Surface modified nanoparticles preparation

Hirai et al [365] reported fabrication of silica-CdS composites by first adding 3-mercaptopropyltrimethoxysilane into freshly prepared CdS nanoparticles in a two -microemulsion system (AOT/isooctane/aqueous solution of cadmium nitrate and sodium sulfide). The surface modified nanoparticles were collected, washed in hexane, and dispersed in tetramethyl orthosilicate, dimethyl formamide, dichloromethane, chloroform etc. When selected dispersions were added to silica sols and properly processed, 100 nm silica particles with CdS core could be prepared. In an earlier work [366], silica particles were first obtained by precipitation in a microemulsion containing Igepal CO-520 i.e. poly(oxyethylene)nonylphenyl ether or Triton N-101 with a similar chemical structure, cyclohexane, hexanol (for the Triton surfactant) and ammonium hydroxide solution. The source of silica was TEOS which was injected into the reverse microemulsion. After this injection, two microemulsions of similar compositions but containing Cd(N03)2 or (NH4)2S in the aqueous phase were simultaneously injected into the microemulsion prepared for silica synthesis. After several hours, the hydrolysis-condensation product of TEOS grew into particles of size 35-50 nm depending on experimental conditions, with uniformly dispersed, 10 mol % CdS nanoparticles (size about 2.5 nm) incorporated in them. Zinc-doped, alkanedithiol-modified silica particles obtained by hydrolysis of TEOS were also used for immobilization of CdS from a reverse micelle system. The general motivation was the development of photocatalysts [367]. 

Bauer F, Sauerland V, Ernst H, Glasel HA, Naumov S and Mehnert R, Preparation of scratch- and abrasion-resistant polymeric nanocomposites by monomer grafting onto nanopaiticles, 4 - Application of MALDI-TOF mass spectrometry to the characterization of surface modified nanoparticles , Macromol Chem Phys 2003 204(3) 375-83. 

Chemically prepared colloidal gold nanoparticles were immobilized as a submonolayer on Au(lll) surface modified with self-assembled monolayers (SAMs) of 4-aminothiophenol [14]. This submonolayer of Au nanoparticles was subsequently characterized using STM. 

Markowitz et al. developed a different approach, again in an attempt to overcome some of the inherent difficulties that arise when imprinted bulk materials are used as catalysts [82], Here, the authors used a template-directed method to imprint an a-chymotrypsin TSA at the surface of silica nanoparticles, prepared with a number of organically modified silanes as functional monomers. Silica particle formation was performed in a microemulsion, where a mixture of a non-ionic surfactant and... 

In spite of a great number of investigations aimed at the preparation of photocatalysts and photoelectrodes based on the semiconductors surface-modified with metal nanoparticles, many factors influencing the photoelectrochemical processes under consideration are not yet clearly understood. Among them are the role of electronic surface (interfacial) states and Schottky barriers at semiconductor / metal nanoparticle interface, the relationship between the efficiency of photoinduced processes and the size of metal particles, the mechanism of the modifying action of such nanoparticles, the influence of the concentration of electronic and other defects in a semiconductor matrix on the peculiarities of metal nanophase formation under different conditions of deposition process (in particular, under different shifts of the electrochemical surface potential from its equilibrium value), etc. 

Lin, W., Garnett, M. C., Davis, S. S., Schacht, E., Ferruti, P., and Ilium, L. (2001), Preparation and characterisation of rose Bengal-loaded surface-modified albumin nanoparticles, J. Controlled Release, 71(1), 117-126. 

Nucleic acid delivery was also studies by Park et al. using CD-based nanoparticles prepared from P-CD-modified poly(ethylenimine) (CD-PEI).The inclusion-forming capability of P-CD was used in order to immobilize the nanoparticles on solid surfaces (adamantine-modified self-assembled monolayers). CD-PEI nanoparticles were proposed as delivery systems onto solid surfaces to attain specific and high affinity loading. The interaction is schematized in Figure 4 [44],... 

Lian and coworkers reported two routes to prepare Au nanoparticle multilayer thin films using two types of Au nanoparticles, respectively surface-modified with carboxylic and pyridine groups. In the first route carboxyhc-functionalized Au particles and P4VP were deposited, whereas in the second route pyridine-fimctionalized Au particles and PAA were used. Similarly, CdSe nanoparticles with acrylic acid surface groups were deposited alternately with P4VP [259,260]. 

