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Yang J.,Institute Of Bioengineering And Nanotechnology, Singapore | Yang J.,CAS Institute of Process Engineering | Ying J.Y.,Institute Of Bioengineering And Nanotechnology, Singapore
Angewandte Chemie - International Edition | Year: 2011

With a little help from my friends: Successive deposition of different noble metals on Ag2S nanocrystals yields binary, ternary, and quaternary hybrid nanocomposites (see picture). In particular, the platinum-containing systems were found to exhibit superior catalytic activity toward methanol oxidation. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Yang J.,Institute Of Bioengineering And Nanotechnology, Singapore | Yang J.,CAS Institute of Process Engineering | Lee J.Y.,National University of Singapore | Ying J.Y.,Institute Of Bioengineering And Nanotechnology, Singapore
Chemical Society Reviews | Year: 2011

As nanoparticle syntheses in aqueous and organic systems have their own merits and drawbacks, specific applications may call for the transfer of newly formed nanoparticles from a polar to a non-polar environment (or vice versa) after synthesis. This critical review focuses on the application of phase transfer in nanoparticle synthesis, and features core-shell structures in bimetallic nanoparticles, replacement reactions in organic media, and catalytic properties of various nanostructures. It also describes the reversible organic and aqueous phase transfer of semiconductor and metallic nanoparticles for biological applications, and the use of phase transfer in depositing noble metals on semiconductor nanoparticles (258 references). © 2011 The Royal Society of Chemistry. Source


Shi J.,CAS Shanghai Institute of Ceramics | Shi J.,East China University of Science and Technology | Shi J.,CAS Institute of Process Engineering
Chemical Reviews | Year: 2013

The heterogeneous catalytic performance is largely dependent on the catalyst nanostructures or, in another word, processing technologies, in addition to the intrinsic physical and chemical properties of the constitutive components. Compared to the amorphous framework of mesoporous silica, mesoporous metal oxides synthesized by a hard templatereplicating method usually have a crystallized structure and exhibit excellent catalytic activities, as reported in many documents. The loading or dispersion of catalytically active guest species into the host mesopore network results in mesostructured composites of a crystallized framework and highly dispersed catalytic species in its mesopore network. Mesoporous inorganic oxide materials, in the form of either powder or thin film, with high surface areas, ordered pore structures, finely tunable pore sizes, and flexible wallcompositions have been investigated widely of their chemical synthesis and potential applications in catalysis, adsorption, chemical sensing, electrochemistry, biomedical areas, and so on. Source


Ma G.,CAS Institute of Process Engineering
Journal of Controlled Release | Year: 2014

Bio-degradable poly(lactide) (PLA)/poly(lactide-glycolide) (PLGA) and chitosan microspheres (or microcapsules) have important applications in Drug Delivery Systems (DDS) of protein/peptide drugs. By encapsulating protein/peptide drugs in the microspheres, the serum drug concentration can be maintained at a higher constant value for a prolonged time, or injection formulation can be changed to orally or mucosally administered formulation. PLA/PLGA and chitosan are most often used in injection formulation and oral formulation. However, in the preparation and applications of PLA/PLGA and chitosan microspheres containing protein/peptide drugs, the problems of broad size distribution and poor reproducibility of microspheres, and deactivation of protein during the preparation, storage and release, are still big challenges. In this article, the techniques for control of the diameter of microspheres and microcapsules will be introduced at first, then the strategies about how to maintain the bioactivity of protein drugs during preparation and drug release will be reviewed and developed in our research group. The membrane emulsification techniques including direct membrane emulsification and rapid membrane emulsification processes were developed to prepare uniform-sized microspheres, the diameter of microspheres can be controlled from submicron to 100 μm by these two processes, and the reproducibility of products can be guaranteed. Furthermore, compared with conventional stirring method, the big advantages of membrane emulsification process were that the uniform microspheres with much higher encapsulation efficiency can be obtained, and the release behavior can be adjusted by selecting microsphere size. Mild membrane emulsification condition also can prevent the deactivation of proteins, which frequently occurred under high shear force in mechanical stirring, sonification, and homogenization methods. The strategies for maintaining the bioactivity of protein drug were developed, such as adding additives into protein solution, using solid drug powder instead of protein solution, and employing hydrophilic poly(lactide)-poly(ethylene glycol) (PELA) as a wall material for encapsulation in PLA/PLGA microspheres/microcapsules; developing step-wise crosslinking process, self-solidification process, and adsorbing protein drug into preformed chitosan microsphere with hollow-porous morphology for encapsulation in chitosan microsphere. As a result, animal test demonstrated that PELA microcapsules with uniform size and containing recombinant human growth hormone (rhGH) can maintain higher blood drug concentration for 2 months, and increased animal weight more apparently only by single dose, compared with PLA and PLGA microcapsules; hollow-porous chitosan microsphere loading insulin decreased blood glucose level largely when it was used as a carrier for oral administration. © 2014 Elsevier B.V. Source


Ge J.,Tsinghua University | Ge J.,CAS Institute of Process Engineering | Lei J.,Stanford University | Lei J.,CAS Institute of Process Engineering | Zare R.N.,CAS Institute of Process Engineering
Nature Nanotechnology | Year: 2012

Flower-shaped inorganic nanocrystals have been used for applications in catalysis and analytical science, but so far there have been no reports of ĝ€ nanoflowersĝ€™ made of organic components. Here, we report a method for creating hybrid organic-inorganic nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the nanoflowers. © 2012 Macmillan Publishers Limited. Source

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