Three-Dimensional Wormhole and Ordered Mesostructures and Their Applicability as Optically Ion-Sensitive Probe Templates

El‐Safty, Sherif A.; Prabhakaran, D.; Ismail, Adel A.; Matsunaga, Hideyuki; Mizukami, Fujio

doi:10.1021/cm701966c

Cited by 67 publications

(51 citation statements)

References 126 publications

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“…These results indicated that the behavior of azo-probe solid strip with the Co(II) analyte and its matrix environments showed conspicuous divergence from their solution chemistry. Such finding might indicate that the orientation and arrangement of the probe molecular assemblies mounted onto HOM-2 solid carriers with open-pore arrays, high surface areas, and high pore volumes allowed stable thermodynamic binding of Co(II)-probe chelates (El-Safty et al 2008a, 2008b, 2008c.…”

Section: Hexagonal Ion Selective Sensor Stripsmentioning

confidence: 98%

“…7A) (Nicole et al 2004). The color intensity and homogeneity increased with increasing Co(II) ion concentration (El-Safty et al 2008a, 2008b, 2008c. The colorimetric quantification of hexagonal strip for Co(II) ion-sensing over a wide range of concentration was also investigated by monitoring the UV/Vis reflectance spectra.…”

Section: Optical Ion-sensing Monolithic Stripsmentioning

confidence: 99%

“…Recently, nanometer-sized materials with engineered features, including size, shape, composition, and function play a leading role for their emerging applications in optical detection of cations and anions (El-Safty et al 2007a, 2007b, 2008a, 2008b, 2008cComes et al 2004;Desacalzo et al 2005). In fact, ordered mesoporous silica monoliths that have a uniformly-sized, monodispersed porosity in the range of 2-20 nm, and a large particle size show promise of a new class of optical sensor materials.…”

Section: Introductionmentioning

confidence: 99%

“…The large particle size of monoliths, however, led to the creation of pore surface grains (macroscale length) that enabled grafting of a large number of probe binding sites to the pore wall surfaces of silica matrices. Although, these successful designs of nanosensors allowed us to controlled assessment processes with naked-eye detection of several toxic heavy metal ions up to nanomolar concentrations (El-Safty et al 2008a, 2008b, 2008c, challenges to make smart detection eco-friendly solid sensors for Co(II) ions in the basic laboratory assays still in demand. The use of the solid optical sensor in a powder form led to constrain use as sensory optical devices.…”

Section: Introductionmentioning

confidence: 99%

“…Ideal sensory systems with small moleculebased sensor strips remain an attractive approach. In this regard, important development has been recently reported to use the 3D nanoscale monolithic discs as chromophore platforms enabled sensitive recognition of metal ions up to sub-picomolar detection limits (∼10 −11 mol/dm 3 ), for first time, with rapid response time within few seconds (El-Safty et al 2008a, 2008b, 2008c.…”

Section: Introductionmentioning

confidence: 99%

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Functionalized hexagonal mesoporous silica monoliths with hydrophobic azo-chromophore for enhanced Co(II) ion monitoring

El‐Safty

2009

Adsorption

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We introduce here new optical strips for the colorimetric monitoring of Co(II) ions in an aqueous solution. The optical nanosensors were designed by direct immobilizing azo-chromophore with long hydrophobic tails onto hexagonal mesoporous silica monoliths (HOM-2). Although, azo-dye probe was used as signaling reporter for selective detection of the Co(II) analyte up to 10 −6 mol/dm 3 in solution, the tailoring of the Co(II) ion-sensing functionality was successfully manipulated up to 10 −9 mol/dm 3 with the incorporation of azo-chromophore into hexagonal mesoporous silica monoliths (HOM-2), which led to small, easy-to-use optical sensor strips. However, our simple design of colorimetric sensors is based on a physical adsorption of chemically responsive dyes onto HOM materials followed by stronger dye-analyte interactions in aqueous sensing systems. No elution of the probe molecules was evident with the addition of Co(II) analyte ions during the sensing process. The binding of Co(II) ions with probes led to the color change of nanosensors corresponding to the formation of the metal-chelate [Co(II)-Probe] n+ complexes. Results indicated that hexagonal nanosensors offer one-step and simple sensing procedures for both quantification and visual detection of Co(II) ions without the need for sophisticated instruments. However, the solid HOM-2 materials immobilized by the these indicator dyes, in principle, could be used as preconcentrators to yield high adsorption capacity and preconcentration efficiency, leading to simultaneThis special Festschrift for Professor Jaroniec.ously visual inspection and simple detection over a wide, adjustable range of Co(II) ions even at trace levels. For Co(II) ion selectivity assays, negligible changes in either the developed color or the reflectance intensities of the [Co-Probe] n+ complex were observed, despite the addition of competitive cations. Moreover, the hexagonal nanosensors are reversible and have the efficient potential to serve for multiple analyses.Hexagonal optical strips for the colorimetric monitoring of Co(II) ions in an aqueous solution was successfully fabricated. This strip enabled to create ion-sensitive responses with revisable, selective and sensitive recognitions of a wide range of detectable Co(II) ions down to sub-nanomolar (∼15 × 10 −9 M) in rapid sensing responses (in the order of minutes)

