Application of 300× Enhanced Fluorescence on a Plasmonic Chip Modified with a Bispecific Antibody to a Sensitive Immunosensor

Abstract

The grating substrate covered with a metal layer, a plasmonic chip, and a bispecific antibody can play a key role in the sensitive detection of a marker protein with an immunosensor, because of the provision of an enhanced fluorescence signal and the preparation of a sensor surface densely modified with capture antibody, respectively. In this study, one of the tumor markers, a soluble epidermal growth factor receptor (sEGFR), was selected as the target to be detected. The ZnO- and silver-coated plasmonic chip with precise regularity and the appropriate duty ratio in the periodic structure further enhanced the fluorescence intensity. As for sensor surface modification with capture antibody, a bispecific antibody (anti-sEGFR and anti-ZnO antibody), the concentrated bispecific antibody solution was found to nonlinearly form a surface densely immobilized with antibody, because the binding process of a bispecific antibody to the ZnO surface can be a competitive process with adsorption of phosphate. As a result, the interface on the plasmonic chip provided a 300× enhanced fluorescence signal compared with that on a ZnO-coated glass slide, and therefore sEGFR was found to be quantitatively detected in a wide concentration range from 10 nM to 700 fM on our plasmonic surface.

Solid-binding peptides: smart tools for nanobiotechnology

“…The antibodies then were subjected to directed evolution to improve their binding avidity and specificity. Recently, these antibodies have been used to mediate the self-assembly of hybrid nanomaterials and the functionalisation of immunosensors [26,27]. Even though antibodies offer a structural scaffold for SBPs that can improve their stability and binding avidity, this approach is complex and suffers from a lack of versatility because it requires the specific modification of antibodies.…”

Molecular recognition and specificity of biomolecules to titanium dioxide from molecular dynamics simulations

“…Solid binding peptides (SBPs) have garnered a lot of attention in the last decade as they are biocompatible and can be efficiently engineered to recognize and pattern a wide variety of interfaces 1,2 . Their applications include nanomaterial synthesis 3,4 , immobilization of biomolecules 5 , medical implants 6 , vaccine stabilization 7 , sensors 8 , and catalysis 9 . A common technique to identify and tailor SBP sequences is by a combinatorial approach known as peptide phage display library, in which a diverse pool of random amino acid sequences are tested, and a few candidates are narrowed down based on the affinity of a sequence to the target material 10,11 .…”

Optimal Structure of a Plasmonic Chip for Sensitive Bio-Detection with the Grating-Coupled Surface Plasmon-Field Enhanced Fluorescence (GC-SPF)

“…In propagating SPR, there are prism-coupled SPR (PC-SPR) and grating-coupled SPR (GC-SPR). Early biosensors were based on PC-SPF [ 11 ], but GC-SPF has recently been applied to biosensors [ 15 , 16 , 17 , 18 ]. Wavelength-scale periodic structure coated with metal films is essential for GC-SPF method.…”

“…Wavelength-scale periodic structure coated with metal films is essential for GC-SPF method. We call it a plasmonic chip [ 15 , 16 , 17 , 18 , 19 , 20 ], which has been used as a sensor-chip. The plasmonic chip used with the SPF method has an overlayer composed of dielectric medium such as SiO 2 on the metal film.…”