Hi folks.
 
You may remember that in March of this year, I posted a suggestion that
we all get together to convince Bangs Laboratories to make some custom
microspheres that we could use for defining point spread functions in our
instruments. It worked, and the beads are now ready to purchase. The
company wanted me to write this quick note to notify all those who are
interested to contact the company
        Bangs Laboratories, Inc.
        317-844-7176 voice
        317-575-8801 fax
        [log in to unmask]
 
I suggest that everyone first ask for their TECH. NOTE #56. It contains
information about the individual beads (three types are available),
including spectra. It also contains some info and results which came out
of a "pre-release" set of beads which the company sent me so that I could
appraise them. The best people to contact directly are either Mary Meza
([log in to unmask]) or Brian Bromberek ([log in to unmask]) I think the
company has done a reasonsible and excellent job in producing these
beads, and I hope everyone finds them useful. I have absolutely NO
financial interest in this deal, but let me give you a
quick run-thru about the beads.....
 
They are pretty cheap. $65 will buy a single vial of beads containing 1
ml suspended in water. A few microliters are all you need (diluted into
your suspension or embedding medium of choice) for your analysis. They
will last a while....
 
They are suprisingly bright. My LSM410 had no problems imaging them. I
think even older instruments (e.g. MRC-600) should have no problems
getting high quality images. The dye is trapped inside the bead, so there
are lots of molecules to excite in these 63nm beasties.
 
These are single-label beads, each useful for a limited set of excitation
wavelengths. One is excited by 350-380nm to emit at a peak of 410nm (half
maximal emission about 445nm). A second bead is excited most
efficiently by 480-540nm and emits at a peak of 570 (half maximal
emission aobut 600nm: utility for 568nm untested so far). The third bead
is excited by 630-660 and emits at a peak of 700 (half maximal emission
about 710). I tested them with Uv-Ar (351/364), visible Ar (488), Green
HeNe (543) and Red HeNe (633). The only weak point was using the weak green
HeNe Laser, which did not overly impress me with the image brightness for
the second bead.
 
I think the beads are more useful than just for point spread function
determination. I think they can also help for detecting mis-alignment of
optical elements (if the XZ images of the PSF is skewed/slanted), and for
determining z-axis registration of different laser lines (if a mix of the
beads settled onto a glass coverslip does not produce images which
coincide at the same z-axis position in response to multiple laser
excitation). Based on work with these beads, our faithful Zeiss tech is
coming out to check our UV laser alignment...
 
So that's it for now. If the company gets enough sales from this round,
maybe we can torture them again and get them to make a "mixed dye" bead
that combines all the different dyes into one bead, or to make other
beads if other laser lines/wavelengths need to be hit. Let them know what
you want, they are pretty receptive to new ideas.
 
Enjoy. Chip
 
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  Chip Montrose
   Johns Hopkins University     tel: 410-955-9681
    Ross 930                      FAX: (410) 955-9677
     720 Rutland Avenue            email: [log in to unmask]
      Baltimore, MD 21205
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