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This biomolecular technology laboratory
at Sabanci University
small experimental trial
error..
showing quantum dots can specifically be loaded into the small porous structures
on silica particles
as drug cargos
First silica particles will be divided equally into two for test and control, respectively
highly porous silica particles with pore diameter of ~15-20 nm
porous structure
we are using quantum dots having mission wavelength
at 625 nm
appear read in color and these
have similar-size as that of the pores on silica particles
these are the silica particles (appear white powder)
we here trying to see the quantum dots going inside the pores of silica particles
We have developed a reagent which
allows quantum dots to spicifically
internalize into small
pores present on the silica particles
first, silica particles will be
suspended suspended in
water allowing the silica particles to
to
have access to it all around its pores
mix well and
all pores present on silica particles to be filled with water
making it look like a transparent gel
making them homogeneously suspended
known quantity of quantum dots
quantum dots will be suspended into the silica suspension
known quantity of quantum dots will be
added to this suspension.... and we will see
a bright red colored fluorescence
once we expose it to the UV light
Note that this is more of a TRIAL experiment....
yes, that is the color of a concentrated quantum dots look like shown holding
small quantity of
diluted sample will be added to
each of these tubes, one of them is control
main purpose of this expt. is
to show the ability of our reagent
to make the quantum dots GO
INTO the
porous structure of silica particles
Note: quantum dots used here are too high ~200 times more than the number of pores present on silica particles
so we took two samples,
one of them serves as control
this control sample will not be added with the reagent developed
after mixing shortly
we'll expose these samples
into the UV light
quickly...
because now
is the time to see quantum dots still remain
in the suspension
POROUS SILICA APPEARS TRANSLUCENT IN THE UV LIGHT....:)
you can see fluorescence all over the tube
My colleague went to turn off the normal light to view them better..
this is how it looks from the beginning
it is fluorescence all over the tube
this fluorescence in the suspension
or supernatant will disappear once we add the reagent
while in the control sample, since
there is no ...reagent added
the quantum dots will remain in suspension
it will remain as is in the supernatant
do not
get internalized in the porous structure (fail to go inside the pores of silica)
This is the reagent that drives quantum dots to go into the silica particles..
okay (ready to go)
this reagent we developed
will be added to the test sample
and same amount of
(a pause to choose which solution to take..finally settle to take water) distilled water will be added
to the control sample
This one is
control sample, similar (identical)
volume of water (instead of reagent)
as a control which do
not influence
quantum dots to go into the porous structure
(mix to homogenize......)
this requires
mixing for about 2~3 min (for video only)
and we will come back then (had to cut it here to save camera battery)
Now that the tubes were mixed
for 2~3 min
and then we will try again to check if the (error not UV emission) it is emission in UV light
Remember!!! silica particles are translucent when suspended in water, they cannot be seen clearly under the UV light! Neither do we get rid of the interfering fluorescence in the supernatant
we assume that by now
our reagent
enables the quantum dots to go inside
the silica porous structures
so (like I said) we still have some quantum dots
left in the supernatant
therefore, we will take the supernatant out by spinning these tubes and..
rechecking their fluorescence emission back
after centrifugation (at 5000 rpm and tell you why I mentioned rpm here in a moment)
so spin these tubes...to remove the supernatant
and see if the quantum dots went inside
the porous structure of the silica particles
These particles (silica) are of 1~2 micron in sizes (these are heavier than the quantum dots)
with 15~20 nm
of porous structure all around them
each particle is like a small ball with plenty of porous structure..
each pore on the
on the surface of particles measures
about 15~20 nm in diameter
these quantum dots we are using now
have diameter of about..
round the same size.... roughly
about 15~20 nm
so those quantum dots that
have diameter of less than their pore sizes (19~15 nm) will get
into the porous structure
only if the reagent was added (be aware that quantum dots of ~20 nm size do not enter the pores any way!) ...so
in order to compare
the effect of the reagent we took test and
control samples, (note that) the control sample has no reagent added to it, instead water was added remember??
in place of reagent same amount of
control... distilled water was added
so now the,,,,,, tubes are
centrifuged (quantum dots do not sediment at this speed!) and the supernatant
will be taken out......after taking out the supernatant
we will come back and see again in the
UV transilluminator
Traces of residual supernatant in control should be removed here to avoid any fluorescence interfering in it.. which is kind a hard.. also, there is some influence on not having quantum dots in silica will make it brittle and collapse easily...Washing helps..I do not have tell you guys..
so the supernatant will be taken out in a fresh tube
just to make sure now how much of quantum dots
were went inside the silica particles
which can be measured by fluorescence spectrometry
which we have
we are not going to do it at this moment (it is just a qualitative trial)
for qantitative experiments we will have to take the
measured quantity
by weighing the amount of silica particles
and estimating the concentration of quantum dots that will be used
that requires standardization and all...
we have already done it, but this just for demonstration
to see the effectiveness
of our reagent.... So we'll go back and see
now thesilica particles for
both control and test samples
Let's see.. Putting tubes for visualizing under the UV light
Ok, here we go...
now
let's see what happens.. look at the sample (on left).. the one
was added with the reagent,...
making the quantum dots all
go into the porous structure of the
silica particles while we have
the same amount of..the
(error here..it is control on the right) sample showing no quantum dots and..
there is little tinge of fluorescence lingering in the
control sample that is not derived from silica particles.. rather
it is coming from the supernatant
so it is quite clear
in this experiment
that the reagent we design
can be used to control
the release
or uptake of quantum dots
inside the silica particles....so..we are aiming to functionalize
these quantum dots with an anti-cancer drug
that that can be carried by the
silica particles as cargos
the and they can be programmable to release
at the target site where the cancer cells are present in the
in the body. So we can control the
release of these quantum dots from the
silica particles, just like we did
control of their uptake by using a special reagent
we are working towards a reagent that
allows
the quantum dots embedded within the (error) silica particle (porous) structure
to be released which can be
very much controlled
again this is a trial experiment
we and have so much of more improvement.... let see
more clearly (error...)
with the both samples under normal light now you can take it out
turn-off the UV lamp
we will we will see these under normal light
can you turn on the (normal) light again?