Innovative and versatile nanoplasmonic approach for the full sensing of proteinogenic aminoacids in nutritional supplements.

A current nourishment issue is the development of smart and reliable analytical strategies to control in a simple way main bioactive compounds of nutritional supplements whose increasing use is deemed a trend nowadays. With this aim a quick and highly sensitive plasmonic sensor using simple citrate coated gold nanoparticles (AuNPs) as optical probe, was developed for both qualitative and quantitative global assessment of all the proteinogenic amino acids in nutritional supplements. AuNPs of five different sizes (from 19 to 74 nm) were synthesized, characterized and evaluated as optimal transductor element for the sensing approach. Critical physic-chemical conditions controlling aggregation (pH, incubation time, AuNPs amount and ionic strength) were investigated on the main five types of aas, structurally different attending to their R-side chain and with expected distinctive behaviour on aggregation mechanisms, which are also discussed. All proteinogenic amino acids induced AuNPs aggregation at low pH (2.5) causing a change in the colour solution from red to blue, as well as a redshift in the plasmon band from 518 nm (disperse NPs) to 650 nm (aggregated NPs). Based on this sensing approach two different strategies are allowed, a preliminary qualitative/semi-quantitative screening just by the naked eye (simple spot test) and a second quantitative confirmation procedure using the analytical signal (A650/A518). Reliability of quantitative approach was assessed by an exhaustive validation procedure, where matrix effects and potential interferences usually present in commercial samples and affecting the analytical signal were mainly focussed. The results for the analysis of complex nutritional samples were validated by means of a statistical comparison with those ones of the official reference Kjeldahl method (paired Student test-t) at a 95% confidence level. This is the first sensing approach able to provide the global estimation of proteinogenic aas amount based on their simply AuNPs aggregation induction, irrespectively of their R-side chain structure.

Cyclodextrin-modified graphene quantum dots as a novel additive for the selective separation of bioactive compounds by capillary electrophoresis.

Highly reliable separation and determination of various biologically active compounds were achieved using capillary electrophoresis (CE) based on ß-cyclodextrin-functionalized graphene quantum dots (ßcd-GQDs) as the background electrolyte additive. ßcd-GQDs improve the separation efficiency between peaks of all analytes. No addition of surfactants or organic solvents was needed in the running buffer containing ßcd-GQDs. Up to eight consecutive runs were acquired with high precision for the separation of resveratrol, pyridoxine, riboflavin, catechin, ascorbic acid, quercetin, curcumin, and even of several of their structural analogs. Baseline separation was achieved within just 13 min as a result of the effective mobility of the analytes along the capillary owing to the differential interaction with the additive. The proposed analytical method displayed a good resolution of peaks for all species selecting two absorption wavelengths in the diode array detector. Detection limits lower than 0.28 µg mL-1 were found for all compounds and precision values were in the range of 2.1-4.0% in terms of the peak area of the analytes. The usefulness of the GQD-assisted selectivity-enhanced CE method was verified by the analysis of food and dietary supplements. The applicability to such complex matrices and the easy and low-cost GQD preparation open the door for routine analyses of food and natural products. The concept of using such a dual approach (macromolecules and nanotechnology) has been explored to tackle the separation of various bioactive compounds in nutritional supplements and food. Schematic illustration of the electrophoretic separation of the bioactive molecules in the capillary which is filled with the running solution without (top) and with ßcd-GQDs (bottom). The fused silica capillary with negatively ionizable silanol groups at the wall. The voltage is applied at positive polarity at the outlet. R, riboflavin; r, resveratrol; P, pyridoxine; C, catechin; c, curcumin; A, ascorbic acid; Q, quercetin.

Association between coffee consumption and total dietary caffeine intake with cognitive functioning: cross-sectional assessment in an elderly Mediterranean population.

