Aptamer-modified DNA tetrahedra-gated metal–organic framework nanoparticle carriers for enhanced chemotherapy or photodynamic therapy

UiO-66 metal–organic framework nanoparticles (NMOFs) gated by aptamer-functionalized DNA tetrahedra provide superior biomarker-responsive hybrid nano-carriers for biomedical applications. Hybrid nano-carriers consisting of ATP-aptamer or VEGF-aptamer functionalized tetrahedra-gated NMOFs are loaded with the chemotherapeutic drug, doxorubicin (DOX). In the presence of ATP or VEGF, both abundant in cancer cells, the tetrahedra-gated NMOFs are unlocked to release the drug. Enhanced and selective permeation of the DOX-loaded ATP/VEGF-responsive tetrahedra-gated NMOFs into MDA-MB-231 breast cancer cells as compared to the reference ATP/VEGF-responsive duplex-gated NMOFs or non-malignant MCF-10A epithelial breast cells is observed. This results in enhanced and selective cytotoxicity of the tetrahedra-gated DOX-loaded NMOFs toward the malignant cells. Additional nano-carriers, consisting of photosensitizer Zn(ii) protoporphyrin IX (Zn(ii)-PPIX)-loaded VEGF-responsive tetrahedra-gated NMOFs, are introduced. The VEGF-triggered unlocking of the NMOFs yields separated G-quadruplex-VEGF aptamer complexes conjugated to the tetrahedra, resulting in the release of loaded Zn(ii)-PPIX. Association of the released Zn(ii)-PPIX to the G-quadruplex structures generates highly fluorescent supramolecular Zn(ii)-PPIX/G-quadruplex VEGF aptamer-tetrahedra structures. The efficient and selective generation of the highly fluorescent Zn(ii)-PPIX/G-quadruplex VEGF aptamer-tetrahedra nanostructures in malignant cells allows the light-induced photosensitized generation of reactive oxygen species (ROS), leading to high-efficacy PDT treatment of the malignant cells.

UiO-66 metal–organic framework nanoparticles (NMOFs) gated by aptamer-functionalized DNA tetrahedra provide superior biomarker-responsive hybrid nano-carriers for biomedical applications.     

Kinetics of graft copolymerization of methyl methacrylate onto polychloroprene with tricaprylylmethylammonium chloride as a phase‐transfer catalyst

The phase‐transfer catalyzed graft copolymerization of methyl methacrylate onto polychloroprene was carried out using tricaprylylmethylammonium chloride as a phase‐transfer catalyst in a two‐phase system of an aqueous Na₂S₂O₈ solution and toluene at 55 °C under a nitrogen atmosphere. The initial rate of graft copolymerization was expressed as the combined terms of quaternary onium cation and peroxydisulfate anion in the aqueous phase rather than the fed concentrations of catalyst and Na₂S₂O₈. The observed initial rate of graft copolymerization was used to analyze the graft copolymerization mechanism with a cycle phase‐transfer initiation step in the heterogeneous liquid–liquid system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3543–3549, 2000     

Bis­[(2,2‐di­methyl‐1,3‐propane­diamine‐κ2N,N′)(piperidine‐2‐car­boxylato‐κ2N,O)­platinum(II)] sulfate

The title compound, [Pt(C₆H₁₀NO₂)(C₅H₁₄N₂)]₂(SO₄), crystallizes with two cations in the asymmetric unit. The two complex cations, which have a square‐planar Pt^II coordination, are chemically identical but differ slightly in the conformations of their amine groups. A neutral complex, viz. (2,2‐di­methyl‐1,3‐propane­di­amine‐κ²N,N′)bis(2‐piperidine­carb­oxyl­ato‐κN)platinum(II), is shown to form in solution and to change rapidly into the title compound.     

Pore formation in in situ processed MgB2 superconductors

MgB₂ bulks were prepared by an in situ process which utilizes the reaction between boron and magnesium powder. The reaction time was fixed at 0.5 h and the temperature was changed from 600 °C to 1000 °C. The density decrease due to pore formation and mass (mainly magnesium) loss during the formation reaction of MgB₂ was observed in all samples. In addition to the pore formation, a pellet expansion which can be explained by the outgrowth of MgB₂ grains was also observed. Two different mechanisms were adopted to explain the pore formation; Kirkendall pores formed at a temperature below the melting point (m.p.) of magnesium by a difference in the diffusivity between magnesium and boron, and the pores formed at a temperature above the m.p. by melting of magnesium and a capillary movement. The density, T_c and J_c results suggest that the current carrying capacity can be improved by a careful control of the process parameters regarding a pore evolution.     

Core-shell structured iron nanoparticles well dispersed on montmorillonite

Iron nanoparticles have been successfully synthesized using sodium borohydride solution reduction of ferric trichloride hexahydrate in the presence of montmorillonite as an effective protective reagent and support as well. A combination of characterizations reveals the well disperse of these obtained iron nanoparticles supported on the external surface of clay with roughly spherical morphology and mean diameter of 55 nm. The particles are oxidation resistant well with iron core-iron oxide shell structure. The shell thickness of 3 nm remains almost invariable under ambient conditions. Discernable hysteresis loop reveals ferromagnetic behavior of the iron nanoparticles, which make them easy for magnetic separation and potential in some practical applications.     

成本有效的用于互连线条的稀释酸刻蚀后清洗

铝线条条和硅氧化物通孔刻蚀后,传统上都是使用包含胺,重金属结合剂,表面活性剂及其他成分进行清洗.这些混合剂是用来高效去除刻蚀后残留物的,而不会对硅氧化物介质造成过量的刻蚀,也不会破坏或进一步腐蚀铝.羟胺(许多此类溶解混合物的主要成分)所带来的供应、成本和残留物等问题,促使集成电路制造商寻求可替换的清洗化学试剂. 在集成电路制造的过程中,在只使用硅和硅氧化物的时期,使用浓缩和稀释的酸混合物用来清洗硅晶已有十多年的历史了.但是,当出现了铝或其他金属后,不能使用浓缩酸进行清洗,因为会对金属产生过量的破坏.近来,稀释酸混合物已成功用来高效去除铝线条和硅氧化物通孔刻蚀后的残留物,而不会对氧化物造成过量的刻蚀,也不会破坏或进一步腐蚀铝.稀释酸混合物的特征是含有两种或两种以上的硫磺酸,双氧和氢氟酸.这些化学试剂在当今的IC制造厂很容易得到,并可采用目前的清洗设备,如FSI ZETA 系统,方便地在线混合稀释.在线混合稀释化学试剂可以明显节约成本.一个批量喷雾系统可以同时处理多达100片的200mm晶圆或50片300mm晶圆,提高了产量从而节约了成本.性价比高的铝互连线条的稀释酸刻蚀后清洗已被成功验证并用于生产中.     

Domination number in graphs with minimum degree two

A set D of vertices of a graph G = （V, E） is called a dominating set if every vertex of V not in D is adjacent to a vertex of D. In 1996, Reed proved that every graph of order n with minimum degree at least 3 has a dominating set of cardinality at most 3n/8. In this paper we generalize Reed＇s result. We show that every graph G of order n with minimum degree at least 2 has a dominating set of cardinality at most （3n ＋IV21）/8, where V2 denotes the set of vertices of degree 2 in G. As an application of the above result, we show that for k ≥ 1, the k-restricted domination number rk （G, γ） ≤ （3n＋5k）/8 for all graphs of order n with minimum degree at least 3.