25th Anniversary Article: Chemically Modified/Doped Carbon Nanotubes & Graphene for Optimized Nanostructures & Nanodevices

Outstanding pristine properties of carbon nanotubes and graphene have limited the scope for real‐life applications without precise controllability of the material structures and properties. This invited article to celebrate the 25^th anniversary of Advanced Materials reviews the current research status in the chemical modification/doping of carbon nanotubes and graphene and their relevant applications with optimized structures and properties. A broad aspect of specific correlations between chemical modification/doping schemes of the graphitic carbons with their novel tunable material properties is summarized. An overview of the practical benefits from chemical modification/doping, including the controllability of electronic energy level, charge carrier density, surface energy and surface reactivity for diverse advanced applications is presented, namely flexible electronics/optoelectronics, energy conversion/storage, nanocomposites, and environmental remediation, with a particular emphasis on their optimized interfacial structures and properties. Future research direction is also proposed to surpass existing technological bottlenecks and realize idealized graphitic carbon applications.     

Carrier-Free ATP-Activated Nanoparticles for Combined Photodynamic Therapy and Chemotherapy under Near-Infrared Light

The combination of photodynamic therapy (PDT) and chemotherapy (chemo-photodynamic therapy) for enhancing cancer therapeutic efficiency has attracted tremendous attention in the recent years. However, limitations, such as low local concentration, non-suitable treatment light source, and uncontrollable release of therapeutic agents, result in reduced combined treatment efficacy. This study considered adenosine triphosphate (ATP), which is highly upregulated in tumor cells, as a biomarker and developed ingenious ATP-activated nanoparticles (CDNPs) that are directly self-assembled from near-infrared photosensitizer (Cy-I) and amphiphilic Cd(II) complex (DPA-Cd). After selective entry into tumor cells, the positively charged CDNPs would escape from lysosomes and be disintegrated by the high ATP concentration in the cytoplasm. The released Cy-I is capable of producing single oxygen (¹O₂) for PDT with 808 nm irradiation and DPA-Cd can concurrently function for chemotherapy. Irradiation with 808 nm light can lead to tumor ablation in tumor-bearing mice after intravenous injection of CDNPs. This carrier-free nanoparticle offers a new platform for chemo-photodynamic therapy.     

石墨烯改性聚氨酯超疏水泡沫的制备与表征

报道了一种将石墨烯共价接枝到聚氨酯泡沫表面制备超疏水泡沫的方法。制备过程包括4个主要环节:(1)利用优化的Hummers法制备氧化石墨烯;(2)通过十二烷二胺对氧化石墨烯进行改性在石墨烯表面引入伯胺基团;(3)制备含有腈基的聚氨酯泡沫;(4)通过伯胺与腈基反应将石墨烯化学接枝到聚氨酯泡沫表面制备超疏水泡沫。采用傅里叶变换红外光谱、原子力显微镜、热重分析对接枝产物进行表征,证明了带有伯胺的石墨烯已成功接枝到聚氨酯泡沫上。利用接触角、油水混合物对制备的超疏水泡沫进行测试。结果表明,此方法制备的超疏水聚氨酯泡沫具有优良的疏水性,聚氨酯泡沫与水的接触角由未改性的121.4°增大到166.2°,同时发现此方法制备的聚氨酯泡沫的超疏水性具有很好的稳定性。     

改性碳纳米材料在低温燃料电池中的应用

碳纳米材料(如炭黑、介孔碳、碳纳米管、石墨烯、碳纳米纤维、碳纳米角等)因其优异的电学性能和结构特性(良好的导电性能和超大的比表面积),被研究者广泛用作低温燃料电池贵金属催化剂的载体.然而,作为催化剂载体的这类碳纳米材料通常都存在电化学腐蚀的问题,碳载体的腐蚀通常会导致贵金属纳米催化剂的聚集,这将使催化剂的性能降低.为了改善碳载体的抗腐蚀性能,提高金属纳米粒子的活性和稳定性,许多研究工作致力于制备特殊结构的碳纳米材料,或对碳纳米材料进行表面修饰、掺杂等.与此同时,为了取代价格昂贵的贵金属催化剂,非贵金属催化剂的研究也成为一大热点,掺杂碳纳米材料就是研究热点之一.对近几年来围绕碳纳米材料制备、改性,以及这些改性碳纳米材料作为金属纳米粒子载体等的研究工作做了较为详细的综述,同时介绍了掺杂碳纳米材料作为氧还原催化剂的研究进展.     

