Surface engineering of nanoparticles has fueled the evolution of nanoscience and nanotechnology through the design of new functional materials with novel electronic, magnetic, optical, and biological properties. Depending on the surface modifier, which can vary from a simple molecule to a complex biomolecule, nanoparticles with a range of functional properties and potential applications can be produced.[1±6] In all these instances, in the absence of any solvent the functionalized nanoparticles appear and behave in a solid-like manner.In the present communication, we describe a novel family of functionalized nanoparticles that exhibit liquid-like behavior in the absence of any solvent. Surface modification of silica or maghemite (c-Fe 2 O 3 ) nanoparticles with a charged organosilane moiety renders the resulting hairy nanoparticles cationic. A counterion is typically present to balance the charge on the nanoparticles (henceforth described as nanosalts), as shown in Figure 1. Depending on the nature of the counterion, it is possible to isolate the nanosalts in liquid form, even at room temperature. These hybrid nanoparticles represent a unique class of solvent-free colloids that are distinguished from conventional colloidal suspensions in a solvent. Their fluidity in the absence of any solvent and zero vapor pressure offers significant new scientific and technological opportunities. For instance, such systems can address some environmental concerns associated with solid nanoparticles. They can also provide a better means to process nanoparticles into films or other functional forms. In addition, they can offer new, solvent-free conducting, magnetic, or electrorheological fluids, among others. Lastly, space restrictions imposed by the dimensions of the nanoparticles, in conjunction with their intrinsic physicochemical properties, make this class of materials particularly attractive as new reaction media.Silica nanoparticles (diameter 7 nm) were modified by condensation of (CH 3 (R = alkyl chain) to obtain the corresponding nanosalts. When chloride is the counter anion, the nanosalt is isolated in a powder form. No melting is observed even after heating to 150 C, above the surface decomposition temperature of the organic-surface modifier. In contrast, replacement of the chloride by R(OCH 2 CH 2 ) 7 O(CH 2 ) 3 SO 3 ± ions yields a clear liquid at room temperature (Fig. 2a). The liquid-like nature of the nanosalt is demonstrated by its ability to dissolve the polar dye methylene blue as a common solvent would. Non-polar dyes (e.g., coumarin derivatives) can also be dissolved in the nanosalt, affording transparent, colored liquids. Furthermore, we were able to dissolve and polymerize pyrrole to form polypyrrole in the nanosalt medium (Fig. 2b). The high organic content of the material (vide infra), nanometer size, and density of the silica all play a key role in producing the liquid nanosalt. The differential scanning calorimetry (DSC) profile of the sulfonate nanosalt shows a reversible first-order endothermic phase ...

We report evidence for the effect of very low magnetic fields on a biological reaction. The presence of magnetite particles (with permanent magnetic moment of 1 emu/g) in the assay had a 30-fold increase on the rate of reaction of horseradish peroxidase. The activity of this enzyme was evaluated with two chromogen systems, and the apparent Michaelis−Menten kinetic parameters were extracted.

This research is aimed at elucidating the removal mechanisms of nutrients due to natural attenuation in drainage canals in Evrotas River delta in Greece. We investigated nutrients fluxes in groundwater, sediments, and reeds (Phragmites Australis and Arundo Donax) of the drainage canal. Groundwater fluxes indicated that the rate of mineralization was 37.6 mg N/m(2) day. The accumulation of toxic ammonia was prevented through the nitrification process (26.6 mg N m(-2) day(-1)). The decrease of NO(3)-N flux in groundwater in the riparian zone was calculated to be 56.1 mg N m(-2) day(-1) (20.48 g N m(-2) year(-1)). Phosphate was adsorbed to sediments and its load to the drainage canal was minimized. Harvesting of above ground reed biomass in mid June, when maximum standing stock of nutrients was attained for both plants, would remove 2.73 g P m(-2) and 11.2 g N m(-2). All the phosphorous (1.39 g P/m(2) year(-1)) and 76.5% of the nitrate nitrogen (14.64 g N m(-2) year(-1)) entering the drainage canal was taken up by plants. Drainage canal management is suggested as an efficient low cost-high gain agri-environmental measure, which is easy to be adapted by farmers, to reduce diffuse nutrient pollution.

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Immobilization of horseradish peroxidase and glucose oxidase on biotinylated layered silicates resulted in high catalytic activity and improved thermal behavior. The immobilization approach involves a simple step, taking advantage of the high affinity of the biotinylated support to avidinylated enzymes. The K m of immobilized horseradish peroxidase-avidin conjugate was different from the K m of the native conjugate. Assuming Arrhenius behavior for the K m , the activation energy, E a , of the immobilized enzyme was 33.3 KJ/mol with a preexponential factor, A, 23 M. The values for the native enzyme-avidin conjugate were 16.8 KJ/mol and 0.04 M. The immobilization resulted in higher activity for the immobilized conjugate at higher temperatures compared to the native. Also, glucose oxidase-avidin conjugate immobilized on layered silicates exhibited improved thermal behavior. The immobilized enzyme conjugate retained 65% of its initial activity at 58ºC, while the native conjugate retained 20% under the same conditions.