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Viladecans, Spain

Shavel A.,Catalonia Institute for Energy Research IREC | Shavel A.,Medcom Advance SA | Ibanez M.,Catalonia Institute for Energy Research IREC | Luo Z.,Catalonia Institute for Energy Research IREC | And 13 more authors.
Chemistry of Materials | Year: 2016

Monodisperse Cu2ZnSnS4 (CZTS) nanocrystals (NCs), with quasi-spherical shape, were prepared by a facile, high-yield, scalable, and high-concentration heat-up procedure. The key parameters to minimize the NC size distribution were efficient mixing and heat transfer in the reaction mixture through intensive argon bubbling and improved control of the heating ramp stability. Optimized synthetic conditions allowed the production of several grams of highly monodisperse CZTS NCs per batch, with up to 5 wt % concentration in a crude solution and a yield above 90%. © 2016 American Chemical Society.

Romo-Herrera J.M.,National Autonomous University of Mexico | Gonzalez A.L.,Autonomous University of Puebla | Guerrini L.,Medcom Advance SA | Castiello F.R.,National Autonomous University of Mexico | And 5 more authors.
Nanoscale | Year: 2016

High and uniform near fields are localized at the eight similar sharp corners of cubic gold nanoparticles. Moreover, by introducing concavity in the particle lateral planes, such field intensities can be further increased and tuned in the near infrared region without altering the overall size of the nanoparticles. Herein, we perform a thorough investigation of the morphological, crystallographic and plasmonic properties of concave gold nanocubes (GNCs) in the sub-70 nm size range, for their potential application as highly efficient SERS substrates in size-limiting cases. Theoretical calculations indicate that the highest increment of the near-field is located at the eight sharp tips and, interestingly, a medium near-field increment is also activated over the volume next to the concave surface. Remarkably, the plasmonic response of the concave cubic morphology showed great sensitivity to the concavity degree. Experimental SERS analysis nicely matches the outcome of the theoretical model, confirming that medium-sized concave GNCs (35 nm side length) possess the highest SERS activity upon excitation with a 633 nm laser, whereas larger 61 nm side concave GNCs dominate the optical response at 785 nm. Due to their size-intensity trade off, we envision that such small concave gold nanocubes can provide a highly active and efficient SERS platform for size-limiting applications, especially when near infrared excitations are required. © The Royal Society of Chemistry 2016.

Tebbe M.,University of Bayreuth | Maennel M.,University of Bayreuth | Fery A.,University of Bayreuth | Pazos-Perez N.,University of Bayreuth | And 5 more authors.
Journal of Physical Chemistry C | Year: 2014

Gold nanorods are among the most efficient structures for optical applications, especially in surface-enhanced Raman scattering applications. Notably, their use directly in colloidal solutions decreases their optical enhancing properties because of the impossibility of generating hot spots and the passivation of their surfaces by the surfactants used during their preparation, hindering the interaction of the analyte with the plasmonic surface. We present an easy and fast method for preparing organized lying-down nanorod films with particles of different aspect ratios, yielding efficient and clean plasmonic films populated with a large number of homogeneous hot spots. © 2014 American Chemical Society.

Trojanowska A.,Rovira i Virgili University | Pazos-Perez N.,Rovira i Virgili University | Pazos-Perez N.,Medcom Advance SA | Panisello C.,Rovira i Virgili University | And 6 more authors.
Journal of Colloid and Interface Science | Year: 2015

Hybrid composites are known to add functionality to plasmonic nanomaterials. Although these substrates can be produced by common synthetic methods, the percentage of metal loaded into the functional material is usually small. Herein, we exploit a phase inversion precipitation method to incorporate large amounts of silver nanoparticles inside the polymeric matrix of polysulfone microbeads. The composite material combines the high SERS activity resulting from the plasmonic coupling of highly interacting nanoparticles and the ability to accumulate analytes of the polysulfone porous support. This allows for the quantitative SERS detection down to the nanomolar level, with a liner response that extends over an impressive concentration range of five orders of magnitude. © 2015 Elsevier Inc.

Guerrini L.,Rovira i Virgili University | Guerrini L.,Medcom Advance SA | Krpetic Z.,University College Dublin | Krpetic Z.,University of Strathclyde | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2015

The exploration of the genetic information carried by DNA has become a major scientific challenge. Routine DNA analysis, such as PCR, still suffers from important intrinsic limitations. Surface-enhanced Raman spectroscopy (SERS) has emerged as an outstanding opportunity for the development of DNA analysis, but its application to duplexes (dsDNA) has been largely hampered by reproducibility and/or sensitivity issues. A simple strategy is presented to perform ultrasensitive direct label-free analysis of unmodified dsDNA with the means of SERS by using positively charged silver colloids. Electrostatic adhesion of DNA promotes nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at nanogram level. As potential applications, we report the quantitative recognition of hybridization events as well as the first examples of SERS recognition of single base mismatches and base methylations (5-methylated cytosine and N6-methylated Adenine) in duplexes. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

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