Facile One-Step Photochemical Fabrication and Characterization of an Ultrathin Gold-Decorated Single Glass Nanopipette

he inner surface of a conical glass nanopipette was modified with ultrathin gold filth by a facile one-step photochemical approach, using HAuCl4, and ethanol as common reagents With the aid Of UV irradiation. The method is simple, straightforward, time-saving, and environmentally friendly. The morphology and.component of. the as-prepared ultrathin gold film was thoroughly characterized by transmission electron microscopy (TM), energy-dispersive X-ray (EDX) analysis, and X-ray photoelectron spectroscopy (XPS). The mechanism of the gold film growth was briefly discussed. Other small photochemical reagents with a fiy,droxy group, e.g., ethylene glycol, methanol, and glucose, may also work but with a different rate of reaction. The facile ultrathin gold decoration of a single glass nanopipette renders the glass nanopipette-based nanopore platform very easy for surface chemical modifications and potential sensing applications. The success of the gold decoration on the inner surface of the glass nariopore was further confirmed electrochemically by surface modification of a small thiol molecule (cysteine), and the pH (surface charge)-dependent ionic current rectification behaviors through the nanopore were investigated. Due to its facile preparation, the method and the Au-decorated glass nanopore would find promising and extended applications in ultrasensitive detection and, biosensing

