Surfactant Directed Synthesis of Intrinsically Chiral Plasmonic Nanostructures and Precise Tuning of their Optical Activity through Controlled Self-Assembly.

Fabrication and transmission of plasmonic chirality is a rapidly developing area of research. While nanoscale chirality is reasonably well explored, research on intrinsically chiral nanostructures, that has ramifications to origin of homochirality, is still in its infancy. Herein, we report the synthesis of dog-bone shaped chiral gold nanostructures using a chiral cationic surfactant with excess ascorbic acid. Chiral growth is attributed to the specific binding and structure breaking ability of chiral surfactant and ascorbic acid. The controlled assembly of particles facilitated tuning and enhancement of chiral signals. Experimental observations were validated with theoretical simulations modelled in frequency domain with a surface integral-equation parameterization. Work highlighting the generation and tuning of plasmonic chirality provides new insights into the understanding of intrinsic chirality and paves way for their application in enantioselective catalysis and biosensing.

Reversible Clustering of Gold Nanoparticles under Confinement.

A limiting factor of solvent-induced nanoparticle self-assembly is the need for constant sample dilution in assembly/disassembly cycles. Changes in the nanoparticle concentration alter the kinetics of the subsequent assembly process, limiting optical signal recovery. Herein, we show that upon confining hydrophobic nanoparticles in permeable silica nanocapsules, the number of nanoparticles participating in cyclic aggregation remains constant despite bulk changes in solution, leading to highly reproducible plasmon band shifts at different solvent compositions.

Myeloid C/EBPß deficiency reshapes microglial gene expression and is protective in experimental autoimmune encephalomyelitis.

BACKGROUND: CCAAT/enhancer binding protein ß (C/EBPß) is a transcription factor that regulates the expression of important pro-inflammatory genes in microglia. Mice deficient for C/EBPß show protection against excitotoxic and ischemic CNS damage, but the involvement in this neuroprotective effect of the various C/EBPß-expressing cell types is not solved. Since C/EBPß-deficient microglia show attenuated neurotoxicity in culture, we hypothesized that specific C/EBPß deficiency in microglia could be neuroprotective in vivo. In this study, we have tested this hypothesis by generating mice with myeloid C/EBPß deficiency. METHODS: Mice with myeloid C/EBPß deficiency were generated by crossing LysMCre and C/EBPßfl/fl mice. Primary microglial cultures from C/EBPßfl/fl and LysMCre-C/EBPßfl/fl mice were treated with lipopolysaccharide ± interferon γ (IFNγ) for 6 h, and gene expression was analyzed by RNA sequencing. Gene expression and C/EBPß deletion were analyzed in vivo in microglia isolated from the brains of C/EBPßfl/fl and LysMCre-C/EBPßfl/fl mice treated systemically with lipolysaccharide or vehicle. Mice of LysMCre-C/EBPßfl/fl or control genotypes were subjected to experimental autoimmune encephalitis and analyzed for clinical signs for 52 days. One- or two-way ANOVA or Kruskal-Wallis with their appropriate post hoc tests were used. RESULTS: LysMCre-C/EBPßfl/fl mice showed an efficiency of C/EBPß deletion in microglia of 100 and 90% in vitro and in vivo, respectively. These mice were devoid of female infertility, perinatal mortality and reduced lifespan that are associated to full C/EBPß deficiency. Transcriptomic analysis of C/EBPß-deficient primary microglia revealed C/EBPß-dependent expression of 1068 genes, significantly enriched in inflammatory and innate immune responses GO terms. In vivo, microglial expression of the pro-inflammatory genes Cybb, Ptges, Il23a, Tnf and Csf3 induced by systemic lipopolysaccharide injection was also blunted by C/EBPß deletion. CNS expression of C/EBPß was upregulated in experimental autoimmune encephalitis and in multiple sclerosis samples. Finally, LysMCre-C/EBPßfl/fl mice showed robust attenuation of clinical signs in experimental autoimmune encephalitis. CONCLUSION: This study provides new data that support a central role for C/EBPß in the biology of activated microglia, and it offers proof of concept for the therapeutic potential of microglial C/EBPß inhibition in multiple sclerosis.

Fast and accurate electromagnetic solutions of finite periodic optical structures.

