The Rise of Scalable Micro/Nanopatterning

All-dielectric concentration of electromagnetic fields at the nanoscale: the role of photonic nanojets

The photonic nanojet (PNJ) is a narrow high-energy beam that was originally found on the back side of all-dielectric spherical structures. It is a unique type of energy concentration mode. The field of PNJs has experienced rapid growth in the past decade: nonspherical and even pixelized PNJ generators based on new physics and principles along with extended photonic applications from linear optics to nonlinear optics have driven the re-evaluation of the role of PNJs in optics and photonics. In this article, we give a comprehensive review for the emerging sub-topics in the past decade with a focus on two specific areas: (1) PNJ generators based on natural materials, artificial materials and nanostructures, and even programmable systems instead of conventional dielectric geometries such as microspheres, cubes, and trihedral prisms, and (2) the emerging novel applications in both linear and nonlinear optics that are built upon the specific features of PNJs. The extraordinary features of PNJs including subwavelength concentration of electromagnetic energy, high intensity focusing spot, and lower Joule heating as compared to plasmonic resonance systems, have made PNJs attractive to diverse fields spanning from optical imaging, nanofabrication, and integrated photonics to biosensing, optical tweezers, and disease diagnosis.

Trimethyl Lock: A Multifunctional Molecular Tool for Drug Delivery, Cellular Imaging, and Stimuli-Responsive Materials

Trimethyl lock (TML) systems are based on ortho-hydroxydihydrocinnamic acid derivatives displaying increased lactonization reactivity owing to unfavorable steric interactions of three pendant methyl groups, and this leads to the formation of hydrocoumarins. Protection of the phenolic hydroxy function or masking of the reactivity as benzoquinone derivatives prevents lactonization and provides a trigger for controlled release of molecules attached to the carboxylic acid function through amides, esters, or thioesters. Their easy synthesis and possible chemical adaption to several different triggers make TML a highly versatile module for the development of drug-delivery systems, prodrug approaches, cell-imaging tools, molecular tools for supramolecular chemistry, as well as smart stimuliresponsive materials.