Applications of Boron Cluster Supramolecular Frameworks as Metal-Free Chemodynamic Therapy Agents for Melanoma.

Chemodynamic therapy (CDT) is a highly targeted approach to treat cancer since it converts hydrogen peroxide into harmful hydroxyl radicals (OH·) through Fenton or Fenton-like reactions. However, the systemic toxicity of metal-based CDT agents has limited their clinical applications. Herein, a metal-free CDT agent: 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT)/ [closo-B12 H12 ]2- (TPT@ B12 H12 ) is reported. Compared to the traditional metal-based CDT agents, TPT@B12 H12 is free of metal avoiding cumulative toxicity during long-term therapy. Density functional theory (DFT) calculation revealed that TPT@B12 H12 decreased the activation barrier more than 3.5 times being a more effective catalyst than the Fe2+ ion (the Fenton reaction), which decreases the barrier about twice. Mechanismly, the theory calculation indicated that both [B12 H12 ]-· and [TPT-H]2+ have the capacity to decompose hydrogen into 1 O2 , OH·, and O2 -· . With electron paramagnetic resonance and fluorescent probes, it is confirmed that TPT@B12 H12 increases the levels of 1 O2 , OH·, and O2 -· . More importantly, TPT@B12 H12 effectively suppress the melanoma growth both in vitro and in vivo through 1 O2 , OH·, and O2 -· generation. This study specifically highlights the great clinical translational potential of TPT@B12 H12 as a CDT reagent.

Anti-tumor therapy through high ROS performance induced by Ag nanoenzyme from boron cluster with halloysite clay nanotubes.

The conventional silver nanoparticles (Ag NPs) are characterized with high loading rate and stacking phenomenon, leading to shedding caused biotoxicity and low catalytic efficiency. This seriously hinders their application in biomedicine. Here, we modified the highly dispersible Ag NPs and Ag single-atoms (SAs) synthesis by combining the halloysite clay nanotubes (HNTs) and dodecahydro-dodecaborate (closo-[B12H12]2-) to increase the biocompatible properties and decrease the loading rate. This novel Ag single-atom nanoenzyme alongside Ag NPs nanoenzyme avoid the elevated-temperature calcination while maintaining the exceptionally high-level efficiency of Ag utilization via the reducibility and coordination stabilization of closo-[B12H12]2- and HNTs. With theoretical calculation and electron paramagnetic resonance, we confirmed that both Ag SAzymes and Ag NPs in HNT@B12H12@Ag nanoenzyme are capable decompose the H2O2 into hydroxyl radical (·OH). For the application, we investigated the catalytic activity in the tumor cells and antitumor effects of HNT@B12H12@Ag nanoenzyme both in vitro and in vivo, and confirmed that it effectively suppressed melanoma growth through ·OH generation, with limited biotoxicity. This study provides a novel Ag nanoenzyme synthesis approach to increase the possibility of its clinical application.

Platinum group nanoparticles doped BCN matrix: Efficient catalysts for the electrocatalytic reduction of nitrate to ammonia.

The effective treatment of nitrate (NO3-) in water as a nitrogen source and electrocatalytic NO3- reduction to ammonia (NH3) (NRA) have become preferred methods for NO3--to-NH3 conversion. Achieving efficient NO3--to-NH3 conversion requires the design and development of electrode materials with high activity and efficiency for the electrocatalytic NRA reaction. Herein, based on the special properties of dodecahydro-closo-dodecaborate anions, a BCN matrix, loaded with platinum-group nanoparticles (namely, Pd/BCN, Pt/BCN, and Ru/BCN), was prepared using a simple method for the electrocatalytic NRA reaction. Results showed that Pd/BCN exerts the best catalytic effect on the NRA reaction. The NH3 production rate reached 12.71 mg h-1 mgcat.-1 at -1.0 V vs. RHE. Faraday efficiency reached 91.79 %, which can be attributed to the more uniform distribution of the nanoparticles. Furthermore, Pd/BCN exhibited high cycling stability and resistance to ionic interference. Moreover, the density functional theory calculations indicated that small and well-distributed Pd nanoclusters in the BCN matrix have a large active surface area and promote the catalytic process. This study provides a new strategy to design catalysts for green ammonia synthesis.

Antitumor Therapy through Photothermal Performance Synergized with Catalytic Activity Based on the Boron Cluster Supramolecular Frameworks.

Chemodynamic therapy (CDT) has received widespread attention as a tumor optical treatment strategy in the field of malignant tumor therapy. Nonmetallic multifunctional nanomaterials as CDT agents, due to their low toxicity, long-lasting effects, and safety characteristics, have promising applications in the integrated diagnosis and treatment of cancer. Here, we modified the supramolecular framework of boron clusters, coupled with a variety of dyes to develop a series of metal-free agent compounds, and demonstrated that these nonmetallic compounds have excellent CDT activities through experiments. Subsequently, the best performing Methylene Blue/[closo-B12H12]2- (MB@B12H12) was used as an example. Through theoretical calculations, electron paramagnetic resonance spectroscopy, and 808 nm light irradiation, we confirmed that MB@B12H12 exhibited photothermal performance and CDT activity further. More importantly, we applied MB@B12H12 to melanoma cells and subcutaneous tumor, demonstrating its effective suppression of melanoma growth in vitro and in vivo through the synergistic effects of photothermal performance and CDT activity. This study emphasizes the generalizability of the coupling of dyes to [closo-B12H12]2- with important clinical translational potential for CDT reagents. Among them, MB@B12H12 may have a brighter future, paving the way for the rapid development of metal-free CDT reagents.

