Multifunctional Au Nanoparticle Dendrimer-Based Surface Plasmon Resonance Biosensor and Its Application for Improved Insulin Detection

Abstract

Bifunctional hydroxyl/thiol-functionalized fourth-generation polyamidoamine dendrimer (G4-PAMAM)-encapsulated Au nanoparticle (NP) was synthesized and immobilized on a mixed self-assembled monolayer (SAM)-modified gold surface. This modified surface was resistant to nonspecific adsorption of proteins having a wide range of molecular weight and isoelectric points. Part of the dendrimer thiol groups were converted to hydrazide functionalities providing an activated surface available to subsequently immobilize the receptor for developing a sensor surface to immunoaffinity reaction. Herein, the surface plasmon resonance (SPR) detection of insulin was obtained by means of a competitive immunoassay principle. The resulting Au NP dendrimer-modified surface provided an assay with high stability, significantly enhanced sensitivity, and a detection limit for analyzing insulin of 0.5 pM. The SPR detection of insulin was amplified due to the changes in the dielectric properties of the matrixes, occurring upon the biorecognition processes on the sensor surface, through the coupling of the localized plasmon of the NPs with the surface plasmon wave. The developed sensor chip was used to analyze insulin in human serum samples from healthy and diabetic patients. The results showed good correlation to the reference method. The specificity and the improved sensitivity of this biosensing platform could have significant implications for the detection of a wide range of molecules and biomarkers in complex biological media.

Synthesis methods of gold nanoparticles for Localized Surface Plasmon Resonance (LSPR) sensor applications

“…An enhance sensitivity with detection limit of 0.5 pM and EPJ Web of Conferences 162, 01002 (2017) DOI: 10.1051/epjconf/201716201002 InCAPE2017 increased stability were resulted from the GNPsmodified dendrimers. By studying human serum samples with good correlation to standard methods by comparing normal and diabetic patients, the sensor was further certified [60]. An alteration happened due to an increased in surface absorption band to the visible colour change caused by the GNPs aggregation.…”

Contribution of gold nanoparticles to the signal amplification in surface plasmon resonance

“…Many approaches have been explored, such as use of fluorescence, 1 modifying the sensor chip with particles, 2,3 performing a labelled assay using large particles, etc. [4][5][6] Among these, the use of gold nanoparticles (AuNPs) [7][8][9][10][11][12] for signal amplification has obtained significantly improved sensitivity. For example, He et al reported the sandwich approach to detect DNA hybridisation.…”

“…4 Corn and coworkers realised 10 fM detection by a combination of poly(A) enzyme chemistry and nanoparticle-amplified SPR imaging. 5 However, the signal enhancement by employing AuNPs can be caused by different factors: [4][5][6][7][8][9][10][11][12] (1) surface mass increase due to AuNPs and more molecules being attached to the AuNPs than the planar gold surface; (2) refractive index change by the particles; (3) electromagnetic field coupling between SPR and localised SPR (LSPR). Among these factors, the coupling effect has been expected to play a dominant role.…”

Oxygen Attachment on Alkanethiolate SAMs Induced by Low-Energy Electron Irradiation

“…[1][2][3] The properties of SAMs (i.e., low thickness, densely packed, ordered stacking, high stability, choice of functional heading groups, and resistance against chemicals) 2,4 make these surface coatings suitable for varied applications including control of wetting and adhesion, 5,6 biosensors, 7 microcontact printing, 8 and cell adhesion. 2 Furthermore, these molecular assemblies present interesting structural and physicochemical properties (i.e., small thickness of about 1-3 nm and the molecular size of its structural elements) for radiation-induced nanostructure patterning lithography.…”