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Nucleic acids, including DNA and RNA, have been considered as powerful and functional biomaterials owing to their programmable structure, good biocompatibility, and ease of synthesis. However, traditional nucleic acid-based probes have always suffered from inherent limitations, including restricted cell internalization efficiency and structural instability. In recent years, DNA nanotechnology has shown great promise for the applications of bioimaging and drug delivery. The attractive superiorities of DNA nanostructures, such as precise geometries, spatial addressability, and improved biostability, have enabled them to be a novel category of nucleic acid delivery systems for biomedical applications. In this review, we introduce the development of DNA nanotechnology, and highlight recent advances of DNA nanostructure-based delivery systems for cellular imaging and therapeutic applications. Finally, we propose the challenges as well as opportunities for the future development of DNA nanotechnology in biomedical research. [ABSTRACT FROM AUTHOR]

Two previously undescribed alkaloids, 4,4′-dihydroxy-3-methoxy-paucine-4′-O-β- D -glucopyranoside and (S)-2-(1,3-propanediol-2-yl)-isococlaurine, and three new lignans, (7R,8S)-9,9′-dihydroxy-3,4-dimethoxy-7,8-dihydrobenzofuran lignan, (7R,8S)-4,9,9′-trihydroxy-3,3′-dimethoxy-9′-acetoxy-7,8-dihydrobenzofuran lignan-4-O-β- D -glucopyranoside, and (7S,8R)-4,9,9′-trihydroxy-3,3′,5-trimethoxy-9′-acetoxy-7,8-dihydro-benzofuran lignan-4-O-β- D -glucopyranoside, together with eleven known compounds, were isolated from the flower buds of Magnolia biondii Pamp. Their structures were determined by extensive spectroscopic analysis, and their absolute configurations were deduced by analysis of optical rotation and electronic circular dichroic (ECD) spectra. All the isolated compounds were evaluated in vitro for their acetylcholinesterase (AChE) inhibitory activity. As a result, it was found that (+)-isococlaurine exhibited the strongest AChE inhibitory effect. Molecular docking experiments were carried out to identify the probable binding mode of this compound in the binding sites of AChE and molecular dynamics simulations were performed to evaluate the stability over time of the main interactions observed during docking calculations. [ABSTRACT FROM AUTHOR]

Hierarchically ordered materials with core/shell structures were synthesized through a layer-by-layer approach. The novel microporous/mesoporous hybrid materials were composed of a TS-1 zeolite particle for the core and mesoporous silica for the shell. The as-synthesized TS-1 crystals were modified with polydiallyldimethylammonium chloride to make their external surface positively charged, which induced an oriented self-assembly of tetraethoxysilane (TEOS) with cetyltrimethyl ammonium bromide on the TS-1 particle surface to form a shell of mesophase silica. The thickness of the mesoporous silica shell was controlled to be in the range 30–55 nm by changing the amount of TEOS added in the synthesis. The mesoporous channels in the shell were perpendicular to the zeolite core, which made the micropores inside the core accessible from the outside through the mesopores. Taking advantage of the confining effect of the mesopores, Au nanoparticles were incorporated into the shell, resulting in bifunctional catalysts which were more selective than conventional Au/TS-1 catalysts in the direct epoxidation of propylene to propylene oxide with H2and O2. [ABSTRACT FROM AUTHOR]