Patterning Conjugated Polymers by Laser: Synergy of Nanostructure Formation in the All-Polymer Heterojunction P3HT/PCDTBT.

In this work we report a broad scenario for the patterning of semiconducting polymers by laser-induced periodic surface structures (LIPSS). Based on the LIPSS formation in the semicrystalline poly(3-hexylthiophene) (P3HT), we have extended the LIPSS fabrication to an essentially amorphous semiconducting polymer like poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT). This polymer shows a good quality and well-ordered nanostructures not only at the 532 nm laser wavelength, as in the case of P3HT, but also at 266 nm providing gratings with smaller pitch.

Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity.

Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars.

Concentration-controlled formation of myoglobin/gold nanosphere aggregates.

Gold nanoparticles are being increasingly proposed as biotechnological tools for medical diagnosis and therapy purposes. Their safety for human beings and the environment is therefore becoming an emerging issue, which calls for basic research on the interactions between nanostructured gold particles and biological materials, including physicochemical studies of model systems. In this Article, we focus on the "reaction products" of a widely known nanoparticle type, citrate-capped 30 nm gold nanospheres, with a model protein, horse myoglobin.

Electrochemical SERS study on a copper electrode of the insoluble organic pigment quinacridone quinone using ionic liquids (BMIMCl and TBAN) as dispersing agents.

SERS detection of quinacridone quinone (QAQ), an insoluble synthetic organic pigment relevant to modern artworks, is reported here. The use of ionic liquids (BMIMCl and TBAN) as dispersing agents has allowed us to carry out electrochemical SERS experiments of QAQ in aqueous solution using a Cu electrode. No SERS spectra were obtained either from the ionic liquids (ILs) or from QAQ when silver/gold colloids were employed.

Effect of metal-liquid interface composition on the adsorption of a cyanine dye onto gold nanoparticles.

Synthesis of asymmetric nanoparticles, such as gold nanorods, with tunable optical properties providing metal structures with improved SERS performance is playing a critical role in expanding the use of SERS to imaging and sensing applications. However, the synthetic methods usually require surfactants or polymers as shape-directing agents. These chemicals normally remain firmly bound to the metal after the synthesis, preventing the direct adsorption of a large number of potential analytes and often hampering the chemical functionalization of the surface unless extended, and critical for the nanoparticle stability, postremoval steps were performed.

Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon.

Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrices was 60 nm, while silver nanoparticles mean diameter was 50 nm.

Cucurbit[8]uril-stabilized charge transfer complexes with diquat driven by pH: a SERS study.

In this work, we have studied the pH-dependence of the formation of DQCB[8] complexes by surface-enhanced Raman scattering (SERS) spectroscopy. The SERS spectra suggest that at acidic pH CB[8] can form a binary complex with the dication DQ(+2) while at higher pH ternary complexes with the radical cation dimer (DQ(+)˙)(2) and the radical cation-dication dimer (DQ(+)˙DQ(+2)) are formed. The pH-enhanced diquat (DQ) dimerization inside the cucurbit[8]uril cavity has not been reported until now.

Adsorption and detection of sport doping drugs on metallic plasmonic nanoparticles of different morphology.

A comparative study of different plasmonic nanoparticles with different morphologies (nanospheres and triangular nanoprisms) and metals (Ag and Au) was done in this work and applied to the ultrasensitive detection of aminoglutethimide (AGI) drug by surface enhanced Raman spectroscopy (SERS) and plasmon resonance. AGI is an aromatase inhibitor used as an antitumoral drug with remarkable pharmacological interest and also in illegal sport doping. The application of very sensitive spectroscopic techniques based on the localization of an electromagnetic field on plasmonic nanoparticles confirms the previous study of the adsorption of drugs onto a metal surface due to the near field character of these techniques.

New insights on the Au(core)/Pt(shell) nanoparticle structure in the sub-monolayer range: SERS as a surface analyzing tool.

Surface-enhanced Raman spectroscopy (SERS) was used as a powerful surface analyzing tool to investigate the core-shell structural evolution of Au@Pt nanoparticles, revealing the templating role of the underlying Au atoms on the nanoscale Pt-phase structure in the sub-monolayer range.

Trace detection of triphenylene by surface enhanced Raman spectroscopy using functionalized silver nanoparticles with bis-acridinium lucigenine.

Surface enhanced raman scattering (SERS) of triphenylene (TP) has been recorded on Ag nanoparticles functionalized with the molecular assembler bis-acridinium lucigenine dication (LG) which approaches the adsorbate to the metal surface allowing for its detection. Structural information on the host and the analyte can be extracted from the SERS spectra of LG and LG/TP complex. The acridinium planes in LG are staggered, so cavities into which hydrophobic TP can be allocated are created.

Aggregation of antitumoral drug emodin on Ag nanoparticles: SEF, SERS and fluorescence lifetime experiments.