3D Aerogel of Graphitic Carbon Nitride Modified with Perylene Imide and Graphene Oxide for Highly Efficient Nitric Oxide Removal under Visible Light

3D materials are considered promising for photocatalytic applications in air purification because of their large surface areas, controllability, and recyclability. Here, a series of aerogels consisting of graphitic‐carbon nitride (g‐C₃N₄) modified with a perylene imide (PI) and graphene oxide (GO) are prepared for nitric oxide (NO) removal under visible‐light irradiation. All of the photocatalysts exhibit excellent activity in NO removal because of the strong light absorption and good planarity of PI–g‐C₃N₄ coupled with the favorable charge transport properties of GO, which slow the recombination of electron–hole pairs. The aerogel containing thiophene displays the most efficient NO removal of the aerogel series, with a removal ratio of up to 66%. Density functional theory calculations are conducted to explain this result and recycling experiments are carried out to verify the stability and recyclability of these photocatalysts.     

Efficacy Dependence of Photodynamic Therapy Mediated by Upconversion Nanoparticles: Subcellular Positioning and Irradiation Productivity

Singlet oxygen (¹O₂), as an important kind of reactive oxygen species (ROS) and main therapeutic agent in photodynamic therapy (PDT), only have a half‐life of 40 ns and an effective radius of 20 nm, which cause significant obstacles for improving PDT efficacy. In this work, novel upconversion nanoparticle (UCN)‐based nanoplatforms are developed with a minimized distance between UCNs and a photosensitizer, protoporphyrin IX (PpIX), and a controllable payload of PpIX, to enhance and control ROS production. The ability of the nanoplatform to target different subcellular organelles such as cell membrane and mitochondria is demonstrated via surface modification of the nanoplatform with different targeting ligands. The results show that the mitochondria‐targeting nanoplatforms result in significantly increased capability of both tumor cell killing and inhibition of tumor growth. Subcellular targeting of nanoparticles leads to the death of cancer cells in different manners. However, the efficiency of ROS generation almost have no influence on the tumor cell viability during the period of evaluation. These findings suggest that specific subcellular targeting of the nanoplatforms enhances the PDT efficacy more effectively than the increase of ROS production, and may shed light on future novel designs of effective and controllable PDT nanoplatforms.     

Highly Selective Metal-Free Electrochemical Production of Hydrogen Peroxide on Functionalized Vertical Graphene Edges

Electrochemical generation of hydrogen peroxide (H₂O₂) is an attractive alternative to the energy-intensive anthraquinone oxidation process. Metal-free carbon-based materials such as graphene show great promise as efficient electrocatalysts in alkaline media. In particular, the graphene edges possess superior electrochemical properties than the basal plane. However, identification and enhancement of the catalytically active sites at the edges remain challenging. Furthermore, control of surface wettability to enhance gas diffusion and promote the performance in bulk electrolysis is largely unexplored. Here, a metal-free edge-rich vertical graphene catalyst is synthesized and exhibits a superior performance for H₂O₂ production, with a high onset potential (0.8 V versus reversible hydrogen electrode (RHE) at 0.1 mA cm^?2) and 100% Faradaic efficiency at various potentials. By tailoring the oxygen-containing functional groups using various techniques of electrochemical oxidation, thermal annealing and oxygen plasma post-treatment, the edge-bound in-plane ether-type (C? O? C) groups are revealed to account for the superior catalytic performance. To manipulate the surface wettability, a simple vacuum-based method is developed to effectively induce material hydrophobicity by accelerating hydrocarbon adsorption. The increased hydrophobicity greatly enhances gas transfer without compromising the Faradaic efficiency, enabling a H₂O₂ productivity of 1767 mmol g_catalyst^?1 h^?1 at 0.4 V versus RHE.     