反应型转光剂制备及其与聚乙烯接枝研究

有机染料类转光剂制备的转光棚膜相较稀土类具有透光性好等优点，但是存在转光剂与聚乙烯等常用基材相容性低导致喷霜等问题，因此需要对有机染料和基材分别进行改性。本论文以制备耐迁移的有机染料类转光膜为目的，合成了两种反应型转光剂N-烯丙基-4-甲氧基-1,8-萘酰亚胺(MOANI)和N, N’-二烯丙基-1,6,7,12-四(4-叔丁基苯氧基)-苝-3,4,9,10-四甲酰二亚胺(DAPBI)，并采用预辐照与熔融接枝联用技术，将两种反应型转光剂接枝到了线性低密度聚乙烯(LLDPE)上，发展了接枝率的测定及转光膜耐迁移性的测试方法，最终制备出了比常规掺混转光膜耐迁移性能更高的荧光有机染料类转光膜。 首先，以4-氯-1,8-萘二甲酸酐为原料通过一锅法一步制得了MOANI；以N,N’-二正丁基-1,6,7,12-四(4-叔丁基苯氧基)-苝-3,4,9,10-四甲酰二亚胺为原料，经水解、烯丙基化，两步制得DAPBI。采用质谱，红外光谱，核磁共振证明了两种产物的组成结构。采用紫外可见及荧光分光光度法测试了产物在溶液中的吸收及发射光谱，两种光谱证明MOANI及DAPBI可以作为转光剂。 随后，将MOANI及DAPBI分别与预辐照的线性低密度聚乙烯进行熔融接枝，纯化后，采用紫外可见、荧光、红外光谱法以及氢核磁共振波谱法对接枝物的结构进行了表征，结果证明MOANI及DAPBI已经分别接枝到了LLDPE分子链上。通过紫外可见分光光度法建立了一套接枝率(GD)的测定方法，测定了两种接枝聚合物的接枝率并计算了接枝效率(GE)，并用其研究了初始单体浓度、反应温度、反应时间三种因素对GD及GE的影响。结果表明，两种单体的接枝率均随这三种因素的增加而增加，但初始单体浓度对MOANI接枝率的影响最大，反应温度对DAPBI的影响最大；相同反应温度及时间的条件下，MOANI的初始单体浓度在1.5wt%时接枝效率最大，DAPBI在0.3wt%时GE最大。对两种接枝物的流变性能、热学性能和样品表面性质的研究表明：1. pi-LLDPE在熔融状态下会发生分子链交联，从而产生长支链，而两种单体的接枝会减少交联过程的发生；2. 接枝上的单体起到了异相成核剂的作用；3. 纯化后的接枝聚合物在与共混物相同荧光性能的条件下不会发生喷霜现象。 最后，为了更贴近工业生产的实际，我们通过预辐照与反应挤出接枝连用技术及色母粒技术制备了一系列浓度未经纯化的接枝聚合物，并研究了它们吹塑成膜后的紫外耐候性能和迁移析出性能。一、紫外耐候性能的研究：我们将紫外耐候试验仪不同时间老化后的样品用荧光分光光度计及万能拉力机测试，得到了老化条件下薄膜的荧光衰减性质及力学老化性质。研究表明：1.接枝上的单体减小了荧光的衰减速率；2.MOANI起到了紫外线吸收剂的作用，但DAPBI却起到了光敏剂的作用。二、薄膜转光效果的评价：我们以氙灯为光源，通过光谱验证仪对所有薄膜样品的透过光谱进行了研究，研究表明：未经纯化的LLDPE-g-MOANI膜起到了紫外转蓝作用，增强了聚乙烯薄膜在400~500nm间的透过光强，初始MOANI浓度为0.15 wt%的膜在该范围内透过光强与300~750nm总透过光强的积分相较LLDPE增加了2.5%；未纯化LLDPE-g-DAPBI膜起到了黄绿转橙红的作用，增强了聚乙烯薄膜在600~750nm间的透过光强，初始DAPBI浓度为0.09 wt%的膜在该范围内透过光强与300~750nm总透过光强的积分比较LLDPE增加了1.7%，此外其红光/远红光量比相较LLDPE膜增加了0.033。三、迁移析出性能的研究：结合转光膜实际使用的特点，我们用流滴膜的测试装置——加速流滴仪结合荧光分光光度计测定了两种接枝聚合物薄膜因单体迁移析出造成的荧光衰减性质。经60℃加速诱导，22天后，初始单体浓度为0.15wt%的未纯化LLDPE-g-MOANI膜（所用1wt%色母粒GD=0.17wt%）的蓝色荧光占初始强度的百分数为64.5%，而对比的同初始浓度的共混膜只有41.6%；相同条件下，47天后，含有流滴剂且初始单体浓度为0.13wt%未纯化LLDPE-g-DAPBI膜（所用1wt%色母粒GD=0.10wt%）的红色荧光占初始强度的百分数为58.4%，而对比的同初始浓度的共混膜只有42.0%。结果表明：接枝上的单体抑制了未接枝单体的迁移析出过程。此外通过复配我们发现，两种接枝物的复配更能延缓未接枝单体的迁移渗出过程。As one kind of light-converting agents, fluorescent organic dyes are widely used, because they are molecular dispersion in the polymer than rare earth type light-converting agents. Unfortunately, fluorescent organic dyes lack an affinity for aliphatic hydrocarbons, consequently migrate to the surface of polyolefins and even crystallize on the surface, so the dyes or polyethylene need to be modified. In this work, we synthesized two polymerisable light-converting agents, 4-methoxy-N-allyl-1,8-naph -thalimide (MOANI) and N,N'-diallyl-1,6,7,12-tetra(4-tert-butylphenoxy)-perylene-3,4, 9,10-tetracarboxylic bisimide (DAPBI), grafted them onto linear low density polyethylene (LLDPE) with the pre-irradiation and melt grafting joint technology and finally the two modified LLDPEs showed the potential application in long-term light-converting films. Firstly, MOANI was synthesized from 4-chloro-1,8-naphthalic anhydride through using a one-pot method. DAPBI was synthesized from N,N'-di-n-butyl-1,6,7,12-tetra(4 -tert-butylphenoxy)-perylene-3,4,9,10-tetracarboxylic bisimide through using hydrolyzation and allylation reaction successively. The chemical structures of products were proved through using MS, FTIR and NMR. The absorption and emission spectra were obtained through using UV/vis spectrometer