Template-Stripped Smooth Ag Nanohole Arrays with Silica Shells for Surface Plasmon Resonance Biosensing

Abstract

Inexpensive, reproducible and high-throughput fabrication of nanometric apertures in metallic films can benefit many applications in plasmonics, sensing, spectroscopy, lithography and imaging. Here we use template stripping to pattern periodic nanohole arrays in optically thick, smooth Ag films with a silicon template made via nanoimprint lithography. Ag is a low-cost material with good optical properties, but it suffers from poor chemical stability and biocompatibility. However, a thin silica shell encapsulating our template-stripped Ag nanoholes facilitates biosensing applications by protecting the Ag from oxidation as well as providing a robust surface that can be readily modified with a variety of biomolecules using well-established silane chemistry. The thickness of the conformal silica shell can be precisely tuned by atomic layer deposition, and a 15-nm-thick silica shell can effectively prevent fluorophore quenching. The Ag nanohole arrays with silica shells can also be bonded to polydimethylsiloxane (PDMS) microfluidic channels for fluorescence imaging, formation of supported lipid bilayers, and real-time, label-free SPR sensing. Additionally, the smooth surfaces of the template-stripped Ag films enhance refractive index sensitivity compared with as-deposited, rough Ag films. Because nearly centimeter-sized nanohole arrays can be produced inexpensively without using any additional lithography, etching or lift-off, this method can facilitate widespread applications of metallic nanohole arrays for plasmonics and biosensing.

Recent Progress on Plasmon-Enhanced Fluorescence

“…In order to avoid the fluorescence quenching effect, silicon oxidation film also introduced as a spacer layer to separate the fluorescent molecule from the substrate [42]. Recently, a periodical nanostructure with nanohole arrays formed in continued silver films was fabricated with template-stripping technique first and then with an atomic layer deposition grown oxide layer on it, such as silica shell or alumina, to prevent fluorophore quenching [43,44].…”

“…[43] [44] Figure 3 (A) The transmission spectra of white light across nanohole arrays. The uncoated nanohole array film with pitch I=440 nm (curve a), p=550 nm(curve b), and coated with a dye film of oxazine 720 with p=440 nm(curved c), B) The calculated factor of enhancement from nanohole arrays with different pitch.…”

Hybrid nanomaterial: biocolloidals

“…IONPs can be biocompatible after certain surface modifications. They are deactivated by the liver as an iron pool, and then they are totally removed in 2 days (Jang et al, 2008;Janib et al, 2010;Im et al, 2011;Baldassarre et al, 2015).…”

“…Recent advances for colloidal particles have enabled the synthesis of highly monodispersed colloidal particles with biomolecules to obtain more functional hybrid nanoscale materials. To utilize the unique properties of nanomaterials, these advanced methods have always been examined for a biological setting (Hayward et al, 2000;Joannopoulos et al, 2011;Im et al, 2011;Hasany et al, 2013;Han et al, 2014;Hashemizadeh and Huyeh, 2014;Hassan and Singh, 2014;Kumar et al, 2014;Gui et al, 2015;Guisbiers et al, 2015;Harris et al, 2015;Rodio et al, 2016).…”

Desarrollo de superficies nanoestructuradas para biosensores ópticos y sensores biomiméticos

“…El metal que presenta mayor conductividad es la plata, seguido del cobre, el oro y el aluminio. Independientemente de la configuración utilizada, los metales empleados en la inmensa mayoría de los biosensores plasmónicos son metales nobles, [47][48][49] principalmente plata 50 y oro, 51 predominando este último debido a su gran estabilidad química (baja reactividad). Sin embargo, estos metales presentan un coste elevado, representando un inconveniente para la fabricación a gran escala, así como para la comercialización y rentabilidad de biosensores basados en los mismos.…”