Co-based Nanozymatic Profiling: Advances Spanning Chemistry, Biomedical, and Environmental Sciences

Multifunctional (Co3Fe)(S2)4-ion-microneedle patch: Synergistic antimicrobial, anti-inflammatory and cell proliferation for accelerating wound healing

Preventing bacterial infection and accelerating wound closure are critical for wound healing. Herein, a novel multifunctional polyvinyl alcohol-polyvinylpyrrolidone (PVA-PVP) microneedle (MN) patch embedded with enzyme-like activity (Co3Fe)(S2)4 (CFS) nanoparticles and metal ions (Co2+ and Fe3+) was systematically synthesized for the management of bacteria-infected wounds. CFS regulated redox homeostasis and achieved bacterial eradication while concomitantly alleviating oxidative damage. Specifically, CFS generated reactive oxygen species (ROS) to eliminate bacteria and concurrently attenuated cellular inflammation by scavenging ROS through their superoxide dismutase-like (SOD) activity. Meanwhile, the results of RNA transcriptome sequencing and quantitative real-time polymerase chain reaction (qRT-PCR) analyses indicated that Co2+ and Fe3+ can inhibit inflammatory responses in mice by modulating the IL-17 and NF-κB signaling pathways. Therefore, CFS-ion-MN significantly enhanced the healing of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) in mice model without eliciting systemic toxicity. Overall, this study offers an innovative methodology for the development of composite materials for the effective treatment of wounds.

Cold Exposure Therapy Enhances Single-Atom Nanozyme-Mediated Cancer Vaccine Therapy

Single-atom nanozymes are highly effective in the preparation of tumor vaccines (TV) due to their superior peroxidase (POD) activity and excellent biocompatibility. However, the immunosuppressive environment within tumors can diminish the efficacy of these vaccines. Cold exposure (CE) therapy, a noninvasive and straightforward antitumor method, not only suppresses tumor metabolism but also ameliorates the immunosuppressive tumor milieu. In this study, we developed personalized TV using copper single-atom nanozyme (Cu SAZ) and enhanced their long-term antitumor efficacy by introducing CE. We initially synthesized the Cu SAZ via high-temperature carbonization, which demonstrated robust POD activity and photothermal characteristics. Upon exposure to 808 nm laser irradiation, the nanozyme generated reactive oxygen species (ROS) and heat, inducing immunogenic cell death in 4T1 breast cancer cells or CT26 colon cancer cells and facilitating TV production. In our in vivo tumor prevention and treatment model, we noted that CE significantly boosted the efficacy of the TV. The primary mechanism involves CE's ability to lower the ratio of myeloid-derived suppressor cells (MDSCs), decrease glucose metabolism in tumor cells, and increase the proportions of CD8+ T cells and memory T cells. Collectively, our findings offer promising avenues for designing innovative TV systems.

Kirkendall Effect-Mediated Transformation of ZIF-67 to NiCo-LDH Nanocages as Oxidase Mimics for Multicolor Point-of-Care Testing of β-Galactosidase Activity and Escherichia coli

Early and portable detection of pathogenic bacteria is crucial for ensuring food safety, monitoring product quality, and tracing the sources of bacterial infections. Moving beyond traditional plate-culture counting methods, the analysis of active bacterial components offers a rapid means of quantifying bacteria. Here, metal-organic framework (MOF)-derived NiCo-layered double hydroxide nanosheets (LDHs), synthesized via the Kirkendall effect, were employed as highly effective oxidase mimics to generate reactive oxygen species (ROS). These ROS quickly etched gold nanobipyramids (Au NBPs), producing a vivid multicolormetric response. Experimental results and theoretical calculations indicated that the exceptional oxidase-like activity of NiCo-LDHs stemmed from the presence of bimetallic active sites and oxygen vacancies modulating the local electronic structure of LDHs. Additionally, β-galactosidase (β-Gal), a biomarker of Escherichia coli, reacted with p-aminophenyl-β-d-galactopyranoside (PAPG) to form p-aminophenol (PAP), a reducing agent which consumes ROS, thereby inhibiting the etching of Au NBPs. Furthermore, a three-dimensional (3D)-printed point-of-care testing (POCT) shell was designed as a portable device to visually detect β-Gal and E. coli in conjugation with smartphones. This study not only provides a novel approach to the rational design of nanozymes but also establishes a vivid and portably visual biosensing platform for detecting β-Gal activity and pathogenic bacteria.