Electromagnetic applications of periodic materials have become popular in many modern optical and RF applications. The accurate computation of the electromagnetic response of large structures requires solving problems with high number of unknowns. Fast methods are useful to deal with such big problems, but, in general they do not take advantage of the periodicity properties. Based on the behaviour of impedance matrices involved in the solution of the surface integral equations with the Method of Moments, an accelerated solution based on the FFT is implemented. The presented approach slots the original impedance matrix and it applies the FFT to calculate the exact solution of the matrix vector product in an iterative process. The proposed solution achieves a linear memory cost proportional to 𝒪(N) and a computing time of 𝒪(N log N), where N is the problem number of unknowns. Also, in this paper, the advantages of this technique are shown in the developed applications.

Human Microglia-Like Cells Differentiated from Monocytes with GM-CSF and IL-34 Show Phagocytosis of α-Synuclein Aggregates and C/EBPß-Dependent Proinflammatory Activation.

Microglia, the main resident immune cells in the central nervous system, are implicated in the pathogenesis of various neurological disorders. Much of our knowledge on microglial biology was obtained using rodent microglial cultures. To understand the role of microglia in human disease, reliable in vitro models of human microglia are necessary. Monocyte-derived microglia-like cells (MDMi) are a promising approach. This study aimed to characterize MDMi cells generated from adult human monocytes using granulocyte-macrophage colony-stimulating factor and interleukin-34. To this end, 49 independent cultures of MDMI were prepared, and various methodological and functional studies were performed. We show that with this protocol, adult human monocytes develop into microglia-like cells, a coating is unnecessary, and high cell density seeding is preferable. When compared to monocytes, MDMi upregulate the expression of many, but not all, microglial markers, indicating that, although these cells display a microglia-like phenotype, they cannot be considered bona fide human microglia. At the functional level, MDMi phagocytose α-synuclein aggregates and responds to lipopolysaccharide (LPS) by nuclear translocation of the transcription factor nuclear factor-kappaB (NFkappaB) and the upregulation of proinflammatory genes. Finally, a long-lasting silencing of the transcription factor CCAAT/enhancer protein ß (C/EBPß) was achieved by small interfering RNA, resulting in the subsequent downregulation of proinflammatory genes. This supports the hypothesis that C/EBPß plays a key role in proinflammatory gene program activation in human microglia. Altogether, this study sheds new light on the properties of MDMi cells and supports these cells as a promising in vitro model for studying adult human microglia-like cells.

Optimization of an optical wireless nanolink using directive nanoantennas.

Optical connects will become a key point in the next generation of integrated circuits, namely the upcoming nanoscale optical chips. In this context, nano-optical wireless links using nanoantennas have been presented as a promising alternative to regular plasmonic waveguide links, whose main limitation is the range propagation due to the metal absorption losses. In this paper we present the complete design of a high-capability wireless nanolink using matched directive nanoantennas. It will be shown how the use of directive nanoantennas clearly enhances the capability of the link, improving its behavior with respect to non-directive nanoantennas and largely outperforming regular plasmonic waveguide connects.

Biofluid Biomarkers in the Prognosis of Amyotrophic Lateral Sclerosis: Recent Developments and Therapeutic Applications.

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by the degeneration of motor neurons for which effective therapies are lacking. One of the most explored areas of research in ALS is the discovery and validation of biomarkers that can be applied to clinical practice and incorporated into the development of innovative therapies. The study of biomarkers requires an adequate theoretical and operational framework, highlighting the "fit-for-purpose" concept and distinguishing different types of biomarkers based on common terminology. In this review, we aim to discuss the current status of fluid-based prognostic and predictive biomarkers in ALS, with particular emphasis on those that are the most promising ones for clinical trial design and routine clinical practice. Neurofilaments in cerebrospinal fluid and blood are the main prognostic and pharmacodynamic biomarkers. Furthermore, several candidates exist covering various pathological aspects of the disease, such as immune, metabolic and muscle damage markers. Urine has been studied less often and should be explored for its possible advantages. New advances in the knowledge of cryptic exons introduce the possibility of discovering new biomarkers. Collaborative efforts, prospective studies and standardized procedures are needed to validate candidate biomarkers. A combined biomarkers panel can provide a more detailed disease status.

Chiral Seeded Growth of Gold Nanorods Into Fourfold Twisted Nanoparticles with Plasmonic Optical Activity.

