SERS Research Applied to Polymer Based Nanocomposites

Polymer based nanocomposites containing metal nanoparticles (e.g. Au, Ag) have gained increased attention as a new class of SERS (Surface Enhanced Raman Scattering) substrates for analytical platforms. On the other hand, the application of SERS using such platforms can also provide new insights on the properties of composite materials. In this chapter, we review recent research on the development of SERS substrates based on polymer nanocomposites and their applications in different fields. The fundamentals of SERS are briefly approached and subsequently there is a reference to the strategies of preparation of polymer based nanocomposites. Here the main focus is on SERS studies that have used a diversity of polymer based nanocomposites, highlighting certain properties of the materials that are relevant for the envisaged functionalities. A final section is devoted to the joint use of Raman imaging and SERS in nanocomposites development, a topic that presents a great potential still to be explored as shown by the recent research in this field

Dendrimer Stabilized Nanoalloys for Ink-Jet Printing of Surface-Enhanced Raman Scattering Substrates

Research on paper substrates prepared by inkjet deposition of metal nanoparticles for sensing applications has become a hot topic in recent years; however, the design of such substrates based on the deposition of alloy nanoparticles remains less explored. Herein, we report for the first time the inkjet printing of dendrimer-stabilized colloidal metal nanoalloys for the preparation of paper substrates for surface-enhanced Raman scattering (SERS) spectroscopy. To this end, nanoassemblies containing variable molar ratios of Au:Ag were prepared in the presence of poly(amidoamine) dendrimer (PAMAM), resulting in plasmonic properties that depend on the chemical composition of the final materials. The dendrimer-stabilized Au:Ag:PAMAM colloids exhibit high colloidal stability, making them suitable for the preparation of inks for long-term use in inkjet printing of paper substrates. Moreover, the pre-treatment of paper with a polystyrene (PS) aqueous emulsion resulted in hydrophobic substrates with improved SERS sensitivity, as illustrated in the analytical detection of tetramethylthiuram disulfide (thiram pesticide) dissolved in aqueous solutions. We suggest that the interactions established between the two polymers (PAMAM and PS) in an interface region over the cellulosic fibres, resulted in more exposed metallic surfaces for the adsorption of the analyte molecules. The resulting hydrophobic substrates show long-term plasmonic stability with high SERS signal retention for at least ninety days.publishe

Reductive nanometric patterning of graphene oxide paper using electron beam lithography

Electron beam lithography (EBL) was used for preparing nanostructured reduced patterns on the GO paper surface, while preserving its mechanical resistance and flexibility. Different EBL parameters, like dose and time of exposure for patterning were tested. SEM analysis showed the consequent increase of contrast of the reduced stripes on the patterned regions due to the increase of electron beam doses. Moreover, surface potential microscopy experiments also exhibited a clear contrast between the patterned and non-patterned regions. Structural analysis of the patterned paper through X-ray diffraction and nanoindentation showed that the interlayer distance between GO sheets decreases after reduction allowing the increase of the Hardness and Young modulus that makes this material able to be manipulated and integrated on different devices. Furthermore, we also observe that exposed areas to electron beam reduction process show an increase in the electrical conductivity up to 3 × 104 times. The developed flexible GO films can have interesting applications such as biosensors or templates for inducing tissue regeneration, by providing a surface with differently patterned cues with contrasting electron mobility. Preliminary in vitro studies with L929 fibroblasts support the cytocompatible nature of this patterned GO paper.Gil Gonçalves thanks the Fundação para a Ciência e a Tecnologia for the PostDoc grant (SFRH/BDP/84419/2012). P.A.A.P.M. acknowledge the FCT/MCTES for a research contract under the Program Investigator 2013 (IF/00917/2013/CP1162/CT0016) and TEMA – Centre for Mechanical Technology and Automation (UID/EMS/00481/2013), financed by national funds through the FCT/MEC. I.B. wish to acknowledge the Portuguese Foundation for Science and Technology for the financial support (grant IF/00582/2015). H·I·S.N. acknowledges CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. The biological studies of this work have been funded by the Ministerio de Economía y Competitividad and the Fondo Europeo de Desarrollo Regional (MAT2016-78857-R, MINECO/FEDER, UE). AGM and MCS acknowledge ISCIII-MINECO-FEDER for respective contracts. Authors would like to thank Dr M. Teresa Portolés from the Biochemistry and Molecular Biology Department at Universidad Complutense de Madrid for the generous supply of L929 fibroblasts. Dr José Ángel Rodríguez and Dr Javier Mazarío from the Service of Microscopy and Image Analysis at the Hospital Nacional de Parapléjicos are acknowledged for assistance with CLSM studies and Dr Enrique Rodríguez from the Servicio Interdepartamental de Investigación at the Universidad Autónoma de Madrid for SEM studies.info:eu-repo/semantics/acceptedVersio

