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Fabrication of magnetic nanocarriers that demonstrate enhanced biocompatibility and excellent colloidal stability is critical for the application of magnetic-motored drug delivery, and it remains a challenge. Herein, a novel approach to synthesize mesoporous magnetic colloidal nanocrystal clusters (MMCNCs) that are stabilized by agarose is described; these clusters demonstrate high magnetization, large surface area and pore volume, excellent colloidal stability, enhanced biocompatibility, and acid degradability. The hydroxyl groups of agarose, which cover the surface of the magnetic nanocrystals, are modified with vinyl groups, followed by click reaction with mercaptoacetyl hydrazine to form the terminal hydrazide (-CONHNH(2)). The anticancer agent doxorubicin (DOX) is then conjugated to MMCNCs through a hydrazone bond. The resulting hydrazone is acid cleavable, thereby providing a pH-sensitive drug release capability. This novel carrier provides an important step towards the construction of a new family of magnetic-motored drug-delivery systems. The experimental results show that the release rate of DOX from the DOX-conjugated MMCNCs (MMCNCs-DOX) is dramatically improved at low pH (tumor cell: pH 4-5 in the late stage of endolysosome and pH 5-6 from the early to late endosome), while almost no DOX is released at neutral pH (blood plasma). The cell cytotoxicity of the MMCNCs-DOX measured by MTT assay exhibits a comparable antitumor efficacy but lower cytotoxicity for normal cell lines, when measured against the free drug, thus achieving the aim of reducing side effects to normal tissues associated with controlled drug release.

Hierarchically porous materials were developed using a two-step procedure by (1) the stacking of high-nitrogen-content polymer nanoparticles to produce inter-particle mesoporous space and (2) chemical activation to create intra-particle micropores. The materials exhibited efficient CO 2 uptake and enhanced CO 2 /N 2 selectivity, which is 40% higher than that of the control material without a hierarchical structure.

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A systematic study for the preparation of Ag nanoparticle (Ag-NP) coated poly(styrene-co-acrylic acid) (PSA) composite nanospheres by in situ chemical reduction is reported. The experimental results showed that the reaction temperature and the surface coverage of the -COOH determined the surface coverage and grain size of Ag nanoparticles on the PSA nanospheres. The surface enhanced Raman spectroscopy (SERS) sensitivity was investigated using 4-hydroxythiophenol (4-HBT) as the model probe in the solution of composite nanospheres stabilized by polyvinylpyrrolidone (PSA/Ag-NPs/PVP), with the detection limit of about 1 × 10(-6) M. Potential application of the new SERS substrate was demonstrated with the detection of melamine, and the detection limit was about 1 × 10(-3) M. Chemical noises from PVP and other impurities were observed and attributed mainly to the competitive adsorption of PVP on the surfaces of Ag-NPs. After tetrahydrofuran washing of the PSA/Ag-NPs/PVP substrates that removed the PVP and other residuals, the signal/noise levels of SERS were greatly improved and the detection limit of melamine was determined to be 1 × 10(-7) M. This result indicated that the new PSA/Ag-NPs system is highly effective and can be used as the SERS-active substrate for trace analysis of a variety of drugs and food additives.

A new controlled release polymer micelle was designed and synthesized based on the concept of the "AND" logic with two orthogonal molecular triggers, namely pH and reduction, for intracellular drug delivery. Specifically, a hydrazine functionalized PEO-b-PMAA block copolymer was used to attach adriamycin (ADR) through the formation of hydrazone, then the as-prepared ADR-conjugated block copolymer micelles could be crosslinked by dithiodiethanoic acid. ADR was found to release most efficiently under both the low pH and the reductive conditions. This smart device is therefore equipped with two triggers with the "AND" logic for the releasing action, which is suitable for more complicated physiological conditions because the "ON" state is only realized under the simultaneous presence of the dual signal stimuli.

In this study, a class of surface enhanced Raman spectroscopy (SERS) encoded core-shell nanospheres was synthesized as nano-SERS-tags for detecting specific DNA targets based on the sandwich hybridization assays. These core-shell nanospheres were synthesized by first depositing a layer of Ag-NPs (nanoparticles) onto the poly(styrene-co-acrylic acid) core and then the formation of a layer of uniform silica as the outer shell. The Ag-NPs served as SERS substrates with Raman active molecular probes adsorbed onto the Ag-NPs as indicative SERS molecular barcodes, and the silica coating shell was used for protecting the Ag-NPs and the Raman molecules from the exterior chemical and biological interference. The silica surfaces of nano-SERS-tags were further conjugated with probe DNA (pDNA) (nano-SERS-probes). The detection of single-stranded oligonucleotide (ssDNA) targets was successfully accomplished using the nano-SERS-probes in a chip-based sandwich hybridization assay in a mixed ssDNA target solution. The as-prepared nano-SERS-probes exhibited high chemical stability during the laser SERS experiments and the results were reproducible after a long-term storage. At least four different tags (a four ''color'' system) were quantitatively differentiated when simultaneously applied in the assays, indicating an excellent multiplexing potential of the method. Therefore, the as-prepared nano-SERS-probes are suitable for high specific detection of biomolecules with high sensitivity and remarkable multiplexing capability associated with the SERS method.

This paper reports for the first time the synthesis and application of miktoarm star copolymers to produce highly ordered honeycomb films using the breath figure technique. Miktoarm star copolymer containing a cross-linked core and two arm species, e.g., polystyrene and poly(t-butyl acrylate), is successfully synthesized using ATRP in a one-pot arm-first method. Various experimental parameters, including polymer architectures, solvents, polymer concentrations, and substrates, are explored to investigate their effects on the structure of the honeycomb films. It is found that miktoarm star copolymers with high molecular weight and spherical shape could readily produce ordered honeycomb films in a broader range of concentrations and humidity than linear block copolymers with similar chemical compositions but lower molecular weight. Partial hydrolysis of poly(t-butyl acrylate) arm species in the honeycomb film transforms the surface property from hydrophobic to hydrophilic while maintaining the film's mechanical stability in water. This porous monolayer film with uniform pore size distribution and inter-connected pore channels is successfully applied for separation of microparticles with different sizes.