Facilitation of Fenton-Like Reaction of Copper-Nitrogen-Doped Carbon-Based Nanocatalysts by Enhancing Hydroxyl Adsorption on Single-Atom Cu-NxC4- x Sites.

Copper-nitrogen-doped carbon-based nanocatalysts (Cu-NCs), containing atomically dispersed Cu-NxC4- x sites, are efficient in boosting the Fenton-like reaction. However, the mechanisms of the Fenton-like reaction, including the pH effect on the products and the effect of the coordination environment on catalytic activity, remain controversial, restricting the development of Cu-NCs. Cu-NCs are experimentally synthesized with Cu-N4 sites and prove that the Fenton-like reaction generates mainly hydroxyl radicals (·OH) in the acidic but ·OH and superoxide radicals (·O2 -) in the neutral. The density functional theory (DFT) calculations reveal that the catalytic activity of Cu-NCs in the Fenton-like reaction is associated with the adsorption strength of ·OH at the Cu site. Further investigation of the effect of the coordination environment of Cu-NCs indicates that the Cu-N2C2 site, which can enhance the ·OH adsorption strength, is an ideal catalyst site for the Fenton-like reaction. These results open the way to facilitating the catalytic activity of Cu-NCs in the Fenton-like reaction.

The Guidelines for the Design and Synthesis of Transition Metal Atom Doped Carbon Dots.

Atoms doping is a practical approach to modulate the physicochemical properties of carbon dots (CDs) and thus has garnered increasing attention in recent years. Compared to non-metal atoms, transition metal atoms (TMAs) possess more unoccupied orbitals and larger atomic radii. TMAs doping can significantly alter the electronic structure of CDs and bestow them with new intrinsic characteristics. TMAs-doped CDs have exhibited widespread application potential as a new class of single-atom-based nanomaterials. However, challenges remain for the successful preparation and precise design of TMAs-doped CDs. The key to successfully preparing TMA-doped CDs lies in anchoring TMAs to the carbon precursors before the reaction. Herein, taking the formation mechanism of TMAs-doped CDs as a starting point, we systematically summarized the ligands employed for synthesizing TMAs-doped CDs and proposed the synthetic strategy involving multiple ligands. Additionally, we summarize the functional properties imparted to CDs by different TMA dopants to guide the design of TMA-doped CDs with different functional characteristics. Finally, we describe the bottlenecks TMAs-doped CDs face and provide an outlook on their future development.

Nickel-Atom Doping as a Potential Means to Enhance the Photoluminescence Performance of Carbon Dots.

Heteroatom doping, particularly with nonmetallic atoms such as N, P, and S, has proven to be an effective strategy for modulating the fluorescent properties of carbon dots (CDs). However, there are few reports on the regulation of the photoluminescence of CDs by transition-metal doping. In this work, nickel-doped CDs (Ni-CDs) were fabricated using the hydrothermal approach. Ni atoms were incorporated into the sp2 domains of the CDs through Ni-N bonds, resulting in an increased degree of graphitization of the Ni-CDs. Additionally, Ni-atom doping served to shorten the electron transition and recombination lifetimes, and suppress the nonradiative recombination process, resulting in an absolute fluorescence quantum yield of 54.7% for the Ni-CDs. Meanwhile, the as-prepared Ni-CDs exhibited excellent biocompatibility and were utilized for fluorescent bioimaging of HeLa cells. Subsequently, the Ni-CDs were employed as fluorescent anticounterfeiting inks for the successful encryption of two-dimensional barcodes. Our work demonstrates a novel heteroatom doping strategy for the synthesis of highly fluorescence-emitting CDs.

Unraveling the Structure Transition and Peroxidase Mimic Activity of Copper Sites over Atomically Dispersed Copper-Doped Carbonized Polymer Dots.

The lack of systematic structural resolution makes it difficult to build specific transition-metal-atom-doped carbonized polymer dots (TMA-doped CPDs). Herein, the structure-activity relationship between Cu atoms and CPDs was evaluated by studying the peroxidase-like properties of Glu-Cu-CPDs prepared by using copper glutamate (Glu) with a Cu-N2 O2 initial structure. The results showed that the Cu atoms bound to Glu-Cu-CPDs in the form of Cu-N2 C2 , indicating that Cu-O bonds changed into Cu-C bonds under hydrothermal conditions. This phenomenon was also observed in other copper-doped CPDs. Moreover, the carboxyl and amino groups content decreased after copper-atom doping. Theoretical calculations revealed a dual-site catalytic mechanism for catalyzing H2 O2 . The detection of intracellular H2 O2 suggested their application prospects. Our study provides an in-depth understanding of the formation and catalytic mechanism of TMA-doped-CPDs, allowing for the generation specific TMA-doped-CPDs.

