Metal enhanced fluorescence biosensing: from ultra-violet towards second near-infrared window

Abstract

To increase disease survival rates, there is a vital need for diagnosis at very preliminary stages.

Engineered Near‐Infrared Fluorescent Protein Assemblies for Robust Bioimaging and Therapeutic Applications

“…Due to the reduced photon scattering and minimal tissue absorption, fluorescence imaging in the NIR window (700–1700 nm) offers increased tissue penetration depths and a better signal‐to‐noise ratio rendering it ideal for biomedical applications. [ 1–7 ] Currently, NIR fluorescent materials mainly comprise quantum dots, [ 8–10 ] lanthanide‐doped upconverting nanoparticles, [ 11–13 ] organic small molecules, [ 14,15 ] and polymer‐based systems. [ 16 ] However, long‐term toxicity and immunogenicity, non‐biodegradability, as well as photo‐instability of these non‐life‐like materials have restricted their translation into clinical applications.…”

Galvanic Replacement Reaction as a Route to Prepare Nanoporous Aluminum for UV Plasmonics

“…UV and DUV excitations can be utilized to perform Raman spectroscopy on biomolecules that have small Raman cross sections in the visible and NIR regions [6][7][8][9]. Additionally, important biomolecules (such as some amino-acids) have intrinsic fluorescence in the UV region [10], and a platform able to enhance the detection limit thanks to plasmonic effects is highly appealing in biosensing [11][12][13]. Several alternative materials have been investigated during the recent years; among them magnesium [14], gallium [15][16][17][18][19], indium, rhodium [20][21][22][23][24], and aluminum (Al) [4,22,[25][26][27].…”

Core size does not affect blinking behavior of dye-doped Ag@SiO2 core–shell nanoparticles for super-resolution microscopy

“…[25][26][27][28][29][30][31] The MEF effect is dependent on several factors including nanoparticle size, material, and morphology, as well as the distance between the metal surface and the uorophore. [25][26][27][28]30,31 It has been shown that uorophores placed approximately 5 nm or less from the metal surface are quenched rather than enhanced, with 10 nm shown to be the optimum distance for MEF with enhancement decreasing at greater distances. 27,29 It is important to note that the uorescence intensity will only be enhanced if there is a spectral overlap between the uorophore excitation/emission range and the surface plasmon resonance band of the nanostructure.…”

“…[25][26][27][28]30,31 It has been shown that uorophores placed approximately 5 nm or less from the metal surface are quenched rather than enhanced, with 10 nm shown to be the optimum distance for MEF with enhancement decreasing at greater distances. 27,29 It is important to note that the uorescence intensity will only be enhanced if there is a spectral overlap between the uorophore excitation/emission range and the surface plasmon resonance band of the nanostructure. [29][30][31] MEF leads to alterations in the quantum yield (Q) and the uorescence lifetime (s) of the uorophore as demonstrated by eqn (1)- (4) where Q is the quantum yield, s is the uorescence lifetime, G is the radiative decay rate, and k nr is the non-radiative decay rate.…”