Liposomes are another type of particles used in experimenting with drug delivery. The basic process of making liposomes, as Al explained to me, is as follows:
First, all the hydrophobic components (lipids, cholesterol) are dissolved in a chloroform: methanol solution. Then, the chloroform and methanol are evaporated, using a rotovap at a temperature above the melting point of the lipids. A rotovap is a machine that uses temperature and pressure as a means to evaporate and then remove liquids from a solution. When the chloroform and methanol are evaporated, all that is left is a film. An inorganic substance called t-butanol is used to dissolve the film, then the solution is frozen in liquid nitrogen. After 2-3 hours, the t-butanol is evaporated using the rotovap again and the remaining film is put on the lyopholizer overnight. Then, you add water and ammonium sulfide to return the frozen sample to an aqueous phase. At this point, the process for making liposomes diverges, depending on the size you desire. Extrusion, or filtering, is one method. The other method is to homogenize the sample for 10 mins, adjusting the speed based on the desired size for the liposomes. Then, the sample is freeze-thawed (transferred back and forth 12 times from liquid nitrogen to hot water). No matter which method is chosen, the final steps include dialysis to get rid of the ammonium sulfide, loading of the drug, and then dialysis to get rid of any outside remnant drug.
As you can see, making liposomes is a long process, but I was able to see the entire process at different points throughout the past week.
In addition to the liposome work, I worked with Al to take pictures of embryonic stem cells in some of the HA hydrogels that Sarah and I had made. I also watched Hila perform a Live/Dead assay on the same cells. I finished the MTT assay for Sarah’s SBA-15 experiment, and my results showed that the supernatant alone had little to no effect on cell viability.
On Tuesday, and extra-early journal club consisted mostly of presentations from summer interns preparing to head back to their respective universities. Topics of discussion included targeted gene delivery of nanoparticles to MDA breast cancer cells and the creation of ‘patterned monolith structures for passive mixing in microfluidic channels.’ Later in the week I attended a poster session for other summer students, where they were able to present their research for the MIT community. I learned a lot, and I was surprised at how much I understood. Also at journal club, a graduate student presented a paper on continuous sensing with magnetic nanoswitches.
Wednesday, I met my aunt (who works only a street away from Langer Lab!) for lunch and we did some shopping in between my liposome work at the lab. Thursday was the Langer Lab beach party. However, because I had my last lecture of the summer session that night, I didn’t attend the party, but instead went on a college visit with my parents before coming back just in time for class. Our last lecture topics included the sexual transmission of HIV, development of a vaccine, and HIV in India.
This weekend I “visited” Harvard with my parents, attending an information session, but opting out of a tour, since I’ve seen nearly all of campus while living there. My final exam is Tuesday night at 6:15 pm, so I spent the remainder of my weekend studying anywhere and everywhere: my room, the library, the science center, the lawn in front of my dorm, the tutoring office, and the hallway. I did, however, make some time to support Jee Su at an orchestra performance and stop by the last dance of the summer.
With only three more days for me at the lab, a final exam, and all my packing to do before I leave on Thursday morning, these last few days in Cambridge will be stressful and busy as everything comes to a close. Wish me luck!
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