Synthesis and characterization of tungsten trioxide powders prepared from tungstic acids

WO3 powders were prepared by the thermal decomposition of tungstic acids (WO3 nH2O, n ¼ 1/3, 1, 2). The tungstic acids were synthesized from WO4 2 aqueous solutions under a variety of conditions of pH, temperature and W(VI) concentrations. The thermal decomposition of the tungstic acids into WO3 was analysed by TG and DSC methods. Nano-sized WO3 powders with different morphological characteristics were obtained by thermal treatment of the tungstic acids at 500 8C in air atmosphere. The morphologies of WO3 powders were characterised by scanning electron microscopy and infrared absorption spectroscopy. Patterns of infrared spectra were related with distinct powder morphologies

Adequacies And Inadequacies In The Anthropometric And Dietetic Profiles Of Preschool Children

Nutritional conditions and food patterns in preschool children are elements that emphasise the importance of health monitoring in this period of nutritional transition, both to ensure nutritional adequacy and how much to intervene in identified inadequacies. Hence, it may also constitute a strategy for public programs and school health services to make decisions. Objective: To analyse the anthropometric and dietary profiles of pre-schoolers of a pole city in Northeastern Brazil. Methods: This is a cross-sectional evaluative study with 114 children aged 2-5 years, of both genders, in three municipal centres of early childhood education. Anthropometry was used to measure weight and height, and the nutritional condition was assessed using the indexes Height for Age (H/A), Weight for Age (W/A), Weight for Height (W/H) and Body Mass Index for Age (BMI/A) in z-score values with classifications established by the World Health Organization. The food intake record was done by direct weighing of the food menu offered during a week in the three institutions. This procedure allowed for the evaluation of the nutritional composition of menus, from the estimates in percentages, average and standard deviations of total calories, macronutrients (proteins, carbohydrates and lipids) and micronutrients (calcium, iron, vitamins A and C), to the adjustments and comparisons to the reference values of the Recommended Dietary Allowances, National Research Council and the PNAE recommendations, by age stages, in full-time units, 1-3 years, 700 kcal; 4-5 years, 950 kcal (70% coverage prediction of daily nutritional requirements) and the part-time units, these same ranges of age, respectively, 200 and 270 kcal (20% coverage for forecasting nutritional needs daily), considering adequate consumption to that with a variation of up to 10% above or below 100% of these recommendations. Results: Most of the preschool children had adequate nutritional conditions, especially those of full-time units, with relative frequencies (W/A: 94.5%; W/H: 89.5%, BMI/A: 81.7%). There were registered also overweight percentages higher than the deficits, in the indices W/A (22.2%), P/E (33.3%) to municipal early childhood centre CMEI-A girls; the indices W/A, W/H, BMI/A (23.8% each) in CMEI B-boys. In relation to the adequacy of the food profile, there was only convergence between the offer and the recommendation of 70% coverage of the daily energy needs, for pre-schoolers of 4-5 years from the centre of full-time units (mean: 951.2 ± 172.3 kcal). As for nutrients, inadequacies had a trend in the coverage of the daily needs on the menu offered in part-time units. Conclusion: Although most children do not present indicative of nutritional risk, requires attention to food portion that was with inadequacies of nutritional condition, with emphasis on weight surplus, while the readjustments in per capita and in portions of the menu implemented in those locations.26223424

Novel luminescent materials based on silica doped with an europium(III) complex of 2,6-dihydroxybenzoic acid: the crystal structure of [(nBu4N)2[Eu(2,6-Hdhb)(5)(H2O)(2)]

Novel luminescent materials were prepared by introducing a new Eu3+ complex of 2,6-dihydroxybenzoic acid (2,6-H2dhb) into a silica gel made by the sol–gel method. The crystal structure of the resulting complex [nBu4N]2[Eu(2,6-Hdhb)5(H2O)2] was determined using single-crystal X-ray diffraction. The compound was further characterised using FTIR, FT-Raman and elemental analysis. Photoluminescence measurements were performed for the isolated Eu(III) 2,6-dihydroxybenzoate complex and also for the related silica composite material