Semiconducting Polymer Nanoreporters for Near-Infrared Chemiluminescence Imaging of Immunoactivation

Real-time in vivo imaging of immunoactivation is critical for longitudinal evaluation of cancer immunotherapy, which, however, is rarely demonstrated. This study reports semiconducting polymer nanoreporters (SPNRs) with superoxide anion (O₂^•−)-activatable chemiluminescence signals for in vivo imaging of immunoactivation during cancer immunotherapy. SPNRs are designed to comprise an SP and a caged chemiluminescence phenoxy-dioxetane substrate, which respectively serve as the chemiluminescence acceptor and donor to enable intraparticle chemiluminescence resonance energy transfer. SPNRs are intrinsically fluorescent but only become chemiluminescent upon activation by O₂^•−. Representing the first O₂^•−-activatable near-infrared chemiluminescent reporter, SPNR3 sensitively differentiates higher O₂^•− levels in immune cells from other cells including cancer and normal cells. Following systemic administration, SPNR3 passively accumulates into tumors in living mice and activates the chemiluminescence signals responding to the concentration of O₂^•− in the tumor microenvironment. Moreover, the enhancement of in vivo chemiluminescence signal after cancer immunotherapy is correlated with increased population of T cells in the tumor, proving its feasibility in tracking of T cell activation. Thus, SPNRs represent the first kind of chemiluminescent reporters competent for in vivo imaging of immunoactivation.     

Real‐Time Analysis of Magnetic Hyperthermia Experiments on Living Cells under a Confocal Microscope

Combining high‐frequency alternating magnetic fields (AMF) and magnetic nanoparticles (MNPs) is an efficient way to induce biological responses through several approaches: magnetic hyperthermia, drug release, controls of gene expression and neurons, or activation of chemical reactions. So far, these experiments cannot be analyzed in real‐time during the AMF application. A miniaturized electromagnet fitting under a confocal microscope is built, which produces an AMF of frequency and amplitude similar to the ones used in magnetic hyperthermia. AMF application induces massive damages to tumoral cells having incorporated nanoparticles into their lysosomes without affecting the others. Using this setup, real‐time analyses of molecular events occurring during AMF application are performed. Lysosome membrane permeabilization and reactive oxygen species production are detected after only 30 min of AMF application, demonstrating they occur at an early stage in the cascade of events leading eventually to cell death. Additionally, lysosomes self‐assembling into needle‐shaped organization under the influence of AMF is observed in real‐time. This experimental approach will permit to get a deeper insight into the physical, molecular, and biological process occurring in several innovative techniques used in nanomedecine based on the combined use of MNPs and high‐frequency magnetic fields.     

氧化石墨烯改性环氧隔热涂层的耐蚀和隔热性能研究

用氧化石墨烯(GO)浓缩浆分散法制备GO改性环氧隔热涂层，在浓度(质量分数)为3.5% 的NaCl溶液(50℃)中进行腐蚀实验并测试其腐蚀前后的隔热性能。432 h的腐蚀电化学测试结果表明，用0.5%(质量分数) 的GO改性显著提高了涂层低频阻抗，涂层的耐蚀性优于无GO改性和1.0% GO改性的涂层；SEM分析结果表明，用0.5%和1.0% GO改性的隔热涂层腐蚀432 h后表面形貌完好，涂层/基体界面处没有出现裂纹和腐蚀产物，而未经GO改性的涂层出现了明显腐蚀破坏。腐蚀试验前，0.5%、1.0% GO改性的涂层与没有改性的涂层的隔热性能没有明显的区别；腐蚀432 h后涂层对250℃热源分别降温98℃、123℃、115℃，粘结强度分别降低了3.9、1.0、2.3 MPa。实验结果表明，用0.5% GO改性的涂层耐蚀和隔热性能最好。     

铝箔阳极氧化后2种铈转化膜的沉积机理

为探讨铝阳极氧化沉积铈转化膜形成机理,分别用化学沉积和电沉积法在铝阳极氧化膜上制备了铈转化膜._用SEM和EDS表征了阳极氧化膜、化学沉积铈转化膜和阴极电沉积铈转化膜的形貌和组分,测试了膜层厚度和膜的耐腐蚀性.结果表明:平均孔径89 nm的铝阳极氧化膜经阴极电沉积、化学沉积铈后平均孔径分别减小为38 nm和32nm,2种沉积分别可得到含铈52.10%和20.39%的铈转化膜.2种铈转化膜的平均膜厚分别比铝阳极氧化膜的大1.96 μm和1.23 μm,极化电阻均是铝阳极氧化膜的近3倍.2种铈转化膜形成机理不同是造成它们性质不同的原因.     

