This week is the ninth week of my trip to China, and the beginning of my third month in HeFei. Since I have about a month left in my trip, I decided to write out some attainable goals for my remaining time here. To begin, I had a long conversation with Yuan Shuai about my short term and long term goals, and how I can achieve them.
A long term release profile study cannot be completed with the short time I have left, so instead, I will be doing a release study lasting slightly less than a month. Completing this will allow me to understand the experiment so I can complete a longer term release study when I am back in America. Yuan Shuai and I outlined the specific goals for each day this week so that the release study will be underway by the end of the week.
On Monday, I was able to practice my first coaxial electrospray experiment using curcurmin. Below is a photo of the Taylor cone I formed. It was very stable and produced a lot of microcapsules that Yuan Shuai collected for his experiment. The inner and outer solutions both contain acetone that must evaporate to create stable microcapsules. While collecting them, Yuan Shuai was saying “they’re all trash” as he placed them in a small container. I was confused by this because he was keeping all the microcapsules that he described as trash. I later realized that he was trying to describe the microbubbles as “ash” because they were all dry and would easily blow away. Microbubbles that behave as ash are ideal, and are not to be confused with trash. Below are two photos of me in the lab. For one experiment I had to wear a heavy mask that can be seen below.
On Tuesday morning I had another practice for the dragon boat rowing team. This was another exhausting practice, but it was nice to have a better understanding of the distances we would travel. Last practice I would see every check point and hope that we might take a break there. Now I understand that we generally row for about 2000 meters at a time. Knowing this has made the practice seem less difficult, even if we row farther distances. It was difficult for me to get a good photo because it was pouring rain all morning, but I did take a photo of the lake as we were leaving.
It is difficult to get back into the lab after a tough practice, but now I have a schedule for myself that I am trying to stick to. In the afternoon I tried to encapsulate rhodamine in a PLGA shell, but rhodamine is only slightly soluble in acetone. Acetone is the ideal solvent because it evaporates quickly and is good for forming stable microcapsules. We tried to encapsulate 2 different concentrations of rhodamine, but in both solutions, there was rhodamine sediment that would not completely dissolve and therefore caused the Taylor cone to be unstable.
Wednesday and Thursday:
Wednesday I began reading 2 papers that Dr. Si sent to the whole lab about modeling the interaction of microbubbles and the affect a shear boundary layer has on the stability of a capillary jet. Later in the afternoon I shadowed Yuan Shuai for his triaxial electrospray experiment. He had a lot of success collecting the microcapsules. The photo below shows how the dry microbubbles collect on the electrode and have the consistency of ash.
Thursday morning we had our usual meeting that lasted up until lunch. In the afternoon I worked with Yuan Shuai to create the rhodamine encapsulated microbubbles. Our first experiment did not go well because we were unable to form a stable Taylor cone for a long period of time. When we did finally form a stable cone, it would not collect any microcapsules. To determine the problem with the experiment Yuan Shaui did his experiment encapsulating curcurmin. He was able to form the Taylor cone easily, so we determined that something may be wrong with the solutions used. We recreated the experiment and were able to form a more stable Taylor cone as a result.
After I collected these microcapsules, Yuan Shuai and I prepared the solutions for the HPLC experiment. The calibration solution was created by dissolving rhodamine in a solution comprised of acetone and hexane. We also created the mobile phase solution that has a ratio of 75 parts methanol to 25 parts water.
Thursday night we were able to go to eat “toast” with some of the other members of the lab again! Though I really enjoyed this night, I stayed up later than I should have the day before another Dragon Boat practice.
Friday, Saturday, and Sunday:
Friday morning was another rainy practice for the team. We traveled another 10,000m before we got our lunch and went back to campus. I had to run straight from the practice to the lab to give my presentation about writing biomedical engineering papers. This week I presented about references and the abstract of a paper. The presentation went well overall, but it was difficult to get participation from the group because most of the examples for these sections were long and dense with scientific terms. Next week will be my last presentation on this book.
After my presentation, Yuan Shuai and I started the release experiment. It was convenient because as I am doing my experiment, Yuan Shuai will also be doing his own experiment. To begin, I placed 45mg of the microbubbles in one dialysis bag, and 10 grams of pure rhodamine B in another. These bags were filled with phosphate buffered saline and placed in a solution of acetone and hexane. The containers with the dialysis bags were placed in a device that consistently shakes the containers at a temperature of 37° C. I took samples from the surrounding solution at 1, 2, 4, 6, 9, 12, and 24 hours. I will also be taking samples every 24 hours for the next few weeks. Since I started the experiment at about 4:00 p.m., this meant that I would have to take a measurement at 1:00 a.m. and 4:00 a.m. I brought snacks and movies to watch for a long night in the lab.
I was very lucky there were two World Cup games on Friday night because some of the other students stayed in the lab all night watching the games. It was nice to have the company. I went back to my room to sleep at about 6:00 in the morning.
Saturday I spent most of my morning catching up on sleep. When I got back into the lab Yuan Shuai informed me of some bad news. It turned out that at some point, the clips holding the bag of the pure rhodamine came off and the rhodamine emptied from the bag. After we discussed the problem, we decided to continue taking samples for the experiment, but I will also begin developing microbubbles using ethanol instead of acetone. If I am successful, this will allow me to encapsulate more rhodamine B in each microbubble and therefore result in a more effective release study.
After I took my sample for the day, I went out to dinner with He Yutong, Lei Fan, and Dr. Tong. We went out to dinner because Dr. Tong will be working at OSU for a year starting this September, and he wanted to practice his English as well as ask some questions about the school. We went to a hot pot restaurant and talked a lot about OSU and what he should expect when he arrives. It was a delicious dinner and nice to meet Dr. Tong. We made plans to have dinner again this coming week!
Right after dinner I went to a swimming practice that the dragon boat team coach asked us to attend. It was nice to be able to swim some laps because the pool is much less crowded at this time. I also attended this practice on Sunday night.
The highlight of my Sunday was meeting 4 other American students that moved in to the guest house. They are from Lehigh and will be in HeFei for about 6 weeks. I am so excited to get to know these people better!