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Ultra‐Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein‐Rich Biomedia
Author(s) -
Ye Ziwei,
Li Chunchun,
Chen Qinglu,
Xu Yikai,
Bell Steven E. J.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201911608
Subject(s) - colloid , ionic strength , raman spectroscopy , emulsion , surface plasmon resonance , chemistry , plasmon , ionic bonding , salt (chemistry) , chemical engineering , nanoparticle , nanotechnology , chemical physics , materials science , ion , organic chemistry , optoelectronics , optics , physics , engineering , aqueous solution
Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface‐enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt‐induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time‐window of a few minutes. Here, we present an emulsion templated method which allows formation of densely‐packed quasi‐spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein‐rich bio‐solutions where conventional aggregated colloids fail.