Uniformly Mesocaged Cubic Fd3m Monoliths as Modal Carriers for Optical Chemosensors

Abstract

With recent advances in materials science and nanotechnology, development of optical chemosensors with uniformly shaped three-dimensional (3D) nanostructures applicable for large-scale sensing systems of toxic pollutants can forge new frontiers in materials. Here, highly ordered cubic Fd3m silica monoliths that had nanopore-like cages were fabricated, for the first time, by direct templating of cationic surfactant phases. This simple strategy offered significant control over the pore connectivity and structural regularity of the cubic Fd3m geometry. The potential functionalities of these uniformly sized cage cubic Fd3m materials show promise as the primary component in efficient sensing systems that can satisfy analytical needs as well, such as simplicity in fabrication design and sensing functionality in terms of selectivity and sensitivity with a fast response time of the recognition of pollutant cations. However, successful immobilization of chromophore probe molecules into the 3D network matrixes enabled manipulation of optically defined chemosensors into new shapes and functionality for visual detection of toxic analytes. Here, 3D cubic Fd3m chemosensors were developed and fabricated and successfully enabled highly revisable, selective and sensitive detection of Bi-(III) target ions down to nanomolar concentrations (∼10 -10 mol/dm 3 ) with rapid response assessment (e25 s). Significantly, the HOM nanosensors not only worked under standardized conditions but also could be used for reliable sensing of the Bi(III) ion in a real-life sample such as wastewater.

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

“…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.…”

“…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.…”

“…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.…”

Hybrid inorganic-organic materials for the optical recognition of neutral and anionic species

“…29 In recent examples, and in order to develop simple synthetic procedures that avoid the covalent anchoring of the probe, Matsunaga and El-Safty have prepared a family of optical sensory materials for the detection of certain metal ions in which the probes are electrostatically attached to the pore walls. [30][31][32][33][34] However, despite these interesting examples for target metal cation sensing, the number of functionalised mesoporous supports for the design of chromo-fluorogenic probes for anions is very scarce. Inspired by this concept shown in Scheme 1, the solid "host" UVM-7 was selected.…”

Superficies químicamente modificadas para la detección colorimétrica y eliminación de aniones de interés medioambiental en aguas

“…107 El último ejemplo de este subapartado esta relacionado con el intento reciente de unir en un mismo material las funciones de detección y almacenaje de iones metálicos. El objetivo es conseguir un material que pueda indicar la concentración de un ion metálico nocivo y a su vez sea capaz de secuestrar el metal cuando se encuentre en una concentración elevada.…”