{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T05:24:16Z","timestamp":1767849856835,"version":"3.49.0"},"reference-count":23,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2006,8,3]],"date-time":"2006-08-03T00:00:00Z","timestamp":1154563200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cytometry Pt A"],"published-print":{"date-parts":[[2006,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background.<\/jats:title><jats:p>The unique discriminative ability of immunofluorescent probes can be severely compromised when probe emission competes against naturally occurring, intrinsically fluorescent substances (autofluorophores). Luminescence microscopes that operate in the time\u2010domain can selectively resolve probes with long fluorescence lifetimes (\u03c4 &gt; 100 \u03bcs) against short\u2010lived fluorescence to deliver greatly improved signal\u2010to\u2010noise ratio (SNR). A novel time\u2010gated luminescence microscope design is reported that employs an ultraviolet (UV) light emitting diode (LED) to excite fluorescence from a europium chelate immunoconjugate with a long fluorescence lifetime.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods.<\/jats:title><jats:p>A commercial Zeiss epifluorescence microscope was adapted for TGL operation by fitting with a time\u2010gated image\u2010intensified CCD camera and a high\u2010power (100 mW) UV LED. Capture of the luminescence was delayed for a precise interval following excitation so that autofluorescence was suppressed. <jats:italic>Giardia<\/jats:italic> cysts were labeled in situ with antibody conjugated to a europium chelate (BHHST) with a fluorescence lifetime &gt;500 \u03bcs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results.<\/jats:title><jats:p>BHHST\u2010labeled <jats:italic>Giardia<\/jats:italic> cysts emit at 617 nm when excited in the UV and were difficult to locate within the matrix of fluorescent algae using conventional fluorescence microscopy, and the SNR of probe to autofluorescent background was 0.51:1. However in time\u2010gated luminescence mode with a gate\u2010delay of 5 \u03bcs, the SNR was improved to 12.8:1, a 25\u2010fold improvement.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion.<\/jats:title><jats:p>In comparison to xenon flashlamps, UV LEDs are inexpensive, easily powered, and extinguish quickly. Furthermore, the spiked emission of the LED enabled removal of spectral filters from the microscope to significantly improve efficiency of fluorescence excitation and capture. \u00a9 2006 International Society for Analytical Cytology<\/jats:p><\/jats:sec>","DOI":"10.1002\/cyto.a.20326","type":"journal-article","created":{"date-parts":[[2006,8,3]],"date-time":"2006-08-03T19:16:44Z","timestamp":1154632604000},"page":"1020-1027","source":"Crossref","is-referenced-by-count":44,"title":["High intensity solid\u2010state UV source for time\u2010gated luminescence microscopy"],"prefix":"10.1002","volume":"69A","author":[{"given":"Russell","family":"Connally","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dayong","family":"Jin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James","family":"Piper","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2006,8,3]]},"reference":[{"key":"e_1_2_5_2_2","doi-asserted-by":"publisher","DOI":"10.1364\/AO.41.003336"},{"key":"e_1_2_5_3_2","first-page":"457","volume-title":"Fluorescence Microscopy","author":"Rost FWD","year":"1995"},{"key":"e_1_2_5_4_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1574-6941.2002.tb00985.x"},{"key":"e_1_2_5_5_2","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1007\/978-1-4757-3061-6","volume-title":"Principles of Fluorescence Spectroscopy","author":"Lakowicz JR","year":"1999"},{"key":"e_1_2_5_6_2","doi-asserted-by":"publisher","DOI":"10.1007\/BF01776683"},{"key":"e_1_2_5_7_2","unstructured":"TakaloH MukkalaVM(toWallac Oy Finland). 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