Biomimetic Ag/ZnO@PDMS Hybrid Nanorod Array-Mediated Photo-induced Enhanced Raman Spectroscopy Sensor for Quantitative and Visualized Analysis of Microplastics

Microplastics are persistent pollutants that accumulate in the environment and can cause serious toxicity to mammals. At present, few technologies are able to quantitatively detect chemicals and provide morphological information simultaneously. Herein, we developed a dragonfly-wing-mimicking ZnO nanorod array decorated with AgNPs on polydimethylsiloxane (PDMS) as a surface-enhanced Raman spectroscopy (SERS) and photo-induced enhanced Raman spectroscopy (PIERS) substrate for trace analysis of microplastics. The Ag/ZnO@PDMS hybrid nanorod array endows the sensor with high sensitivity and signal repeatability (RSD ∼ 5.89%), ensuring the reliable quantitative analysis of microplastics. Importantly, when the noble metal–semiconductor substrate was pre-radiated with ultraviolet light, a surprising PIERS was attained, achieving an additional enhancement of 11.3-fold higher than the normal SERS signal. By combining the PIERS technology with the “coffee ring effect”, the sensor successfully discerned microplastics of polyethylene (PE) and polystyrene (PS) at a trace level of 25 μg/mL even with a portable Raman device. It was capable of identifying PS microspheres in contaminated tap water, lake water, river water, and seawater with detection limits of 25, 28, 35, and 60 μg/mL, respectively. The recovery rates of PS microspheres in four water environments ranged from 94.8 to 102.4%, with the RSD ranging from 2.40 to 6.81%. Moreover, quantitative and visualized detection of microplastics was readily realized by our sensor. This portable PIERS sensor represents a significant step toward the generalizability and practicality of quantitative and visual sensing technology

Rationally Designed Graphene/Bilayer Silver/Cu Hybrid Structure with Improved Sensitivity and Stability for Highly Efficient SERS Sensing

A simple and cost-effective strategy was rationally designed to fabricate a special sandwich structure consisting of graphene, bilayer silver, and a copper plate, which was used as a surface-enhanced Raman scattering (SERS) substrate for highly efficient SERS sensing and detection of trace molecules. Silver dendrite (AgD) nanostructures were subsequently grown on a silver nanosphere (AgNS)/Cu surface to form a bilayer silver/Cu structure, which showed a 1.5-fold Raman enhancement compared to that of the AgNS/Cu substrate. After depositing graphene on the bilayer silver/Cu substrate to obtain a sandwich structure, a higher SERS enhancement and better durability were enabled. The SERS performances, measured by a portable Raman instrument, showed that the optimized sandwich structure substrate exhibited high SERS sensitivity to crystal violet (CV) and rhodamine 6G (R6G) with low limit of detection of 10^–9 and 10^–8 M, respectively. Such a sandwich-structured substrate exhibited good reproducibility across the entire detection areas with an average relative standard deviation less than 5.9%, which permits its reliable quantitative detection of CV and R6G molecules. In addition, graphene both effectively improved the SERS performances and protected Ag nanocrystals from oxidation, which endowed the sandwich structure a long-term stability with deviation of characteristic peaks’ intensity lower than 3.6% after 25 days. This study indicates that the graphene/bilayer silver/Cu sandwich structure as a SERS substrate has a great potential in detecting environmental pollutants

Structure-Based Discovery and Optimization of Benzo[<i>d</i>]­isoxazole Derivatives as Potent and Selective BET Inhibitors for Potential Treatment of Castration-Resistant Prostate Cancer (CRPC)

The bromodomain and extra-terminal (BET) family proteins have gained increasing interest as drug targets for treatment of castration-resistant prostate cancer (CRPC). Here, we describe the design, optimization, and evaluation of benzo­[<i>d</i>]­isoxazole-containing compounds as potent BET bromodomain inhibitors. Cocrystal structures of the representative inhibitors in complex with BRD4(1) provided solid structural basis for compound optimization. The two most potent compounds, <b>6i</b> (Y06036) and <b>7m</b> (Y06137), bound to the BRD4(1) bromodomain with <i>K</i>_d values of 82 and 81 nM, respectively. They also exhibited high selectivity over other non-BET subfamily members. The compounds potently inhibited cell growth, colony formation, and the expression of AR, AR regulated genes, and MYC in prostate cancer cell lines. Compounds <b>6i</b> and <b>7m</b> also demonstrated therapeutic effects in a C4-2B CRPC xenograft tumor model in mice. These potent and selective BET inhibitors represent a new class of compounds for the development of potential therapeutics against CRPC