Monolayer transition metal dichalcogenides exhibit remarkable electronic and optical properties, making them candidates for application within flexible nano-optoelectronics, however direct experimental determination of their thermal expansion coefficients (TECs) is difficult. Here, we propose a non-destructive method to probe the TECs of monolayer materials using surface-enhanced Raman spectroscopy (SERS). A strongly coupled Ag nanoparticle over-layer is used to controllably introduce temperature dependent strain in monolayers. Changes in the first-order temperature coefficient of the Raman shift, produced by TEC mismatch, can be used to estimate relative expansion coefficient of the monolayer. As a demonstration, the linear TEC of monolayer WS₂ is probed and is found to be 10.3 × 10⁻⁶ K⁻¹, which would appear support theoretical predictions of a small TEC. This method opens a route to probe and control the TECs of monolayer materials.

Arguments regarding the biocompatibility of graphene-based materials (GBMs) have never ceased. Particularly, the genotoxicity (e.g., DNA damage) of GBMs has been considered the greatest risk to healthy cells. Detailed genotoxicity studies of GBMs are necessary and essential. Herein, we present our recent studies on the genotoxicity of most widely used GBMs such as graphene oxide (GO) and the chemically reduced graphene oxide (RGO) toward human retinal pigment epithelium (RPE) cells. The genotoxicity of GO and RGOs against ARPE-19 (a typical RPE cell line) cells was investigated using the alkaline comet assay, the expression level of phosphorylated p53 determined via Western blots, and the release level of reactive oxygen species (ROS). Our results suggested that both GO and RGOs induced ROS-dependent DNA damage. However, the DNA damage was enhanced following the reduction of the saturated C–O bonds in GO, suggesting that surface oxygen-containing groups played essential roles in the reduced genotoxicity of graphene and had the potential possibility to reduce the toxicity of GBMs via chemical modification.

Orderly YPO₄:Eu³⁺ olivary architectures with a length of about 8 μm and a diameter of about 5 μm have been synthesized successfully by a limited anion-exchange reaction (LAER) under hydrothermal conditions. These 3D olives in fact are composed of irregular tetragonal nanoflakes with an average size of 1500 × 1000 × 60 nm³, these flakes align parallel or interlace with each other. The evolution of this special morphology of the samples has been investigated in detail. It was found that the amount of the HNO₃ used in the solution, the change of the phosphorous sources, and the reaction time have visible influences on the morphologies of the product. A possible formation and growth mechanism of the hierarchical structures was suggested according to the experimental results and analysis. The luminescent properties of the products were also studied. Both the obtained products and the synthesis methods used in the preparation may shed some light on the further synthesis and application.

In this study, a one-step electrochemical aptasensor was developed to detect the biomarker vascular endothelial growth factor (VEGF), an important protein in the pathogenesis of many retinal diseases, including age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, and retinal vein occlusion. The aptamer has a good affinity and can rapidly identify and capture VEGF based on its unique structure. We designed a VEGF aptasensor based on the aptamer recognition and complex metallo nanoenzyme particles as an electron exchange center and bridge between capture DNA and electrode. The aptamers maintained the hairpin structure to avoid nonspecific surface adsorption and expose the capture sequence outwards when the target was inexistent. Conversely, the aptamers opened the hairpin structure to release space to accomplish binding between VEGF and DNA, resulting in increased impedance. The performance of the electrochemical aptasensor is detected by electrochemical impedance spectroscopy (EIS). The limit of detection by EIS was as low as 8.2 pg ml⁻¹, and the linear range was 10 pg ml⁻¹–1 μg ml⁻¹. The electrochemical aptasensor also showed high specificity and reproducibility.