and fluorospectrometer, and they prove that MOANI and DAPBI can be as light-converting agents. Secondly, MOANI and DAPBI were respectively grafted onto pre-irradiated linear low density polyethylene (LLDPE) with a melt reactive mixing process, and charactered spectral, thermo and rheological properties of two grafting polymers (LLDPE-g-MOANI, LLDPE-g-DAPBI) obtained in mixer after purification. By comparing UV/vis, fluorescence, FTIR, 1HNMR spectra of the LLDPE, two grafting polymers and two polymerisable light-converting agents, it was proved that MOANI and DAPBI were grafted on LLDPE. The grafting degree (GD) of MOANI or DAPBI in LLDPE-g-MOANI or LLDPE-g-DAPBI was determined by UV/Vis spectra and relevant grafting efficiency (GE) was also calculated. The effects of monomer concentration, chamber temperature and reaction time on GD and GE were systematically studied. The results show that GDs of MOANI and DAPBI increased with increasing initial monomer concentration, chamber temperature and reaction time. However, the initial monomer concentration and chamber temperature are the main processing parameters for controlling the GD to MOANI and DAPBI, respectively. In the same chamber temperature and reaction time, the highest GE of MOANI was reached in 1.5wt% of initial monomer concentration of MOANI, but in 0.3wt% of initial monomer concentration of DAPBI. The rheological behaviors of LLDPE-g-MOANI and LLDPE-g-DAPBI suggest that the crosslinking of LLDPE can be inhibited effectively by graft of MOANI and DAPBI. The grafted monomer acts as a nucleation agent, which improves the crystallization rates of LLDPE molecular chains. Surface morphologies of LLDPE-g-MOANI and LLDPE-g-DAPBI demonstrating the grafted monomer are difficult to migrate to the surface of the films. Finally, accelerated migration and UV weathering of blown films of unpurified LLDPE-g-MOANI and LLDPE-g-DAPBI obtained in extruder were tested in order to close to actual industrial production. Mechanical properties of unpurified LLDPE-g-MOANI films as function of UV weathering period mean that MOANI acts as the role of ultraviolet absorber and inhibited the aging process of LLDPE. But for unpurified LLDPE-g-DAPBI films, DAPBI acts as the role of sensitizer and accelerated the aging process of LLDPE. The test results of spectrograph suggest that unpurified LLDPE-g-MOANI and LLDPE-g-DAPBI films can increase light intensity of blue-violet light and orange-red light compared with LLDPE film, respectively. Besides, the intensity ratio of red and far-red light of unpurified LLDPE-g-DAPBI film with 0.09 wt% DAPBI initial concentration increased by 0.033, compared with LLDPE film. The test results of accelerated migration and UV weathering indicate that migration processes of the free MOANI or DAPBI in unpurified LLDPE-g-MOANI or LLDPE-g-DAPBI films were delayed effectively by the grafted MOANI or DAPBI in these films. Through blown films of mixture of unpurified LLDPE-g-MOANI and LLDPE-g-DAPBI, migration processes of the free MOANI or DAPBI were delayed further, compared with unpurified LLDPE-g-MOANI or LLDPE-g-DAPBI with same MOANI or DAPBI initial concentration

