A "schizophotonic" all-in-one nanoparticle coating for multiplexed SE(R)RS biomedical imaging.

Pasquale Iacono,Hazem Karabeber,Moritz F Kircher

doi:10.1002/anie.201403835

Abstract

SERS nanoprobes for in vivo biomedical applications require high quantum yield, long circulation times, and maximum colloidal stability. Traditional synthetic routes require high metal–dye affinities and are challenged by unfavorable electrostatic interactions and limited scalability. We report the synthesis of a new near-IR active poly(N-(2-hydroxypropyl) methacrylamide) (pHPMA). The integration of various SERS reporters into a biocompatible polymeric surface coating allows for controlled dye incorporation, high colloidal stability, and optimized in vivo circulation times. This technique allows the synthesis of very small (<20 nm) SERS probes, which is crucial for the design of excretable and thus highly translatable imaging agents. Depending on their size, the “schizophotonic” nanoparticles can emit both SERS and fluorescence. We demonstrate the capability of this all-in-one gold surface coating and SERS reporter for multiplexed lymph-node imaging.

Highlights

New molecular-based imaging techniques are consistently sought after for the real-time visualization of micro- and macroscopic biological processes.[1]
Silication of a dye-adsorbed nanoparticle has been most effective in retaining in vivo surfaceenhanced Raman scattering (SERS) tag stability and biocompatibility.[5b] current silication methods depend on high dye– metal affinities, which can be limited by unfavorable electrostatic interactions
We report a class of hydrophilic NIR dye-loaded poly(N-(2-hydroxypropyl) methacrylamides) and their application for gold nanoparticle-based SERS imaging of lymph nodes

Summary

Introduction

New molecular-based imaging techniques are consistently sought after for the real-time visualization of micro- and macroscopic biological processes.[1]. Competition for vacant binding sites can limit signal intensities and/or polymer grafting densities.[5b,9] a hydrophilic NIR-active polymer with the potential for further modification would be an ideal substrate for SERS applications, allowing for an all-encompassing surface coating for gold nanoparticles, retaining optimal (multi-)chromophore loading efficiency, minimizing size, and retaining its biocompatibility, water solubility, and circulative properties.

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