Vitamin B12-Immobilized Graphene Oxide for Efficient Electrocatalytic Carbon Dioxide Reduction Reaction

Tuning the CO2 Reduction Selectivity of an Immobilized Molecular Ag Complex beyond CO

The electrochemical reduction of carbon dioxide (CO2) to produce fuels and chemicals has garnered significant attention. However, achieving control over the selectivity of the resulting products remains a challenging task, particularly within molecular systems. In this study, we employed a molecular silver complex immobilized on graphitized mesoporous carbon (GMC) as a catalyst for converting CO2 into CO, achieving an impressive selectivity of over 90% at -1.05 V vs RHE. Notably, the newly formed silver nanoparticles emerged as the active sites responsible for this high CO selectivity rather than the molecular system. Intriguingly, the introduction of copper ions into the restructured Ag-nanoparticle-decorated carbon altered the product selectivity. At -1.1 V vs RHE in 0.1 M KCl, we achieved a high C2 selectivity of 75%. Furthermore, not only the Ag-Cu bimetallic nanoparticle but also the small-sized Ag-Cu nanocluster decorated over GMC was proposed as active sites during catalytic reactions. Our straightforward approach offers valuable insights for fine-tuning the product selectivity of immobilized molecular systems, extending beyond C1 products.

Protein-coated cobalt oxide-hydroxide nanospheres deliver photosensitizer IR780 iodide for near-infrared light-triggered photodynamic/photothermal/chemodynamic therapy against colon cancer

Phototherapy has garnered worldwide attention for its minimal invasiveness, controllability, and spatial selectivity in treating cancer. One promising approach involves the use of near-infrared dye IR780, which demonstrates both photodynamic therapy (PDT) and photothermal therapy (PTT) effects under 808 nm laser irradiation. However, this hydrophobic dye's toxicity and limited tumor targeting ability severely hamper its suitability for cancer applications. Herein, a biocompatible nanoplatform CoOOH-IR780@BSA (CoIRB) is developed to efficiently deliver IR780 and provide multi-mode treatments for colon tumors. Due to the nanocarrier coating, CoIRB nanoparticles demonstrated reliable dispersion and stability, and their biotoxicity was substantially reduced for safer blood circulation, which overcame the biological barrier of IR780. The nanoplatform has also shown considerable results in phototherapy in vivo and in vitro experiments, with successful inhibition of MC38 tumor growth through intravenous administration. Additionally, the introduction of cobalt ions could induce Fenton-like reactions to activate the production of toxic hydroxyl radicals (˙OH), exerting an assisted chemodynamic therapy (CDT) effect. Notably, these nanodrugs also exhibited potential as scavengers of reductive glutathione (GSH) and hydrogen sulfide (H2S), leading to amplifying oxidative damage of reactive oxygen species (ROS). Overall, the versatile therapeutic platform, CoIRB, has opened up considerable prospects as a biotherapeutic option for combining PDT/PTT/CDT against colon cancer.

Cyclic iron tetra N-heterocyclic carbenes: synthesis, properties, reactivity, and catalysis

Cyclic iron tetracarbenes are an emerging class of macrocyclic iron N-heterocyclic carbene (NHC) complexes. They can be considered as an organometallic compound class inspired by their heme analogs, however, their electronic properties differ, e.g. due to the very strong σ-donation of the four combined NHCs in equatorial coordination. The ligand framework of iron tetracarbenes can be readily modified, allowing fine-tuning of the structural and electronic properties of the complexes. The properties of iron tetracarbene complexes are discussed quantitatively and correlations are established. The electronic nature of the tetracarbene ligand allows the isolation of uncommon iron(III) and iron(IV) species and reveals a unique reactivity. Iron tetracarbenes are successfully applied in C-H activation, CO₂ reduction, aziridination and epoxidation catalysis and mechanisms as well as decomposition pathways are described. This review will help researchers evaluate the structural and electronic properties of their complexes and target their catalyst properties through ligand design.

Graphene and its derivatives: understanding the main chemical and medicinal chemistry roles for biomedical applications

Over the past few years, there has been a growing potential use of graphene and its derivatives in several biomedical areas, such as drug delivery systems, biosensors, and imaging systems, especially for having excellent optical, electronic, thermal, and mechanical properties. Therefore, nanomaterials in the graphene family have shown promising results in several areas of science. The different physicochemical properties of graphene and its derivatives guide its biocompatibility and toxicity. Hence, further studies to explain the interactions of these nanomaterials with biological systems are fundamental. This review has shown the applicability of the graphene family in several biomedical modalities, with particular attention for cancer therapy and diagnosis, as a potent theranostic. This ability is derivative from the considerable number of forms that the graphene family can assume. The graphene-based materials biodistribution profile, clearance, toxicity, and cytotoxicity, interacting with biological systems, are discussed here, focusing on its synthesis methodology, physicochemical properties, and production quality. Despite the growing increase in the bioavailability and toxicity studies of graphene and its derivatives, there is still much to be unveiled to develop safe and effective formulations.

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Non-stoichiometric cobalt sulfide nanodots enhance photothermal and chemodynamic therapies against solid tumor

Photodynamic therapy (PDT) mainly relies on reactive oxygen species generated by light- activated photosensitizers and oxygen to kill tumor cells. However, a critical limitation of the current PDT is that it is less effective in solid tumors where the microenvironment is hypoxic, and, therefore, repeated treatment is required. Here, non-stoichiometric Co_2.19S₄ nanodots (NDs), which can be rapidly degraded to cobalt (Co²⁺) and sulfur (S^2-) ions, were developed to enhance tumor photothermal therapy (PTT) and chemodynamic therapy (CDT) via the capture of copper (Cu²⁺) ions (starvation therapy) in the hypoxic tumor microenvironment under near-infrared irradiation. Co_2.19S₄ NDs with excellent photothermal conversion efficiency (ɳ = 52%) can be used for PTT, and the Co²⁺ ions produced by their degradation can catalyze the endogenous hydrogen peroxide of tumor cells to produce highly toxic hydroxyl radicals to achieve tumor CDT. The mechanism of starvation therapy was explored using western blotting, and the results indicated that blocking the uptake of Cu²⁺ ions could restrain the growth and proliferation of tumors by inhibiting the BRAF/mitogen-activated extracellular signal regulated kinase (MEK)/extracellular regulated protein kinases (ERK) signaling pathway. Our work highlights the great potential of Co_2.19S₄ NDs as a theranostic agent for implementing photoacoustic/photothermal imaging and starvation therapy-enhanced PTT/CDT.