Selenium-Functionalized Graphene Oxide That Can Modulate the Balance of Reactive Oxygen Species

New Advances in Covalent Network Polymers via Dynamic Covalent Chemistry

Covalent network polymers, as materials composed of atoms interconnected by covalent bonds in a continuous network, are known for their thermal and chemical stability. Over the past two decades, these materials have undergone significant transformations, gaining properties such as malleability, environmental responsiveness, recyclability, crystallinity, and customizable porosity, enabled by the development and integration of dynamic covalent chemistry (DCvC). In this review, we explore the innovative realm of covalent network polymers by focusing on the recent advances achieved through the application of DCvC. We start by examining the history and fundamental principles of DCvC, detailing its inception and core concepts and noting its key role in reversible covalent bond formation. Then the reprocessability of covalent network polymers enabled by DCvC is thoroughly discussed, starting from the significant milestones that marked the evolution of these polymers and progressing to their current trends and applications. The influence of DCvC on the crystallinity of covalent network polymers is then reviewed, covering their bond diversity, synthesis techniques, and functionalities. In the concluding section, we address the current challenges faced in the field of covalent network polymers and speculates on potential future directions.

Intracellular infection-responsive macrophage-targeted nanoparticles for synergistic antibiotic immunotherapy of bacterial infection

Intracellular bacteria are considered to play a key role in the failure of bacterial infection therapy and increase of antibiotic resistance. Nanotechnology-based drug delivery carriers have been receiving increasing attention for improving the intracellular antibacterial activity of antibiotics, but are accompanied by disadvantages such as complex preparation procedures, lack of active targeting, and monotherapy, necessitating further design improvements. Herein, nanoparticles targeting bacteria-infected macrophages are fabricated to eliminate intracellular bacterial infections via antibiotic release and upregulation of intracellular reactive oxygen species (ROS) levels and proinflammatory responses. These nanoparticles were formed through the reaction of the amino group on selenocystamine dihydrochloride and the aldehyde group on oxidized dextran (ox-Dex), which encapsulates vancomycin (Van) through hydrophobic interactions. These nanoparticles could undergo targeted uptake by macrophages via endocytosis and respond to the bacteria-infected intracellular microenvironment (ROS and glutathione (GSH)) for controlled release of antibiotics. Furthermore, these nanoparticles could consume intracellular GSH and promote a significant increase in the level of ROS in macrophages, subsequently up-regulating the proinflammatory response to reinforce antibacterial activity. These nanoparticles can accelerate bacteria-infected wound healing. In this work, nanoparticles were fabricated for bacteria-infected macrophage-targeted and microenvironment-responsive antibiotic delivery, cellular ROS generation, and proinflammatory up-regulation activity to eliminate intracellular bacteria, which opens up a new possibility for multifunctional drug delivery against intracellular infection.

Covalent functionalization of 1D and 2D sp2-carbon nanoallotropes - twelve years of progress (2011-2023)

Carbon nanoallotropes have attracted significant attention in the field of materials science due to their unique combination of physicochemical and biological properties, with numerous applications. One-dimensional (1D) and two-dimensional (2D) sp2-carbon nanoallotropes, such as carbon nanohorns (CNHs), carbon nanotubes (CNTs), and graphene, have emerged as prominent candidates for a variety of technological advancements. To fully exploit their exceptional characteristics, the covalent functionalization of these nanostructures may alleviate the problems with the processing and final performance. This route of the carbon nanoallotrope functionalization is based on a covalent attachment of functional groups or molecules (via linkers of various strengths) to their surfaces, enabling precise control over physical, chemical, biological, and electronic properties. Such an approach opens up new avenues for tailoring the nanoallotrope characteristics, such as solubility/dispersibility, reactivity, and interactions with other materials. Over more than the last decade, significant progress has been made in the covalent functionalization of both 1D and 2D sp2-carbon nanoallotropes, paving the way for diverse applications in the nanoelectronics, energy storage, sensing, and biomedical fields. In this comprehensive review, we provide state-of-the-art advancements and achievements in the covalent functionalization of 1D and 2D sp2-carbon nanoallotropes during the past dozen years. We aim to highlight the key strategies, methodologies, and breakthroughs that have significantly contributed to this field. Eventually, we discuss the implications of those advancements and explore the opportunities for future research and applications.

Glutathione peroxidase-like nanozymes: mechanism, classification, and bioapplication

The field of nanozymes is developing rapidly. In particular, glutathione peroxidase (GPx)-like nanozymes, which catalytically reduce H₂O₂/organic hydroperoxides to H₂O/alcohols, have attracted considerable attention. GPx-like nanozymes are powerful antioxidant enzymes known to combat oxidative stress. They have broad applications, including cytoprotection, anti-inflammation, neuroprotection, tumor therapy, and anti-aging. Although much progress has been made, GPx-like nanozymes have not been well discussed or fully reviewed as other nanozymes. This review aims to summarize recent advances on GPx-like nanozymes from the vantage point of mechanism, classification, and bioapplication. Future prospects for advancing their design and application are also discussed.

Reactive Oxygen Species Responsive Polymers for Drug Delivery Systems

Reactive oxygen species (ROS) play an essential role in regulating various physiological functions of living organisms; however, as the concentration of ROS increases in the area of a lesion, this may undermine cellular homeostasis, leading to a series of diseases. Using cell-product species as triggers for targeted regulation of polymer structures and activity represents a promising approach for the treatment. ROS-responsive polymer carriers allow the targeted delivery of drugs, reduce toxicity and side effects on normal cells, and control the release of drugs, which are all advantages compared with traditional small-molecule chemotherapy agents. These formulations have attracted great interest due to their potential applications in biomedicine. In this review, recent progresses on ROS responsive polymer carriers are summarized, with a focus on the chemical mechanism of ROS-responsive polymers and the design of molecular structures for targeted drug delivery and controlled drug release. Meanwhile, we discuss the challenges and future prospects of its applications.

