Preparation of albumin–ferrite superparamagnetic nanoparticles using reverse micelles

BACKGROUND: Micellar systems are widely applied as reactors to encapsulate inorganic nanoparticles in polymeric materials. However, only low inorganic contents and microscale dimensions are often achieved. RESULTS: The adsorption of albumin protein on ferrite nanoparticles permits to increase the stability of inorganic dispersions in water by inhibiting particle flocculation. Subsequent glutaraldehyde addition induces protein crosslinking and ferrite entrapment. Polymer–ferrite composite nanoparticles were obtained in this way. The magnetic albumin nanoparticles (25 nm mean diameter) obtained contain about 40 wt% of ferrite and show superparamagnetic behaviour. The composite powder was successfully functionalized with a model drug and the biological activity was evaluated. CONCLUSION: Using a reverse micelle approach, ferrite–albumin composite nanoparticles with a high inorganic content were obtained. The method permits the formulation of biocompatible magnetic particles of nanoscale dimensions. The exhibited superparamagnetic behaviour permits to hypothesize an application of the powder composite as a carrier in biomedical technologies. Copyright © 2009 Society of Chemical Industry     

Amino acids profile of sugar cane spirit (cachaça), rum,and whisky

An analytical procedure for the separation and quantification of 20 amino acids in cachaças has been developed involving C18 solid phase cleanup, derivatization with o-phthalaldehyde/2-mercaptoethanol, and reverse phase liquid chromatography with fluorescence detection. The detection limit was between 0.0050 (Cys) and 0.25 (Ser) mg L⁻¹, whereas the recovery index varies from 69.5 (Lys) to 100 (Tyr)%. Relative standard deviations vary from 1.39 (Trp) to 13.4 (Glu)% and from 3.08 (Glu) to 13.5 (His) for the repeatability and intermediate precision, respectively. From the quantitative profile of amino acids in 41 cachaças, 5 rums, and 12 whisky samples, the following order of amino acids in significant quantities is observed: Gly = Ser < Cys < Ile < His < Pro = Asp < Asn < Tyr for cachaça; Phe < Glu = Gln = Val = Ala < His = Gly = Thr = Arg = Tyr < Asn = Ser = Lys = Pro < Cys = Asp for rum; and Ala = Asn < Trp < Gln = His = Met = Ile = Cys < Thr < Asp = Leu < Phe = Lys < Ser = Gly = Tyr = Val < Glu = Pro < Arg for whisky samples.     

Differentiation of group I and group II strains of Clostridium botulinum by focal plane array Fourier transform infrared spectroscopy

A method was developed for whole-organism fingerprinting of Clostridium botulinum isolates by focal plane array Fourier transform infrared (FPA-FTIR) spectroscopy. A database of 150,000 infrared spectra of 44 strains of C. botulinum was acquired using a FPA-FTIR imaging spectrometer equipped with a 16 x 16 array detector to evaluate the ability of FTIR spectroscopy to differentiate the 44 strains. The database contained strains from C. botulinum groups I and II producing botulinum neurotoxin of serotypes A, B, E, and F. All strains were grown on each of three agar media (brain heart infusion, McClung Toabe agar base, and universal) prior to spectral acquisition. Given the dependence of the infrared spectra of microorganisms on the composition of the growth medium, the spectra were initially separated into three subsets corresponding to the three growth media employed. However, the replicate spectra of all strains, regardless of growth medium, were properly clustered by hierarchical cluster analysis based on differences in their infrared spectral profiles in three narrow spectral regions (1,428 to 1,412, 1,296 to 1,284, and 1,112 to 1,100 cm(-1)). The dendrogram generated from the FTIR data revealed complete separation between group I and group II strains. The spectral differences between group I and group II strains allowed accurate classification of C. botulinum strains at the group level in two blind validation studies (n = 40). These results demonstrate that FPA-FTIR spectroscopy has the potential for rapid discrimination of group I and group II C. botulinum strains in less than 3 min per sample.     

Influence of Clay Modification on the Properties of Resol Nanocomposites

Two organically modified (Cloisite® 30B and 10A) and one unmodified clay (Cloisite® Na) were added to a resol‐type phenolic prepolymer. The modified montmorillonites showed a better dispersion in the prepolymer. The dispersion of the clay, the chemical structure as well as the thermal degradation behavior of the cured polymer and nanocomposites were studied. It was observed that the addition of Cloisite® Na leads to enhanced crosslinking of the cured polymer, leading to a higher activation energy for thermal degradation. The resol with Cloisite® 10A contained a higher percentage of voids, which seems to be one of the major factors that reduce hardness and adhesive strength when the nanocomposite was applied to a metal substrate.

     

A Layered Alumina Composite Tested at High Temperature in Air

An oxidation-resistant interphase for layered alumina composites was prepared by aerosol spray deposition of submicrometer alumina powder. A model composite specimen was made by placing the interphase between thin layers of monolithic alumina. The composite sandwich was hot-pressed to control the interphase fracture resistance for successful crack deflection. Specimens were tested under four-point bending in air at two crosshead speeds at ambient temperature, 1000°C, and 1200°C. The fracture behavior was temperature dependent, with a higher work of fracture at higher temperatures. Interphase delamination and composite toughening behavior were very pronounced at all temperatures. At the highest temperature, the transition to multiple widely distributed cracks and increased crack deflection may be related to inelastic deformation in the alumina.