Separation of Electromagnetic and Chemical Contributions to Surface-Enhanced Raman Spectra on Nanoengineered Plasmonic Substrates

Raman signals from molecules adsorbed on a noble metal surface are enhanced by many orders of magnitude due to the plasmon resonances of the substrate. Additionally, the enhanced spectra are modified compared to the spectra of neat molecules; many vibrational frequencies are shifted, and relative intensities undergo significant changes upon attachment to the metal. With the goal of devising an effective scheme for separating the electromagnetic and chemical effects, we explore the origin of the Raman spectra modification of benzenethiol adsorbed on nanostructured gold surfaces. The spectral modifications are attributed to the frequency dependence of the electromagnetic enhancement and to the effect of chemical binding. The latter contribution can be reproduced computationally using molecule−metal cluster models. We present evidence that the effect of chemical binding is mostly due to changes in the electronic structure of the molecule rather than to the fixed orientation of molecules relative to the substrate.Chemistry and Chemical BiologyEngineering and Applied Science

Enzymatic signal amplification of molecular beacons for sensitive DNA detection

Molecular beacons represent a new family of fluorescent probes for nucleic acids, and have found broad applications in recent years due to their unique advantages over traditional probes. Detection of nucleic acids using molecular beacons has been based on hybridization between target molecules and molecular beacons in a 1:1 stoichiometric ratio. The stoichiometric hybridization, however, puts an intrinsic limitation on detection sensitivity, because one target molecule converts only one beacon molecule to its fluorescent form. To increase the detection sensitivity, a conventional strategy has been target amplification through polymerase chain reaction. Instead of target amplification, here we introduce a scheme of signal amplification, nicking enzyme signal amplification, to increase the detection sensitivity of molecular beacons. The mechanism of the signal amplification lies in target-dependent cleavage of molecular beacons by a DNA nicking enzyme, through which one target DNA can open many beacon molecules, giving rise to amplification of fluorescent signal. Our results indicate that one target DNA leads to cleavage of hundreds of beacon molecules, increasing detection sensitivity by nearly three orders of magnitude. We designed two versions of signal amplification. The basic version, though simple, requires that nicking enzyme recognition sequence be present in the target DNA. The extended version allows detection of target of any sequence by incorporating rolling circle amplification. Moreover, the extended version provides one additional level of signal amplification, bringing the detection limit down to tens of femtomolar, nearly five orders of magnitude lower than that of conventional hybridization assay

Enrichment of Smectite in the REY‐Rich Mud of the Clarion‐Clipperton Fracture Zone in the Eastern Pacific and Its Geological Significance

Abstract REY‐rich mud, consisting of deep‐sea sediments with high concentrations of rare‐earth elements and yttrium (REY), holds significant economic potential. Many studies have been conducted on biogenic apatite, ferromanganese micronodule, and phillipsite within these deposits to ascertain the REY enrichment mechanisms. However, the knowledge of clay minerals in REY‐rich mud, which is the predominant component of pelagic sediments, is still limited. In this study, two adjacent gravity cores (core GC02: REY‐rich mud; core GC03: typical sediments of equatorial Pacific) were collected from the Clarion‐Clipperton Fracture Zone (CCFZ) of the Eastern Pacific to study the role of different clay minerals in REY enrichment. The clay minerals in core GC03 and core GC02 are primarily illite (averaging 60%) and smectite (averaging 63%), respectively, and the smectite in core GC02 was mainly Fe‐rich, which was probably formed via the reaction between opal and FeOOH. Moreover, multiple studies have reported similar smectite enrichment in REY‐rich mud, suggesting that it is a common characteristic. The presumed hydrothermal or volcanic origination of smectite in REY‐rich layers of core GC02 indicates the essential role of hydrothermal and volcanic activities in REY‐rich mud formation during the Oligocene in the western CCFZ

Detection of Genetic Mutations by Next-Generation Sequencing for Predicting Prognosis of Extensive-Stage Small-Cell Lung Cancer