A Chinese drug-compatibility-based approach to purslane hydrogels for acute eczema therapy

Purslane (Portulaca oleracea L.) with heat-clearing and detoxicating, anti-inflammatory and resolving swelling, relieving itching and astringing function, has remarkable efficacy for acute eczema. However, most of the clinical applications of purslane are freshly prepared decoction, not as easy to apply as cream, because the decoction is easy to breed bacteria and easy to oxidize. Here, based on the theory of Chinese medicines compatibility, we made a purslane-tannic acid hydrogel (PL-HATA) by simple methods under mild conditions to solve the drawbacks of easy oxidation and inconvenience of use of Purslane. The antimicrobial activity of PL-HATA hydrogel can exert an excellent antimicrobial effect, reducing the flora on the skin of acute eczema and further relieving the symptoms of acute eczema. At the same time, it creates a normal reactive oxygen species (ROS) microenvironment for acute eczema and promotes recovery from acute eczema. It also improves the symptoms of acute eczema by promoting cell proliferation and migration. Importantly, it resulted in improved skin lesion scores, scratching behavior, eosinophil infiltration, swelling and inflammation levels, immune homeostasis, and histopathological changes in rats with acute eczema. Besides, HATA hydrogel is not only suitable for Purslane's decocted metabolites but also for Purslane's freshly squeezed metabolites. This purslane application protocol solved the drawbacks of Purslane's decoction, improved its storage stability and convenience of use, which is the key issue to further promote its clinical application.

Upgrading the Bioinspired Iron-Polyporphyrin Structures by Abiological Metals Toward New-Generation Reactive Oxygen Biocatalysts

Developing artificial enzymes based on organic molecules or polymers for reactive oxygen biocatalysis has broad applicability. Here, inspired by heme-based enzyme systems, we construct the abiological iron group metal-based polyporphyrin (Ru/Os-coordinated porphyrin-based biocatalyst, Ru/Os-PorBC) to serve as a new generation of efficient and versatile reactive oxygen species (ROS)-related biocatalyst. Due to the structural benefits, including excellent electron configuration, appropriate bandgap, and optimized adsorption and activation of reaction intermediates, Ru/Os-PorBC shows unparalleled ROS-production activities regarding maximum reaction rate and turnover numbers, which also demonstrates superior pH and temperature adaptability compared to natural enzymes. Impressively, the Os-PorBC manifests the most efficacious ROS-production capabilities, surpassing not only Ru/Fe-PorBC but also the existing state-of-the-art ROS-related biocatalyst. Our findings provide a pivotal direction for developing next-generation polyporphyrin-based biocatalysts, setting the stage for a new era of upgrading the artificial metalloenzymes by abiological metals.

Engineering EVs-Mediated mRNA Delivery Regulates Microglia Function and Alleviates Depressive-Like Behaviors

The development of new non-neurotransmitter drugs is an important supplement to the clinical treatment of major depressive disorder. The latest development of mRNA therapy provides the possibility for the treatment of some major diseases. The endoplasmic reticulum (ER) and mitochondria constitute a highly interconnected set of fundamental organelles within cells. The interconnection between them forms specific microdomains that play pivotal roles in calcium signaling, mitochondrial dynamics, inflammation, and autophagy. Perturbations in ER-mitochondrial connections may contribute to the progression of neurological disorders and other diseases. Herein, an extracellular vesicles-based delivery system, grounded in mRNA gene therapy and integrated with nanomedicine technology is devised. This system is engineered to traverse the blood-brain barrier and specifically target the central nervous system (CNS), facilitating the simultaneous delivery of mRNA drugs and metallic nanozymes into the brain. This dual-pronged approach, targeting ER and mitochondrial crosstalk, inhibits microglial overactivation, promotes M2 polarization of microglia, and suppresses the NF-κB signaling pathway. Consequently, it significantly alleviates Lipopolysaccharides-induced neuroinflammatory responses and ameliorates anxiety- and depression-like behaviors. This study demonstrates a novel antidepressant therapeutic strategy and establishes a new paradigm for mRNA gene therapy in CNS diseases.

Gold Nanoparticles Decorated CoAl LDH Monolayer: A Peroxidase-Like Nanozyme for Sensitive Colorimetric Detection of Acetylcholinesterase and Inhibitors

Monitoring acetylcholinesterase (AChE) activity and its inhibitor is crucial yet challenging for the early diagnosis and treatment of neurological diseases. In this study, we present Au nanoparticle decorated CoAl layered double hydroxide monolayer (Au@CoAl-LDH-m) as a peroxidase-like (POD) nanozyme for the sensitive colorimetric detection of AChE and its inhibitor, thiamine pyrophosphate (TPP). Remarkably, the Au@CoAl-LDH-m nanozyme can catalyze the oxidation of chromogenic substrates through its POD-like activity, which is effectively inhibited by thiocholine (TCh, a catalytic product of AChE), thereby enabling detection of AChE and TPP through a visible colorimetric readout. The approach provides a highly sensitive and specificity assay with a broader linear response range (1-100 mU mL-1 for AChE and 1-1000 ng mL-1 for TPP) and a low detection limit (0.092 mU mL-1 for AChE and 0.201 ng mL-1 for TPP), respectively. These results highlight the significant potential of Au@CoAl-LDH-m for advancing colorimetric sensors in detecting small molecules across various biological applications.