Tumor microenvironment-responsive fenton nanocatalysts for intensified anticancer treatment.

Chemodynamic therapy (CDT) based on Fenton or Fenton-like reactions is an emerging cancer treatment that can both effectively fight cancer and reduce side effects on normal cells and tissues, and it has made important progress in cancer treatment. The catalytic efficiency of Fenton nanocatalysts(F-NCs) directly determines the anticancer effect of CDT. To learn more about this new type of therapy, this review summarizes the recent development of F-NCs that are responsive to tumor microenvironment (TME), and detailedly introduces their material design and action mechanism. Based on the deficiencies of them, some effective strategies to significantly improve the anticancer efficacy of F-NCs are highlighted, which mainly includes increasing the temperature and hydrogen peroxide concentration, reducing the pH, glutathione (GSH) content, and the dependence of F-NCs on acidic environment in the TME. It also discusses the differences between the effect of multi-mode therapy with external energy (light and ultrasound) and the single-mode therapy of CDT. Finally, the challenges encountered in the treatment process, the future development direction of F-NCs, and some suggestions are analyzed to promote CDT to enter the clinical stage in the near future.

Bimetallic Nanomaterials: A Promising Nanoplatform for Multimodal Cancer Therapy.

Bimetallic nanomaterials (BMNs) composed of two different metal elements have certain mixing patterns and geometric structures, and they often have superior properties than monometallic nanomaterials. Bimetallic-based nanomaterials have been widely investigated and extensively used in many biomedical fields especially cancer therapy because of their unique morphology and structure, special physicochemical properties, excellent biocompatibility, and synergistic effect. However, most reviews focused on the application of BMNs in cancer diagnoses (sensing, and imaging) and rarely mentioned the application of the treatment of cancer. The purpose of this review is to provide a comprehensive perspective on the recent progress of BNMs as therapeutic agents. We first introduce and discuss the synthesis methods, intrinsic properties (size, morphology, and structure), and optical and catalytic properties relevant to cancer therapy. Then, we highlight the application of BMNs in cancer therapy (e.g., drug/gene delivery, radiotherapy, photothermal therapy, photodynamic therapy, enzyme-mediated tumor therapy, and multifunctional synergistic therapy). Finally, we put forward insights for the forthcoming in order to make more comprehensive use of BMNs and improve the medical system of cancer treatment.

Fluorescent Organic Small Molecule Probes for Bioimaging and Detection Applications.

The activity levels of key substances (metal ions, reactive oxygen species, reactive nitrogen, biological small molecules, etc.) in organisms are closely related to intracellular redox reactions, disease occurrence and treatment, as well as drug absorption and distribution. Fluorescence imaging technology provides a visual tool for medicine, showing great potential in the fields of molecular biology, cellular immunology and oncology. In recent years, organic fluorescent probes have attracted much attention in the bioanalytical field. Among various organic fluorescent probes, fluorescent organic small molecule probes (FOSMPs) have become a research hotspot due to their excellent physicochemical properties, such as good photostability, high spatial and temporal resolution, as well as excellent biocompatibility. FOSMPs have proved to be suitable for in vivo bioimaging and detection. On the basis of the introduction of several primary fluorescence mechanisms, the latest progress of FOSMPs in the applications of bioimaging and detection is comprehensively reviewed. Following this, the preparation and application of fluorescent organic nanoparticles (FONPs) that are designed with FOSMPs as fluorophores are overviewed. Additionally, the prospects of FOSMPs in bioimaging and detection are discussed.

Interfacial Microstructure and Enhanced Mechanical Properties of Carbon Fiber Composites Caused by Growing Generation 1-4 Dendritic Poly(amidoamine) on a Fiber Surface.