Removal of Cu2+ from Aqueous Solutions by Adsorption on Chemically Modified Cellulosic Supports

Low-cost materials containing carboxyl groups have been synthesized by grafting succinic anhydride onto sawdust and cotton fibers. These materials were used after activation with NaHCO₃ for the removal of Cu²⁺ from water. Removal of copper was carried out at different concentrations in a discontinuous reactor and in a continuous adsorption column. The adsorption of Cu²⁺ obeys to the Langmuir isotherm law and the values determined for the separation factor show that the system adsorbent/adsorbed substance is favorable to the adsorption process. Copper desorption and adsorbent regeneration can be achieved with diluted acid.     

Self-Assembly of Selenium-Doped Carbon Quantum Dots as Antioxidants for Hepatic Ischemia-Reperfusion Injury Management

Hepatic ischemia-reperfusion injury (HIRI) is a critical complication after liver surgery that negatively affects surgical outcomes of patients with the end-stage liver-related disease. Reactive oxygen species (ROS) are responsible for the development of ischemia-reperfusion injury and eventually lead to hepatic dysfunction. Selenium-doped carbon quantum dots (Se-CQDs) with an excellent redox-responsive property can effectively scavenge ROS and protect cells from oxidation. However, the accumulation of Se-CQDs in the liver is extremely low. To address this concern, the fabrication of Se-CQDs-lecithin nanoparticles (Se-LEC NPs) is developed through self-assembly mainly driven by the noncovalent interactions. Lecithin acting as the self-assembly building block also makes a pivotal contribution to the therapeutic performance of Se-LEC NPs due to its capability to react with ROS. The fabricated Se-LEC NPs largely accumulate in the liver, effectively scavenge ROS and inhibit the release of inflammatory cytokines, thus exerting beneficial therapeutic efficacy on HIRI. This work may open a new avenue for the design of self-assembled Se-CQDs NPs for the treatment of HIRI and other ROS-related diseases.     

煤气组分对固体氧化物燃料电池碳沉积的影响

以煤气化合成气作为固体氧化物燃料电池的燃料是煤炭清洁利用的重要方式之一, 但是存在碳沉积会对SOFC的运行造成一定影响. 本文构建了基于实验的全三维SOFC数学模型, 考虑了化学/电化学反应、气体的流动和扩散、气固耦合换热、过电势等多种运行参数, 计算了煤气化合成气中不同组分对以Ni-YSZ为阳极的SOFC碳沉积的影响. 可以看出, 增加水蒸气以及二氧化碳有助于碳沉积的降低, 但是过多的水蒸气和二氧化碳也会导致SOFC输出电压的降低. 较高的氢气含量对碳沉积也有一定的抑制作用. 一氧化碳含量的增加有助于减少碳沉积的范围, 但在SOFC入口处却增加了碳沉积活性. 同时, 甲烷能导致剧烈的碳沉积, 因此, 在煤气化合成气中应尽量去除甲烷.     

Sterilization Matters: Consequences of Different Sterilization Techniques on Gold Nanoparticles

Nanoparticles (NPs) can offer many advantages over traditional drug design and delivery, as well as toward medical diagnostics. As with any medical device or pharmaceutical drug intended to be used for in vivo biomedical applications, NPs must be sterile. However, very little is known regarding the effect of sterilization methods on the intrinsic properties and stability of NPs. Herein a detailed analysis of physicochemical properties of two types of AuNPs upon sterilization by means of five different techniques is reported. In addition, cell viability and production of reactive oxygen species are studied. The results indicate that sterilization by ethylene oxide seems to be the most appropriate technique for both types of NPs. It is concluded that it is crucial to test several methods in order to establish the specific type of sterilization to be performed for each particular NP.