Choosing filter configurations for Qdots in Flow

Uriel TK utk1 at
Thu Jun 14 17:35:52 EDT 2007

Dear Joanna:
Qdots are very bright, so if you're getting a new instrument with a good laser, I guess a narrower filter would do the job and reduce compensation issues. Of course, as always, it depends on the applications intended. If there are low-signal studies, then get the wider bands. Bear in mind that a Qdot is excited by all lines shorter than it's emission. Therefore, exactly due to the fact that Qdots are very bright, if doing multi-laser works you might encounter some trouble there, with a red Qdot being excited by UV, V, 488, and maybe the red laser as well. Check out Mol Probes spectra viewer. It could be small emission, but then you have compensation all over the place, which might or might not be an issue for you - again, depends on your application and instrument. Maybe people with more experience with Qdots can share their experience on this respect? This characteristic has been keeping me from getting more into Qdots because I commonly use all 4 lasers on the LSR II. 

Good luck,

Uriel Trahtemberg, M.Sc.
MD/PhD student
The Laboratory for Cellular and Molecular Immunology
The Hebrew University - Hadassah Medical Organization
Jerusalem - ISRAEL
  ----- Original Message ----- 
  From: Roberts Joanna 
  To: Cytometry Mailing List 
  Sent: Thursday, June 14, 2007 18:11
  Subject: Choosing filter configurations for Qdots in Flow

  Dear Flow Cytometry Community, 


  I have a question about filter configurations for Qdots in flow cytometry. 


  I would like to order a new instrument with a violet laser to measure the full range of qdot fluorochromes. From quick talks with BD, I have a list of the filters they suggest. They represent slightly narrower signal ranges in just about all cases than the filters used by the fellows in the paper by Chattopadhyay et al in Nature Immunology last year. 


  For those of you working with these reagents in flow, could you offer your opinion on this matter? Would you recommend collecting more signal (and probably doing a bit more 'inter-qdot' compensation) or would you suggest taking the narrower band pass, collecting less signal and needing less compensation? 


  Here is a list of the bandpass filters suggested from BD as well as those used in the paper mentioned above. 


		       Chattopadhyay et al	 Suggestion from BD

  QDOT800	  780/60 (750LP)	  800/30

  QDOT705	  705/70 (670LP)	  710/50

  QDOT655	  660/40 (640LP)	  660/20

  QDOT605	  605/40 (595LP)	  610/20

  QDOT585	  585/42 (570LP)	  585/42

  QDOT565	  560/40 (557LP)	  560/40

  QDOT525	  515/20		       525/50



  Any and all recommendations, ideas and advice are appreciated. 


  Thanks a lot to the organisers and moderators who run this list and all the people who take the time to dish out their 2 cents- it is great!


  Best wishes, 



  Flow Cytometry Core Facility

  EPFL, Swiss Federal Institute of Technology

  SV-SG, Station 15

  CH 1015, Lausanne



  +41 21 69 39 547

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