Nanoparticles modification

The same protocol based on aggregation of metallic particles may be used for detection and determination of various biomolecules and even simple inorganic ions. Antibodies, enzymes, biotin, streptavidin, or lectins can be used for nanoparticle modification [138] (Figure 16.24). 

Due to their small size and high surface area, nanoparticles can be applied to modify electrode surface property. Convenient and sensitive electrochemical sensors to various targets have been set up by using nanoparticle modification. The determination of acetaminophen in a commercial paracetamol oral solution was reported using a multiwall CNTs composite film-modified glassy carbon electrode with a detection limit of 50 nM (Li etal. 2006a). Heavy metal ions, such as ar-senite (Dai and Compton 2006 Majid et al. 2006) and lead ion (Cui et al. 2005),... 

Cheow, W., Hadinoto, K. Enhancing encapsulation efficiency of highly watersoluble antibiotic in poly(lactic-co-glycolic acid) nanoparticles modifications of standard nanoparticle preparation methods. Coll. Surf. A Physicochem. Eng. Asp. 2010, 370 (1-3), 79-86. 

To the best of our knowledge, the previous 1-b-l nanoparticle modifications of latex have all been directed at incorporation into the walls of hollow capsules, as described below. However, if metal nanoparticles are stabilized by a surface charge then they can be adsorbed to appropriately modified 1-b-l latex by electrostatic attraction, as shown in Fig. 8.1b. In this figure, the gold nanoparticles were produced by citrate reduction and so had a negative charge... 

Nanoparticle Modification of Electrodes and Their Use as Supports for DNA Immobilization... 

Figure 6.5. Possible nanoparticle modifications within the environment. Reproduced with permission from Alvarez, P. J. J. Colvin, V. Lead, J. Stone, V. ACS Nano 2009,3,1616. Copyright 2009 American Chemical Society.

As nanoparticle modification did not always yield the expected toughness enhancement, researchers tried to combine the nanomodification strategy with that of the state-of-the-art toughening. 

A similar procedure was adopted for synthesis of nanoparticles of cellulose (CelNPs). The polysaccharide nanoparticles were derivatised under ambient conditions to obtain nanosized hydrophobic derivatives. The challenge here is to maintain the nanosize even after derivatisation due to which less vigorous conditions are preferred. A schematic synthesis of acetyl and isocyanate modified derivatives of starch nanoparticles (SNPs) is shown in scheme 3. The organic modification was confirmed from X-ray diffraction (XRD) pattern which revealed that A- style crystallinity of starch nanoparticles (SNPs) was destroyed and new peaks emerged on derivatisation. FT-IR spectra of acetylated derivatives however showed the presence of peak at 3400 cm- due to -OH stretching indicating that the substitution is not complete. 

One of the few disadvantages associated with nanoparticle incorporation concerns the loss of some properties. Some of the data presented have suggested that nanoclay modification of polymers such as polyamide could reduce impact performance [28]. Nanofillers are sometimes very matrix-specific. High cost of nanofillers prohibits their use. 

Nanoparticles of the semicondnctor titanium dioxide have also been spread as mono-layers [164]. Nanoparticles of TiOi were formed by the arrested hydrolysis of titanium iso-propoxide. A very small amount of water was mixed with a chloroform/isopropanol solution of titanium isopropoxide with the surfactant hexadecyltrimethylammonium bromide (CTAB) and a catalyst. The particles produced were 1.8-2.2 nm in diameter. The stabilized particles were spread as monolayers. Successive cycles of II-A isotherms exhibited smaller areas for the initial pressnre rise, attributed to dissolution of excess surfactant into the subphase. And BAM observation showed the solid state of the films at 50 mN m was featureless and bright collapse then appeared as a series of stripes across the image. The area per particle determined from the isotherms decreased when sols were subjected to a heat treatment prior to spreading. This effect was believed to arise from a modification to the particle surface that made surfactant adsorption less favorable. 

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