Some studies have revealed that specific genetic mutations could be associated with chemotherapy response or even survival in small-cell lung cancer (SCLC). Our retrospective study aimed to identify the correlation between genetic mutations and progression-free survival (PFS) in extensive-stage SCLC after first-line chemotherapy. A total of 75 patients with extensive-stage SCLC confirmed by histopathology from February 2018 to February 2019 were retrospectively analyzed. The biopsy specimens of all patients were analyzed by Next-Generation Sequencing (NGS). All patients received first-line chemotherapy and follow-up at Shanghai Chest Hospital. Eleven genes were mutated in, at least, 10% of the 75 patients, including TP53 (96%), RB1 (77%), SMAD4 (32%), NOTCH1 (21%), PTEN (16%), FGFR1 (16%), KDR (15%), PIK3CA (15%), ROS1 (15%), BRCA2 (13%), and ERBB4 (10%). The median number of mutated genes among all patients was 5. Patients with more than 5 mutated genes (PFS = 6.7 months, P=0.004), mutant TP53 (PFS = 5.0 months, P=0.011), and mutant BRCA2 (PFS = 6.7 months, P=0.046) had better PFS after first-line chemotherapy than other patients. Multivariate Cox regression analysis showed that patients who achieved a PR (HR 3.729, 95% CI 2.038–6.822), had more than 5 mutated genes (HR 1.929, 95% CI 1.096–3.396), had BRCA2 mutations (HR 4.581, 95% CI 1.721–12.195), and had no liver metastasis (HR 0.415, 95% CI 0.181–0.951) showed improvements in PFS after first-line chemotherapy. In conclusion, the number of mutated genes and BRCA2 mutation status in extensive-stage SCLC were significantly related to PFS after first-line chemotherapy

Observations and analysis of the K2 4Σg+ state using the infrared-infrared double resonance spectroscopy

International audienc

Separation of Electromagnetic and Chemical Contributions to Surface-Enhanced Raman Spectra on Nanoengineered Plasmonic Substrates

Raman signals from molecules adsorbed on a noble metal surface are enhanced by many orders of magnitude due to the plasmon resonances of the substrate. Additionally, the enhanced spectra are modified compared to the spectra of neat molecules; many vibrational frequencies are shifted, and relative intensities undergo significant changes upon attachment to the metal. With the goal of devising an effective scheme for separating the electromagnetic and chemical effects, we explore the origin of the Raman spectra modification of benzenethiol adsorbed on nanostructured gold surfaces. The spectral modifications are attributed to the frequency dependence of the electromagnetic enhancement and to the effect of chemical binding. The latter contribution can be reproduced computationally using molecule−metal cluster models. We present evidence that the effect of chemical binding is mostly due to changes in the electronic structure of the molecule rather than to the fixed orientation of molecules relative to the substrate

Viral proteases activate the CARD8 inflammasome in the human cardiovascular system

Nucleotide-binding oligomerization domain (NBD), leucine-rich repeat (LRR) containing protein family (NLRs) are intracellular pattern recognition receptors that mediate innate immunity against infections. The endothelium is the first line of defense against blood-borne pathogens, but it is unclear which NLRs control endothelial cell (EC) intrinsic immunity. Here, we demonstrate that human ECs simultaneously activate NLRP1 and CARD8 inflammasomes in response to DPP8/9 inhibitor Val-boro-Pro (VbP). Enterovirus Coxsackie virus B3 (CVB3)-the most common cause of viral myocarditis-predominantly activates CARD8 in ECs in a manner that requires viral 2A and 3C protease cleavage at CARD8 p.G38 and proteasome function. Genetic deletion of CARD8 in ECs and human embryonic stem cell-derived cardiomyocytes (HCMs) attenuates CVB3-induced pyroptosis, inflammation, and viral propagation. Furthermore, using a stratified endothelial-cardiomyocyte co-culture system, we demonstrate that deleting CARD8 in ECs reduces CVB3 infection of the underlying cardiomyocytes. Our study uncovers the unique role of CARD8 inflammasome in endothelium-intrinsic anti-viral immunity.Nanyang Technological UniversityNational Research Foundation (NRF)Published versionThis work is supported by NRF-NRFF2017-05 from the National Research Foundation and MOH-000439 from the National Medical Research Council/Ministry of Health awarded to L. Ho, and NRF-NRFF11-2019-0006 from the National Research Foundation and Nanyang Assistant Professorship (Nanyang Technological University) awarded to F. Zhong