PURPOSE: Coffee is rich in compounds such as polyphenols, caffeine, diterpenes, melanoidins and trigonelline, which can stimulate brain activity. Therefore, the possible association of coffee consumption with cognition is of considerable research interest. In this paper, we assess the association of coffee consumption and total dietary caffeine intake with the risk of poor cognitive functioning in a population of elderly overweight/obese adults with metabolic syndrome (MetS). METHODS: PREDIMED-plus study participants who completed the Mini-Mental State Examination test (MMSE) (n = 6427; mean age = 65 ± 5 years) or a battery of neuropsychological tests were included in this cross-sectional analysis. Coffee consumption and total dietary caffeine intake were assessed at baseline using a food frequency questionnaire. Logistic regression models were fitted to evaluate the association between total, caffeinated and decaffeinated coffee consumption or total dietary caffeine intake and cognitive impairment. RESULTS: Total coffee consumers and caffeinated coffee consumers had better cognitive functioning than non-consumers when measured by the MMSE and after adjusting for potential confounders (OR 0.63; 95% CI 0.44-0.90 and OR 0.56; 95% CI 0.38-0.83, respectively). Results were similar when cognitive performance was measured using the Clock Drawing Test (CDT) and Trail Making Test B (TMT-B). These associations were not observed for decaffeinated coffee consumption. Participants in the highest tertile of total dietary caffeine intake had lower odds of poor cognitive functioning than those in the reference tertile when screened by the MMSE (OR 0.64; 95% CI 0.47-0.87) or other neurophysiological tests evaluating a variety of cognitive domains (i.e., CDT and TMT-A). CONCLUSIONS: Coffee consumption and total dietary caffeine intake were associated with better cognitive functioning as measured by various neuropsychological tests in a Mediterranean cohort of elderly individuals with MetS. TRIAL REGISTRATION: ISRCTN89898870. Registration date: July 24, 2014.

Relationship between olive oil consumption and ankle-brachial pressure index in a population at high cardiovascular risk.

BACKGROUND AND AIMS: The aim of this study was to ascertain the association between the consumption of different categories of edible olive oils (virgin olive oils and olive oil) and olive pomace oil and ankle-brachial pressure index (ABI) in participants in the PREDIMED-Plus study, a trial of lifestyle modification for weight and cardiovascular event reduction in individuals with overweight/obesity harboring the metabolic syndrome. METHODS: We performed a cross-sectional analysis of the PREDIMED-Plus trial. Consumption of any category of olive oil and olive pomace oil was assessed through a validated food-frequency questionnaire. Multivariable linear regression models were fitted to assess associations between olive oil consumption and ABI. Additionally, ABI ≤1 was considered as the outcome in logistic models with different categories of olive oil and olive pomace oil as exposure. RESULTS: Among 4330 participants, the highest quintile of total olive oil consumption (sum of all categories of olive oil and olive pomace oil) was associated with higher mean values of ABI (beta coefficient: 0.014, 95% confidence interval [CI]: 0.002, 0.027) (p for trend = 0.010). Logistic models comparing the consumption of different categories of olive oils, olive pomace oil and ABI ≤1 values revealed an inverse association between virgin olive oils consumption and the likelihood of a low ABI (odds ratio [OR] 0.73, 95% CI [0.56, 0.97]), while consumption of olive pomace oil was positively associated with a low ABI (OR 1.22 95% CI [1.00, 1.48]). CONCLUSIONS: In a Mediterranean population at high cardiovascular risk, total olive oil consumption was associated with a higher mean ABI. These results suggest that olive oil consumption may be beneficial for peripheral artery disease prevention, but longitudinal studies are needed.

Discrimination between nanocurcumin and free curcumin using graphene quantum dots as a selective fluorescence probe.

Accurate-controlled sized graphene quantum dots (GQDs) have been used as an analytical nanoprobe for detecting curcumin as a function of the photoluminescent quenching upon increasing concentrations of the analyte. Regarding the importance of curcumin nanoparticles in nutraceutical food, the analytical method described herein was also proven for the discrimination of curcumin remaining in free solution from that encapsulated into water-soluble nanomicelles of ca. 11 nm. This recognition is based on the displacement of GQD emission when interacting with both curcumin species. Maximum emission wavelength of GQDs suffers a gradual quenching as well as a red-shifting upon increasing concentrations of free curcumin (from 458 to 490 nm, exciting at 356 nm). On the other hand, in the presence of nanocurcumin, GQD photoluminescent response only displays a quenching effect (458/356 nm). The sensitivity of the described method in terms of detection limits was 0.3 and 0.1 µg mL-1 for curcumin and nanocurcumin, respectively. The applicability of the photoluminescent probe for the quantification and discrimination between both curcumin environments was demonstrated in nutraceutical formulations namely functional food capsules and fortified beverages such as ginger tea. Graphical abstract.