A robust and reproducible methodology to prepare stable inorganic nanoparticles with chiral morphology may hold the key to the practical utilization of these materials. An optimized chiral growth method to prepare fourfold twisted gold nanorods is described herein, where the amino acid cysteine is used as a dissymmetry inducer. Four tilted ridges are found to develop on the surface of single-crystal nanorods upon repeated reduction of HAuCl4 , in the presence of cysteine as the chiral inducer and ascorbic acid as a reducing agent. From detailed electron microscopy analysis of the crystallographic structures, it is proposed that the dissymmetry results from the development of chiral facets in the form of protrusions (tilted ridges) on the initial nanorods, eventually leading to a twisted shape. The role of cysteine is attributed to assisting enantioselective facet evolution, which is supported by density functional theory simulations of the surface energies, modified upon adsorption of the chiral molecule. The development of R-type and S-type chiral structures (small facets, terraces, or kinks) would thus be non-equal, removing the mirror symmetry of the Au NR and in turn resulting in a markedly chiral morphology with high plasmonic optical activity.

Knowledge of stroke warning symptoms and intended action in response to stroke in Spain: a nationwide population-based study.

BACKGROUND: Worldwide thrombolysis rates remain suboptimal. Ambulance transfer is associated with greater use of this time-dependent treatment. Information on public awareness of stroke symptoms is important for planning effective education programs to promote calling of emergency services for suspected stroke. However, there is a paucity of data on this subject in European countries. Our objectives were to explore the recognition of stroke symptoms, awareness of the need to activate the emergency medical services for acute stroke events, and the association between knowledge of warning symptoms and intent to call for an ambulance among a sample representative of the adult population of Spain. This is the largest study on this subject to date in Europe. METHODS: The data were taken from the Study on Nutrition and Cardiovascular Risk in Spain, a cross-sectional study conducted in a sample representative of the Spanish noninstitutionalized population aged ≥18 years in 2008-2010. Study participants were selected by multistage clustered random sampling. The households within each section were selected by random telephone dialing using the landline telephone directory as the sampling frame. Subjects in the households were selected proportionally to the distribution of the population of Spain by sex and age. The study included a computer-assisted telephone interview on stroke symptom knowledge and the first action to perform in a stroke event, based on the American Heart Association and American Stroke Association recommendations, and two home visits to perform a physical examination and to obtain blood samples. RESULTS: Among 11,827 adults, 7,711 (65.2%; 95% CI = 64.1-66.3) identified 4-6 stroke warning symptoms, considered as adequate knowledge. A total of 1,348 (11.4%) were unable to classify any of the symptoms correctly. In the multivariate analysis, higher education was significantly associated with better knowledge of symptoms, and age ≥65 years, fair/poor self-rated health, history of obesity and known diabetes were significantly associated with less knowledge of stroke symptoms. One in 5 individuals indicated they would do something other than calling for an ambulance if they thought someone was having a stroke. The number of specific stroke warning symptoms known was directly associated with the intent to call an ambulance in a stroke event (OR adjusted for sociodemographic and clinical variables = 1.06 per symptom, 95% CI = 1.03-1.09; p < 0.001). CONCLUSIONS: In this population-based study, stroke symptom knowledge was suboptimal and only modestly associated with the intent to call for an ambulance. Educational interventions are needed to link stroke recognition more strongly to an immediate need to call for an ambulance in order to increase stroke patients' access to thrombolysis.

Morphological and Optical Transitions during Micelle-Seeded Chiral Growth on Gold Nanorods.

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.

Method-of-moments formulation for the analysis of plasmonic nano-optical antennas.

We present a surface integral equation (SIE) to model the electromagnetic behavior of metallic objects at optical frequencies. The electric and magnetic current combined field integral equation considering both tangential and normal equations is applied. The SIE is solved by using a method-of-moments (MoM) formulation. The SIE-MoM approach is applied only on the material boundary surfaces and interfaces, avoiding the cumbersome volumetric discretization of the objects and the surrounding space required in differential-equation formulations. Some canonical examples have been analyzed, and the results have been compared with analytical reference solutions in order to prove the accuracy of the proposed method. Finally, two plasmonic Yagi-Uda nanoantennas have been analyzed, illustrating the applicability of the method to the solution of real plasmonic problems.

Integrating Plasmonic Supercrystals in Microfluidics for Ultrasensitive, Label-Free, and Selective Surface-Enhanced Raman Spectroscopy Detection.