聚合物的碳化反应及其应用

伴随着大量聚合物材料的广泛应用，如何处理日益增长的废旧聚合物，特别是塑料，成为影响我国乃至全世界可持续发展的重要因素之一。由于聚合物中含有碳元素（比如聚烯烃中碳元素高达85.7%），将聚合物或者废旧聚合物转化成高附加值的碳材料是一种新的聚合物回收方法。我们课题组在2005年提出了“组合催化剂”策略，发现固体酸或者氯化物与Ni2O3的组合催化剂可以高效催化聚烯烃碳化制备碳纳米管（CNTs）。但是，还存在许多问题需要解决，比如碳化机理不清楚、碳材料形貌较差、碳化效率不高以及缺乏对碳材料应用的探索。事实上，众多国内外以聚合物回收为目的的碳化研究小组都存在类似的问题。因而，还需要进一步研究聚合物的碳化反应。另一方面，由于实际的废旧塑料包含了多种类型的塑料，比如聚丙烯（PP）、聚乙烯（PE）、聚苯乙烯（PS）、聚对苯二甲酸二甲酯（PET）和聚氯乙烯（PVC），同时还有许多类型的填料。那么，为了研究废旧混合塑料转化成高附加值的碳材料，就必须弄清楚单独的和混合的塑料的碳化反应规律，同时还需要弄清楚填料对于碳化反应的影响。更为重要的是目前关于回收聚合物碳化产物的应用还缺乏研究，探索其在环境污染治理、能源存储、催化和阻燃等领域的应用就非常必要。 本论文研究了聚合物碳化反应，制备了零维碳材料（包括中空碳球（HCS）、核壳结构的Co@C球和Fe3O4-微米碳球杂化材料）、一维碳材料（包括CNTs、碳纳米纤维（CNFs）、“杯叠”碳纳米管（CS-CNTs）、多孔“杯叠”碳纳米管（P-CSCNT）、盘子状碳纤维（PL-CF）和CF/CNT杂化材料）和二维碳材料（包括碳纳米薄片（CNS）和多孔碳薄片（PCNS）），并且探索了它们在锂离子电池、光催化降解染料、吸附污染物（重金属离子、油和染料）、吸附二氧化碳、存储氢气以及提高聚合物阻燃性能方面的应用。不仅丰富了“组合催化剂”策略，还提出了“快速碳化”和“模板碳化”新的聚合物碳化策略。具体内容如下： 1、系统研究聚合物催化碳化制备HCS及其杂化材料。首先，研究PS的碳化反应规律，利用钴催化剂/有机改性蒙脱土（OMMT）组合催化剂，制备了介孔的HCS。接着，通过调节Co3O4催化剂的量，首次将混合塑料转化成尺寸可控的HCS。在此基础上，考察四种常见的填料对于HCS生长的影响，发现填料与钴催化剂的相互作用是填料影响HCS的主要因素。此外，成功将五组份混合废旧塑料转化成介孔HCS，并且探索了其在锂离子电池方面的应用。之后，发现如果不加入OMMT，一步就能将混合塑料转化成尺寸均一的磁性核壳结构的Co@C球。它在光催化降解染料刚果红（CR）中表现出较高的催化效率、很好的回收性能、重复使用性能以及较好的长效稳定性能。 2、在利用“组合催化剂”催化非成碳聚合物碳化制备CNTs的基础上，探索新的成碳聚合物碳化策略—“催化碳化”，从而调控成碳聚合物的碳化反应。系统研究了Fe2O3对于氯化聚氯乙烯（CPVC）的碳转化率、产率、形貌和组成的影响。发现Fe2O3被还原成Fe3O4，并且以微晶的形式镶嵌在微米碳球表面。证明了Fe2O3可以催化CPVC微球表面快速脱氯化氢以及随后的交联反应，从而避免了CPVC微球的熔融粘接。制备的Fe3O4-微米碳球杂化材料在光催化降解染料CR方面有着较高的效率、回收性能、重复使用性能和长效稳定性，表明其在环境污染治理方面有着潜在的应用。更为重要的是，根据“形状复制”的碳化反应原理，还可以制备功能性纳米球、纤维和棒状等各种形貌的碳材料或者碳基杂化材料。 3、系统研究了氯化物/Ni2O3组合催化剂中氯化物对于聚合物碳化反应的影响。首先研究了Cl/Ni摩尔比对碳材料的产率和形貌的影响。考察了Cl/Ni摩尔比对碳材料活性位点和PP降解产物的影响。然后将制备Cu-Ni/C杂化材料用于催化“Click”反应，产率高达97%。因而，提供了新的制备金属-碳杂化材料的方法。接着，发现PVC也可以充当氯源，与Ni2O3协同催化线性低密度聚乙烯（LLDPE）碳化制备磁性Ni/C杂化材料。PVC的种类对于Ni/C杂化材料的产率影响不大，但是PVC的含量决定了Ni/C杂化材料的产率。随着PVC含量的增加，Ni/C杂化材料的产率快速增加，而后减少。当PVC含量较低时，生成了较长的CNTs；当PVC含量较高时，得到的是较短的CNFs和无定形碳。这主要是由于PVC分解生成的氯自由基促进了LLDPE大分子自由基的脱氢和芳构化反应。Ni/C杂化材料被用于吸附亚甲基蓝（MB），表现出较快的吸附速率、较高的吸附量和磁性吸附等三大特点。此外，发现活性炭与Ni2O3组合协同催化PP碳化制备CNTs，分析了CNTs生长机理，证明了活性炭表面的官能团是协同催化的关键因素。首次提出了基于苯环的层层组装的CNTs生长机理，为将塑料或者废旧塑料转化成CNTs提供了理论指导。 4、为了改善碳材料形貌，从催化剂设计角度出发，用溶胶-凝胶-燃烧法合成了NiO纳米粒子成碳催化剂。首先，考察了OMMT/NiO组合催化PP碳化制备CS-CNTs，发现OMMT的含量对于CS-CNTs的产率和形貌起到决定性的作用。CS-CNTs的石墨层排列与轴向存在20–25o夹角。证明了少量的OMMT可以促进PP碳正离子的脱氢和芳构化从而生成大量的小分子碳氢化合物和芳烃化合物，这些降解产物促进NiO纳米粒子的熔结和重建生成双锥结构的NiO。接着，重建的NiO催化剂再催化这些降解产物碳化生成较长且表面平整的CS-CNTs。在此基础上，系统考察了卤化物/NiO组合催化剂催化PP碳化制备碳纳米材料（CNM）。证明了组合催化剂的催化效率为氟化物/NiO << 氯化物/NiO < 溴化物/NiO < 碘化物/NiO。这主要是因为卤素自由基催化PP大分子自由基的脱氢和芳构化能力为F << Cl < Br < I。此外，将CS-CNTs酸处理制备酸化的CS-CNTs（CS-CNT-H）。它表现出较高的吸附重金属离子和有机染料的性能，这表明CS-CNT-H在废水处理方面有着潜在应用。Langmuir模型更适合于拟合吸附数据，吸附动力学数据则由Pseudo second-order模型拟合更为准确。 5、在（4）基础上，系统研究了NiO尺寸（18–227 nm）对于CS-CNTs生长的影响，发现在OMMT/NiO催化PP碳化制备CS-CNTs过程中NiO纳米粒子的熔结和重建过程是CS-CNTs生长的关键步骤。