PT  - JOURNAL ARTICLE
AU  - Peter W. Tinning
AU  - Aimee J. P.M. Franssen
AU  - Shehla U. Hridi
AU  - Trevor J. Bushell
AU  - Gail McConnell
TI  - A 340/380 nm Light Emitting Diode Illuminator For Fura-2 AM Ratiometric Ca<sup>2+</sup> Imaging Of Live Cells With Better Than 5 nM Precision
AID  - 10.1101/138495
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 138495
4099  - http://biorxiv.org/content/early/2017/05/16/138495.short
4100  - http://biorxiv.org/content/early/2017/05/16/138495.full
AB  - We report the first demonstration of a fast wavelength-switchable 340/380 nm light emitting diode (LED) illuminator for Fura-2 ratiometric Ca2+ imaging of live cells. The LEDs closely match the excitation peaks of bound and free Fura-2 and enables the precise detection of cytosolic Ca2+ concentrations, which is only limited by the Ca2+ response of Fura-2. Using this illuminator, we have shown that Fura-2 acetoxymethyl ester (AM) concentrations as low as 250 nM can be used to detect induced Ca2+ events in tsA-201 cells and while utilizing the 150 µs switching speeds available, it was possible to image spontaneous Ca2+ transients in hippocampal neurons at a rate of 24.39 Hz that were blunted or absent at typical 0.5 Hz acquisition rates. Overall, the sensitivity and acquisition speeds available using this LED illuminator significantly improve the temporal resolution that can be obtained in comparison to current systems and supports optical imaging of fast Ca2+ events using Fura-2.