Defluorinative Diazolation-Cyclization Relay for Synthesis of Furan-Bridged Triheterocycles and Colorimetric Sensor Application

Polyaromatics, as the assembly of diverse cyclic π-systems, exhibit unique physicochemical properties when compared to their individual constituents. In this study, we developed a strategic connection of two azacycles via a furan bridge through a defluorinative diazolation-cyclization reaction of trifluoromethyl enones and N-heterocycles. A range of modular 2,4-furan-bridged triheterocycles (FBTHs), featuring a C3-trifluoromethyl group, was synthesized with broad substrate scope and good regioselectivity under transition metal-free conditions. This three-component protocol was achieved through successive C(sp3)-F bond functionalization of one trifluoromethyl group, which is recognized for its stability and durability. Moreover, the synthetically useful functionalities such as bromide and formyl group could be easily installed on the resulting products, and the imidazole-containing FBTH could serve as a valuable ligand in the preparation of an advanced colorimetric sensor, thereby underscoring their potential applications.

A Review of Current Developments in Functionalized Mesoporous Silica Nanoparticles: From Synthesis to Biosensing Applications

Functionalized mesoporous silica nanoparticles (MSNs) have been widely investigated in the fields of nanotechnology and material science, owing to their high surface area, diverse structure, controllable cavity, high biocompatibility, and ease of surface modification. In the past few years, great efforts have been devoted to preparing functionalized MSNs for biosensing applications with satisfactory performance. The functional structure and composition in the synthesis of MSNs play important roles in high biosensing performance. With the development of material science, diverse functional units have been rationally incorporated into mesoporous structures, which endow MSNs with design flexibility and multifunctionality. Here, an overview of the recent developments of MSNs as nanocarriers is provided, including the methodologies for the preparation of MSNs and the nanostructures and physicochemical properties of MSNs, as well as the latest trends of MSNs and their use in biosensing. Finally, the prospects and challenges of MSNs are presented.

Structural Regulation of Au-Pt Bimetallic Aerogels for Catalyzing the Glucose Cascade Reaction

Bimetallic nanostructures are promising candidates for the development of enzyme-mimics, yet the deciphering of the structural impact on their catalytic properties poses significant challenges. By leveraging the structural versatility of nanocrystal aerogels, this study reports a precise control of Au-Pt bimetallic structures in three representative structural configurations, including segregated, alloy, and core-shell structures. Benefiting from a synergistic effect, these bimetallic aerogels demonstrate improved peroxidase- and glucose oxidase-like catalytic performances compared to their monometallic counterparts, unleashing tremendous potential in catalyzing the glucose cascade reaction. Notably, the segregated Au-Pt aerogel shows optimal catalytic activity, which is 2.80 and 3.35 times higher than that of the alloy and core-shell variants, respectively. This enhanced activity is attributed to the high-density Au-Pt interface boundaries within the segregated structure, which foster greater substrate affinity and superior catalytic efficiency. This work not only sheds light on the structure-property relationship of bimetallic catalysts but also broadens the application scope of aerogels in biosensing and biological detections.

Nanozyme-Based Microfluidic Chip System for pH-Regulated Pretreatment and Sensitive Sensing

Nanozymes, possessing nanomaterial properties and catalytic activities, offer great opportunities to design sensitive analytical detection systems. However, the low interference resistance of nanozymes poses a significant limitation on the precise detection of target substances. Herein, a nanozyme-based microfluidic chip system for pH-regulated pretreatment and sensitive sensing of cysteine (Cys) is reported. The copper metal-organic framework (Cu MOF) exhibits good cysteine oxidase-like activity at pH 7.0, while demonstrating excellent laccase-like activity at pH 8.0. Taking advantage of the pH-regulated enzyme-like activity, the integrated microfluidic device involving the immobilization of Cu MOF eliminates the interference of dopamine (DA) and accurately detects the target Cys. Compared with the untreated reaction system, the developed nanozyme system shows a significantly improved accuracy in detecting Cys, with an R2 value of 0.9914. This work provides an efficient method to enhance the interference resistance of nanozymes and broadens the application in sample pretreatment.

