(Georgia Institute of Technology, 2020-05)
Shaver, Joseph
Based on the studies conducted, 40 kDa PEG NIR, 50 kDa HA-NIR and Albumin NIR can be successfully synthesized and purified and are therefore suitable for injection for in vivo imaging. In addition to the synthesis and purification of the tracers, various considerations were discovered during the synthesis of tracers containing sulfhydryl functional groups, such as the formation of disulfide bridges. Therefore, we determined that the optimal reactive group is primary amines, and have elected to use them going forward. In this thesis, we also explored the ability to modify the zeta potential of polymers using methyl-PEG NHS Ester. We found that if the charge is the result of primary amines, the charge can be significantly reduced after being reacted with methyl-PEG NHS Ester. Methyl PEGylation would enable the effect of a molecule’s charge on its clearance rate to be studied in vivo and should be studied with more negatively charged molecules like HA. Lastly, we also showed that amine functionalized HA can be characterized and conjugated to NIR dye. However, further work is needed to purify this bioconjugate. Also, in order to mimic naturally occurring HA in the knee space, HA-NIR must be able to be enzymatically degraded, which has not yet been demonstrated. Despite this, 1.5 and 2.5 MDa HA-NIR can still be used in vivo to investigate how HA is cleared from the knee space when it cannot be degraded by HYAL and to explore other mechanisms by which it can be degraded and transported in the joint.