Metallodrugs in cancer nanomedicine

Metal complexes are extensively used for cancer therapy. The multiple variables available for tuning (metal, ligand, and metal-ligand interaction) offer unique opportunities for drug design, and have led to a vast portfolio of metallodrugs that can display a higher diversity of functions and mechanisms of action with respect to pure organic structures. Clinically approved metallodrugs, such as cisplatin, carboplatin and oxaliplatin, are used to treat many types of cancer and play prominent roles in combination regimens, including with immunotherapy. However, metallodrugs generally suffer from poor pharmacokinetics, low levels of target site accumulation, metal-mediated off-target reactivity and development of drug resistance, which can all limit their efficacy and clinical translation. Nanomedicine has arisen as a powerful tool to help overcome these shortcomings. Several nanoformulations have already significantly improved the efficacy and reduced the toxicity of (chemo-)therapeutic drugs, including some promising metallodrug-containing nanomedicines currently in clinical trials. In this critical review, we analyse the opportunities and clinical challenges of metallodrugs, and we assess the advantages and limitations of metallodrug delivery, both from a nanocarrier and from a metal-nano interaction perspective. We describe the latest and most relevant nanomedicine formulations developed for metal complexes, and we discuss how the rational combination of coordination chemistry with nanomedicine technology can assist in promoting the clinical translation of metallodrugs.

MOF Synthesis Prediction Enabled by Automatic Data Mining and Machine Learning

Despite rapid progress in the field of metal–organic frameworks (MOFs), the potential of using machine learning (ML) methods to predict MOF synthesis parameters is still untapped. Here, we show how ML can be used for rationalization and acceleration of the MOF discovery process by directly predicting the synthesis conditions of a MOF based on its crystal structure. Our approach is based on: i) establishing the first MOF synthesis database via automatic extraction of synthesis parameters from the literature, ii) training and optimizing ML models by employing the MOF database, and iii) predicting the synthesis conditions for new MOF structures. The ML models, even at an initial stage, exhibit a good prediction performance, outperforming human expert predictions, obtained through a synthesis survey. The automated synthesis prediction is available via a web‐tool on https://mof‐synthesis.aimat.science.

Reticular Nanoscience: Bottom-Up Assembly Nanotechnology

The chemistry of metal-organic and covalent organic frameworks (MOFs and COFs) is perhaps the most diverse and inclusive among the chemical sciences, and yet it can be radically expanded by blending it with nanotechnology. The result is reticular nanoscience, an area of reticular chemistry that has an immense potential in virtually any technological field. In this perspective, we explore the extension of such an interdisciplinary reach by surveying the explored and unexplored possibilities that framework nanoparticles can offer. We localize these unique nanosized reticular materials at the juncture between the molecular and the macroscopic worlds, and describe the resulting synthetic and analytical chemistry, which is fundamentally different from conventional frameworks. Such differences are mirrored in the properties that reticular nanoparticles exhibit, which we described while referring to the present state-of-the-art and future promising applications in medicine, catalysis, energy-related applications, and sensors. Finally, the bottom-up approach of reticular nanoscience, inspired by nature, is brought to its full extension by introducing the concept of augmented reticular chemistry. Its approach departs from a single-particle scale to reach higher mesoscopic and even macroscopic dimensions, where framework nanoparticles become building units themselves and the resulting supermaterials approach new levels of sophistication of structures and properties.

Functional Janus structured liquids and aerogels

Janus structures have unique properties due to their distinct functionalities on opposing faces, but have yet to be realized with flowing liquids. We demonstrate such Janus liquids with a customizable distribution of nanoparticles (NPs) throughout their structures by joining two aqueous streams of NP dispersions in an apolar liquid. Using this anisotropic integration platform, different magnetic, conductive, or non-responsive NPs can be spatially confined to opposite sides of the original interface using magnetic graphene oxide (mGO)/GO, Ti3C2Tx/GO, or GO suspensions. The resultant Janus liquids can be used as templates for versatile, responsive, and mechanically robust aerogels suitable for piezoresistive sensing, human motion monitoring, and electromagnetic interference (EMI) shielding with a tuned absorption mechanism. The EMI shields outperform their current counterparts in terms of wave absorption, i.e., SET ≈ 51 dB, SER ≈ 0.4 dB, and A = 0.91, due to their high porosity ranging from micro- to macro-scales along with non-interfering magnetic and conductive networks imparted by the Janus architecture.

Zirconium vs. hafnium: a comparative study of mesoporous MOF stability

A wide range of mesoporous Zr and Hf metal-organic frameworks (MOFs), namely MIP-206, MOF-808, and NU-1000, as well as the microporous UiO-66, were systematically investigated and compared in terms of thermal and chemical stability. The holistic effects of metal type (Zr vs. Hf), linker type (small and rigid vs. large and flexible), and framework topology (2D vs. 3D) on the overall framework stability were investigated.

