Yucheng Wang

Non-radiative decay of surface plasmon (SP) offers a novel paradigm for efficient conversion of photons into carriers. However, the narrow bandwidth of SP has been a significant obstacle to the widespread applications. Previously, research and applications mainly focused on noble metals such as Au, Ag, and Cu. In this article, we report an Ag-Al alloy material, μ-Ag₃Al, in which the surface plasmon operating bandwidth is 1.7 times that of Ag and hot carrier transport properties are comparable with those of AuAl. The results show that μ-Ag₃Al allows efficient direct interband electronic transitions from ultraviolet (UV) to near infrared range. Spherical nanoparticles of μ-Ag₃Al exhibit the localized surface plasmon resonance (LSPR) effect in the ultraviolet region. Its surface plasmon polariton (SPP) shows strong non-radiative decay at 3.36 eV, which is favorable for the generation of high-energy hot carriers. In addition, the penetration depth of SPP in μ-Ag₃Al remains high across the UV to the near-infrared range. Moreover, the transport properties of hot carriers in μ-Ag₃Al are comparable with those in Al, borophene and Au-Al intermetallic compounds. These properties can provide guidance for the design of plasmon-based photodetectors, solar cells, and photocatalytic reactors.

Compared with traditional far-field objective lenses, microparticle lenses have a distinct advantage of nonobservance of the diffraction limit, which has attracted extensive attention for its application in subwavelength photolithography and super-resolution imaging. In this article, a complete simulation model for a microparticle lens assisted microscopic imaging system was built to analyze the imaging characteristics of any shape of microparticle lens. With this model, we simulated the resolution of a conventional objective lens, a microsphere lens and a hollow microsphere lens, which verified the correctness of our simulation model and demonstrated the super-resolution imaging ability of microsphere lenses. Secondly, the focusing and imaging characteristics of four typical microparticle lenses are illustrated, and how the focal spot affects imaging resolution and imaging quality is analyzed. Upon this conclusion, we reformed and upgraded the microsphere lens with several parameters for smaller focal spots and higher imaging resolution. Finally, three types of microparticle lenses were designed through the optimized parameters and their focusing and imaging characteristics were demonstrated with a minimum FWHM of 140 nm at the focal plane and a highest imaging resolution around 70 nm (~λ/6). Our work opens up a new perspective of super-resolution imaging with near-field microparticle lens.

Quantum dots (QDs) are luminescent nanocrystals with rich surface chemistry and unique optical properties that make them useful as probes or carriers for traceable targeted delivery and therapy applications. QDs can be functionalized to target specific cells or tissues by conjugating them with targeting ligands. Recent advancement in making biocompatible QD formulations has made these nanocrystals suitable for in vivo applications. This review provides an overview of the preparation of QDs and their use as probes or carriers for traceable, targeted therapy of diseases in vitro and in vivo. More specifically, recent advances in the integration of QDs with drug formulations for therapy and their potential toxicity in vitro and in vivo are highlighted. The current findings and challenges for optimizing QD/drug formulations with respect to optimal size and stability, short-term and long-term toxicity, and in vivo applications are described. Lastly, we attempt to predict key trends in QD/drug formulation development over the next few years and highlight areas of therapy where their use may provide breakthrough results in the near future.

A variety of title fluoroquinolone derivatives such as (VII) and (IX) are synthesized and evaluated for their in vitro antibacterial activities.