This afternoon, I began my Work Experience Program at Dr. Ken Gall’s lab in the Chesterfield at downtown Durham (a Duke labspace). After receiving a short tour of the lab space from a friendly student, I met with the supervisor Dr. Kirillova and Olivia, one of the undergraduate students working in the lab, and we discussed the specific project they are currently working on. Dr. Kirillova is working with another startup, Launchpad Medical LLC, to create a bioresorbable bone adhesive that can ideally be used efficiently and effectively with future medical patients that require bone treatment. To my surprise, the creation of such mineral-organic bone adhesive was inspired by the sandcastle worm, an animal that secretes unique fluids that has the power to “glue sand together.” I learned today that the bone adhesive used in the lab is formally known as “tetranite,” a powder made up of tetracalcium phosphate (Ca4O(PO4)2) and O-phospho-L-serine. The adhesive is unique in that its initial powder form turns gooey immediately after contacting water and eventually solidifies into a solid. In theory, the adhesive may be applied in between two broken bones and solidify quickly to hold the bones together. The substance’s strength and porosity can be adjusted based on the porosity of the bone marrow being treated. For example, a cortical bone requires a “uniform layer of adhesive” because it is less porous and a cancellous bone will host an “irregular adhesive that penetrates into pores” due to its higher porosity. Additionally, the bone adhesive is biodegradable, so in theory, the adhesive will extinguish itself overtime within the bone and new bone marrow will form to fully heal the broken bone. In fact, previously conducted research on a rabbit revealed that 75% of original bone tissue reformed in just one year after it was originally broken, using the bone adhesive to mend the broken bones back together.
As I mentioned earlier, the bone adhesive can be modified for different strengths and porosity using “fillers.” (Usually, higher porosity will decrease the strength of the adhesive, so finding the right balance for different applications is crucial to the use of these adhesives). The three main fillers I learned about were NaCl, fibers, and powdered titanium, which we tested today in the lab for the first time! Generally, adhesives with added NaCl demonstrate higher porosity and that with added fibers yields higher strength; the titanium has yet to provide conclusions. Today, I learned how the samples of bone adhesives with added fillers are made in the lab prior to being tested for strength and porosity. Olivia prepared samples with added titanium powder, and I had to exciting opportunity to prepare samples with added NaCl.
The process by which the sample is made is quite interesting. I was provided with the luxury of using a pre-made mixture of tetranite and NaCl, but in theory I would have first calculated the right amounts of each separate powder and mixed them together. After massing out the correct amount of the combined powder into a small mixing apparatus, I ensured that the powders were mixed homogeneously to create the most accurate sample. I then pipetted 405 microliters of deionized water into the mixer and quickly mixed the water in before the bone adhesive started to solidify. The immediate reaction between the powder and the water really surprised me at first! To create a sample of a specific shape and size, I put the new gooey substance into a syringe and excreted it into a small cylindrical mold, scraping off the top edges for excess material in order to ensure a smooth sample. The substance fully solidified after about 15 minutes, and I used a drill bit to pop it out of the mold and put it in a phosphate buffered saline. This vial was placed in a warm water bath at 37*C (close to body temperature), and we plan to polish the samples after they sit in the water for another 48 hours. The solid samples will be strength tested in order to predict their strength performance in real-world applications, like when inside patients’ bones.
I am happy to say that my first day at the Chesterfield lab was an exciting and rewarding one. I was delighted to be given the wonderful opportunity to actually create some samples myself! At first, I was a bit apprehensive of my abilities to create a sample that would match the quality of the ones Olivia made. Yet, after about three tries, I can confidently say that I made a sample that was much better than what I had expected. After spending less than four hours in the lab today, I left feeling that I had accomplished something substantial and learned about a project that truly intrigued me. Overall, the state-of-the-art lab equipment in Suite 420 was more impressive than anything I have ever laid my eyes on, and I cannot wait for another day of learning at the lab tomorrow!