尺寸较小的NiO促进较长且表面平整的CS-CNTs的形成。这主要是由于尺寸较小的NiO更容易发生熔结和重建。40 nm的NiO最适合于CS-CNTs生长，制备“海绵”状的CS-CNTs。它具有较高的吸附油的性能、较好的重复使用性能、较高的机械强度以及磁性。另外，研究了催化剂中晶格氧在PP碳化过程中的作用，发现CNM的产率随着晶格氧含量的增加而增加。当晶格氧含量很低时，得到的是较粗而弯曲的PL-CFs。增加晶格氧后，得到的是较细、弯曲且较短的CNFs。但是当晶格氧含量很高时候，得到的是较长、直且表面平整的CS-CNTs。晶格氧不仅促进镍纳米粒子重建成双锥结构、抑制催化剂团聚成大颗粒，还促进聚合物降解产物的碳化。这部分工作有助于进一步了解塑料的碳化反应机理以及将废旧塑料转化成高附件值的碳材料。 6、探讨了聚合物种类、HZSM-5含量以及镍催化剂种类对于CNM的产率和形貌的影响。随着HZSM-5含量的增加，CNM的产率先增加而后变化不明显。聚合物种类和镍催化剂种类对于CNM的产率并不明显，但是对于CNM的形貌有着显著影响。另外，相比于PP，LLDPE降解产物中芳烃含量较高，从而使得LLDPE作为碳源时生成的CNM中含有较少的石墨化结构以及较多的无定形碳。这部分工作为将混合塑料转化成高附加值碳材料奠定基础。在此基础上，研究了PE的链结构对于PE碳化反应的影响。发现不论PE的结构，PE的产率都随着CuBr含量的增加而增加，达到最大值后逐渐减低。LLDPE作为碳源时，得到的是较长且表面平整的CS-CNTs，但是低密度聚乙烯或者高密度聚乙烯作为碳源时到的是较短、弯曲且表面粗糙的CNFs。这主要是归因于不同链结构的PE在CuBr催化作用下生成不同的降解产物。 7、在制备CS-CNTs的基础上，首次提出了利用碱处理的办法来制备P-CSCNT。P-CSCNT包含了许多尺寸在几纳米到十几纳米、连接P-CSCNT表面和内部且与轴向存在一定夹角的孔通道。与CSCNTs比较，P-CSCNT具有较高的比表面积（558.7 m2/g）、较大孔容（1.993 cm3/g）以及较多的表面官能团。此外，P-CSCNT表现出较高的MB吸附量。Langmuir模型可以很好地拟合吸附数据，P-CSCNT的MB最大吸附量可达319.1 mg/g。这主要归因于P-CSCNT较高的比表面积和较大的孔容，以及多种类型的吸附机理。更为重要的是，P-CSCNT表现出很好的回收性能和重复使用性能。这表明P-CSCNT在废水治理中有着潜在应用。这部分工作为P-CSNT的大规模应用奠定了基础。 8、除了“组合催化剂”和“快速碳化”策略，提出了聚合物碳化的第三种策略—“模板碳化”。即利用OMMT作为模版，将塑料转化成CNS，经过KOH活化后制备了PCNS，并且探索了PCNS在能源存储和环境污染治理方面的应用。CNS的产率随着OMMT/废旧PP的重量比的增加而增加。制备的CNS具有褶皱的形貌，层数在几层到十几层，并且石墨层并不连续同时具有很多缺陷。此外，制备的CNS有着较高的纯度以及一定量的表面官能团。OMMT不仅充当了聚合物降解催化剂With the wide application of polymer materials in our daily life, the treatment of ever-increasing waste polymer materials, especially waste plastics, has been the major factor which influences the sustainable development in both our country and the world. Converting the polymer materials and waste polymer materials into high value-added carbon materials is a potential way to largely recycle them. In 2005, our group put forward the strategy of "combined catalysts", and found the combination of solid acids or chlorinated compound with Ni2O3 could effectively catalyze the carbonization of polyolefins into carbon nanotubes (CNTs). However, many questions are still needed to be solved, for example, the carbonization mechanism of polyolefins is not clear, the morphology of carbon materials should be improved and adjusted, the efficiency of carbonization should be enhanced, and the applications of carbon materials should be explored. Actually, all the groups which study the carbonization of waste polymer materials around the world confront with the same questions. Therefore, much work should been done to better understand the carbonization of polymer materials. On the other hand, the real waste plastics consisted of many kinds of plastics, such as polypropylene (PP), polyethylene (PE), polystyrene (PS), poly(ethylene