A novel nanocontainer, which could regulate the release of payloads, has been successfully fabricated by attaching zwitterionic sulfobetaine copolymer onto the mesoporous silica nanoparticles (MSNs). RAFT polymerization is employed to prepare the hybrid poly(2-(dimethylamino)ethyl methacrylate)-coated MSNs (MSN-PDMAEMA). Subsequently, the tertiary amine groups in PDMAEMA are quaternized with 1,3-propanesultone to get poly(DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate)-coated MSNs [MSN-Poly(DMAEMA-co-DMAPS)]. The zwitterionic PDMAPS component endows the nanocarrier with biocompatibility, and the PDMAEMA component makes the copolymer shell temperature-responsive. Controlled release of loaded rhodamine B has been achieved in the saline solutions.

Cu–ZnO–Al2O3 catalysts are used as the industrial catalysts for water gas shift (WGS) and CO hydrogenation to methanol reactions. Herein, via a comprehensive experimental and theoretical calculation study of a series of ZnO/Cu nanocrystals inverse catalysts with well-defined Cu structures, we report that the ZnO–Cu catalysts undergo Cu structure-dependent and reaction-sensitive in situ restructuring during WGS and CO hydrogenation reactions under typical reaction conditions, forming the active sites of CuCu(100)-hydroxylated ZnO ensemble and CuCu(611)Zn alloy, respectively. These results provide insights into the active sites of Cu–ZnO catalysts for the WGS and CO hydrogenation reactions and reveal the Cu structural effects, and offer the feasible guideline for optimizing the structures of Cu–ZnO–Al2O3 catalysts.

Nanoring materials with multiple functionalities have attracted significant attention owing to their potential applications in optical and electronic resonators, biological and chemical sensors, molecular imaging, and gene delivery. [1] Recently, several approaches have been proposed for fabricating nanoring materials, including synthesis of silver nanorings prepared from a one-pot procedure, [2] Au and Ag nanorings fabricated using the outer profile of silica nanoparticles as template, [3] and mesoscopic rings prepared by a method based on capillary force in the colloidal crystal. [4] Also, many interesting and unique properties of nanoring materials have been observed; for example, the toroidal structure of packed DNA is natures most efficient morphology for transporting genetic information, done particularly well by viruses. Some researchers want to mimic this process by condensing DNA into a nanoring morphology to improve the effect of gene therapy. The DNA nanoring packed in viruses is multifunctional, but the nanoring materials fabricated to date are limited by a lack of the multiple functionalities. Thus, the preparation of nanoring materials with multiple functionalities of stimuliresponsiveness, biocompatibility, biodegradability, and photoluminescence will be very attractive.[5] We report herein an easy approach to fabricating multifunctional nanorings by the assembly of DNA with a novel multifunctional hyperbranched macromolecule.It has been reported that multivalent cations can condense DNA into nanorings under suitable conditions. [1a,c,i] To prepare nanorings with multiple functionalities of stimuli-responsiveness, biodegradability, and photoluminescence, multivalent cations having these functionalities are prepared first and then used to condense plasmid DNA. Hyperbranched macromolecules are a special kind of macromolecule with three-dimensional structure. It is very easy to incorporate different functionalities into a single molecule of this type. [6,7] To develop photoluminescent nanorings with multiple functionalities, we prepared a novel disulfide-containing hyperbranched poly(amido amine) (HPAA) by Michael addition polymerization. Note that the syntheses of some linear disulfide-containing poly(amido amine)s have been reported, but these species easily condense plasmid DNA into nanoparticles; therefore, we prepared hyperbranched analogues.The co-polyaddition reaction of 1-(2-aminoethyl)piperazine (AEPZ) with N,N'-cystaminebisacrylamide (CBA) and N,N'-methylenebisacrylamide (MBA; Scheme 1) was employed in the preparation of the HPAA containing a 1:2 molar ratio of the CBA unit to the MBA unit (HPAA12). This synthetic route was chosen for three reasons: 1) The disulfidecontaining HPAA with a 1:0 molar ratio of CBA to MBA (HPAA10) obtained by polyaddition of AEPZ and CBA (at a molar ratio of 1:2) and the disulfide-containing HPAA with a 1:1 molar ratio of CBA to MBA (HPAA11) obtained by polyaddition of AEPZ with CBA and MBA at a 1:2 molar ratio of AEPZ to CBA + MBA are not water-soluble, an...

