Gold Nanoparticle-Enhanced Detection of DNA Hybridization by a Block Copolymer-Templating Fiber-Optic Localized Surface Plasmon Resonance Biosensor.

Mengdi Lu,Wei Peng,Ming Lin,Yang Zhang,Fang Wang

doi:10.3390/nano11030616

Abstract

To overcome low surface coverage and aggregation of particles, which usually restricts the sensitivity and resolution of conventional localized surface plasmon resonance (LSPR) fiber-optic sensors, we propose a simple self-assembled templating technique that uses a nanometer thickness block copolymer (BCP) layer of poly(styrene-b-4-vinylpyridine) to form a 33 nm gold nanoparticle (AuNP) monolayer with high uniformity and density for LSPR sensing. The LSPR resonance wavelength for this PS-b-P4VP templated methodology is 592 nm and its refractive index sensitivity is up to 386.36 nm/RIU, both of which are significantly improved compared to those of conventional LSPR techniques. Calibrated by a layer-by-layer polyelectrolyte deposition procedure, the decay length of this LSPR sensor is calculated to be 78 nm, which is lower than other traditional self-assembled LSPR sensors. Furthermore, hybridization between target ssDNA, which is linked with capture ssDNA on the LSPR biosensor and DNA–AuNP conjugates, leads to a low detection limit of 67 pM. These enhanced performances are significant and valuable for high-sensitivity and cost-effective LSPR biosensing applications.

Highlights

Localized surface plasmon resonance (LSPR) fiber-optic sensors have been widely investigated in recent years for biomolecule analysis [1,2], since the surface metallic nanoparticle arrays are extremely sensitive to the refractive index (RI) variation of the surrounding medium [3,4], which includes but is not restricted to their applications in antigen–antibody interactions [5,6] and biotin-streptavidin [7]
To evaluate the surface morphology of the block copolymer (BCP)-templated AuNP film on the fiber, two other standard methods based on silane coupler and polyelectrolytes were performed for the self-assembly film of 33 nm AuNPs
We used the ratio of the absorbance of AuNPs at the surface plasma resonance peak (Aspr ) to the absorbance at 450 nm (A450 ) to calculate the particle diameters

Summary

Introduction

Localized surface plasmon resonance (LSPR) fiber-optic sensors have been widely investigated in recent years for biomolecule analysis [1,2], since the surface metallic nanoparticle arrays are extremely sensitive to the refractive index (RI) variation of the surrounding medium [3,4], which includes but is not restricted to their applications in antigen–antibody interactions [5,6] and biotin-streptavidin [7]. The self-assembly of metallic nanoparticle arrays for most LSPR fiber-optic sensors uses silane as a linking agent [12,13]. This method requires precise controlling of the self-assembly time and temperature, even though low-coverage and vast particle aggregations are still inevitable on particle arrays [14,15]. Some polyelectrolyte alternate deposition methods are proposed to simplify the operating procedures for particle self-assembly [16,17] This multilayer structure is used as the adhesion layer for nanoparticle fabrication while the deposition time is significantly reduced owing to the rapid electrostatic adsorption compared with the silane coupler method [14]. The surface coverage of particles is expected to be improved and the sensitivity of the polyelectrolytebased LSPR sensor is increased ; particle aggregations still exist when

Methods

Results

Conclusion