ENGINEERING OF LIPID NANOPARTICLES FOR ADVANCED DRUG DELIVERY APPLICATIONS

‘Nanomedicine’, the application of nanotechnology principles to the field of medicine, has stimulated the development of nano-platforms for next generation drug delivery. By exploiting nanoscale properties of materials to selectively alter intrinsic characteristics of therapeutics, researchers have improved the efficacy and pharmacokinetic profiles for a variety of drug types. Despite preliminary commercial and clinical success, there still remains a need to develop an improved delivery platform that can provide high cargo entrapment, efficient intracellular delivery, evasion of intracellular degradation pathways, and provide cell population specific targeting. In this study we engineered a nanocarrier system composed of a core bilayer structure of biocompatible lipids and cholesterol, and an exterior surface coating of hyaluronic acid (HA). We optimized both the HA crosslinking reaction to the nanoparticle surface (HA-LNP), as well as the rehydration and entrapment conditions for optimal encapsulation efficiency. The HA-LNP system promoted uptake of an impermeable fluorescent model cargo as well as increased the therapeutic index of Doxorubicin by over 30 % compared to the free form counterpart. Confocal microscopy was used to probe the endolysomal fate of HA-LNPs in cardiac, brain, and breast cells leading to validation of cell-dependent cytoplasmic distributions of the nanocarrier system with minimal lysosomal co-localization. In order to investigate the effect of stiffness on nanoparticle uptake, we created 2D gel substrates with physiologically relevant stiffness ranging from 2kPa to 70 kPa. Flow cytometry was used to quantify HA-LNP uptake as a function of time and substrate stiffness in metastatic breast cancer cells. Interestingly we observed an initial preferential uptake mechanisms with cells on soft substrates both per cell and population wide, however at later time points we found that the overall capacity for HA-LNP uptake between all the substrates is equivalent, signifying the stiffness effect on HA-LNP uptake is transient. Further analysis of this mechanism could lead to the development of drug delivery platforms with increased intracellular delivery efficiency and specificity. Advisor: Srivatsan Kidamb