Highly stable amorphous calcium phosphate (ACP) porous nanospheres with a relatively uniform size and an average pore diameter of about 10 nm have been synthesized by using a microwave‐assisted hydrothermal method with adenosine 5′‐triphosphate disodium salt (ATP) as the phosphorus source and stabilizer. The as‐prepared ACP porous nanospheres have a high stability in the phosphate buffer saline (PBS) solution for more than 150 h without phase transformation to hydroxyapatite, and the morphology and size were essentially not changed. The important role of ATP and effects of experimental conditions on the formation of ACP porous nanospheres were also investigated. The ACP porous nanospheres were characterized by X‐ray powder diffraction (XRD), Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). This method is facile, rapid, surfactant‐free and environmentally friendly. The as‐prepared ACP porous nanospheres are efficient for anticancer drug (docetaxel) loading and release. The ACP porous nanosphere drug‐delivery system with docetaxel shows a high ability to damage tumor cells, thus, is promising for the application in anticancer treatment. 相似文献
Calcium phosphates (CPs), as the major inorganic component of biological hard tissues, have been investigated for applications as biomaterials owing to their excellent biocompatibility. However, the traditional synthetic CPs are usually prepared from inorganic phosphorus and calcium sources. Herein, we report a new strategy for the synthesis of a variety of calcium–phosphate nanostructures, including porous amorphous calcium phosphate (ACP) microspheres, hydroxyapatite (HAP) nanorods, and ACP/HAP composite microspheres, by using fructose 1,6‐bisphosphate trisodium salt (FBP) as an organic phosphorus source in aqueous solution in a rapid microwave‐assisted hydrothermal reaction. The important role of FBP and the effect of the experimental conditions on the formation and evolution of the CPs nanostructures were investigated. The crystal phase and composition of the as‐prepared products were characterized by powder X‐ray diffraction (XRD), FTIR spectroscopy, and thermogravimetric (TGA) analysis and the morphologies of the products were characterized by SEM and TEM. This method is facile, rapid, surfactant‐free, and environmentally friendly. The as‐prepared porous ACP microspheres have a relatively high drug‐loading capacity and good sustained drug‐release behavior; thus, they are promising for applications in drug delivery. 相似文献
The phase behavior of a dendritic amphiphile containing a Newkome‐type dendron as the hydrophilic moiety and a cholesterol unit as the hydrophobic segment is investigated at the air–liquid interface. The amphiphile forms stable monomolecular films at the air–liquid interface on different subphases. Furthermore, the mineralization of calcium phosphate beneath the monolayer at different calcium and phosphate concentrations versus mineralization time shows that at low calcium and phosphate concentrations needles form, whereas flakes and spheres dominate at higher concentrations. Energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy, and electron diffraction confirm the formation of calcium phosphate. High‐resolution transmission electron microscopy and electron diffraction confirm the predominant formation of octacalcium phosphate and hydroxyapatite. The data also indicate that the final products form via a complex multistep reaction, including an association step, where nano‐needles aggregate into larger flake‐like objects.
Herein we demonstrate the synthesis of a helicene‐based imidazolium salt. The salt was prepared by starting from racemic 2‐methyl[6]helicene, which undergoes radical bromination to yield 2‐(bromomethyl)[6]helicene. Subsequent treatment with 1‐butylimidazole leads to the corresponding salt 1‐butyl‐3‐(2‐methyl[6]helicenyl)‐imidazolium bromide. The prepared salt was subsequently characterized by using NMR spectroscopy and X‐ray analysis, various optical spectrometric techniques, and computational chemistry tools. Finally, the imidazolium salt was immobilized onto a SiO2 substrate as a crystalline or amorphous deposit. The deposited layers were used for the development of organic molecular semiconductor devices and the construction of a fully reversible humidity sensor. 相似文献
Kidney stone disease causes substantial suffering and occasional renal failure. The content of calcium oxalate (CaOxa) is up to 70-80% in the stones1,2. However, the mechanism of the formation of urinary stones is not yet clearly understood and the questi… 相似文献
Stable suspensions of zeolite nanosheets (3 nm thick MFI layers) were prepared in ethanol following acid treatment, which partially removed the associated organic structure‐directing agent. Nanosheets from these suspensions could then be dispersed at the air–water interface and transferred to silicon wafers using Langmuir–Schaefer deposition. Using layer‐by‐layer deposition, control on coating thickness was demonstrated. In‐plane X‐ray diffraction (XRD) revealed that the deposited nanosheets contract upon calcination similar to bulk MFI crystals. Different methods for secondary growth resulted in preferentially oriented thin films of MFI, which had sub‐12‐nm thickness in certain cases. Upon calcination, there was no contraction detectable by in‐plane XRD, indicating well‐intergrown MFI films that are strongly attached to the substrate. 相似文献
This paper presents a nondestructive X‐ray diffraction method for the accurate determination of thicknesses of polycrystalline TiN and amorphous‐like TiAl coatings deposited by DC magnetron sputtering onto thick polycrystalline stainless steel and carbon steel substrates. This method relies on the measurement of intensity loss of a substrate reflection caused by the deposition of the coating. The uncertainty of the thickness measurements by the X‐ray diffraction depends on the mass absorption coefficient of the coating material and the quality of the collected diffraction patterns. For the coatings considered, thicknesses determined by the X‐ray diffraction method show very good agreement with the thickness values measured by scanning electron microscopy and ball crater techniques. 相似文献
Crystals of anhydrous cadmium oxalate, β‐[Cd(C2O4)], have been synthesized hydrothermally and the crystal structure solved using single‐crystal X‐ray diffraction data. The Cd and oxalate ions lie about independent inversion centres. The structure consists of a three‐dimensional framework built from sheets of cadmium octahedra linked together by oxalate groups. 相似文献
We report the cocrystallization of the regio‐ and stereoregular chiral copolymer poly(limonene carbonate). To the best of our knowledge, this marks the first example of an amorphous, enantiomerically pure polymer that becomes crystalline upon stereocomplexation with its complementary enantiomer. By analyzing X‐ray powder diffraction data, we propose a packing model in which sheets of enantiopure chains interdigitate with layers of the opposite enantiomer, forming a “steric zipper”. 相似文献
Calcium pyrophosphate hydrate (CPP, Ca2P2O7·nH2O) and calcium orthophosphate compounds (including apatite, octacalcium phosphate etc.) are among the most prevalent pathological calcifications in joints. Even though only two dihydrated forms of CPP (CPPD) have been detected in vivo (monoclinic and triclinic CPPD), investigations of other hydrated forms such as tetrahydrated or amorphous CPP are relevant to a further understanding of the physicochemistry of those phases of biological interest. The synthesis of single crystals of calcium pyrophosphate monohydrate (CPPM; Ca2P2O7·H2O) by diffusion in silica gel at ambient temperature and the structural analysis of this phase are reported in this paper. Complementarily, data from synchrotron X‐ray diffraction on a CPPM powder sample have been fitted to the crystal parameters. Finally, the relationship between the resolved structure for the CPPM phase and the structure of the tetrahydrated calcium pyrophosphate β phase (CPPT‐β) is discussed. 相似文献