A facile temperature induced self-assembly and self-crosslinking method has been developed for preparing bioreducible nanogels/microgels without need of any stabilizer, catalyst or additional crosslinking agent. The size of formed nanogels/microgels can be easily tuned via the polymer concentration.

The identification of the contribution of different surface sites to the catalytic activity of a catalyst nanoparticle is one of the most challenging issues in the fundamental studies of heterogeneous catalysis. We herein demonstrate an effective strategy of using a series of uniform cubic Cu2O nanocrystals with different sizes to identify the intrinsic activity and contributions of face and edge sites in the catalysis of CO oxidation by a combination of reaction kinetics analysis and DFT calculations. Cu2O nanocrystals undergo in situ surface oxidation forming CuO thin films during CO oxidation. As the average size of the cubic Cu2O nanocrystals decreases from 1029 nm to 34 nm, the dominant active sites contributing to the catalytic activity switch from face sites to edge sites. These results reveal the interplay between the intrinsic catalytic activity and the density of individual types of surface sites on a catalyst nanoparticle in determining their contributions to the catalytic activity.

No abstract

Cu2O-derived nanoparticles are efficient catalysts for the electrochemical conversion of CO and CO2 to multicarbon products. Generation of multicarbon products requires dimerization of adsorbed CO, which is accelerated when the coverage of CO is high. The electrolyte cation and the initially exposed crystal plane of the catalyst both affect the reaction rate, but the relation between these effects and CO coverage is unclear, especially given the surface reconstruction that occurs during reduction reactions on Cu2O. We prepared a series of shape-controlled Cu2O nanoparticles with similar sizes but different initially exposed crystal planes [cubes (100), octahedra (111), and dodecahedra (110)], and we used the infrared absorption bands detected in situ to compare the potential-dependent CO coverage on each of the nanomaterials in CO-saturated 0.1 M NaHCO3 and CsHCO3 during cyclic voltammetry. After correcting for the shape of the particle, there was less than 20% difference in the coverage of adsorbed CO on the different structures. The fact that the surface coverages are so similar may be a result of surface reconstruction occurring during the reaction. If so, the fact that it occurs so rapidly shows that the surface structure will not, in practical situations, impact the surface coverage of CO. In CsHCO3, a lower surface coverage of CO was measured, even for potentials at which CO dimerization is very slow. Although Cs+ accelerates the reduction of CO through interaction with adsorbed intermediates, its ability to adsorb to the electrode surface likely enables it to block potential adsorption sites for CO. Therefore, the effect of interaction with intermediates must have more impact than the reduced surface coverage of CO caused by cation adsorption.

Propylene epoxidation with O2 to propylene oxide is a very valuable reaction but remains as a long-standing challenge due to unavailable efficient catalysts with high selectivity. Herein, we successfully explore 27 nm-sized cubic Cu2O nanocrystals enclosed with {100} faces and {110} edges as a highly selective catalyst for propylene epoxidation with O2, which acquires propylene oxide selectivity of more than 80% at 90–110 °C. Propylene epoxidation with weakly-adsorbed O2 species at the {110} edge sites exhibits a low barrier and is the dominant reaction occurring at low reaction temperatures, leading to the high propylene oxide selectivity. Such a weakly-adsorbed O2 species is not stable at high reaction temperatures, and the surface lattice oxygen species becomes the active oxygen species to participate in propylene epoxidation to propylene oxide and propylene partial oxidation to acrolein at the {110} edge sites and propylene combustion to CO2 at the {100} face sites, which all exhibit high barriers and result in decreased propylene oxide selectivity.