Original Covalent Approach for Gold Nanorods Immobilization onto Acid-Terminated-Cysteamine Self-Assembled Monolayers for FT-SPR Biosensor Applications

Politi J De Stefano L

doi:10.4172/2155-6210.1000167

Abstract

In this paper, we report an original method to immobilize gold nanorods onto mixed self-assembled monolayers (SAMs) of Mercaptoundecanoic Acid (MUA), Mercaptohexanol (MOH) and cysteamine (CYS) onto planar gold surface. Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed a remarkable shape and size narrow distribution on well functionalized gold surfaces, as well as a tendency to form linear assemblies after immobilization. The results highlight the good distribution of gold nanorods with an average length of 32.6 ± 0.9 nm and width of 13 ± 1.8 nm, the simplicity of the immobilization procedure of gold nanorods and the interest of using them as labels to enhance the sensitivity of FT-SPR-based sensors. gold nanostructured surface FT-SPR measurements of biorecognition using gold nanorods immobilized onto gold surfaces were performed at various prostatic antigen specific (PSA) concentrations, from 5 mg/L to 0.5 mg/L reaching a system sensitivity of 37 ± 2 cm-1/ mgL-1.

Highlights

Antibody immobilization is an important subject with a variety of purposes such as in diagnostic immunoassays
The immobilization of Au nanorods (AuNr) onto planar gold surface using by Self-assembling monolayers (SAMs) functionalization, was performed by PM-IRRAS providing to identification of chemical groups onto gold planar surface after each step of functionalization
We described a new concept of functionalization and self-organization of gold nanorods, bearing Cetyltrimethylammonium bromide (CTAB) positively charged ligands, in order to bind proteins in an anisotropic way, and form linear chains after functionalization

Summary

Introduction

Antibody immobilization is an important subject with a variety of purposes such as in diagnostic immunoassays. Self-assembling monolayers (SAMs) offer the possibility to modify the terminal functions of thiol-chains to bind any type of ligands by covalent, ionic or hydrogen interactions [4]. Some methods include organization of nanospheres via simple solvent evaporation [6], attachment onto SAMs via covalent interactions and by Langmuir-Blodgett (LB) technique [7,8]. El Sayed [9] have demonstrated that simple solvent evaporation leads to the organization of gold nanorods into one, two, and three-dimensional structures. Most of the above-mentioned methods use either nonspecific interactions [11,12] or specialized techniques for the organization of nanorods onto 2D surfaces. A simple method for programmated assembly of nanorods using covalent interactions is yet to be investigated

Methods

Results

Conclusion