Al2O3-Stabilized Pt Nanozymes: Peroxidase Mimetics and Application in Glucose Detection

As promising alternatives for natural enzymes, much attention has been paid to nanozymes. And our recent study showed that the medium acid sites on the support are the active sites for the adsorption and oxidation of the substrate. Thus, in this work, due to the abundance of medium acid sites, Al2O3 was chosen as the support to prepare Pt/Al2O3 nanozymes. Through the Pt/Al2O3 samples, we further proved that the distribution of the Pt clusters and the amount of the medium acid sites can significantly influence the peroxidase-like activity. Then the Pt/Al2O3 sample was used for the detection of glucose. And as low as 0.96 μM glucose could be detected with a linear range from 5-60 μM via our method. This work showed the great potential applications of the easily prepared Pt/Al2O3 samples in varieties of simple, robust, and easy-to-make analytical approaches in the future.

Choline Phosphate-Grafted Nanozymes as Universal Extracellular Vesicle Probes for Bladder Cancer Detection

Urinary extracellular vesicles (uEVs) are regarded as highly promising liquid-biopsy biomarkers for the early diagnosis and prognosis of bladder cancer (BC). However, detection of uEVs remains technically challenging owing to their huge heterogeneity and ultralow abundance in real samples. We herein present a choline phosphate-grafted platinum nanozyme (Pt@CP) that acts as a universal EV probe for the construction of a high-throughput and high-sensitivity immunoassay, which allowed multiplex profiling of uEV protein markers for BC detection. With the Pt@CP-based immunoassays, three uEV protein markers (MUC-1, CCDC25, and GLUT1) were identified for BC, by which the BC cases (n = 48), cystitis patients (n = 27), and healthy donors (n = 24) were discriminated with high clinical sensitivity and specificity (area under curve = 98.3%). For the BC cases (n = 9) after surgery, the Pt@CP-based immunoassay could report the postoperative residual tumor that cannot be observed by cystoscopy, which is clinically significant for assessing BC recurrence. This work provides generally high sensitivity for EV detection, facilitating the discovery and clinical use of EV-based biomarkers.

Nanoscience and nanotechnology for water remediation: an earnest hope toward sustainability

Water pollution and the global freshwater crisis are the most alarming concerns of the 21st century, as they threaten the sustainability and ecological balance of the environment. The growth of global population, climate change, and expansion of industrial processes are the main causes of these issues. Therefore, effective remediation of polluted water by means of detoxification and purification is of paramount importance. To this end, nanoscience and nanotechnology have emerged as viable options that hold tremendous potential toward the advancement of wastewater treatment methods to enhance treatment efficiency along with augmenting water supply via utilization of unconventional water sources. Materials at the nano level have shown great promise toward water treatment applications owing to their unique physicochemical properties. In this focus article, we highlight the role of new fundamental properties at the nano scale and material properties that are drastically increased due to the nano dimension (e.g. volume-surface ratio) and highlight their impact and potential toward water treatment. We identify and discuss how nano-properties could improve the three main domains of water remediation: the identification of pollutants, their adsorption and catalytic degradation. After discussing all the beneficial aspects we further discuss the key challenges associated with nanomaterials for water treatment. Looking at the current state-of-the-art, the potential as well as the challenges of nanomaterials, we believe that in the future we will see a significant impact of these materials on many water remediation strategies.

In Vivo Toxicology of Metabolizable Atomically Precise Au25 Clusters at Ultrahigh Doses

Ultrasmall Au25(MPA)18 clusters show great potential in biocatalysts and bioimaging due to their well-defined, tunable structure and properties. Hence, in vivo pharmacokinetics and toxicity of Au nanoclusters (Au NCs) are very important for clinical translation, especially at high dosages. Herein, the in vivo hematological, tissue, and neurological effects following exposure to Au NCs (300 and 500 mg kg-1) were investigated, in which the concentration is 10 times higher than in therapeutic use. The biochemical and hematological parameters of the injected Au NCs were within normal limits, even at the ultrahigh level of 500 mg kg-1. Meanwhile, no histopathological changes were observed in the Au NC group, and immunofluorescence staining showed no obvious lesions in the major organs. Furthermore, real-time near-infrared-II (NIR-II) imaging showed that most of the Au25(MPA)18 and Au24Zn1(MPA)18 can be metabolized via the kidney. The results demonstrated that Au NCs exhibit good biosafety by evaluating the manifestation of toxic effects on major organs at ultrahigh doses, providing reliable data for their application in biomedicine.