Selenium-doped two-photon fluorescent carbon nanodots for in-situ free radical scavenging in mitochondria

Mitochondrial oxidative stress is associated with the occurrence and development of a wide range of human diseases. The development of methodologies to alleviate oxidative stress-mediated injury may have therapeutic potential. Herein, we report the design and preparation of triphenylphosphonium-functionalized selenium-doped carbon nanodots (TPP-Se-CDs) that can efficiently scavenging hydroxyl radicals (OH) and superoxide anions (O₂^-) in mitochondria region. Se-CDs with two-photon blue fluorescence were initially prepared by facile hydrothermal treatment of selenomethionine, followed by the covalent conjugation with TPP. The as-obtained TPP-Se-CDs showed high colloidal stability, strong scavenging abilities towards OH and O₂^-. Moreover, TPP-Se-CDs exhibited low cytotoxicity and mitochondria targeting ability. Taking advantages of these prominent features, TPP-Se-CDs have been successfully applied to combat H₂O₂ and phorbol 12-myristate 13-acetate (PMA) induced oxidative stress in mitochondria.

Benzeneselenol-modified gold nanoclusters for cancer therapy

We report that benzeneselenol-modified gold nanoclusters (Se_Au NCs) can induce autophagy and interfere with actin expressions in cancer cells.

Mechanisms of graphene oxide aggregation, retention, and release in quartz sand

The roles of graphene oxide (GO) particle geometry, GO surface orientation, surface roughness, and nanoscale chemical heterogeneity on interaction energies, aggregation, retention, and release of GO in porous media were not fully considered in previous studies. Consequently, mechanisms controlling the environmental fate of GO were incompletely or inaccurately quantified. To overcome this limitation, plate-plate interaction energies were modified to account for these factors and used in conjunction with a mathematical model to interpret the results of GO aggregation, retention, and release studies. Calculations revealed that these factors had a large influence on the predicted interaction energy parameters. Similar to previous literature, the secondary minimum was predicted to dominate on smooth, chemically homogeneous surfaces that were oriented parallel to each other, especially at higher ionic strength (IS). Conversely, shallow primary minimum interactions were sometimes predicted to occur on surfaces with nanoscale roughness and chemical heterogeneity due to adsorbed Ca²⁺ ions, especially when the GO particles were oriented perpendicular to the interacting surface. Experimental results were generally consistent with these predictions and indicated that the primary minimum played a major role in GO retention and the secondary minimum contributed to GO release with IS reduction. Cation exchange (Na⁺ replacing Ca²⁺) enhanced GO release with IS reduction when particles were initially deposited in the presence of Ca²⁺ ions. However, retained GO were always completely recovered into the excess deionized water when the sand pore structure was destroyed during excavation, and this indicates that primary minima were shallow and that the pore structure also played an important role in GO retention. Further evidence for the role of pore structure on GO retention was obtained by conducting experiments in finer textured sand and at higher input concentrations that induced greater aggregation. In both cases, greater GO retention occurred, and retention profiles became more hyperexponential in shape.

Nanozymes: Classification, Catalytic Mechanisms, Activity Regulation, and Applications

Because of the high catalytic activities and substrate specificity, natural enzymes have been widely used in industrial, medical, and biological fields, etc. Although promising, they often suffer from intrinsic shortcomings such as high cost, low operational stability, and difficulties of recycling. To overcome these shortcomings, researchers have been devoted to the exploration of artificial enzyme mimics for a long time. Since the discovery of ferromagnetic nanoparticles with intrinsic horseradish peroxidase-like activity in 2007, a large amount of studies on nanozymes have been constantly emerging in the next decade. Nanozymes are one kind of nanomaterials with enzymatic catalytic properties. Compared with natural enzymes, nanozymes have the advantages such as low cost, high stability and durability, which have been widely used in industrial, medical, and biological fields. A thorough understanding of the possible catalytic mechanisms will contribute to the development of novel and high-efficient nanozymes, and the rational regulations of the activities of nanozymes are of great significance. In this review, we systematically introduce the classification, catalytic mechanism, activity regulation as well as recent research progress of nanozymes in the field of biosensing, environmental protection, and disease treatments, etc. in the past years. We also propose the current challenges of nanozymes as well as their future research focus. We anticipate this review may be of significance for the field to understand the properties of nanozymes and the development of novel nanomaterials with enzyme mimicking activities.

Visible Light-Induced Plasticity of Shape Memory Polymers

Plasticity of thermoset polymers has been realized by introducing exchangeable bonds, and the plasticity is mostly triggered via heat or UV light. Visible light is a relatively mild trigger that has not been used to induce plasticity in polymer materials. Herein, thermoset polyurethanes (PUs) containing diselenide bonds are fabricated that possess visible light-induced plasticity along with shape memory behavior. A series of PUs with different diselenide bond contents were tested and their shape memory properties and plasticity varied. With a higher diselenide bond content, both shape memory and light-induced plasticity are achieved. By combining these two properties, reshaping the permanent shapes of the PUs is easier. Compared with heat or UV light, visible light has the advantage of spatial control. For instance, a pattern of visible light was introduced by a commercial projector to demonstrate facile reshaping of the materials. Because visible light can be introduced via various methods, PUs with visible light-induced plasticity have great potential applications.