ABSTRACT
Chiral plasmonics is a rapidly developing field where breakthroughs and unsolved problems coexist. We have recently reported binary surfactant-assisted seeded growth of chiral gold nanorods (Au NRs) with high chiroptical activity. Such a seeded-growth process involves the use of a chiral cosurfactant that induces micellar helicity, in turn driving the transition from achiral to chiral Au NRs, from both the morphological and the optical points of view. We report herein a detailed study on both transitions, which reveals intermediate states that were hidden so far. The correlation between structure and optical response is carefully analyzed, including the (linear and CD) spectral evolution over time, electron tomography, the impact of NR dimensions on their optical response, the variation of the absorption-to-scattering ratio during the evolution from achiral to chiral Au NRs, and the near-field enhancement related to chiral plasmon modes. Our findings provide further understanding of the growth process of chiral Au NRs and the associated optical changes, which will facilitate further study and applications of chiral nanomaterials.
ABSTRACT
The development of novel, highly efficient, reliable, and robust surface enhanced Raman scattering (SERS) substrates containing a large number of hot spots with programmed size, geometry, and density is extremely interesting since it allows the sensing of numerous (bio-)chemical species. Herein, an extremely reliable, easy to fabricate, and label-free SERS sensing platform based on metal nanoparticles (NPs) thin-film is developed by the layer-by-layer growth mediated by polyelectrolytes. A systematic study of the effect of NP composition and size, as well as the number of deposition steps on the substrate's performance, is accomplished by monitoring the SERS enhancement of 1-naphtalenethiol (532 nm excitation). Distinct evidence of the key role played by the interlayer (poly(diallyldimethylammonium chloride) (PDDA) or PDDA-functionalized graphene oxide (GO@PDDA)) on the overall SERS efficiency of the plasmonic platforms is provided, revealing in the latter the formation of more uniform hot spots by regulating the interparticle distances to 5 ± 1 nm. The SERS platform efficiency is demonstrated via its high analytical enhancement factor (≈106 ) and the detection of a prototypical substance(tamoxifen), both in Milli-Q water and in a real matrix, viz. tap water, opening perspectives towards the use of plasmonic platforms for future high-performance sensing applications.
Subject(s)
Gold , Metal Nanoparticles , Polyelectrolytes , Spectrum Analysis, Raman , WaterABSTRACT
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Subject(s)
Humans , Cooperative Behavior , Societies, Medical/legislation & jurisprudence , Societies, Medical/standards , Iatrogenic Disease/prevention & control , Delivery of Health Care/legislation & jurisprudence , Delivery of Health Care , Infectious Disease Transmission, Professional-to-Patient/prevention & control , Delivery of Health Care/organization & administration , Iatrogenic Disease/economicsABSTRACT
La hepatitis isquémica o hipóxica es una entidad clínica caracterizada por una importante elevación de las amino-transferasas de forma aguda y reversible que ocurre en aquellas situaciones que pueden ocasionar una reducción del flujo sanguíneo hepático, especialmente la insuficiencia cardiaca; sin embargo, se trata de un diagnóstico de exclusión ya que se deben descartar previamente otras causas potencialmente responsables de una hepatitis aguda, especialmente víricas y farmacológicas. Histológicamente se caracteriza por una necrosis centrolobulillar. Se presenta un caso ingresado en el servicio de medicina interna durante un periodo de dos meses
Ischemic hepatitis is characterized by a marked and reversible elevation in either the serum alanine or aspartate aminotransferase level in a appropriate clinical setting that could lead to a reduction in hepatic blood flow, mainly in patients with heart failure. To establish the diagnosis other causes of hepatitis, such as virus and drugs, must be previously excluded. Centrilobular necrosis is the main histologic feature. In the present study we describe the one cases of ischemic hepatitis seen in our medical service during a period of two months.
