Hydrogel Bead Generation

Aidan Johnson Author

04/05/2021 Added

11 Plays

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An overview of the uses and way to generate hydrogel beads in modeling drug delivery to the brain

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[00:00:02.490]Hello.
[00:00:03.420]My name is Aidan Johnson. I'm a senior mechanical engineering student here at UNL,
[00:00:08.730]and I'd like to show you the progress I've made in my project on hydrogen bead
[00:00:13.260]generation.
[00:00:16.200]The goals of this project are to create a heterogeneous brain model in order
[00:00:20.790]to model diffusion through convection enhanced delivery, convection
[00:00:25.560]enhanced delivery is a new technique that creates a pressure differential in
[00:00:30.150]the brain cavity in order to induce flow,
[00:00:33.090]that allows for faster drug delivery than through diffusion alone.
[00:00:38.250]Our model in particular involves suspending Agarose gel beads,
[00:00:42.030]which can be seen as the little pale blue dots in the Petri dish down to the
[00:00:46.980]bottom right.
[00:00:48.540]And then you spend the hydro gel beads in a larger agarose solution.
[00:00:56.150]Convection enhanced delivery is a promising new technique,
[00:00:59.240]but there are several aspects about it that should be understood better in order
[00:01:03.170]to advance the technology further. In particular,
[00:01:06.650]the transport process through soft tissues is not fully understood as well as
[00:01:11.420]the effects of deformation on overall drug propagation.
[00:01:17.330]Since hydrogels have very similar properties as brain tissue,
[00:01:22.010]they make great models. And in fact, several homogeneous
[00:01:26.810]models have been made in the past.
[00:01:30.770]It's our goal to make a heterogeneous model
[00:01:33.590]in order to more accurately reflect the heterogeneous composition of the brain.
[00:01:41.630]Now I'm going to explain the process in which the beads are made first and agarose
[00:01:46.280]solution is prepared and placed into a temperature controlled syringe
[00:01:51.230]in order to prevent premature solidification.
[00:01:55.160]Then the gel is pumped using a syringe pump through a system of tubing,
[00:02:00.380]which is also temperature controlled down to the tip of needle that is
[00:02:04.760]submerged in a container of rotating mineral oil on a
[00:02:09.230]turntable. This can be seen over in the figure off to the right,
[00:02:14.060]However, before I get into the figure,
[00:02:16.940]I'd like to mention that it mentioned that the dispersed phase is water in
[00:02:21.920]the figure in reality, this is Agarose gel on in this experiment.
[00:02:28.150]As you can see in the figure, the rotating,
[00:02:32.900]the mineral oil sheers,
[00:02:36.320]the gel beads off the tip of the needle,
[00:02:38.690]and then forms them into spheres as they fall down to the bottom of the
[00:02:42.320]container as and cool off in solidify.
[00:02:49.670]This is a video of a trial that I did on, as you can see,
[00:02:54.920]the gel beads are shearing off and then falling down to the bottom where they
[00:02:59.920]can be collected and imaged under a microscope. And then,
[00:03:04.270]the size of the beads can be determined using image processing,
[00:03:08.440]which I'll get into on the next slide.
[00:03:16.740]So I ended up creating a program in Matlab that measures the,
[00:03:22.280]the circles. It's a three point program.
[00:03:26.040]It assumes that all the beads are spherical.
[00:03:30.960]So then it takes three points on the outside edge of the bead,
[00:03:35.670]which you select and then draws a circle around
[00:03:41.010]the bead and measures the size of the circle
[00:03:45.840]from there.
[00:03:47.850]a reference image can be used in order to find the radius of the beads,
[00:03:52.320]given the radius of the circles and pixels.
[00:03:59.100]This is
[00:04:01.500]an image of the bead general on the bead distribution of
[00:04:06.390]the previous image.
[00:04:08.760]as you can see here on the number of samples,
[00:04:12.240]the number of beads in that image is 85.
[00:04:15.390]And they've got an average radius of about 0.7 millimeters and a very,
[00:04:20.220]small standard deviation of only four,
[00:04:24.150]one hundredths of a millimeter.
[00:04:29.340]So there are several areas in which this project can be continued in the future,
[00:04:34.200]the elastic modulus,
[00:04:36.030]as well as the bead size can be measured and
[00:04:40.470]see how that changes with different inputs.
[00:04:44.730]Elastic modulus has been touched at all.
[00:04:47.850]Whereas the bead size has been touched quite a bit, but definitely has some,
[00:04:53.280]some ways to be expounded upon in the future. And then finally,
[00:04:56.880]a creation of a heterogeneous model and testing
[00:05:01.500]the diffusion differences between different types of beads can also be
[00:05:06.090]tested in the future. In conclusion,
[00:05:10.500]I have explained the process in which the hydro gel beads have been
[00:05:15.240]created and measured by,
[00:05:17.730]and this is done by injecting liquid Agarose into a rotating
[00:05:22.470]container.
[00:05:23.040]Mineral oil beads can then solidify on their way down to the bottom of the
[00:05:27.450]container, be gathered and measured using image processing.
[00:05:32.250]Finally, there are many ways to achieve
[00:05:36.690]beads with different properties using this technique.
[00:05:39.060]So it is very use versatile that way. And then finally,
[00:05:43.830]I'd like to give out some acknowledgements,
[00:05:47.130]I'd like to acknowledge the UCare program as well as the John Woolam
[00:05:51.110]scholarship for giving me the opportunity to do this.
[00:05:54.570]I really appreciate it as well as for the financial support as well.
[00:05:59.360]And then I'd like to thank Dr. Ryu as well as haipeng.
[00:06:02.960]They've been the best, uh,
[00:06:06.050]lab professor and lab TA that I could hope for.
[00:06:09.770]They've been super helpful and really helps me get this project done.
[00:06:14.060]And then I'd like to thank Henry and Paul for helping me get my feet wet with
[00:06:17.900]temperature controlling. Thank you very much.
[00:06:21.440]I'll leave you with that.

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