Long-lived visible luminescence of UV LEDs and impact on LED excited time-resolved fluorescence applications

We report the results of a detailed study of the spectral and temporal properties of visible emission from three different GaN-based ultraviolet (UV) light emitting diodes (UV LEDs). The primary UV emission in the 360–380 nm band decays rapidly (less than 1 µs) following switch-off; however, visible luminescence (470–750 nm) with a decay lifetime of tens of microseconds was observed at approximately 10−4 of the UV intensity. For applications of UV LEDs in time-resolved fluorescence (TRF) employing lanthanide chelates, the visible luminescence from the LEDs competes with the target Eu3+ or Tb3+ fluorescence in both spectral and temporal domains. A UV band-pass filter (Schott UG11 glass) was therefore used to reduce the visible luminescence of the UV LEDs by three orders of magnitude relative to UV output to yield a practical excitation source for TRF.

[1]  James Piper,et al.  High resolution detection of fluorescently labeled microorganisms in environmental samples using time-resolved fluorescence microscopy. , 2002, FEMS microbiology ecology.

[2]  Tsutomu Araki,et al.  Phase-Modulation Fluorometer Using an Ultraviolet Light-Emitting Diode , 2000 .

[3]  Veli-Matti Mukkala,et al.  Time-Resolution in Fluorometry Technologies, Labels, and Applications in Bioanalytical Assays , 2001 .

[4]  Jianzhong Li,et al.  Light emitting diode-based detectors: Absorbance, fluorescence and spectroelectrochemical measurements in a planar flow-through cell , 2003 .

[5]  R. Haugland,et al.  Fluorescent Molecular Probes II. The Synthesis, Spectral Properties and Use of Fluorescent Solvatochromic Dapoxyl Dyes , 1997 .

[6]  Chong-Qiu Jiang,et al.  Spectrofluorimetric determination of human serum albumin using a doxycycline–europium probe , 2004 .

[7]  B. Maliwal,et al.  Frequency‐domain fluorescence microscopy with the LED as a light source , 2001, Journal of microscopy.

[8]  M. Tan,et al.  Development of functionalized fluorescent europium nanoparticles for biolabeling and time-resolved fluorometric applications , 2004 .

[9]  S Sueda,et al.  Homogeneous DNA hybridization assay by using europium luminescence energy transfer. , 2000, Bioconjugate chemistry.

[10]  J Yuan,et al.  Synthesis of a new tetradentate beta-diketonate-europium chelate and its application for time-resolved fluorimetry of albumin. , 1997, Journal of pharmaceutical and biomedical analysis.

[11]  Russell Connally,et al.  BHHST: An improved lanthanide chelate for time-resolved fluorescence applications , 2005, SPIE BiOS.

[12]  Paul R Selvin,et al.  Principles and biophysical applications of lanthanide-based probes. , 2002, Annual review of biophysics and biomolecular structure.

[13]  James Piper,et al.  Flash lamp-excited time-resolved fluorescence microscope suppresses autofluorescence in water concentrates to deliver an 11-fold increase in signal-to-noise ratio. , 2004, Journal of biomedical optics.

[14]  H. Morkoç,et al.  Luminescence properties of defects in GaN , 2005 .

[15]  Hans Peter Henrik Grieneisen,et al.  Performance of an ultraviolet light‐emitting diode‐induced fluorescence detector in capillary electrophoresis , 2002, Electrophoresis.

[16]  J. Lakowicz.  Principles of fluorescence spectroscopy , 1983 .

[17]  Tero Soukka,et al.  Highly sensitive immunoassay of free prostate-specific antigen in serum using europium(III) nanoparticle label technology. , 2003, Clinica chimica acta; international journal of clinical chemistry.

[18]  Russell Connally,et al.  Novel flashlamp-based time-resolved fluorescence microscope reduces autofluorescence for 30-fold contrast enhancement in environmental samples , 2003, SPIE BiOS.

[19]  Jingli Yuan,et al.  Synthesis of a New Tetradentate ß-Diketonate-Europium Chelate That Can Be Covalently Bound to Proteins in Time-Resolved Fluorometry , 1996 .

[20]  James Piper,et al.  Time‐resolved fluorescence microscopy using an improved europium chelate BHHST for the in situ detection of Cryptosporidium and Giardia , 2004, Microscopy research and technique.

[21]  Russell Connally,et al.  Ultrasensitive time-resolved nanoliter volume fluorometry based on UV LEDs and a channel photomultiplier tube , 2005, SPIE BiOS.