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Photon Upconversion in Homogeneous Fluorescence‐based Bioanalytical Assays
Author(s) -
Soukka Tero,
Rantanen Terhi,
Kuningas Katri
Publication year - 2008
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1430.027
Subject(s) - förster resonance energy transfer , photon upconversion , autofluorescence , fluorescence , bioanalysis , biomolecule , optoelectronics , fluorophore , resonant inductive coupling , chemistry , nanosensor , nanotechnology , energy transfer , materials science , luminescence , optics , physics , molecular physics
Upconverting phosphors (UCPs) are very attractive reporters for fluorescence resonance energy transfer (FRET)‐based bioanalytical assays. The large anti‐Stokes shift and capability to convert near‐infrared to visible light via sequential absorption of multiple photons enable complete elimination of autofluorescence, which commonly impairs the performance of fluorescence‐based assays. UCPs are ideal donors for FRET, because their very narrow‐banded emission allows measurement of the sensitized acceptor emission, in principle, without any crosstalk from the donor emission at a wavelength just tens of nanometers from the emission peak of the donor. In addition, acceptor dyes emitting at visible wavelengths are essentially not excited by near‐infrared, which further emphasizes the unique potential of upconversion FRET (UC‐FRET). These characteristics result in favorable assay performance using detection instrumentation based on epifluorometer configuration and laser diode excitation. Although UC‐FRET is a recently emerged technology, it has already been applied in both immunoassays and nucleic acid hybridization assays. The technology is also compatible with optically difficult biological samples, such as whole blood. Significant advances in assay performance are expected using upconverting lanthanide‐doped nanocrystals, which are currently under extensive research. UC‐FRET, similarly to other fluorescence techniques based on resonance energy transfer, is strongly distance dependent and may have limited applicability, for example in sandwich‐type assays for large biomolecules, such as viruses. In this article, we summarize the essentials of UC‐FRET, describe its current applications, and outline the expectations for its future potential.