We have studied the fluorescence and Raman emission of the anthraquinone drug emodin immobilized molecules on nanostructured silver surfaces, prepared through two different methods. Two different pHs (pH = 10 and pH = 6) have been used. The dye aggregation favors SEF at pH = 6, whereas quenching of fluorescence is observed at pH = 10, due to the short distance between emodin and Ag particles.

Self-assembly of alpha,omega-aliphatic diamines on Ag nanoparticles as an effective localized surface plasmon nanosensor based in interparticle hot spots.

The adsorption and self-assembly of alpha,omega-aliphatic diamines on silver nanoparticles is studied in this work by surface-enhanced Raman scattering (SERS) spectroscopy and plasmon resonance. These bifunctional diamines can act as linkers of metal nanoparticles (NPs) inducing the formation of hot spots (HS), i.e.

Self-assembly of a dithiocarbamate calix[4]arene on Ag nanoparticles and its application in the fabrication of surface-enhanced Raman scattering based nanosensors.

The absorption and self-assembly of a dithiocarbamate calix[4]arene derivative (DTCX) on Ag nanoparticles (NPs) was characterized in this work by surface-enhanced Raman scattering (SERS). This study was carried out on Ag NPs prepared by chemical reduction of silver nitrate with two different reducing agents: sodium citrate or hydroxylamine hydrochloride. SERS was able to discriminate between the different conformations and interaction geometries adopted by DTCX when adsorbed and self-assembled on Ag NPs at different surface coverings.

Nanosensors based on viologen functionalized silver nanoparticles: few molecules surface-enhanced Raman spectroscopy detection of polycyclic aromatic hydrocarbons in interparticle hot spots.

The functionalization of silver nanoparticles (Ag NPs) by viologen dications (VGDs) is reported in this work as well as their applications in the surface-enhanced Raman scattering (SERS) detection of polycyclic aromatic hydrocarbons (PAHs). VGDs are able to form intermolecular cavities at interparticle junctions (SERS hot spots) where the analyte can be allocated. This leads to a giant intensification of the Raman emission of the target molecule.

Sensing polycyclic aromatic hydrocarbons with dithiocarbamate-functionalized ag nanoparticles by surface-enhanced Raman scattering.

Trace detection of polycyclic aromatic hydrocarbons is reported in this work on dithiocarbamate calix[4]arene functionalized Ag nanoparticles by using surface-enhanced Raman scattering (SERS). SERS spectra informed about the existence of the pollutant by measuring its characteristic fingerprint vibrational features. In addition, SERS revealed important structural information from both the host and the analyte which was crucial to understand and deduce the host-guest interaction mechanism.

Identification of the antitumoral drug emodin binding sites in bovine serum albumin by spectroscopic methods.

Using SERS, fluorescence, circular dichroism and stopped-flow, we have unequivocally characterized the binding sites of emodin in bovine serum albumin. Emodin interacts with protein through two different binding sites corresponding to Sudlow's sites 1 and 2. Site 2, where the binding drug presents, in the cavity, a form between neutral and mono-anionic species slightly displaced to the neutral one, is the primary interaction site, with higher association binding constant, and hence, higher affinity than the other binding site.

Functionalization of Ag nanoparticles with dithiocarbamate calix[4]arene as an effective supramolecular host for the surface-enhanced Raman scattering detection of polycyclic aromatic hydrocarbons.

We report the use of 25,27-diethyl-dithiocarbamic-26,28-dihydroxy-p-tert-butylcalix[4]arene in the functionalization of Ag nanoparticles for pyrene detection by surface-enhanced Raman scattering (SERS). SERS spectra provided information about the calixarene orientation on the metal surface and the interaction mechanism with pyrene. Thus, in this work, we have combined a powerful spectroscopy technique such as SERS, the electronic plasmon-based properties of nanostructured metals, the molecular size-selective recognition of calixarene, and the strong chelating properties of the dithiocarbamate group toward the metal surface in the detection of polycyclic aromatic hydrocarbons.

Interaction of antitumoral 9-aminoacridine drug with DNA and dextran sulfate studied by fluorescence and surface-enhanced Raman spectroscopy.

Fluorescence spectroscopy and surface-enhanced Raman spectroscopy are applied to study the interaction of the drug 9-aminoacridine (9AA) with DNA and dextran sulfate. The effect of the electrostatic interaction between the positively charged 9AA and negatively charged groups in relation to the excimer or exciplex emission is investigated. The exciplex emission of 9AA is connected to the intercalation of this drug between nucleic base residues.

Light scattering from self-affine fractal silver surfaces with nanoscale cutoff: far-field and near-field calculations.

We study the light scattered from randomly rough, one-dimensional, self-affine fractal silver surfaces with nanoscale lower cutoff illuminated by s- or p-polarized Gaussian beams a few micrometers wide. By means of rigorous numerical calculations based on the Green's theorem integral equation formulation (GTIEF), we obtain both the far- and near-field scattered intensities. The influence of diminishing the size of the fractal lower-scale irregularities (from approximately 50 nm to a few nanometers) is analyzed in the case of both single realization and ensemble-average magnitudes.