In an attempt to improve the mechanical properties of carbon fiber composites, propagation of poly(amidoamine) (PAMAM) dendrimers by in situ polymerization on a carbon fiber surface was performed. During polymerization processes, PAMAM was grafted on carbon fiber by repeated Michael addition and amidation reactions. The changes in surface microstructure and the chemical composition of carbon fibers before and after modification were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. All the results indicated that PAMAM was successfully grown on the carbon fiber surface. Such propagation could significantly increase the surface roughness and introduce sufficient polar groups onto the carbon fiber surface, enhancing the surface wettability of carbon fiber. The fractured surface of carbon fiber-reinforced composites showed a great enhancement of interfacial adhesion. Compared with those of desized fiber composites, the interlaminar shear strength and interfacial shear strength of PAMAM/fiber-reinforced composites showed increases of 55.49 and 110.94%, respectively.

Synergistic effects of earthworms and cow manure under reduced chemical fertilization modified microbial community structure to mitigate continuous cropping effects on Chinese flowering cabbage.

The substitution of chemical fertilizers with organic fertilizers is a viable strategy to enhance crop yield and soil quality. In this study, the aim was to investigate the changes in soil microorganisms, soil chemical properties, and growth of Chinese flowering cabbage under different fertilization treatments involving earthworms and cow manure. Compared with the control (100% chemical fertilizer), CE (30% reduction in chemical fertilizer + earthworms) and CFE (30% reduction in chemical fertilizer + cow dung + earthworms) treatments at soil pH 8.14 and 8.07, respectively, and CFC (30% reduction in chemical fertilizer + cow manure) and CFE treatments increased soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available potassium (AK) contents. Earthworms and cow manure promoted the abundance of Bacillus and reduced that of the pathogens Plectosphaerella and Gibberella. The mantle test revealed that pH was not correlated with the microbial community. Random forest analysis verified that AN, SOM, and TN were important factors that jointly influenced bacterial and fungal diversity. Overall, the synergistic effect of earthworms and cow manure increased soil fertility and microbial diversity, thereby promoting the growth and development of Chinese flowering cabbage. This study enhanced the understanding of how bioregulation affects the growth and soil quality of Chinese flowering cabbage, and thus provided a guidance for the optimization of fertilization strategies to maximize the yield and quality of Chinese flowering cabbage while reducing environmental risks.

Dual enzyme-mimicking carbon dots for enhanced antibacterial activity.

Carbon dot (CD)-based nanozymes have great potential in antibacterial applications. In order to achieve enhanced broad-spectrum antibacterial capacity, we synthesized Co-doped drug-based CDs (Co-Lvx-CDs) using levofloxacin and vitamin B12 as precursors by mimicking the catalysis of antibacterial activity of natural enzymes. The Co-Lvx-CDs retained not only the effective functional groups of the traditional antibiotic levofloxacin but also achieved oxidase-like and peroxidase-like activities to generate reactive oxygen species (ROS) through Co doping. Additionally, the Co-Lvx-CDs had superb fluorescence properties and could be applied in information encryption. The CDs were validated to have a broad-spectrum bactericidal effect against Gram-positive and -negative bacteria, compensating for the limitations of levofloxacin while also having enhanced sterilization ability. Importantly, the proposed Co-Lvx-CDs provide a new idea for the design of multifunctional CD-based nanozymes with preconceived outcomes.

In situ detection of exosomal RNAs for cancer diagnosis.

Exosomes are considered as biomarkers reflecting the physiological state of the human body. Studies have revealed that the expression levels of specific exosomal RNAs are closely associated with certain cancers. Thus, detection of exosomal RNA offers a new avenue for liquid biopsy of cancers. Many exosomal RNA detection methods based on various principles have been developed, and most of the methods detect the extracted RNAs after lysing exosomes. Besides complex and time-consuming extraction steps, a major drawback of this approach is the degradation of the extracted RNAs in the absence of plasma membrane and cytosol. In addition, there is considerable loss of RNAs during their extraction. In situ detection of exosomal RNAs can avoid these drawbacks, thus allowing higher diagnostic reliability. In this paper, in situ detection of exosomal RNAs was systematically reviewed from the perspectives of detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, and involved functional materials. Furthermore, the limitations and possible improvements of the current in situ detection methods for exosomal RNAs towards the clinical diagnostic application are discussed. This review aims to provide a valuable reference for the development of in situ exosomal RNA detection strategies for non-invasive diagnosis of cancers. STATEMENT OF SIGNIFICANCE: Certain RNAs have been identified as valuable biomarkers for some cancers, and sensitive detection of cancer-related RNAs is expected to achieve better diagnostic efficacy. Currently, the detection of exosomal RNAs is receiving increasing attention due to their high stability and significant concentration differences between patients and healthy individuals. In situ detection of exosomal RNAs has greater diagnostic reliability due to the avoidance of RNA degradation and loss. However, this mode is still limited by some factors such as detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, etc. This review focuses on the progress of in situ detection of exosomal RNAs and aims to promote the development of this field.