Alignment of Breathing Metal-Organic Framework Particles for Enhanced Water-Driven Actuation

As the majority of known metal-organic frameworks (MOFs) possess anisotropic crystal lattices and thus anisotropic physicochemical properties, a pressing practical challenge in MOF research is the establishment of robust and simple processing methods to fully harness the anisotropic properties of the MOFs in various applications. We address this challenge by applying an E-field to precisely align MIL-88A microcrystals and generate MIL-88A@polymer films. Thereafter, we demonstrate the impact of MOF crystal alignment on the actuation properties of the films as a proof of concept. We investigate how different anisotropies of the MIL-88A@polymer films, specifically, crystal anisotropy, particle alignment, and film composition, can lead to the synergetic enhancement of the film actuation upon water exposure. Moreover, we explore how the directionality in application of the external stimuli (dry/humid air stream, water/air interface) affects the direction and the extent of the MIL-88A@polymer film movement. Apart from the superior water-driven actuation properties of the developed films, we demonstrate by dynamometer measurements the higher degree of mechanical work performed by the aligned MIL-88A@polymer films with the preserved anisotropies compared to the unaligned films. The insights provided by this work into anisotropic properties displayed by aligned MIL-88A@polymer films promise to translate crystal performance benefits measured in laboratories into real-world applications. We anticipate that our work is a starting point to utilize the full potential of anisotropic properties of MOFs.

The chemistry behind room temperature synthesis of hafnium and cerium UiO-66 derivatives

RT formation of Hf and Ce UiO-66 derivatives is investigated using a one-step method where the linker and metal salt are simply combined, and a two-step method where the inorganic component is pre-heated to form metal clusters.

Unravelling the Potential of Crude Enzyme Extracts for Biocatalyst Entrapment in Metal-Organic Frameworks

To bolster the applicability of enzymes as catalysts, it is imperative not only to address their inherent fragility, particularly when used under harsh organic-synthetic reaction conditions, but also to mitigate deactivation during purification and enable applicability in a broad range of organic-synthetic transformations. Currently, the process of purification of crude enzyme extracts and subsequent heterogenization to obtain immobilized biocatalysts often leads to partial enzyme deactivation and represents, at least in part, a resource-intensive process that is driving up the overall production efforts. To tackle both the enzyme fragility and deactivation during purification and immobilization, we propose the direct use of crude enzyme extracts obtained from cell lysis instead of pure enzymes and their entrapment in metal-organic framework (MOF) structures. We focus on three enzyme types with varying sensitivities: aldoxime dehydratase, imine reductase, and lipase. We evaluate the effects of different metal sources (Al, Fe, Co, Ni, Cu, and Zn), their oxidation state and counterions, and MOF synthesis parameters on enzyme stability and activity during their entrapment in the MOF structures. Based on this, we optimize protocols for enzyme entrapment in Fe-MIL-88A, Fe-MIL-100, Zn-MOF-74, and Zn-ZIF-8 and develop a fast-aqueous room temperature synthesis of Al-MIL-53. Investigation of the biocatalytic performance of the enzyme@MOF biocomposites suggests that enzyme entrapment in MOFs using crude enzyme extracts can effectively maintain enzyme activity and stability in various catalytic reactions, offering a perspective for an efficient pathway for industrial applications.

Robust Immobilization and Activity Preservation of Enzymes in Porous Frameworks by Silica-Based "Inorganic Glue"

The development of novel methods to enhance enzyme-carrier interactions in situ, at a feasible cost, and on a large scale is crucial for improving the stability and durability of current immobilized enzyme systems used in industrial settings. Here, a pioneering approach termed "silica-based inorganic glue" is proposed, which utilizes protein-catalyzed silicification to fix enzyme within porous matrix while preserving enzyme activity. This innovative strategy offers several key benefits, including conformational stabilization of enzymes, improved interactions between enzymes and the matrix, prevention of enzyme leakage, and mitigation of pore blocking. Moreover, the controllable and scalable nature of this method renders it a cost-effective solution for enhancing enzyme immobilization in industrial contexts. To demonstrate the effectiveness of the "silica-based inorganic glue" technology, it has applied to three different enzymes exhibiting varying surface characteristics, sizes, and functions and in diverse porous supports, including a metal-organic framework (MOF) and a commercial macroporous resin, which resulted in a significant improvement of the stability and longevity of the immobilized enzymes. Overall, this findings represent a significant advancement in enzyme immobilization techniques, signaling a paradigm shift in current industrial catalysis.