Core-based materials

Core-based materials differ from exo-active surfaces as they produce a signal or response that occurs predominantly at the NP core (Fig. 11.1b). Core-based materials typically can be used for sensing applications as they provide a suitable... 

Figure 11.1 Categories for functional NPs based upon location of electrochemical response, (a) Exo-active surfaces, (b) Core-based materials.

While the variety of NPs used in catalytic and sensor applications is extensive, this chapter will primarily focus on metallic and semiconductor NPs. The term functional nanoparticle will refer to a nanoparticle that interacts with a complementary molecule and facilitate an electrochemical process, integrating supramolecular and redox function. The chapter will first concentrate on the role of exo-active surfaces and core-based materials within sensor applications. Exo-active surfaces will be evaluated based upon their types of molecular receptors, ability to incorporate multiple chemical functionalities, selectivity toward distinct analytes, versatility as nanoscale receptors, and ability to modify electrodes via nanocomposite assemblies. Core-based materials will focus on electrochemical labeling and tagging methods for biosensor applications, as well as biological processes that generate an electrochemical response at their core. Finally, this chapter will shift its focus toward the catalytic nature of NPs, discussing electrochemical reactions and enhancement in electron transfer. 

Willner and coworkers have extended this approach to electron relay systems where core-based materials facilitate the electron transfer from redox enzymes in the bulk solution to the electrode.56 Enzymes usually lack direct electrical communication with electrodes due to the fact that the active centers of enzymes are surrounded by a thick insulating protein shell that blocks electron transfer. Metallic NPs act as electron mediators or wires that enhance electrical communication between enzyme and electrode due to their inherent conductive properties.47 Bridging redox enzymes with electrodes by electron relay systems provides enzyme electrode hybrid systems that have bioelectronic applications, such as biosensors and biofuel cell elements.57... 

NPs provide highly efficient catalysts and sensors due to their unique chemical and physical properties. NPs can be used as exo-active surfaces where a multitude of molecular receptors can bind analytes and generate a signal. Alternatively, NPs can be used as core-based materials in which biocatalytic processes can activate their core or they provide a biologically inert electrochemical label. As catalysts, NPs utilize their large surface area to volume ratio and enhance either electrochemical reactions or electron transfer at an electrode. The use of NPs in catalysts and sensors will continue as these functional materials serve as active units within these applications. 

As mentioned in Section 2.3.2, there have been several reports on perdeuter-ated PMMA (PMMA-dg) as a base material for fabricating lower loss POPs. The replacement of hydrogen with deuterium in PMMA results in a considerable reduction in the C-H vibrational absorptions in the IR region and in its overtones in the visible to near-IR region. As a result, loss reductions to 20 and 63 dB/km at 670-680 nm for an SI POP [1] and a GI POP [2], respectively, were successfully achieved using PMMA-dg as the core base material. The refractive index profile of a GI POP was nearly optimized, and the —3-dB bandwidth was enhanced to 1.2 GHz over 300 m in an over-field-launch condition. 

C in most cases. In other words, it is advantageous for the core base material to have Tg of at least 110 °C in terms of the plasticization effect. 

The jalapin-like chloroform-soluble material from the dried tubers of I. batatas was subjected to successive column chromatography over silica gel and HPLC to yield batatosides J-L (55-57) with the oligosaccharide core based on operculinic acid E. The lactonization site was placed at C-2 of the first rhamnose unit. Cinnamic acid was present as the esterifying residue at the C-2 position of the third rhamnose unit. These resin glycosides also contain esterifying residues composed of n-dodecanoic or (25)-methylbutyric acids at the C-2 or C-3 positions on the second rhamnose unit of the oligosaccharide core as well as n-decanoic or n-dodecanoic acids at C-4 on the third rhamnose (40). 

The methodology may also be applicable to the synthesis of pharmacodynamic agents based on the alkoxythiophene core. Such materials should be readily accessible via our new cydization methodology " which utilizes the y-keto acid precursors. 

Lead-Antimony (For Use in Ammunition). Material used by the USA Armed Forces for the manuf of bullet cores, base fillers and point fillers. Three grades are covered in specification MIL-L-13283B (MR) (19 Aug 1970) with the following compn requirements ... 

Except for the Zircaloy in the reactor core, the reactor internals are stainless steel or other common corrosion-resistant alloys. The reactor vessel is a pressure vessel with a single full-diameter removable head. The base material of the vessel is low alloy steel, which is clad on the... 

To achieve a catalytic layer on base materials is the core process for DSA-electrode fabrication. To ensure the layer stability, it is important to try to make the layer better adhesion with the base surface. We have tried several methods in the electrode preparation, including pretreatment, pyrolysis technologies, and electrodeposition. Till now, our research revealed that the electrode service life and the behaviors have been influenced by the electrode preparation methods and technological factors. 

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