terephthalate) (PET) and poly(vinyl chloride) (PVC), along with a lot of fillers. Hence, in order to transform the waste mixed plastics into high value-added carbon materials, the carbonization of single and mixed plastics should be studied and also the effects of fillers on the carbonization should be clear. In this dissertation, the carbonization of polymer materials were studied, carbon materials including zero dimensional carbon materials (such as carbon spheres (HCS), core/shell Co@C spheres and Fe3O4/carbon microspheres), one dimensional carbon materials (such as CNTs, carbon nanofibers (CNFs), cup-stacked CNTs (CS-CNTs), porous CS-CNTs (P-CSCNT), plate-like carbon fibers (PL-CF) and CF/CNT hybrid) and two dimensional carbon materials (such as carbon nanosheet (CNS) and porous CNS (PCNS)) were synthesized, and were explored in the applications of Li-ion batteries, photo-degradation of dyes, adsorption of pollutants (such as heavy metal ions, oils and organic dyes), adsorption of carbon dioxide, storage of hydrogen and the improvement of the flame retardancy of polymer materials. These results not only enriched the strategy of "combined catalysts", but also put forward the two new strategies of fast carbonization and template carbonization. Detail work is as follows: 1. Zero-dimensional carbon materials and their hybrids were synthesized by catalytic carbonization of polymer materials. Firstly, the carbonization mechanism of PS was studied, and the mesoporous HCS was synthesized by the combined catalysts of cobalt catalyst and organically-modifiedmontmorillonite (OMMT). Subsequently, HCS with controllable size was prepared from mixed plastics (PP, PE and PS) by adjusting the amount of Co3O4. Based on this result, the effect of four fillers on the formation of HCS was studied, and the interaction between filler and cobalt catalyst was found to be the crucial factor influcing the formation of HCS. At the same time, the waste five-component plastics (PP, PE, PE, PET and PVC) were converted into mesoporous HCS, which was used in Li-ion batteries. Afterwards, without OMMT, mixed plastics consisting of PP, PE and PS were catalyzed by Co3O4 into uniform magnetic core/shell Co@C spheres via a one-pot approach. It showed high performance in the photo-degradation of Congo red (CR) with good recycling, good reusability and stability. 2. On the basis of the strategy of "combined catalysts" to convert polymer materials into CNTs, a new strategy of "fast carbonization" was put forward to promote the carbonization of charring polymer materials. The effect of Fe2O3 on the yield, carbon conversion, morphology and composition of ca

