Templated synthesis of patterned gold nanoparticle assemblies for highly sensitive and reliable SERS substrates

Formation of plasmonic structure in closely packed assemblies of metallic nanoparticles(NPs)is essential for various applications in sensing,renewable energy,authentication,catalysis,and metamaterials.Herein,a surface-enhanced Raman scattering(SERS)substrate is fabricated for trace detection with ultrahigh sensitivity and stability.The SERS substrate is constructed from a simple yet robust strategy through in situ growth patterned assemblies of Au NPs based on a polymer brush templated synthesis strategy.Benefiting from the dense and uniform distribution of Au NPs,the resulting Au plasmonic nanostructure demonstrates a very strong SERS effect,while the outer polymer brush could restrict the excessive growth of Au NPs and the patterned design could achieve uniform distribution of Au NPs.As results,an ultra-low limit of detection(LOD)of 10^(−15)M,which has never been successfully detected in other work,is determined for 4-acetamidothiophenol(4-AMTP)molecules and the Raman signals in the random region show good signal homogeneity with a low relative standard deviation(RSD)of 7.2%,indicating great sensitivity and reliability as a SERS substrate.The LOD values of such Au plasmonic nanostructures for methylene blue,thiram,and R6G molecules can also reach as low as 10^(−10)M,further indicating that the substrate has a wide range of applicability for SERS detection.With the help of finite difference time domain simulations(FDTD)calculation,the electric field distribution of the Au plasmonic nanostructures is simulated,which quantitatively matches the experimental observations.Moreover,the Au plasmonic nanostructures show good shelf stability for at least 10 months of storage in an ambient environment,indicating potentials for practical applications.

Recent progress in periodic patterning fabricated by self-assembly of colloidal spheres for optical applications

Colloidal crystals are periodically ordered arrays of monodisperse colloidal particles which represent a new class of self-assembled materials showing potential applications in many fields.Two-dimensional graphic nanostructures based on colloidal crystals have inherent periodicity from tens of nanometers to several micrometers,which gives them rich and interesting optical properties.This article presents a comprehensive review about the current research activities on the self-assembly of colloidal spheres which is an effective strategy for fabrication of various hierarchical and ordered nanostructures,with particular attention paid to the unique properties and applications of the colloidal crystal-based nanostructures.Three main aspects are elaborated:a)controllable self-assembly of colloidal crystals;b)the functions of the obtained colloidal spheres acting as the patterned mask for successive construction of numerous nanostructures;c)the novel properties and promising optical applications of the patterned nanostructures in various domains,such as plasmonic-related fields,antireflection,photonic crystals,photocatalysis and electronic devices.After that,the current challenges and future perspectives in this area are provided.This review aims to inspire more ingenious designs and exciting research for manufacturing nanostructures utilizing colloidal self-assembly.

Recent advances in photonic crystal with unique structural colors:A review

Inspired by special color-forming organisms in nature,photonic crystal materials with structural color function have been developed significantly with great potential applications for displays,sensors,anti-counterfeiting inks,etc.This review aims to summarize the functions,self-assembly modes,and ap-plications of different kinds of photonic crystal materials.The preparation methods and characteristics of monodisperse inorganic nanoparticles,polymer nanoparticles,inorganic/organic core-shell nanoparti-cles,and MOFs are discussed.Subsequently,we summarize the method of assembling colloidal parti-cles into photonic crystals,which is a template induction method,inkjet printing method,drop coating method,etc.Moreover,the potential application of structural color is presented including humidity re-sponse and magnetic field response in sensors fields,as well as the advantages and disadvantages of anti-counterfeiting,fabric coloring,displays,smart windows,and Biomedical Applications.Finally,we present the development prospects and key problems of photonic crystals.