnitude than those attributed to malaria, schistosomiasis, or leishmaniasis. A factor in the socioeconomic development of poor countries, Chagas disease can cause death due to a high parasitic burden during its acute phase due and irreversible damage in organs such as the heart, esophagus, and colon during its chronic phase, even when the number of parasites is minimal. For treating Chagas disease, benznidazole (BNZ) remains the drug of choice and, in Latin America, the only drug on the market for treating the disease. However, BNZ has exhibited insufficient activity in the chronic phase of Chagas disease, required administration in large doses, prolonged treatment, and shown a high incidence of adverse reactions (vomiting, rash, peripheral neuropathy, and spinal cord depression), toxicity, and low solubility in water. As an antidote, pharmaceutical technologies have been introduced that can improve BNZ's solubility and dissolution, as well as reduce side effects in light of its bioavailability, all of which can enhance therapy for Chagas disease. In response to that trend, by conducting a literature review, we sought to identify current pharmaceutical technologies used in tandem with BNZ to improve therapy for Chagas disease. Documented techniques include emulsion and microemulsion formation, solutions, parenteral formulas, micronization, and drug delivery systems supported by the development of nanoparticles and cyclodextrins, solid dispersions, and the use of metal-organic frameworks as innovative excipients. Such technologies increase the water solubility of BNZ by 4-25-fold on dissolution and an 85% release with efficacy in only a few minutes, as recorded during a viability experiment with nanoparticle suspensions. That experiment demonstrated the need for a lower concentration of BNZ to kill 50% of trypomastigote forms of T. cruzi, described in terms of the formation of BNZ-cyclodextrin complexes, and modulating and vectoring of the antichagasic by using metal-organic frameworks. Altogether, the promising results of research identified can enable strategies to improve solubility and efficacy of BNZ, as well as therapy for Chagas disease.

Bioactive nano-metal-organic frameworks as antimicrobials against Gram-positive and Gram-negative bacteria

More effective antibiotics are needed to overcome the problem of multidrug resistance. The antibacterial efficacies of three Zn-based nano metal-organic frameworks (nMOFs) - IRMOF-3, MOF-5, and Zn-BTC - were explored, both alone and as mixtures with ampicillin and kanamycin. When tested against Escherichia coli, Staphylococcus aureus, Staphylococcus lentus, and Listeria monocytogenes, the nMOF/drug mixtures demonstrated synergistic (IRMOF-3/kanamycin) or additive (other nMOF/drug combinations) effects compared with the nMOFs or antibiotics alone. Zn-Based nMOFs can reduce the burden of the new discovery of antimicrobial pharmaceuticals by increasing the potency of existing antibiotics.

Amine-functionalized diatom frustules: a platform for specific and sensitive detection of nitroaromatic explosive derivative

In the present study, an attempt was made to develop a proof of concept for the detection of nitroaromatic explosive derivatives through the photoluminescence (PL) quenching process using functionalized diatom frustules as a sensing platform. The diatom frustules are composed of nanostructured, highly porous biogenic silica material and emit strong, visible blue PL upon UV excitation. PL-active biosilica was isolated from the marine diatom Nitzschia sp. and was amine-functionalized to develop a sensing platform. Functionalized diatom frustules were further characterized using field emission scanning electron microscope and a series of spectroscopic methods. When nitroaromatic compounds were bound to the functionalized diatom frustules biosilica, the PL intensity from the functionalized biosilica was partially quenched due to the electrophilic nature of the nitro (-NO) groups. The quenching process confirmed the Meisenheimer complex formation and was investigated by using Fourier transform infrared spectroscopy and time-resolved photoluminescence studies. The developed platform was further evaluated for its sensitivity and specificity, and the limit of detection (LOD) of the assay was determined as 1 μM for a series of nitroaromatic explosive compounds. In conclusion, the developed sensing platform will have great utility in the development of on-site detection platforms for sensitive detection of warfare explosive nitroaromatic compounds from the environment.

A luminescent ratiometric pH sensor based on a nanoscale and biocompatible Eu/Tb-mixed MOF

The precise and real-time monitoring of localized pH changes is of great importance in many engineering and environmental fields, especially for monitoring small pH changes in biological environments and living cells. Metal-organic frameworks (MOFs) with their nanoscale processability show very promising applications in bioimaging and biomonitoring, but the fabrication of nanoscale MOFs is still a challenge. In this study, we synthesized a nanoscale mixed-lanthanide metal-organic framework by a microemulsion method. The morphology and size of the NMOF can be simply adjusted by the addition of different amounts of the CTAB surfactant. This NMOF exhibits significant pH-dependent luminescence emission, which can act as a self-referenced pH sensor based on two emissions of Tb³⁺ at 545 nm and Eu³⁺ at 618 nm in the pH range from 3.00 to 7.00. The MTT assay and optical microscopy assay demonstrate the low cytotoxicity and good biocompatibility of the nanosensor.

