Metal Ion‐Terpyridine‐Functionalized L‐Tyrosinamide Aptamers: Nucleoapzymes for Oxygen Insertion into C?H Bonds and the Transformation of L‐Tyrosinamide into Amidodopachrome

A series of metal ion‐terpyridine‐modified L‐tyrosinamide aptamers (M^{n +} = Cu²⁺ or Fe³⁺) act as enzyme‐mimicking catalysts (nucleoapzymes) for oxygen‐insertion into C? H bonds and the transformation of L‐tyrosinamide into amidodopachrome. The reaction proceeds in the presence of H₂O₂ and coadded L‐ascorbic acid. In one series of experiments, the catalyzed oxidation of L‐tyrosinamide to amidodopachrome by a set of nucleoapzymes consisting of Fe³⁺‐ or Cu²⁺‐terpyridine complexes tethered directly or through a 4 × thymidine (4 × T) bridge, to the 5′‐ or 3′‐end of the 49‐mer L‐tyrosinamide aptamer or to a shorter 23‐mer L‐tyrosinamide aptamer is examined. All nucleoapzymes reveal catalytic Michaelis–Menten enzyme‐like activities and the separated Fe³⁺‐ or Cu²⁺‐terpyridine and L‐tyrosinamide aptamer units show only minute catalytic properties. The catalytic activities of the nucleoapzymes are attributed to the concentration of the L‐tyrosinamide substrate by the aptamer units in proximity to the catalytic sites (K_d = (14 ± 0.1) × 10^?6 m for all 49‐mer catalysts and K_d = (2.5 ± 0.1) × 10^?6 m and K_d = (0.8 ± 0.04) × 10^?6 m for the 23‐mer catalysts). Electron spin resonance experiments reveal that ?OH radicals and ascorbate radicals participate in the transformation of tyrosine derivatives to catechol products. An autocatalytic feedback mechanism for the amplified generation of the two radicals is suggested.     

Synthesis of MoSe2/CoSe2 Nanosheets for NIR-Enhanced Chemodynamic Therapy via Synergistic In-Situ H2O2 Production and Activation

Currently, the limited intratumoral H₂O₂ level restricts the development of chemodynamic therapy (CDT). Herein, MoSe₂/CoSe₂@PEG nanosheets are prepared to reveal NIR-photocatalytic H₂O₂ generation to insure the intracellular H₂O₂ supplement. The formation mechanism is investigated, showing the dissolved O₂ and photo-excited electrons to determine H₂O₂ production via sequential single-electron transfer process. The experimental data and density functional theory calculation further display their typical-II heterostructure, which possesses the effective charge separation and nearly four times H₂O₂ generation than MoSe₂@PEG. In addition, the nanocomposites also reveal the peroxidase/catalase activity, making the in-situ H₂O₂ activation and ·OH generation. And, the O₂ production derived from catalase-mimic activity not only relieves hypoxia but also offers the source for H₂O₂ production. Because of the decreased resistance for charge transfer, MoSe₂/CoSe₂@PEGs also reveal more than three times enzyme-activity for MoSe₂@PEG. With the narrow band gap and high NIR-harvest, MoSe₂/CoSe₂@PEG exhibits the great photothermal converting ability (62.5%). MoSe₂/CoSe₂@PEG reveals the novel biodegradation, and most of them can be eliminated via urine and feces within 2 weeks. Here, the computed tomography/magnetic resonance imaging/photothermal imaging and the synergistic photothermal therapy/CDT treatments further make sure potential application on anticancer.     

A Bionanozyme with Ultrahigh Activity Enables Spatiotemporally Controlled Reactive Oxygen Species Generation for Cancer Therapy

Nanozymes hold great potential in nanomedicine, yet biotoxicity limits their clinical translation because of their uncontrolled catalytic activity, artificial inorganic components, and harsh synthesis conditions. Herein, a peroxidase-like bionanozyme with ultrahigh and photocontrolled catalytic activity through the self-assembly of biomolecules, hemin, and in situ polymerization of pyrrole in an aqueous solution is reported. Such bionanozymes leverage the specific cues of the tumor microenvironment and precise light-induced photothermal heating for spatiotemporally controlled reactive oxygen species generation in tumors. The tunable catalytic activity and excellent biocompatibility of the bionanozyme result in high cancer cell apoptosis and tumor growth inhibition in murine models with negligible biotoxicity. This work highlights the potential of biomolecule-based nanozymes for cancer-specific therapy. Bionanozymes with ultrahigh and tunable catalytic activity may lay the important foundation for more advanced nanomedicine and biosensing.     

Enzyme Mimic Nanomaterials and Their Biomedical Applications

Nanomaterials with enzyme-mimicking behavior (nanozymes) have attracted a lot of research interest recently. In comparison to natural enzymes, nanozymes hold many advantages, such as good stability, ease of production and surface functionalization. As the catalytic mechanism of nanozymes is gradually revealed, the application fields of nanozymes are also broadly explored. Beyond traditional colorimetric detection assays, nanozymes have been found to hold great potential in a variety of biomedical fields, such as tumor theranostics, antibacterial, antioxidation and bioorthogonal reactions. In this review, we summarize nanozymes consisting of different nanomaterials. In addition, we focus on the catalytic performance of nanozymes in biomedical applications. The prospects and challenges in the practical use of nanozymes are discussed at the end of this Minireview.     

