Optical Nanosensor Design with Uniform Pore Geometry and Large Particle Morphology (original) (raw)
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Chemistry of …, 2008
Large-scale cubic Pm3n silica monoliths (HOM) were fabricated in wormhole and ordered mesostructures and in shape-and size-controlled cage pores by using a simple and fast strategy. The functional use of these 3D HOM monoliths as probe anchoring templates enabled the efficient designs of optical nanosensors. In this regard, the synthesized chromoionophore was physisorbed into the 3D HOM pore surface carriers without potential leaching. Results revealed that the structural features of the HOM monoliths such as ordered and worm-like cage pores substantially influenced the ion-sensing functionality in terms of their probe inclusion capacities, ion-transport diffusion, optical responsive profile, and visual color transition series during the detection of ultratraces of toxic Pb(II) ions. The nanosensors were selective in discriminating trace Pb(II) ions over multicomponent matrix species, with reliable and reproducible detection and quantification limits. A comparative study on the ion-sensing efficiency of the chromoionophore in both solution and solid phases indicated that the solid HOM monoliths show promise as probe templates to design-made nanosensors for the detection of ultratraces Pb(II) ions. Considering the environmental factors, nanosensors were solvent-free systems and had the capacity to serve as ion preconcentrators with complete reversibility and reusability. The significant features of the probe-design nanosensors led to overcoming the disposal problems, which were normally associated with the liquid probe systems.
Optical Nanoscale Pool‐on‐Surface Design for Control Sensing Recognition of Multiple Cations
Advanced …, 2008
General design of optical chemical nanosensors is needed to develop efficient sensing systems with high flexibility, and low capital cost for control recognition of toxic analytes. Here, we designed optical chemical nanosensors for simple, high-speed detection of multiple toxic metal ions. The systematic design of the nanosensors was based on densely patterned chromophores with intrinsic mobility, namely, ''building-blocks'' onto three-dimensional (3D) nanoscale structures. The ability to precisely modify the nanoscale pore surfaces by using a broad range of chromophores that have different molecular sizes and characteristics enables detection of multiple toxic ions. A key feature of this building-blocks design strategy is that the surface functionality and good adsorption characteristics of the fabricated nanosensor arrays enabled the development of ''pool-on-surface'' sensing systems in which high flux of the metal analytes across the probe molecules was achieved without significant kinetic hindrance. Such a sensing design enabled sensitive recognition of metal ions up to sub-picomolar detection limits ($10 À11 mol dm À3 ), for first time, with rapid response time within few seconds. Moreover, because these sensing pools exhibited long-term stability, reversibility and selectivity in detecting most pollutant cations, for example, Cr(VI), Pb(II), Co(II), and Pd(II) ions, they are practical and inexpensive. The key result in our study is that the pool-on-surface design for optical nanosensors exhibited significant ion-selective ability of these target ions from environmental samples and waste disposals.
Microporous and Mesoporous Materials, 2009
Spherical mesoporous silica particles with tunable pore size and tunable outer particle diameter in the nanometer range were successfully prepared in a water/oil phase using organic templates method. This method involves the simultaneous hydrolytic condensation of tetraorthosilicate to form silica and polymerization of styrene into polystyrene. An amino acid catalyst, octane hydrophobic-supporting reaction component, and cetyltrimethylammonium bromide surfactant were used in the preparation process. The final step in the method involved removal of the organic components by calcinations, yielding the mesoporous silica particles. Interestingly, unlike common mesoporous materials, the particle with controllable pore size (4-15 nm) and particle diameter (20-80 nm) were produced using the method described herein. The ability to control pore size was drastically altered by the styrene concentration. The outer diameter was mostly controlled by varying the concentration of the hydrophobic molecules. Relatively large organic molecules (i.e. Rhodamine B) were well-absorbed in the prepared sample. Furthermore, the prepared mesoporous silica particles may be used efficiently in various applications, including electronic devices, sensors, pharmaceuticals, and environmentally sensitive pursuits, due to its excellent adsorption properties.
Annual Review of Analytical Chemistry, 2008
There are thousands of different nanometer-scale pores in biology, many of which act as sensors for specific chemical agents. Recent work suggests that protein and solid-state nanopores have many potential uses in a wide variety of analytical applications. In this review we survey this field of research and discuss the prospects for advances that could be made in the near future.
Ordered Mesostructured Silica Films: Effect of Pore Surface on its Sensing Properties
Journal of Sol-gel Science and Technology, 2004
An electrochemical resistive-type sensor device, with a mesoporous silica thin film as sensitive membrane, has been developed and characterised. The silica film has been obtained via evaporation-induced self-assembly (EISA) using a tri-block copolymer (Pluronic F-127) as templating agent. It has been deposited by dip-coating on a silicon substrate with metallic interdigitated electrodes. Fast, reversible and reproducible electrical responses to relative humidity changes have been observed for the sensor device. The conduction mechanism has been related to chemical properties, structural order and surface morphology of the porosity in the silica film, confirming the dependence on the film preparation method and overall the importance of calcination temperature.
Nanoscopic Porous Sensors | NIST
2008
There are thousands of different nanometer-scale pores in biology, many of which act as sensors for specific chemical agents. Recent work suggests that protein and solid-state nanopores have many potential uses in a wide variety of analytical applications. In this review we survey this field of research and discuss the prospects for advances that could be made in the near future.
Recent Advancements in Novel Sensing Systems through Nanoarchitectonics
Biosensors
The fabrication of various sensing devices and the ability to harmonize materials for a higher degree of organization is essential for effective sensing systems. Materials with hierarchically micro- and mesopore structures can enhance the sensitivity of sensors. Nanoarchitectonics allows for atomic/molecular level manipulations that create a higher area-to-volume ratio in nanoscale hierarchical structures for use in ideal sensing applications. Nanoarchitectonics also provides ample opportunities to fabricate materials by tuning pore size, increasing surface area, trapping molecules via host–guest interactions, and other mechanisms. Material characteristics and shape significantly enhance sensing capabilities via intramolecular interactions, molecular recognition, and localized surface plasmon resonance (LSPR). This review highlights the latest advancements in nanoarchitectonics approaches to tailor materials for various sensing applications, including biological micro/macro molecule...
Chemical Sensors Based on Distributed Bragg Reflector Porous Silicon Smart Particles
Journal of the Chosun Natural Science, 2015
Sensing characteristics for porous smart particle based on DBR smart particles were reported. Optically encoded porous silicon smart particles were successfully fabricated from the free-standing porous silicon thin films using ultrasono-method. DBR PSi was prepared by an electrochemical etch of heavily doped p ++-type silicon wafer. DBR PSi was prepared by using a periodic pseudo-square wave current. The surface-modified DBR PSi was prepared by either thermal oxidation or thermal hydrosilylation. Free-standing DBR PSi films were generated by lift-off from the silicon wafer substrate using an electropolishing current. Free-standing DBR PSi films were ultrasonicated to create DBR-structured porous smart particles. Three different surface-modified DBR smart particles have been prepared and used for sensing volatile organic vapors. For different types of surface-modified DBR smart particles, the shift of reflectivity mainly depends on the vapor pressure of analyte even though the surfaces of DBR smart particles are different. However huge difference in the shift of reflectivity depending on the different types of surface-modified DBR smart particles was obtained when the vapor pressures are quite similar which demonstrate a possible sensing application to specify the volatile organic vapors.
Uniformly Mesocaged Cubic Fd 3 m Monoliths as Modal Carriers for Optical Chemosensors
The Journal of …, 2008
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.