Bimetallic PdPt nanowire networks with enhanced electrocatalytic activity for ethylene glycol and glycerol oxidation

In this report, bimetallic PdPt nanowire networks (NNWs) with tunable compositions were successfully synthesized via a simple and efficient method. Electrocatalytic analyses prove that the catalytic activity of the as-prepared NNWs is related to their composition, and the synthesized NNWs display great potential as substitutes for commercial Pt/C catalysts for effective catalysis of ethylene glycol and glycerol electrooxidation in an alkaline solution; among the prepared PdPt NNWs, Pd55Pt30 shows the best electrocatalytic activity

Nanogel-Incorporated Physical and Chemical Hybrid Gels for Highly Effective Chemo-Protein Combination Therapy

Chemo- and protein-based therapeutics are two major modalities for the treatment of malignant tumors with drastically different therapeutic indices, toxicity, and other pharmacological properties. For intended in vivo applications, they also have distinctly different formulation challenges to be addressed separately. In this study, we attempt to overcome the formulation barriers of chemo- and protein-based therapeutics, and report the development of injectable nanogels, a class of crosslinked physical and chemical composite gels (nPCGs), for the joint delivery of doxorubicin (DOX), protein cytokines recombinant human interleukin-2 (IL-2), and recombinant human interferon-gamma (IFN-gamma). The nPCGs are designed through a quick gelation induced by ionic crosslinking of 4-arm poly(ethylene glycol)-b-poly(L-glutamic acid) (PPLG) and hydroxypropyl chitosan/4-arm poly(ethylene glycol)-b-poly(L-lysine) (HPCS/PPLL), followed by the formation of covalent bonds via a Schiff-base reaction of the oxidized, cholesterol-bearing dextran (OCDEX) nanogels with HPCS/PPLL, which results in increased hydrogel moduli (G' around 13.8 kPa) and improved stability. This nPCG, which contains DOX, IL-2, and IFN-gamma, shows a synergistic anticancer efficacy through the regulation of apoptosis-related genes in Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathways and mitochondrial pathways in xenograft tumor-bearing mice

Surface Oxidized Cobalt-Phosphide Nanorods As an Advanced Oxygen Evolution Catalyst in Alkaline Solution

Electrochemical water splitting in alkaline solution plays a growing role in alternative energy devices due to the need for clean and sustainable energy. However, catalysts that are active for both hydrogen evolution and oxygen evolution reactions are rare. Herein, we demonstrate that cobalt phosphide (CoP), which was synthesized via the hydrothermal route and has been shown to have hydrogen evolution activity, is highly active for oxygen evolution. A current density of 10 mA cm(-2) was generated at an overpotential of only 320 mV in 1 M KOH for a CoP nanorod-based electrode (CoP NR/C), which was competitive with commercial IrO2. The Tafel slope for CoP NR/C was only 71 mV dec(-1), and the catalyst maintained high stability during a 12 h test. This high activity was attributed to the formation of a thin layer of ultrafine crystalline cobalt oxide on the CoP surface

Ultrafast Tracking of a Single Live Virion During the Invagination of a Cell Membrane

The first step in most viral infections is the penetration of the cell membrane via endocytosis. However, the underlying mechanism of this important process has not been quantitatively characterized; for example, the velocity and force of a single virion during invagination remain unknown. Here, the endocytosis of a single live virion (Singapore grouper iridovirus, SGIV) through the apical membranes of a host cell is monitored by developing and using a novel ultrafast (at the microsecond level) tracking technique: force tracing. For the first time, these results unambiguously reveal that the maximum velocity during the cell entry of a single SGIV by membrane invagination is approximately 200 nm s(-1), the endocytic force is approximately 60.8 +/- 18.5 pN, and the binding energy density increases with the engulfment depth. This report utilizing high temporospatial resolution (subnanometer and microsecond levels) approaches provides new insight into the dynamic process of viral infection via endocytosis and the mechanism of membrane invagination at the single-particle level

Gold nanocluster-based vaccines for dual-delivery of antigens and immunostimulatory oligonucleotides

We here report a facile one-pot synthesis of fluorescent gold nanoclusters (AuNCs) via the peptide bio-mineralization method, which can elicit specific immunological responses. The as-prepared peptide-protected AuNCs (peptide-AuNCs) display strong red fluorescence, and more importantly, as compared to the peptide alone, the immune stimulatory ability of the resulting peptide-AuNCs can not only be retained, but can also be efficaciously enhanced. Moreover, through a dual-delivery of antigen peptides and cytosine-phosphate-guanine (CpG) oligodeoxynucleotides (ODNs), the as-prepared peptide-AuNC-CpG conjugates can also act as smart self-vaccines to assist in the generation of high immunostimulatory activity, and be applied as a probe for intracellular imaging. Both in vitro and in vivo studies provide strong evidence that the AuNC-based vaccines may be utilized as safe and efficient immunostimulatory agents that are able to prevent and/or treat a variety of ailments

Enzyme-free and DNA-based multiplexer and demultiplexer

A DNA-based 2:1 multiplexer and 1:2 demultiplexer have been conceptually realized in enzyme-free conditions. For the first time, the designed DNA-based multiplexer could be implemented by keeping input/output signal homogeneity, which has great potential application in information processing