Surface-enhanced Raman spectroscopy (SERS) microfluidic chips for label-free and ultrasensitive detection are fabricated by integrating a plasmonic supercrystal within microfluidic channels. This plasmonic platform allows the uniform infiltration of the analytes within the supercrystal, reaching the so-called hot spots. Moreover, state-of-the-art simulations performed using large-scale supercrystal models demonstrate that the excellent SERS response is due to the hierarchical nanoparticle organization, the interparticle separation (IPS), and the presence of supercrystal defects. Proof-of-concept experiments confirm the outstanding performance of the microfluidic chips for the ultradetection of (bio)molecules with no metal affinity. In fact, a limit of detection (LOD) as low as 10-19 M was reached for crystal violet. The SERS microfluidic chips show excellent sensitivity in the direct analysis of pyocyanin secreted by Pseudomonas aeruginosa grown in a liquid culture medium. Finally, the further integration of a silica-based column in the plasmonic microchip provides charge-selective SERS capabilities as demonstrated for a mixture of positively and negatively charged molecules.

Micelle-directed chiral seeded growth on anisotropic gold nanocrystals.

Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20). Through variation of the dimensions of chiral wrinkles, the chiroptical properties can be tuned within the visible and near-infrared electromagnetic spectrum. The micelle-directed mechanism allows extension to other systems, such as the seeded growth of chiral platinum shells on gold nanorods. This approach provides a reproducible, simple, and scalable method toward the fabrication of NPs with high chiral optical activity.

5'-Upstream variants of CRHR1 and MAPT genes associated with age at onset in progressive supranuclear palsy and cortical basal degeneration.

Two different H1 sub-haplotypes at chromosome 17q21, H1C and H1E'A, have been associated with progressive supranuclear palsy (PSP) and cortical basal degeneration (CBD). We analyzed the SNPs included in the H1C and H1E'A haplotypes in a large Spanish PSP/CBD series and their interaction with age at onset (AAO). Survival analysis of rs1880753 marker was consistently associated with disease risk and with an earlier age at onset under an additive model. Its location at 160 kb and 50 kb upstream of tau and CRHR1 genes, respectively, suggests that it might act as a cis-element that regulates gene expression. Rs45502095(H1) was also associated with AAO under a recessive model. Haplotype analysis failed to replicate the association of H1C and H1E'A haplotypes with PSP/CBD. However, we found a strong association of two H1 sub-haplotypes with PSP and CBD (H1E'C and H1Q), which include MAPT and CRHR1 genes where the risk variant for PSP/CBD could lie.

Identification of proteomic differences in asthenozoospermic sperm samples.

BACKGROUND: Asthenozoospermia is one of the most common findings present in infertile males, but its aetiology remains unknown in most cases. Present proteomic tools now offer the opportunity to identify proteins which are differentially expressed in asthenozoospermic semen samples and potentially involved in infertility. METHODS: We compared the expression of 101 sperm protein spots in 20 asthenozoospermic samples to that of 10 semen donor controls using two-dimensional proteomic analysis. RESULTS: Seventeen protein spots have been identified at different amounts in the asthenozoospermic samples compared with controls. These are cytoskeletal actin-B, annexin-A5, cytochrome C oxidase-6B, histone H2A, prolactin-inducible protein and precursor, calcium binding protein-S100A9 (2 spots), clusterin precursor, dihydrolipoamide dehydrogenase precursor, fumarate hydratase precursor, heat shock protein-HSPA2, inositol-1 monophosphatase, 3-mercapto-pyruvate sulfurtransferase/dienoyl-CoA isomerase precursor, proteasome subunit-PSMB3, semenogelin 1 precursor and testis expressed sequence 12. The detected amount of these proteins enabled the grouping of asthenozoospermic sperm samples in an unsupervised clustering analysis. CONCLUSIONS: We have identified several proteins present at different amount in asthenozoospermic sperm samples. These proteins could be candidates towards the development of diagnostic markers, and open up the opportunity to gain further insight into the pathogenic mechanisms involved in asthenozoospermia.

Multilayer homogeneous dielectric filler for electromagnetic invisibility.

In recent years, invisibility has become a research area of increasing interest due to the advances in material engineering. It may be possible to achieve invisibility through cloaking devices by coating the body using one or more layers of materials with the proper electromagnetic properties. By using techniques associated to plasmonic cloaking it is maybe possible to obtain also invisibility for small objects with several layers of homogeneous materials working from inside the object. We demonstrate numerically that it is, therefore, possible to achieve invisibility through an inner system based on scattering cancellation techniques.

Association of the CX3CR1-V249I Variant with Neurofibrillary Pathology Progression in Late-Onset Alzheimer's Disease.

