Lamellar aluminophosphates with surface patterns that mimic diatom and radiolarian microskeletons

Oliver, Scott R. J.; Kuperman, Alex; Coombs, Neil; Lough, Alan J.; Ozin, Geoffrey A.

doi:10.1038/378047a0

Cited by 355 publications

(225 citation statements)

References 9 publications

Supporting

Mentioning

217

Contrasting

Unclassified

Order By: Relevance

“…More recently, mesoporous silica with morphologies including thin films, monoliths, hexagonal prisms, toroids, discoids, spirals, dodecahedron and hollow tubular shapes have been synthesized [8][9][10][11][12] . In conventional procedures, silica spheres have been obtained using surfactants, block copolymers and recently by using colloidal suspensions 13 .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of mesoporous silica microsphere from dual surfactant

Narayanan

2008

Mat. Res.

View full text Add to dashboard Cite

A new procedure is reported to synthesis mesoporous silica micro sphere for the first time. In these method two surfactants namely Span 80 and Tween 80 were used. Small angle X ray diffraction and N2 adsorption analysis shows the synthesized material has mesoporous property. The material has spherical morphology with 1-10 µm particle size. Beside the material found to have microcapsule property as observed from the Transmission electron microscopy. The Fourier transform Infrared spectroscopic analysis reveals that the materials are similar to other mesoporous materials. We also encapsulated an UV-absorber Ibuprofen inside the microcapsule, by mixing it before the synthesis. This shows a possibility of the materials in cosmetic applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Synthesis of mesoporous silica microsphere from dual surfactant

Narayanan

2008

Mat. Res.

View full text Add to dashboard Cite

show abstract

“…Among the most famous examples are unicellular algaediatoms-that possess a cell wall composed of silica and organic molecules or macromolecules (2). Most interestingly, diatom biosilica displays a dazzling variety of species-specific silica patterns that are structured on a nanometer-to-micrometer scale (3)(4)(5)(6). Elucidating the mechanism that controls production of nanostructured biosilica is a fascinating biochemical problem and, in addition, is of great interest in materials chemistry.…”

mentioning

confidence: 99%

Species-specific polyamines from diatoms control silica morphology

Kröger

Deutzmann²,

Bergsdorf³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

627

620

View full text Add to dashboard Cite

Biomineralizing organisms use organic molecules to generate species-specific mineral patterns. Here, we describe the chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic constituent of diatom biosilica. These substances are the longest polyamine chains found in nature and induce rapid silica precipitation from a silicic acid solution. Each diatom is equipped with a species-specific set of polyamines and silica-precipitating proteins, which are termed silaffins. Different morphologies of precipitating silica can be generated by polyamines of different chain lengths as well as by a synergistic action of long-chain polyamines and silaffins.T he biological formation of inorganic structures, termed biominerals, is a widespread phenomenon in nature (1). Among the most famous examples are unicellular algaediatoms-that possess a cell wall composed of silica and organic molecules or macromolecules (2). Most interestingly, diatom biosilica displays a dazzling variety of species-specific silica patterns that are structured on a nanometer-to-micrometer scale (3-6). Elucidating the mechanism that controls production of nanostructured biosilica is a fascinating biochemical problem and, in addition, is of great interest in materials chemistry. Biomimetic approaches are believed to allow the production of advanced materials at ambient temperature and with high precision, which are expected to exhibit superior properties in a wide range of applications (7,8). Reaching this goal, however, requires a detailed knowledge of the organic molecules that govern silica biomineralization.Recently, cationic polypeptides (called silaffins) isolated from purified cell walls of the diatom Cylindrotheca fusiformis were shown to generate networks of silica nanospheres within seconds when added to a solution of silicic acid (9). The silaffins are tightly associated with the biosilica so that they can only be solubilized after dissolution of the cell wall in hydrogen fluoride (HF). Silaffin-1 contains a previously undescribed type of protein modification, a polyamine consisting of 6-11 repeats of the N-methyl-propylamine unit (a mass increment of 71 Da per repeat) covalently attached to specific lysine residues (9). It is probably this structural element that accelerates silicic acid polymerization and promotes production of nanosphere networks. Previously, ultrastructural work on cell wall biogenesis in a number of diatoms led to the conclusion that silica appears to be deposited in different forms during valve morphogenesis. Especially evident was the participation of silica spheres ranging up to 100 nm in diameter (4, 10). If silaffins are indeed involved in the process of pattern formation that creates the amazingly rich variety of diatom shell silica structures, then different diatom species are expected to contain different types of silaffins or silaffin-like molecules. We therefore analyzed the HFextractable organic cell wall components from a wide range of diatom species. Surprisingly, th...