Synthesis of iron-boride/carbon-nitride composites and their applications in chemodynamic therapy.

Chemodynamic therapy (CDT) is an emerging treatment strategy that inhibits tumor growth by catalyzing the generation of reactive oxygen species (ROS), such as hydroxyl radicals (•OH), using specific nanomaterials. Herein, we have developed a new class of iron-based nanomaterials, i.e., iron-based borides (FeB), using the superchaotropic effect of a boron cluster (closo-[B12H12]2-) and organic ligands, followed by high-temperature calcination. Experimental data and theoretical calculations revealed that FeB nanoparticles exhibit a Fenton-like effect, efficiently decomposing hydrogen peroxide into •OH and thus increasing the concentration of ROS. FeB nanomaterials demonstrate excellent catalytic performance, efficiently generate ROS, and exert significant antitumor effects in cell experiments and animal models. Therefore, FeB nanomaterials have considerable potential for application in tumor treatment and offer new insights for the development of novel and efficient cancer therapy strategies.

Performance and mechanism of ammonia production by electrocatalytic nitrate reduction based on dodecahydro-closo-dodecaborate hybrid.

Ammonia is an essential food and fertilizer component and is a fundamental raw material for industry and agriculture. In contrast, nitrate is the main pollutant that causes eutrophication in water. Electrocatalysis is a clean and efficient method for simultaneous nitrate removal and ammonia production. However, because ammonia production from the electrocatalytic nitrate reduction reaction (NO3RR) is a complex eight-electron process with slow kinetics, designing the cathode catalyst is critical for improving the ammonia yield. In this study, boron (B) doped metal oxides (TiZn2O4@B-x) obtained by coupling dodecahydro-closo-dodecaborate anions ([closo-B12H12]2-) and ZnTi-layered double hydroxides (ZnTi-LDH) after calcination was used as the cathode for the NO3RR. Specifically, TiZn2O4@B-700 exhibited excellent ammonia yield (21809.24 µg h-1 mgcat-1) and Faraday efficiency (FE) of (93.15%) at -1.8 V versus saturated calomel electrode (SCE). Furthermore, TiZn2O4@B-700 exhibited superior cycling stability and resistance to ionic interference. Moreover, density functional theory (DFT) calculations indicated that incorporating B increased the electron transfer rate and reduced the free energy required for the rate-limiting step of ammonia production via the NO3RR, thereby increasing the ammonia yield. This study provides a new concept for designing catalysts for green ammonia synthesis.

Shape-Controlled Dodecaborate Supramolecular Organic-Framework-Supported Ultrafine Trimetallic PtCoNi for Catalytic Hydrolysis of Ammonia Borane.

On the basis of the unique chaotropic supramolecular assembly of cucurbit[5]uril (CB5) and dodecahydro- closo-dodecaborate anion [ closo-B12H12]2-, we have developed an efficient and universal platform to fabricate shape-controlled dodecaborate-based supramolecular organic frameworks (BOFs) decorated with ultrafine monodispersed trimetallic alloys. Simply by regulating the molar ratio of CB5 and [ closo-B12H12]2-, a series of fascinating morphologies, such as flowerlike structures, nanorods, nanocubes, and nanosheets, were successfully constructed. These obtained BOFs were proved to be good substrate supports for in situ synthesis of trimetallic PtCoNi nanoalloys, where the final PtCoNi-BOFs materials were obtained efficiently as a precipitate from aqueous solutions, and showed excellent catalytic performance in ammonia borane hydrolysis with a high turnover frequency of 1490 molH2 molPt-1 min-1 and a low activation energy of 15.79 kJ mol-1.

Cellulosic Cr(salen) complex as an efficient and recyclable catalyst for copolymerization of SO2 with epoxide.

The search for green catalytic processes for the synthesis of useful polymers and incorporating the waste SO2 in highly-selective pathways become extremely important in the coming years. Herein, cellulose was modified by ethylenediamine, and then synthesized Schiff base with 3,5-di-tert-butyl-2-hydroxybenzaldehyde to immobilize chromium chloride and formed a novel heterogeneous cellulosic Cr(salen)-type catalyst for the first time. The cellulosic Cr(salen)-type catalyst shows high efficiency and recyclability in copolymerization of cyclohexene oxide with SO2. The influence factors such as the molar ratio of the catalyst and cyclohexene oxide, reaction temperature, and reaction time were researched in detail to study the optimal conditions. The copolymer product was characterized by FTIR and 1H NMR for confirming the structure. The possible copolymer mechanism is given, and we believed that the novel cellulosic Cr(salen)-type complex will be used as an efficient catalyst in other chemical reactions.