Helicoid plasmonic nanoparticles with intrinsic chirality are an emerging class of artificial chiral materials with tailorable properties. The ability to extend their chiroplasmonic responses to the near-infrared (NIR) range is critically important for biomedical and nanophotonic applications, yet the rational design of such materials remains challenging. Herein, a strategy employing chiral plasmon-dielectric coupling is proposed to manipulate the chiroptical responses into the NIR region with high optical anisotropy. Through this strategy, the helicoid Au@Cu₂O nanoparticles with structural chirality are designed and synthesized with tunable and enriched NIR chiroptical responses. Specially, a high optical anisotropy (g-factor) with a value of 0.35 is achieved in the NIR region, and multi-band chiroptical behaviors are observed. Spectral and electromagnetic simulations elucidate that strong coupling between chiroplasmonic core and chiral dielectric shell with high refractive index contributes to the rich and strong chiroptical responses, which are related to the interplay between various emerged and enhanced electric and magnetic multipolar resonance modes proved by multipole expansion analysis. Moreover, the helicoid Au@Cu₂O nanoparticles display greater polarization rotation capability than the helicoid Au nanoparticles. This work offers mechanistic insights into chiral plasmon-dielectric coupling and suggests a general approach of creating NIR chiroplasmonic materials.

A novel PDI-bridged Au–graphene nanohybrid was synthesized and used to fabricate a label-free hpDNA biosensor.

In this study, a low-cost disposable graphene sensor was fabricated for detecting heavy metals such as Cd²⁺, Pb²⁺ and Cu²⁺ by the anodic stripping voltammetry method (ASV). Vacuum compacted graphene films were used as the three electrodes, and they showed excellent conductivity and low noise signals. A big advantage was the simple fabrication process of graphene films without any binder. Furthermore, a ferrocene-based internal reference was introduced in the working electrode. The analytes were recognized by the relative distances of the stripping potential peaks between the working electrode and internal reference electrode. Finally, the all-graphene-based sensor was successfully built for the electrochemical analysis and then applied for determination of heavy metals in real river-water samples.