Hierarchically Structured Plasmonic Nanoparticle Assemblies with Dual-Length Scale Electromagnetic Hot Spots for Enhanced Sensitivity in the Detection of (Bio)Molecular Analytes

Rishabh Rastogi,Sivashankar Krishnamoorthy,Remi Vincent,Pierre-Michel Adam,Suresh Poovathingal,Ekoue A Dogbe Foli

doi:10.1021/acs.jpcc.0c10467

Abstract

High sensitivity in plasmon-enhanced spectroscopies results not only from high electromagnetic (EM) field enhancements at the vicinity of nanostructured metal surfaces but also the ability to lever...

Highlights

Reliable and quantitative detection of bioanalytes with high sensitivity down to few molecules, response times within few minutes, and miniaturized volumes is a key to advancing a range of diagnostic goals including detection of diseases at an early stage, predicting disease risk, identification of infections for the point of care, and delivering therapies tailored to the individual patients.[1]
Ordered arrays of the gold nanoparticle clusters (NCA) exhibiting dual-length scale EM hot spots were obtained by the self-assembly of block copolymer colloids as reported earlier.[21]
The nanoparticle cluster arrays (NCAs) conserves the periodicity of the original templates, which in turn can be controlled by spin-coating speeds or polymer solution concentrations

Summary

Introduction

Reliable and quantitative detection of bioanalytes with high sensitivity down to few molecules, response times within few minutes, and miniaturized volumes is a key to advancing a range of diagnostic goals including detection of diseases at an early stage, predicting disease risk, identification of infections for the point of care, and delivering therapies tailored to the individual patients.[1]. Spectroscopic detection relying on EM fields allows unique identification of analytes using plasmonenhanced Raman or fluorescence assays, with competitively low limits of detection compared to other techniques.[3] These EM fields on a nanostructured metal surface are heterogeneously distributed and are concentrated in nanogaps or sharp corners of metal nanostructures that act as EM hot spots.[4] Gap hot spots are known to be stronger than curvature hot spots,[5−7] and several studies have shown an exponential rise in the EM enhancement as the function of the closing gap distance between the metal nanostructures.[6,8−10] To attain the best sensitivities, the analyte needs to be colocalized within the EM hot spots where these EM fields are concentrated.[11] these gaps are typically in the order of few nanometers and can permit only those analytes with dimensions smaller than the gap themselves.

Methods

Results

Conclusion