show abstract

“…8 The unit cell parameter (a o ) for a hexagonal structure is calculated from 2d(100)/3 1/2 from d(100) which is obtained from the 2 value of the first peak in the thin-film XRD pattern from d(100) ‫ס‬ /2sin, where ‫ס‬ 0.15417 nm for the Cu K ␣ line. 9,10 The unit cell parameter a o is equal to the internal pore diameter plus one pore wall thickness. As-synthesized film shows d(100) spacing of 4.3 nm and a unit cell parameter of 5.0 nm.…”

mentioning

confidence: 99%

Photoluminescence of mesoporous silica films impregnated with an erbium complex

et al. 2003

View full text Add to dashboard Cite

Transparent mesoporous silica films were prepared by sol-gel spin coating on silicon wafers at room temperature. An erbium complex, erbium tris 8-hydroxyquinoline (ErQ), was homogeneously impregnated into the pores of the mesoporous silica films, and its concentration was easily controlled by using a solution immersing technique. The ErQ-impregnated mesoporous silica films show a room-temperature photoluminescence at 1.5 m.Erbium-doped material films have received growing interest over the last decade due to their multiple applications such as use in integrated lasers or amplifiers for telecommunications.1 Since planar optical amplifiers have a smaller interaction length with respect to erbiumdoped fiber amplifiers, higher erbium concentration is required to obtain a sufficient optical gain. However, high doping levels of erbium quench the fluorescence emission and reduce the performance of the amplifier. Especially, the clustering of Er 3+ ions is a main obstacle preventing concentration quenching because a silicabased inorganic matrix is fabricated by high-temperature processes such as flame hydrolysis deposition and chemical vapor deposition.2 To reduce concentration quenching, erbium ions should disperse uniformly on a molecular level. When Er 3+ ions are surrounded by bulky organic ligands, the average minimum distance between Er 3+ ions increases due to the steric hindrance. Thus, introduction of an erbium complex can be a solution to reducing concentration quenching. Er complex is generally used with a polymer matrix because of its solubility and the processing temperature. There have been several reports concerning room-temperature photoluminescence in polymer/Er complex systems.3,4 However, the polymer matrix is largely composed of a linear CH chain and thus large CH quenching can occur. Therefore, a general polymer matrix is not suitable to the incorporation of an Er complex. Theoretically, the most effective method for uniform dispersion is the periodic arrangement of erbium ions in a matrix when high doping levels of Er 3+ ions are required. Thus, we selected mesoporous materials as the host matrix. Mesoporous materials were developed for constructing a periodic pore structure, which has pores of a few nanometers in size.5 They can also be made of various inorganic components, such as silica and alumina, which have low optical losses.Recently, mesoporous materials were used for encapsulating organic dyes to prevent aggregation of the dye molecules.6 Impregnation of Er complex into mesoporous silica has some advantages over incorporation of Er complex in the matrix. First, the mesoporous silica has a periodic pore distribution such that the impregnated Er ions are expected to be uniformly dispersed. Moreover, the absorption cross section can increase compared to Er 3+ ion by doping Er complex into a low loss silica matrix.7 Although the mesoporous film is fabricated through a high-temperature process, there is no temperature restriction to impregnate Er complex because it can be impregnated by a solut...

show abstract

Lamellar aluminophosphates with surface patterns that mimic diatom and radiolarian microskeletons

Cited by 355 publications

References 9 publications

Synthesis of mesoporous silica microsphere from dual surfactant

Synthesis of mesoporous silica microsphere from dual surfactant

Species-specific polyamines from diatoms control silica morphology

Photoluminescence of mesoporous silica films impregnated with an erbium complex

Contact Info

Product

Resources

About