Analytical strategy based on asymmetric flow field flow fractionation hyphenated to ICP-MS and complementary techniques to study gold nanoparticles transformations in cell culture medium.

An analytical methodology based on asymmetric flow field flow fractionation (AF4) hyphenated to inductively coupled plasma mass spectrometry (ICP-MS) has been developed to study gold nanoparticles (AuNPs) in cell culture medium (Dulbecco's Modified Eagle Medium, DMEM, containing 10% fetal bovine serum, FBS, and antibiotics) used for in vitro toxicological studies. AF4-ICP-MS separation of AuNPs was performed using a regenerated cellulose membrane (molecular weight cut-off, MWCO, of 10 kDa). The carrier composition and the AF4 separation program were optimized. Under the optimum conditions, AuNPs of different types, i.e. phosphate buffered saline (PBS) and citrate stabilized, and sizes (10, 30 and 40 nm), without and with cell culture medium could be separated. The developed method allowed to detect transformations in AuNPs and dissolved gold species (Au3+) induced by this medium, such as an increase in the hydrodynamic volume and oxidation. Centrifugal ultrafiltration (CU), transmission electron microscopy (TEM) and Ultraviolet-visible (UV-vis) absorption spectrophotometry have been used as complementary techniques to study these processes. This information is of major interest to have a correct interpretation of the in vitro toxicological studies of NPs, which are more and more demanded due to the increasing concerns about the safe use of these materials and their impacts. This work demonstrates the potential of hyphenated techniques based on AF4 to achieve this relevant information.

Serum 25 Hydroxy Vitamin D Levels in Very Low Birth Weight Infants Receiving Oral Vitamin D Supplementation.

BACKGROUND AND OBJECTIVE: Vitamin D supplementation in preterm infants has been recommended by American Academy of Pediatrics (AAP); however, its efficacy and safety has not been well studied. To study 25-hydroxy vitamin D (25OHD) levels as a marker of vitamin D status of very low birth weight infants while on vitamin D supplementation during neonatal intensive care unit hospitalization. METHODS: Retrospective study of preterm infants with birth weight <1500 g admitted to our unit from January 2013 to December 2015 who were on oral vitamin D3 400 IU supplementation. Serum 25OHD level were checked at 4, 8, and 12 weeks of age or before discharge and the levels were stratified as deficient <20 ng/mL, insufficient 20 to 29 ng/mL, normal 30 to 60 ng/mL, high 61 to 100 ng/mL and very high >100 ng/mL. RESULTS: A total of 301 infants were enrolled, 186 very low birth weight (VLBW; 1000-1499 g) infants and 115 extremely low birth weight (ELBW; <1000 g) infants. Approximately 80% of both VLBWs and ELBWs had deficient or insufficient 25OHD levels at 4 weeks of age. On oral vitamin D supplementation, VLBW infants increased their 25OHD levels significantly by 8 and 12 weeks of age, whereas ELBW infants lagged behind at 8 weeks and increased their 25OHD levels by 12 weeks of age. CONCLUSIONS: Eighty percent of ELBW and VLBW infants have either deficient or insufficient vitamin D status at 4 weeks of age. Vitamin D supplementation helps in improving the vitamin D levels, VLBW infants significantly more than ELBW infants. AAP recommendation appears to be safe; however, if using higher supplement dosing, 25OHD level should be monitored to avoid high and very high vitamin D levels.

Magnetic/non-magnetic argan press cake nanocellulose for the selective extraction of sudan dyes in food samples prior to the determination by capillary liquid chromatograpy.

Two methods for the determination of Sudan dyes (Sudan I, Sudan II, Sudan III and Sudan IV) in food samples, by solid phase extraction - capillary liquid chromatography, are proposed. Both methods use nanocellulose (NC) extracted from bleached argan press cake (APC), as a nano-adsorbent recycled from an agricultural waste material. One of the methods involves the dispersion of NC in food sample extracts, along with the waste and eluents being separated by centrifugation. In the other method, NC was modified by magnetic iron nanoparticles before using it in the extraction of Sudan dyes. The use of a magnetic component in the extraction process allows magnetic separation to replace the centrifugation step in a convenient and economical way. The two proposed methods allows the determination of Sudan dye amounts at the 0.25-2.00µgL-1 concentration range. The limit of detections, limit of quantifications and standard deviations achieved were lower than 0.1µgL-1, 0.20µgL-1 and 3.46% respectively, when using NC as a nano-adsorbent, and lower than 0.07µgL-1, 0.23µgL-1 and 2.62%, respectively, with the magnetic nanocellulose (MNC) was used. Both methods were applied to the determination of Sudan dyes in barbeque and ketchup sauce samples, obtaining recoveries between 93.4% and 109.6%.

