Dendrimer-Functionalized Self-Assembled Monolayers as a Surface Plasmon Resonance Sensor Surface

Abstract

We report here a multistep route for the immobilization of DNA and proteins on chemically modified gold substrates using fourth-generation NH(2)-terminated poly(amidoamine) dendrimers supported by an underlying amino undecanethiol (AUT) self-assembled monolayer (SAM). Bioactive ultrathin organic films were prepared via layer-by-layer self-assembly methods and characterized by fluorescence microscopy, variable angle spectroscopic ellipsometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR). The thickness of the AUT SAM base layer on the gold substrates was determined to be 1.3 nm from ellipsometry. Fluorescence microscopy and AFM measurements, in combination with analyses of the XPS/ATR-FTIR spectra, confirmed the presence of the dendrimer/biopolymer molecules on the multilayer sensor surfaces. Model proteins, including streptavidin and rabbit immunoglobulin proteins, were covalently attached to the dendrimer layer using linear cross-linking reagents. Through surface plasmon resonance measurements, we found that sensor surfaces containing a dendrimer layer displayed an increased protein immobilization capacity, compared to AUT SAM sensor surfaces without dendrimer molecules. Other SPR studies also revealed that the dendrimer-based surfaces are useful for the sensitive and specific detection of DNA-DNA interactions. Significantly, the multicomponent films displayed a high level of stability during repeated regeneration and hybridization cycles, and the kinetics of the DNA-DNA hybridization process did not appear to be influenced by surface mass transport limiting effects.

Surface plasmon resonance for detecting clenbuterol: Influence of monolayer structure

“…In order to add high selectivity, biochemical recognition elements, such as antibodies, enzymes, proteins, DNA and cells are immobilized on the solid surface of the SPR sensor [7][8][9][10]. Biochemical recognition elements can be immobilized by physical adsorption [11], by embedding in polymers or membranes [12,13], by trapping in solgels [14,15], and by using functionalized alkanethiol or functionalized alkylsilane self-assembled monolayer (SAM) [16,17]. Each immobilization approach has advantages.…”

Dendrimers as Dopant Atom Carriers

“…Ordinary amino-terminated dendrimers are often anchored by covalent bonds with carboxyl groups. For example, Mark et al [92] reported in Figure 18 that the gold surface was firstly modified by AUT and bis-[sulfosuccinimidyl]suberate molecules through Au-S bonds. Then, through the activated carboxyl by NHS, the G4 dendrimer can be bonded to the carboxyl group by formation of amide bonds.…”

Demonstration of near infrared gas sensing using gold nanodisks on functionalized silicon

“…In order to use metallic nanoparticles for sensing purposes, a number of different approaches have been demonstrated for immobilization of different molecules on the metal surfaces, such as physical adsorption [8,9], embedding in polymers [10], self-assembly [11,12], or Langmuir-Blodgett deposition [13]. Among them, use of self-assembly monolayers (SAMs) for coating metal surfaces before immobilization is of considerable interest because they help to minimize the non-specific adsorption problem and to introduce reactive groups for specific immobilization [7].…”