MoS2@Ti3C2 nanohybrid-based photoelectrochemical biosensor: A platform for ultrasensitive detection of cancer biomarker exosomal miRNA.

As a class of newly identified biomarkers, miRNAs show enormous potential in cancer diagnosis. The sensitive detection of abnormal miRNAs concentration to realize early diagnosis of malignant tumors is a frontier in the field of biosensing. In this work, a photoelectrochemical (PEC) biosensor based on MoS2@Ti3C2 nanohybrid was fabricated for the ultrasensitive detection of miRNAs. The hybridization of Ti3C2 with excellent electron transfer capability significantly enhances the photocurrent response of the PEC biosensor. Moreover, the electrodeposition of Au nanoparticles on the surface of MoS2@Ti3C2 nanohybrid further enhances the photocurrent. The detection performance of the PEC biosensor has been tested using colorectal cancer-related exosomal miRNA (miR-92a-3p) as the target. The PEC biosensor shows a broad linear detection ranged from 1 fM to 100 nM and a calculated detection limit of 0.27 fM. In terms of selectivity, the PEC biosensor can distinguish miR-92a-3p from mismatched sequences. The 16 continuous radiation source on-off cycles test indicates the high stability of the PEC biosensor. Furthermore, the accurate detection of exosomal miR-92a-3p concentrations of patients and healthy controls demonstrates the clinical feasibility of the PEC biosensor. Based on these outcomes, the PEC biosensor exhibits the prospect of realizing the ultrasensitive point-of-care detection of miRNAs.

NIR-â ¡ window Triple-mode antibacterial Nanoplatform: Cationic Copper sulfide nanoparticles combined vancomycin for synergistic bacteria eradication.

The widespread use of antibiotics leads to the increasing drug resistance of bacteria and poses a threat to human health. Therefore, there is an urgent need to develop new antibacterial strategies. Herein, based on the good photothermal properties of Copper sulfide (CuS) nanoparticles under near infrared (NIR) laser, we developed a NIR-Ⅱ window triple-mode synergetic antibacterial cCuS (cationic CuS) @Vancomycin (Van) nanoplatform. In the proposed nanoplatform, the positive charge on the surface makes cCuS@Van nanoplatform show better bacterial uptake and membrane damage; vancomycin induces chemical sterilization and provides a targeting effect to the nanoplatform; combined with the strong photothermal effect and deep tissue penetration at the excitation of 1064 nm laser, cCuS@Van nanoplatform can effectively kill bacterial. The photothermal conversion efficiency of the nanoplatform can reach 49.12 % and in vitro experiments show a sterilizing rate of more than 99.5 % to staphylococcus aureus (S. aureus) at the concentration of 3.0 µM, which also demonstrated the synergistic effect of cCuS@Van nanoplatform. In addition, low cytotoxicity to human cells conforms the good biocompatibility of the as-prepared cCuS@Van nanoplatform, which endows it a good application prospect in the field of antibacterial, such as wound healing and implant sterilization.

Self-assembled anionic and cationic Au nanoparticles with Au nanoclusters for the exploration of different biological responsiveness in cancer therapy.

Self-assembly overcomes the biodegradation resistance of some traditional inorganic drug carriers. Herein, we prepared self-assembled Au nanocluster-based nanoparticles with different sizes and charges based on solvent- and cation-induced self-assembly nanotechnology as anti-cancer drug vehicles to solve the potential metabolism problems of solid gold nanoparticles. We also systematically explored the responsiveness of cancer cells to self-assembled Au nanocluster-based nanoparticles with different sizes and surface modified properties. We discovered that self-assembled nanoparticles inherited molecular-like properties of small-size Au NCs and exhibited an aggregation-induced emission (AIE) phenomenon with intense luminescence. Self-assembled Au nanocluster-based nanoparticles (Au NPs and cAu NPs) taking advantage of their size and positive charge exhibited better cell uptake than Au NCs. Encouraged by the excellent biological compatibility and cell uptake of these nanomaterials, we prepared drug-loaded nanomaterials by diffusion absorption and hydrophobic-induced embedding. cAu NPs@DOX showed an excellent anti-cancer effect owing to efficient cell internalization; Au NPs@DOX exhibited slow release of cargo drugs which might be significant to in vivo drug delivery. This work plays a crucial role in the rational design of self-assembled multifunctional gold-based nanoparticles in the application of nanomaterial-assisted multifunctional drug delivery systems (DDSs).