Vitamin D Intake in Very Low Birth Weight Infants in Neonatal Intensive Care Unit.

It is unknown how often preterm infants in neonatal intensive care units achieve the American Academy of Pediatrics-recommended daily intake of 400 international units of Vitamin D. We studied 378 preterm infants with birth weight 1500 g or less admitted to our neonatal intensive care unit, 151 infants before and 227 infants after daily vitamin D-intake monitoring was introduced. Infants were stratified into 2 groups: extremely low birth weight (<1000 g) and Very low birth weight (1000-1500 g). Monitoring of daily intake coincided with significant improvement in vitamin D intake in both extremely low birth weight and very low birth weight groups.

Capillary electrophoresis coupled to evaporative light scattering detection for direct determination of underivatized amino acids: application to tea samples using carboxyled single-walled carbon nanotubes for sample preparation.

An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single-walled carbon nanotubes were used for the first time to perform the clean-up of the analyzed samples, which were afterwards analyzed by CE-ELSD. White tea samples were used to demonstrate the usefulness of the CE-ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5-5.3% range. The LOD obtained for the proposed method were in the 1.2-2.1 pg range and the LOQ, were in the 2.0-11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques.

Achiral liquid chromatography with circular dichroism detection for the determination of carnitine enantiomers in dietary supplements and pharmaceutical formulations.

A simple and enantioselective method for the separation and determination of carnitine enantiomers in dietary supplements and pharmaceutical formulation samples is proposed. This method is based on achiral liquid chromatographic separation of carnitine enantiomers from interferences and direct circular dichroism (CD) detection. The calibration curve of the anisotropy factor (g) versus the enantiomeric excess was linear, with a correlation coefficient (R(2)) of 0.996. The precision evaluated by UV peak area and CD peak area was suitable (RSD <5% in all cases). The usefulness of the proposed method was demonstrated by analysing natural dietary supplements and pharmaceutical formulation samples. This method has the advantages of being rapid and precise, without using an expensive chiral column. The method was suitable for the simultaneous determination of both enantiomers and for assessing the chemical purity of carnitine.

Fast single run of vanilla fingerprint markers on microfluidic-electrochemistry chip for confirmation of common frauds.

A new strategy based on the fast separation of the fingerprint markers of Vanilla planifolia extracts and vanilla-related samples on microfluidic-electrochemistry chip is proposed. This methodology allowed the detection of all required markers for confirmation of common frauds in this field. The elution order was strategically connected with sequential sample screening and analyte confirmation steps, where first ethyl vanillin was detected to distinguish natural from adultered samples; second, vanillin as prominent marker in V. planifolia, but frequently added in its synthetic form; and third, the final detection of the fingerprint markers (p-hydroxybenzaldehyde, vanillic acid, and p-hydroxybenzoic acid) of V. planifolia with confirmation purposes. The reliability of the proposed methodology was demonstrated in the confirmation the natural or non-natural origin of vanilla in samples using V. planifolia extracts and other selected food samples containing this flavor.

Supercritical fluid extraction--achiral liquid chromatography with circular dichroism detection for the determination of menthone enantiomers in natural peppermint oil samples.

A simple and enantioselective method for the determination of menthone enantiomers in peppermint essential oil samples is proposed. The method involves the initial supercritical fluid extraction (SFE) to clean-up and extraction of analytes and their preconcentration on C(18) adsorption cartridges followed by achiral liquid chromatographic separation and direct circular dichroism (CD) detection. The calibration curve of the anisotropy factor (g) versus the enantiomeric excess was linear, with a correlation coefficient (R(2)) of 0.9970. The precision evaluated by UV peak area and CD peak area was suitable both in terms of intra- and inter-day precision (RSD<5.1% in all cases). The usefulness of the proposed method was demonstrated by analyzing natural and spiked peppermint oil samples. This method has the advantages of being rapid and precise without using an expensive chiral column. It was demonstrated to be suitable for the simultaneous determination of both enantiomers and for assessing the chemical purity of menthone.