Proteomics study of silver nanoparticles on Caco-2 cells.

Silver nanoparticles (AgNPs) have been incorporated into several consumer products. While these advances in technology are promising and exciting, the effects of these nanoparticles have not equally been studied. Due to the size, AgNPs can penetrate the body through oral exposure and reach the gastrointestinal tract. The present study was designed as a comparative proteomic analysis of Caco-2 cells, used as an in vitro model of the small intestine, exposed to 30 nm citrate stabilized-silver nanoparticles (AgNPs) for 24 or 72 h. Using two complementary proteomic approaches, 2D gel-based and label-free mass spectrometry, we present insight into the effects of AgNPs at proteins level. Exposure of 1 or 10 µg/mL AgNPs to Caco-2 cells resulted in 56 and 88 altered proteins at 24 h and 72 h respectively, by 2D gel-based technique. Ten of these proteins were found to be common between the two time-points. Using label-free mass spectrometry technique, 291 and 179 altered proteins were found at 24 h and 72 h, of which 24 were in common. Analysis of the proteomes showed several major biological processes altered, from which, cell cycle, cell morphology, cellular function and maintenance were the most affected.

Analytical ultracentrifugation for analysis of doxorubicin loaded liposomes.

Analytical ultracentrifugation (AUC) is a powerful tool for the study of particle size distributions and interactions with high accuracy and resolution. In this work, we show how the analysis of sedimentation velocity data from the AUC can be used to characterize nanocarrier drug delivery systems used in nanomedicine. Nanocarrier size distribution and the ratio of free versus nanoparticle-encapsulated drug in a commercially available liposomal doxorubicin formulation are determined using interference and absorbance based AUC measurements and compared with results generated with conventional techniques. Additionally, the potential of AUC in measuring particle density and the detection of nanocarrier sub-populations is discussed as well. The unique capability of AUC in providing reliable data for size and composition in a single measurement and without complex sample preparation makes this characterization technique a promising tool both in nanomedicine product development and quality control.

Fast method for multielemental analysis of plants and discrimination according to the anatomical part by total reflection X-ray fluorescence spectrometry.

Fast and reliable analytical methodologies are required for quality control of plants in order to assure human health. Ultrasound-assisted extraction in combination with total reflection X-ray fluorescence is proposed as a fast and simple method for multielemental analysis of plants on a routine basis. For this purpose, five certified reference materials have been analysed for the determination of P, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb. Different extractant media (acids and oxidants) were tried. A mixture of diluted HNO(3)+HCl+HF, was selected as the best option for the achievement of complete extractions. Accurate and precise results can be reached in most cases along with a high sample throughput. Different plants (i.e., herbs, spices and medicinal plants) were analysed. Linear discriminant analysis together with the elemental concentrations allowed the differentiation of commercial preparations corresponding to flower, fruit and leaf.

Enzymatic single-drop microextraction for the assay of ethanol in alcohol-free cosmetics using microvolume fluorospectrometry detection.

A green assay based on the development of an enzymatic reaction in drop format under headspace single-drop microextraction conditions is described for the first time. An aqueous drop containing the enzyme alcohol dehydrogenase and the cofactor ß-Nicotinamide adenine dinucleotide has been used as fluorescence probe for determining ethanol in alcohol-free cosmetics by microvolume fluorospectrometry. Experimental parameters affecting the microextraction performance were carefully optimized. Under the conditions employed, the contribution of other alcohols was found to be negligible. After 10 min of microextraction, a detection limit of 0.04 µg g(-1) ethanol, a repeatability, expressed as relative standard deviation, of 5.3% for a 0.05 mM ethanol standard and a preconcentration factor of 391, were reached. Accuracy of the proposed methodology was evaluated by comparison of calibration slopes corresponding to external calibration with aqueous standards and standard addition calibration. The method was successfully applied to different alcohol-free cosmetics (external calibration was carried out in all cases). Additional advantages such as simplicity and high sample throughput can be highlighted. The greenness profile of proposed methodology was established using NEMI criteria (US National Environmental Methods Index).

Fast screening of terpenes in fragrance-free cosmetics by fluorescence quenching on a fluorescein-bovine serum albumin probe confined in a drop.

A headspace single drop microextraction procedure is proposed for terpene screening in fragrance-free cosmetics. The drop is composed by an aqueous solution of a fluorescence probe formed by bovine serum albumin and fluorescein. Extracted volatile terpenes produce a fluorescence quenching that can be monitored by microvolume-fluorospectrometry. This quenching is observed on the fluorescein fluorescence only when it is linked to bovine serum albumin. A mechanism of contact quenching is proposed. Variables related to the terpene microextraction procedure were carefully studied, namely drop composition and volume, microextraction time, sample volume and temperature, stirring rate and salt addition. The only sample treatment is the dilution of cosmetic with 40% (v/v) ethanol. Citronellol was selected as a representative terpene for calibration purposes. According to the European legislation, the probability-concentration graph of the screening system was established using 0.001% (w/w) as the cut-off level. Low limits of detection with simple instrumentation, absence of matrix effects and high sample throughput can be emphasized.

Directly suspended droplet microextraction in combination with microvolume UV-vis spectrophotometry for determination of phosphate.

A miniaturized methodology for the determination of phosphate in waters has been developed by combining directly suspended droplet microextraction (DSDME) with microvolume spectrophotometry. The method is based on the extraction of the ion pair formed between 12-molybdophosphate and malachite green onto a microdrop of methyl isobutyl ketone and subsequent spectrophotometric determination with no dilution. An enrichment factor of 325 was obtained after 7.5 min of microextraction. The detection limit was 6.1 nM phosphate and the repeatability, expressed as relative standard deviation, was 2.7% (n=6). The method was successfully applied to the determination of dissolved reactive phosphorus in different freshwater samples.

Ultrasound-assisted emulsification microextraction with simultaneous derivatization coupled to fibre optics-based cuvetteless UV-vis micro-spectrophotometry for formaldehyde determination in cosmetic samples.

In this work, ultrasound-assisted emulsification microextraction in combination with fibre optics-based cuvetteless UV-vis micro-spectrophotometry has been proposed as a novel method for the determination of formaldehyde in water-based cosmetics such as shampoo, conditioner and shower gel. The use of a powerful cup-horn sonoreactor allows simultaneous extraction and derivatization of the samples without any pre-treatment. The type and volume of organic extractant solvent, need for a disperser solvent, sonication conditions (sonication time and amplitude), ionic strength and centrifuging time have been carefully studied. Matrix effects were also evaluated. The European official method for quantification of formaldehyde in cosmetic products was used for comparison purposes. An important improvement in sensitivity and sample throughput as well as miniaturization was achieved. A limit of detection of 0.02 microg g(-1) of formaldehyde and a repeatability expressed as relative standard deviation of 5.9% were obtained.