Neuroinflammation and microglial dysfunction have a prominent role in the pathogenesis of late-onset Alzheimer's disease (LOAD). CX3CR1 is a microglia-specific gene involved in microglia-neuron crosstalk and neuroinflammation. Numerous evidence show the involvement of CX3CR1 in AD. The aim of this study was to investigate if some functional genetic variants of this gene could influence on LOAD's outcome, in a neuropathologically confirmed Spanish cohort. We designed an open, pragmatic, case-control retrospective study including a total of 475 subjects (205 pathologically confirmed AD cases and 270 controls). We analyzed the association of the two CX3CR1 functional variants (V249I, rs3732379; and T280M, rs3732378) with neurofibrillary pathology progression rate according to Braak's staging system, age at onset (AAO), survival time, and risk of suffering LOAD. We found that individuals heterozygous for CX3CR1-V249I presented a lower neurofibrillary pathology stage at death (OR = 0.42, 95%CI [0.23, 0.74], p = 0.003, adj-p = 0.013) than the other genotypes. Eighty percent of the subjects homozygous for 249I had higher neurofibrillary pathology progression (Braak's stage VI). Moreover, homozygosis for 280M and 249I could be associated with a higher AAO in the subgroups of AD with Lewy bodies and without Lewy bodies. These CX3CR1 genetic variants could represent new modifying factors of pathology progression and age at onset in LOAD. These results provide further evidence of the involvement of CX3CR1 pathway and microglia/macrophages in the pathogenesis of LOAD.

RNA-Seq transcriptomic profiling of primary murine microglia treated with LPS or LPS + IFNγ.

Microglia, the main resident immune cells in the CNS, are thought to participate in the pathogenesis of various neurological disorders. LPS and LPS + IFNγ are stimuli that are widely used to activate microglia. However, the transcriptomic profiles of microglia treated with LPS and LPS + IFNγ have not been properly compared. Here, we treated murine primary microglial cultures with LPS or LPS + IFNγ for 6 hours and then performed RNA-Sequencing. Gene expression patterns induced by the treatments were obtained by WGCNA and 11 different expression profiles were found, showing differential responses to LPS and LPS + IFNγ in many genes. Interestingly, a subset of genes involved in Parkinson's, Alzheimer's and Huntington's disease were downregulated by both treatments. By DESeq analysis we found differentially upregulated and downregulated genes that confirmed LPS and LPS + IFNγ as inducers of microglial pro-inflammatory responses, but also highlighted their involvement in specific cell functions. In response to LPS, microglia tended to be more proliferative, pro-inflammatory and phagocytic; whereas LPS + IFNγ inhibited genes were involved in pain, cell division and, unexpectedly, production of some inflammatory mediators. In summary, this study provides a detailed description of the transcriptome of LPS- and LPS + IFNγ treated primary microglial cultures. It may be useful to determine whether these in vitro phenotypes resemble microglia in in vivo pathological conditions.

KATP Channel Expression and Genetic Polymorphisms Associated with Progression and Survival in Amyotrophic Lateral Sclerosis.

The ATP-sensitive potassium (KATP) channel directly regulates the microglia-mediated inflammatory response following CNS injury. To determine the putative role of the KATP channel in amyotrophic lateral sclerosis (ALS) pathology, we investigated whether ALS induces changes in KATP channel expression in the spinal cord and motor cortex. We also characterized new functional variants of human ABCC8, ABCC9, KCNJ8, and KCNJ11 genes encoding for the KATP channel and analyzed their association with ALS risk, rate of progression, and survival in a Spanish ALS cohort. The expression of ABCC8 and KCNJ8 genes was enhanced in the spinal cord of ALS samples, and KCNJ11 increased in motor cortex of ALS samples, as determined by real-time polymerase chain reaction. We then sequenced the exons and regulatory regions of KATP channel genes from a subset of 28 ALS patients and identified 50 new genetic variants. For the case-control association analysis, we genotyped five selected polymorphisms with predicted functional relevance in 185 Spanish ALS (134 spinal ALS and 51 bulbar ALS) patients and 493 controls. We found that bulbar ALS patients presenting the G/G genotype of the rs4148646 variant of ABCC8 and the T/T genotype of the rs5219 variant of KCNJ11 survived longer than other ALS patients presenting other genotypes. Also, the C/C genotype of the rs4148642 variant of ABCC8 and the T/C genotype of the rs148416760 variant of ABCC9 modified the progression rate in spinal ALS patients. Our results suggest that the KATP channel plays a role in the pathophysiological mechanisms of ALS.