In Vitro Neurotoxicity Resulting from Exposure of Cultured Neural Cells to Several Types of Nanoparticles

Laboratory and industrial production of various nanoparticles, single-walled nanotubes (SWNTs), fullerene (C60), cadmium selenide (CdSe) quantum dots, carbon black (CB), and dye-doped silica nanospheres (NSs), has greatly increased in the past 15 years. However, little research has been done to analyze the toxicity of these materials. With recent studies showing that nano-substances can cross the blood–brain barrier, we examined the neurotoxicity of these manufactured nanoparticles. By employing the rat PC-12 neuronal-like cell line as the basis for our studies, we were able to evaluate the toxicity caused by these five nanoparticles. The level of toxicity was measured by testing for cell viability using the lactate dehydrogenase (LDH) cell viability assay, morphological analysis of changes in cellular structures, and Western blot analyses of αII-spectrin breakdown products (SBDP) as cell death indicators. Our results showed cytotoxicity in nondifferentiated PC-12 cells exposed to CB (10–100 µg/mL), SWNTs (10–100 µg/mL), C60 (100 µg/mL), CdSe (10 µg/mL), CB (500 µg/mL), and dye-doped silicon NSs (10 µg/mL). Exposure to higher concentrations (100 µg/mL) of SWNTs, CB, and C60 increased the formation of SBDP150/145, as well as cell membrane contraction and the formation of cytosolic vacuoles. The incorporations of the nanoparticles into cell cytoplasm were observed using the fluorescent dye-doped NSs in both nondifferentiated and nerve growth factor (NGF)-differentiated PC-12 cells. When PC-12 cells are differentiated, they appeared to be even more sensitive to cytotoxicity of nanoparticles such as CB 10 nm (10–100 µg/mL), CB 100 nm (10–100 µg/mL), and CdSe (1–10 µg/mL).

Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design

BACKGROUND

Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment.

MATERIALS AND METHODS

NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc)₂] and benzene-1,3,5-tricarboxylic acid (H₃BTC) with benzoic acid (C₆H₅COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated.

RESULTS

Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2-5 nm. The half-maximal lethal concentration (LC₅₀) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL.

CONCLUSION

The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system.

Detoxification of hydroxylated polychlorobiphenyls by Sphingomonas sp. strain N-9 isolated from forest soil

To examine the biodegradation of hydroxylated polychlorobiphenyls (OH-PCBs), we isolated Sphingomonas sp. strain N-9 from forest soil using mineral salt medium containing 4-hydroxy-3-chlorobiphenyl (4OH-3CB) at the concentration of 10 mg/L. Following incubation with strain N-9, the concentration of 4OH-3CB decreased in inverse proportion to strain N-9 proliferation, and it was converted to 3-chloro-4-hydroxybenzoic acid (4OH-3CBA) after 1 day. We observed that strain N-9 efficiently degraded lowly chlorinated OH-PCBs (1-4 Cl), while highly chlorinated OH-PCBs (5-6 Cl) were less efficiently transformed. Additionally, strain N-9 degraded PCBs and OH-PCBs with similar efficiencies, and the efficiency of OH-PCB degradation was dependent upon the positional relationships between OH-PCB hydroxyl groups and chlorinated rings. OH-PCB biodegradation may result in highly toxic products, therefore, we evaluated the cytotoxicity of two OH-PCBs [4OH-3CB and 4-hydroxy-3,5-dichlorobiphenyl (4OH-3,5CB)] and their metabolites [4OH-3CBA and 3,5-chloro-4-hydroxybenzoic acid (4OH-3,5CBA)] using PC12 rat pheochromocytoma cells. Our results revealed that both OH-PCBs induced cell membrane damage and caused neuron-like elongations in a dose-dependent manner, while similar results were not observed for their metabolites. These results indicated that strain N-9 can convert OH-PCBs into chloro-hydroxybenzoic acids having lower toxicity.

Metal-Organic Frameworks as a Potential Platform for Selective Treatment of Gaseous Sulfur Compounds

The release of various anthropogenic pollutants such as gaseous sulfur compounds into the environment has been accelerated as globalization has promoted the production of high-quality products at lower prices. Because of strict enforcement of mitigation technologies, advanced materials have been developed to efficiently remove gaseous sulfur compounds released from various source processes. Metal-organic frameworks (MOFs) are promising materials to treat sulfur compounds via adsorption, catalysis, or separation. Nonetheless, the practical applicability of MOFs is limited by a number of factors including loss of structural integrity after use, limited reusability of spent MOFs, and low stability toward omnipresent molecules (e.g., H₂O). Here, we provide a comprehensive assessment of MOF technology for the effective control of gaseous sulfur compounds. This review will thus help expand the fields of real-world application for MOFs with a roadmap for this highly challenging area of research.