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Section: Hexagonal Ion Selective Sensor Stripsmentioning

confidence: 98%

Section: Optical Ion-sensing Monolithic Stripsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Functionalized hexagonal mesoporous silica monoliths with hydrophobic azo-chromophore for enhanced Co(II) ion monitoring

El‐Safty

2009

Adsorption

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Supramolecular Hybrid Nanomaterials As Prospective Sensing Platforms

Biyikal

Hecht

Martínez‐Máñez

et al. 2012

Supramolecular Chemistry

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Supramolecular interactions are vital processes in many chemical sensors, biochemical assays, and other analytical detection schemes. On the background of the current, rapidly developing, and constantly changing requirements for (bio)analytical techniques, the classical molecular host is increasingly overburdened to accomplish a specific analytical task with the desired selectivity and sensitivity. Instead, other signaling strategies have to be conceived that overcome the limits in signal output, dynamic range, or compound targeting, which are imminent to various traditional methods. A very promising approach is the combination of concepts of supramolecular chemistry with nanostructured or nanoscopic inorganic materials, that is, the development of hybrid sensor materials. Such hybrids often lead to improved functionality and enhanced performance, and the present chapter discusses the contributory features in relation to the major aspects, which are related to the enhanced coordination by the preorganization of binding sites, signal amplification by the preorganization on surfaces, aggregation‐mediated signaling, surface‐modification‐based signaling, the tuning of selectivity through polarity and size, and gated signaling.

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Mesoporous Cage‐Like Silica Monoliths for Optical Sensing of Pollutant Ions

El‐Safty

Halada

Yamada

2009

Nanotechnologies for the Life Sciences

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5.1 IntroductionThe aim of this chapter is to provide details of a new class of nanosensor based on mesoporous silica monoliths with cage -like pores as carriers. Comprehensive up -to -date information is provided regarding the environmental chemistry and toxicity of mercury, antimony, cadmium and lead, in the quest to design simple, eco -friendly and smart sensing systems. A critical review of the literature is also provided in terms of the chemical toxicity of mercury, antimony, cadmium and lead, and their treatments with different processes and under varying environmental conditions.In order to provide a simple, yet general, design for optical nanosensors based on a dense pattern of immobilized hydrophobic ' neutral ' and/or hydrophilic ' charged ' chromophores that are both mobile and robust, with three -dimensional (3 -D) nanoscale structure, attention was focused on the highly toxic ions of mercury, antimony, cadmium and lead. Initially, the basic concept of optical nanosensor schemes is outlined, in addition to details of the toxicity and deleterious effects of these metal ions. We then describe the sensing methods used to quantify trace elements, and the general design of optical nanosensors based on mesoporous silica monoliths. The optical sensing and one -step visual detection of Hg 2+ , Sb 3+ , Cd 2+ and Pb 2+ ions, without need for sophisticated instruments and quantitative calibration of nanosensors, are evaluated. The potential of nanosensors in the visual detection of these toxic ions, as well as the advantages of nanosensor designs in terms of the retention of uniformity of nanosensor cage -like sinks, the rapid response of metal ion -sensing systems, the stability of monolithic nanosensors, the reversibility of metal ion -sensing systems and optical selective nanosensor for monitoring trace levels of toxic ions, are each discussed. Ultimately, it is likely that these sensing systems will be employed in basic laboratory set -ups, in fi eld measurements using portable devices, and for household uses as commercial indicators.

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Three-Dimensional Wormhole and Ordered Mesostructures and Their Applicability as Optically Ion-Sensitive Probe Templates

Cited by 67 publications

References 126 publications

Functionalized hexagonal mesoporous silica monoliths with hydrophobic azo-chromophore for enhanced Co(II) ion monitoring

Functionalized hexagonal mesoporous silica monoliths with hydrophobic azo-chromophore for enhanced Co(II) ion monitoring

Supramolecular Hybrid Nanomaterials As Prospective Sensing Platforms

Mesoporous Cage‐Like Silica Monoliths for Optical Sensing of Pollutant Ions

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