Figure 6. SEM image of glassy carbon electrode surface modified with gold nanoparticles prepared with the seed-mediated growth approach. Reproduced from [32], copyright 2007, with permission from the Japan Society for Analytical Chemistry.

Standard Si wafers (n-Si (100), 0 5 cm, resistance 0.5 Q cm, surface roughness 3 nm) were used for preparation of hybrid structures. Cleaned Si wafers were immersed for 4 min into 1% APTES (3-aminopropy 1-triethoxy silane) solution in toluene at 60°C. According to ellipsometric data, the thickness of APTES layer was 10 nm. The hybrid samples were prepared by deposition of DNA and Ag nanoparticles from solution on Si substrates with modified surface. Ag nanoparticles (0 5 nm) were covered by polyvynilpropylene (PVP). 

Q. Cheng, C. Li, V. Pavlinek, P. Saha, H. Wang, Surface-modified antibacterial Ti02/Ag+ nanoparticles Preparation and properties . Applied Surface Science, 252, 4154-4160, (2006). 

As prepared silver nanoparticles were centrifuged at 8000 rpm for 1 h. Then the supernatant was removed and one of the above mentioned polyelectrolytes was added. The nano-silver polyelectrolyte mixture was incubated for 0.5 h. After incubating the mixture was washed by centrifugation under the same conditions and surface-modified silver nanoparticles were resuspended with water in the ratio 1 2. 

Composites of PANI-NFs, synthesized using a rapid mixing method, with amines have recently been presented as novel materials for phosgene detection [472]. Chemiresistor sensors with nanofibrous PANI films as a sensitive layer, prepared by chemical oxidative polymerization of aniline on Si substrates, which were surface-modified by amino-silane self-assembled monolayers, showed sensitivity to very low concentration (0.5 ppm) of ammonia gas [297]. Ultrafast sensor responses to ammonia gas of the dispersed PANI-CSA nanorods [303] and patterned PANI nanobowl monolayers containing Au nanoparticles [473] have recently been demonstrated. The gas response of the PANI-NTs to a series of chemical vapors such as ammonia, hydrazine, and triethylamine was studied [319,323]. The results indicated that the PANI-NTs show superior performance as chemical sensors. Electrospun isolated PANI-CSA nanofiber sensors of various aliphatic alcohol vapors have been proven to be comparable to or faster than those prepared from PANI-NF mats [474]. An electrochemical method for the detection of ultratrace amount of 2,4,6-trinitrotoluene with synthetic copolypeptide-doped PANI-NFs has recently been reported [475]. PANI-NFs, prepared through the in situ oxidative polymerization method, were used for the detection of aromatic organic compounds [476]. 

Poly(amino acid)-based nanoparticles with different surface PEGylation were prepared. a,b-Poly(A-2-hydroxyethyl)-D,L-aspartamide (PHEAS) and PEG-modified PHEA (PHEAS-PEG) were functionalized with a methacrylate group and then polymerized by UV irradiation in inverse microemulsion. The resulting nanoparticles had a size of around 250 nm in diameter by TEM. The fluorescein-loaded PHEA-based nanoparticles were prepared in the presence of fluorescein sodium salts, and examined for cellular uptake using macrophage cells. ... 

Gupta Ajay, K. Wells, S. Surface-modified superparamagnetic nanoparticles for drug delivery Preparation, characterization, and cytotoxicity studies. IEEE Trans. Nanobiosci. 2004, 3 (1), 66-73. 

Cobalt nanoparticles (surface modified with L-cysteine ethyl ester) ethanol wet are available as 10mn black powder (wet with EtOH) which is best used within 3 months. The material can be easily transferred into stable aqueous suspensions, and can be used as a starting material for surface modifications (e.g. dextran coating) or the preparation of magnetic polymer microspheres. 

Nakayama, N. H ashi, T. Preparation of Ti02 nanoparticles surface-modified by both carboxylic acid and amine Dispersibility and stabilization in organic solvents. Coll. Surf. A, 2008, 317, 543-550. 

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