Gold Nanorods (AuNRs) and Zeolitic Imidazolate Framework-8 (ZIF-8) Core-Shell Nanostructure-Based Electrochemical Sensor for Detecting Neurotransmitters.

The development of novel electrode materials for rapid and sensitive detection of neurotransmitters in the human body is of great significance for early disease diagnosis and personalized therapy. Herein, gold nanorod@zeolitic imidazolate framework-8 (AuNR@ZIF-8) core-shell nanostructures were prepared by controlled encapsulation of gold nanorods within a ZIF-8 assembly. The designed AuNR@ZIF-8 nanostructures have uniform morphology, good dispersion, a large specific surface area, and an average size of roughly 175 nm. Compared with individual ZIF-8 and AuNR-modified electrodes, the obtained core-shell-structured AuNR@ZIF-8 nanocomposite structure-modified electrode shows excellent electrocatalytic performance in the determination of dopamine (DA) and serotonin (ST). The designed AuNR@ZIF-8 exhibited a wide linear range of 0.1-50 µM and low detection limit (LOD, 0.03 µM, S/N = 3) for the determination of DA, as well as a linear range of 0.1-25 µM and low LOD (0.007 µM, S/N = 3) for monitoring ST. The improved performance is attributed to the synergistic effect of the high conductivity of AuNRs and multiple catalytic sites of ZIF-8. The good electroanalytical ability of AuNR@ZIF-8 for detection of DA and ST can provide a guide to efficiently and rapidly monitor other neurotransmitters and construct novel electrochemical sensors.

[Effectiveness of posterior intercostal artery perforator flap in repair of donor defect after latissimus dorsi myocutaneous flap transfer].

Objective: To investigate the feasibility and effectiveness of the latissimus dorsi myocutaneous flap in repair of large complex tissue defects of limb and the relaying posterior intercostal artery perforator flap in repair of donor defect after latissimus dorsi myocutaneous flap transfer. Methods: Between January 2016 and May 2017, 9 patients with large complex tissue defects were treated. There were 8 males and 1 female with a median age of 33 years (range, 21-56 years). The injury caused by traffic accident in 8 cases, and the time from post-traumatic admission to flap repair was 1-3 weeks (mean, 13 days). The defect in 1 case was caused by the resection of medial vastus muscle fibrosarcoma. There were 5 cases of upper arm defects and 4 cases of thigh defects. The size of wounds ranged from 20 cm×12 cm to 36 cm×27 cm. There were biceps brachii defect in 2 cases, triceps brachii defect in 3 cases, biceps femoris defect in 2 cases, quadriceps femoris defect in 2 cases, humerus fracture in 2 cases, brachial artery injury in 2 cases, and arteria femoralis split defect combined with nervus peroneus communis and tibia nerve split defect in 1 case. The latissimus dorsi myocutaneous flaps were used to repair the wounds and reconstruct the muscle function. The size of the skin flaps ranged from 22 cm×13 cm to 39 cm×28 cm; the size of the muscle flaps ranged from 12 cm×3 cm to 18 cm×5 cm. The wounds were repaired with pedicle flaps and free flaps in upper limbs and lower limbs, respectively. The donor sites were repaired with posterior intercostal artery perforator flaps. The size of flaps ranged from 10 cm×5 cm to 17 cm×8 cm. The second donor sites were sutured directly. Results: All the flaps survived smoothly and the wounds and donor sites healed by first intention. All patients were followed up 10-19 months (mean, 13 months). At last follow-up, the flaps had good appearances and textures. The muscle strength recovered to grade 4 in 5 cases and to grade 3 in 4 cases. After latissimus dorsi myocutaneous flap transfer, the range of motion of shoulder joint was 40-90°, with an average of 70°. The two-point discrimination of latissimus dorsi myocutaneous flap was 9-15 mm (mean, 12.5 mm), and that of posterior intercostal artery perforator flap was 8-10 mm (mean, 9.2 mm). There were only residual linear scars at the second donor sites. Conclusion: The latissimus dorsi myocutaneous flap combined with posterior intercostal artery perforator flap for the large complex tissue defects and donor site can not only improve the appearance of donor and recipient sites, but also reconstruct muscle function, and reduce the incidence of donor complications.