Iridescent Colloidal Crystals Composed of SiO₂ Porous Hollow Sphere for SERS Application

Abstract

In recent years, the application of low-refractiveindex materials in the optical field has attracted considerable attention due to it high transmittance and high optical sensitivity. In this study, we synthesized SiO 2 porous hollow spheres (SPHS) with an ultralow refractive index (n = 1.05) by using a templating method. Their refractive indices could be easily controlled from 1.05 to 1.08 by tuning the thickness of shell. In addition, a droplet coatings method is proposed for SPHS colloidal crystal (CC) by controlling the temperature and humidity. The SPHS CCs displayed distinct structural colors when the incident angle was adjusted and demonstrated high angular resolution. Moreover, the iridescent color changes could be observed with the naked eye. For surface-enhanced Raman scattering application, more analyte could be absorbed by the porous shells, and metal nanoparticles were coated on the SPHSs surface to increase the hot spot density for improving the SERS intensity.

Ordered Anodic Aluminum Oxide-Based Nanostructures for Surface-Enhanced Raman Scattering: A Review

“…Owing to the strong optical confinement of PS microcavity and the LSPR of AuNPs, the biosensors showed excellent SERS performance with detection limit as low as 0.045 pg·mL –1 for the Epstein–Barr virus antibody (EBV IgG). Liu et al synthesized Au-coated SiO 2 porous hollow spheres that provided substantial absorption sites for Rhodamine 6G (R6G) molecules during SERS detecting . To further expand the library of semiconductor-based SERS substrates, Li and co-workers utilized TiO 2 nanotubes as the template for Au nanoparticles and realized bacteria discrimination .…”

Controllable Synthesis, Formation Process, and Luminescence Performances of Diverse Yttrium Compounds with Hollow Structures

“…18 Among multiform morphologies, hollow spherical micro/nanostructures have attracted great interest due to their low density and refractive index, excellent encapsulation capacity, and surface permeability. 19,20 The hollow spherical inorganic compounds exhibit great prospects in biochemistry and materials research, including drug delivery, optoelectronic devices, catalysis, sensors, and electrode materials. 21−24 The controlled fabrication of rare earth compounds with hollow spherical structures has been a hot research topic in the past few decades.…”

“…To date, Y 2 O 3 and YBO 3 micro/nanostructures with various dimensions, morphologies, and particle sizes have been synthesized, including nanorods, nanospheres, nanosheets, and core–shell structures . Among multiform morphologies, hollow spherical micro/nanostructures have attracted great interest due to their low density and refractive index, excellent encapsulation capacity, and surface permeability. , The hollow spherical inorganic compounds exhibit great prospects in biochemistry and materials research, including drug delivery, optoelectronic devices, catalysis, sensors, and electrode materials. − The controlled fabrication of rare earth compounds with hollow spherical structures has been a hot research topic in the past few decades. On the other hand, hollow spherical rare earth functional materials would save expensive rare earth resources based on ensuring reliable performance.…”

Enhancing Detection Reproducibility of Surface-Enhanced Raman Scattering by Controlling Analytes under One Laser Spot

“…For example, Liang Zhang et al employed evaporation-induced relatively uniform transients to detect creatinine in human serum to avoid the “coffee-ring” effect . Some research groups increased the resistance of analyte molecules to radial outward flow by using a hydrophobic substrate − and decreased droplet deposition on the contact line by using electrically controlled enrichment, , among other things. Although these methods have improved the detection reproducibility by effectively avoiding the “coffee-ring” effect, there are still some problems that need to be solved.…”