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Surface enhanced Raman spectroscopy (SERS) is a unique analytical technique with excellent performance in terms of sensitivity, non-destructive detection and resolution. However, due to the randomness and poor repeatability of hot spot distribution, SERS quantitative analysis is still challenging. Meanwhile, snus is a type of tobacco product that can release nicotine and other components in the mouth without burning, and the rapid detection technique based on SERS can reliably evaluate the amount of nicotine released from snus, which is of great significance for understanding its characteristics and regulating its components. Herein, the strategy was proposed to solve the feasibility of SERS quantitative detection based on self-assembled core-shell nanoparticles with embedded internal standards (EIS) due to EIS signal can effectively correct SERS signal fluctuations caused by different aggregation states and measurement conditions, thus allowing reliable quantitative SERS analysis of targets with different surface affinity. By means of process control, after the Au nanoparticles (Au NPs) were modified with 4-Mercaptobenzonitrile (4-MBN) as internal standard molecules, Ag shell with a certain thickness was grown on the surface of the AuNP@4-MBN, and then the Au@4-MBN@Ag NPs were used to regulate and control the assembly of liquid-liquid interface. The high-density nano-arrays assembled at the liquid-liquid interface ensure high reproducibility as SERS substrates, and which could be used for SERS detection of nicotine released from snus products. In addition, time-mapping research shows that this method can also be used to dynamically monitor the release of nicotine. Moreover, such destruction-free evaluation of the release of nicotine from snus products opens up new perspectives for further research about the impact of nicotinoids-related health programs. [ABSTRACT FROM AUTHOR]

To detect biomarkers from human exhalation, air flow dynamics on the nanoparticle surface were explored by a surface-enhanced Raman scattering (SERS) sensor. A hollow Co-Ni layered double hydroxide (LDH) nanocage on Ag nanowires (Ag@LDH) was prepared. Ag nanowires provided amplified Raman signals for trace determination; hollow LDH nanocages served as the gaseous confinement cavity to improve capture and adsorption of gaseous analytes. The Raman intensity and logarithmic analyte concentration exhibit an approximately linear relationship; the detection limit of SERS sensors for aldehyde is 1.9×10 -9 v/v (1.9 ppb). Various aldehydes in mixed mimetic gas are distinguished by Raman spectra statistical analysis assisted by multivariate methods, including principal component analysis and hierarchical cluster analysis. The information was recorded in a barcode, which can be used for the design and development of a desktop SERS sensor analysis system for large-scale lung cancer detection., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

N 6 -methyladenine (m 6 A), one of the most common chemical modifications of eukaryotic RNA, participates in many important biological processes. An effective strategy for the quantitative determination of m 6 A is of great significance. Herein, we used methylated microRNA-21 (miRNA21) as the model target to propose a simple and sensitive electrogenerated chemiluminescence (ECL) biosensing platform to detect a specific m 6 A RNA sequence. This strategy is based on the fact that the anti-m 6 A-antibody can specifically recognize and bind to the m 6 A site in the RNA sequence, resulting in a quenching effect between Ru(bpy) 3 2+ -functionalized metal-organic frameworks and ferrocene. Luminescent metal-organic frameworks (Ru@MOFs) not only act as ECL indicators but also serve as nanoreactors for the relative ECL reactions owing to their porous or multichannel structure, which overcomes the fact that Ru(bpy) 3 2+ is easily released when used for aqueous-phase detection, thus enhancing the ECL efficiency. Moreover, the ECL method has fewer modification steps and uses only one antibody to recognize the target RNA sequence, which simplifies the operation process and reduces the detection time, presenting a wide linear range (0.001-10 nM) for m 6 A RNA determination with a low detection limit (0.0003 nM). Additionally, this developed strategy was validated for m 6 A RNA detection in human serum. Thus, the ECL biosensing method provides a new method for m 6 A RNA determination that is simple, highly specific, and sensitive.

A simple method was adopted in which ultrathin cerium oxide nanoplates (<1.4 nm) were synthesized to increase the surface atomic content, allowing transformation from a face-centered cubic (fcc) phase to a body-centered tetragonal (bct) phase. Three types of cerium oxide nanoparticles of different thicknesses (1.2 nm ultrathin nanoplates, 2.2 nm nanoplates, and 5.4 nm nanocubes) were examined using transmission electron microscopy and X-ray diffraction. The metastable bct phase was observed only in ultrathin nanoplates. Thermodynamic energy analysis confirmed that the surface energy of the ultrathin nanoplates is the cause of the remarkable stabilization of the metastable bct phase. The mechanism of surface energy regulation can be expanded to other metallic oxides, thus providing a new means for manipulating and stabilizing novel materials under ambient conditions that otherwise would not be recovered., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)