A Bimetallic Nanozyme with Cascade Effect for Synergistic Therapy of Cancer

Novel nanocomposites were constructed through encapsulation of Au nanoparticles and Ru nanoparticles into dendritic mesoporous silica (DMSN-Au-Ru NPs). These exhibit improved effects due to a cascade catalytic ability for the synergistic therapy of cancer. Au nanoparticles with glucose oxidase-like properties were found to catalyze the oxidation of glucose to produce H₂O₂, while Ru nanoparticles could decompose H₂O₂ and produce toxic ¹O₂ for improved photodynamic therapy (PDT). In addition, the nanocomposites were found to have good photothermal performance under irradiation by near-infrared (NIR) light. Both in vitro and in vivo experiments show that the nanocomposites have good therapeutic effects due to the cascade catalytic effect and synergistic effect. These findings provide an effective way to design a new generation of nanodrugs for highly efficient cancer treatment.     

Single‐Atom Nanozyme Based on Nanoengineered Fe–N–C Catalyst with Superior Peroxidase‐Like Activity for Ultrasensitive Bioassays

Single‐atom catalysts are becoming a hot research topic owing to their unique characteristics of maximum specific activity and atomic utilization. Herein, a new single‐atom nanozyme (SAN) based on single Fe atoms anchored on N‐doped carbons supported on carbon nanotube (CNT/FeNC) is proposed. The CNT/FeNC with robust atomic Fe–N_x moieties is synthesised, showing superior peroxidase‐like activity. Furthermore, the CNT/FeNC is used as the signal element in a series of paper‐based bioassays for ultrasensitive detection of H₂O₂, glucose, and ascorbic acid. The SAN provides a new type of signal element for developing various biosensing techniques.     

Self-Amplified Competitive Coordination of MnO2-Doped CeO2 Nanozyme for Synchronously Activated Combination Therapy

Tumor-specific combination therapy has shown great promise in cancer theranostics. However, the therapeutic efficacy is usually suppressed because most of the therapeutic systems are not able to synchronously activate their different therapeutic approaches and the local concentration of tumor-associated stimulus is generally insufficient to fully activate the combination therapy process. Herein, a MnO₂-doped CeO₂ nanozyme-based nanomedicine (Ce6@CMNRs) is reported for tumor-specific synchronously activated chemodynamic/photodynamic combination therapy. The tumor-overexpressed H₂O₂ substitutes the Ce6 on Ce6@CMNRs surfaces via competitive coordination and then decomposes into •OH under acidic condition, achieving the chemodynamic therapy (CDT). Meanwhile, the substituted Ce6 triggers photodynamic therapy (PDT) under laser irradiation that is suppressed before the substitution occurs. Thus, H₂O₂ can synchronously activate both CDT and PDT of Ce6@CMNRs with a similar level in tumor sites. Moreover, the activated PDT-induced oxygen starvation further triggers the generation of H₂O₂ to continuously replace the residual Ce6 coordinated on the nanorod surface, thereby leading to the full activation of PDT and CDT. Also, the doped MnO₂ enhances the generation of •OH and provides high contrast for magnetic resonance imaging (MRI) with the help of glutathione. Therefore, Ce6@CMNRs are promising candidates for MRI-guided CDT/PDT combination therapy with minimized side effects and high efficiency.     

多级结构羟基硝酸铜纳米酶的制备及其对酚类污染物的降解

漆酶是一种多铜氧化酶,在空气条件下即可催化氧化多胺、多酚类有机物,被认为是水处理及土壤修复领域的绿色催化剂。纳米酶是一种具有酶催化活性的纳米材料,因其具有多功能性、低成本、高稳定性等优点,近年来引起广泛关注。因此,本文以尿素水解过程中产生的异氰酸根离子为模板剂,与Cu(NO₃)₂溶液反应制备具有漆酶活性的多级结构羟基硝酸铜[H-Cu₂(OH)₃NO₃]纳米酶。其催化活性是传统Cu(NO₃)₂与尿素水解法制备的羟基硝酸铜的1.85倍,其最大反应速率是漆酶的1.27倍。H-Cu₂(OH)₃NO₃纳米酶在不同pH、温度、储存时间和盐浓度条件下体现良好的催化稳定性。在重复利用12次后,保持58%的催化活性,体现出良好的重复利用性。而且H-Cu₂(OH)₃NO₃纳米酶具有降解土壤与地下水中常见的2,4-二氯苯酚、对...     

铂壳金核纳米酶介导的磁弛豫免疫传感器快速检测食源性沙门氏菌

构建了一种基于铂壳金核(Au@Pt)纳米酶介导顺磁离子价态转变的磁弛豫免疫传感器,并用于鸡蛋中沙门氏菌的快速、高灵敏检测。首先通过微波水热法合成了稳定性高、催化性能强的Au@Pt纳米酶,并利用其过氧化氢类酶活性催化过氧化氢(H₂O₂),而剩余的H₂O₂可将MnO₄^-还原为Mn²⁺。由于MnO₄^-/Mn²⁺两者之间磁信号差异显著,可实现H₂O₂的定量分析。结合免疫反应,沙门氏菌浓度与“检测抗体-Au@Pt纳米酶”含量呈正比,而Au@Pt纳米酶可调控H₂O₂介导的MnO₄^-/Mn²⁺转化体系,进而控制磁信号的变化,最终实现沙门氏菌的定量分析。本方法的检出限为50 CFU/mL,线性范围为1×10²～5...     

IrO2@MnO2纳米酶的制备及用于抗坏血酸的检测

通过原位整合法制备了粒径约为136?nm,形态均一的方块状IrO2@MnO2纳米复合物.经实验证明该复合物具有协同提高的氧化酶模拟活性,其Km值为6.50?×?10?3?mmol/L,远优于IrO2纳米颗粒(IrO2?Nanoparticles,IrO2?NPs)(Km?=9.73?×?10?2?mmol/L)和MnO...