Poster X8 - Chemotherapy Drug Release from Hollow Core Polyethyleneimine Nanoparticles.

Introduction: Novel anticancer agents are arising from engineered nanostructured materials. This work
involved the synthesis, characterization, and release of novel hollow core polymeric
nanoparticles (HCPNPs) for controlled drug delivery. Polyethyleneimine (PEI) was bound to
AuNPs, forming polymer-shell nanoparticles with dissolution of the gold core via iodine forming
HCPNPs and a high density of DNA intercalated with daunorubicin was
conjugated. HCPP-DNA-Daun have potential as a novel anticancer material with greater efficacy than
traditional treatment methods.

Materials and

Methods: PEI were heated until reaching a temperature of 80°C, taking 30 minutes for the desired temperature. AuNPs were added to samples at a volumetric ratio of 2:1 PEI:AuNP resulting in 1 mL of solution. Particles were incubated overnight at 37°C, resulting in PEI coated Gold Nanoparticles (PEI-AuNPs). PEI-AuNPs were crosslinked using succinic Acid, N-Hydroxysuccinimide, and EDC, added at a molar ratio of 100:1:1.4:1.4 PEI:SA:NHS:EDC then sonicated with 40 kHz for 15 minutes, resulting in crosslinked PEI-coated gold nanoparticles (PEI-X-AuNPs). The resultant mixture was centrifuged at 13500 rpm and 37°C for one hour, then resuspended in 1 mL of Tris Buffer. I2 was added to the PEI-X-AuNPs samples in a molar ratio of 2:10 (I2): PEI-X-AuNPs. This reaction was left to complete over the course of one hour with intermittent vortexing, resulting in hollow core PEI-shell nanoparticles (HCPNPs). Samples of DNA were preloaded with daunorubicin by incubating with 100 µL of daunorubicin to 20 µL of DNA for 1 hour, then loaded into samples to create 1 mL of 0.3 µM DNA and 1.5 µL of 1 M MgCl was added. Samples were sonicated at 40 kHz for 15 minutes. Particles were then incubated overnight at 37°C, resulting in hollow core PEI particles conjugated with DNA (HCPNPs-DNA). 100 uL of 200 uM daunorubicin was added to 1000 uL of HCPNPs-DNA solution then placed in darkness on a rotator overnight to maximize exposure of the drug to particle surface and interior and create hollow core PEI-shell nanoparticles with DNA and daunorubicin (HCPNPs-DNA-Daun).

Results, Conclusions, and Discussions: Gold nanoparticles were found to have an average diameter of 18 ± 0.29 nm. When coated with PEI, particle diameter increased to 70.22 ± 7.4 nm. Loading of DNA to the surface of the HCPNPs increased overall diameter to 105.7 ± 17.3 nm with condensation of the DNA to the surface through non-covalent ionic binding between PEI’s primary amines and DNA’s backbone phosphates. An original high negative zeta potential of –27.2 ± 0.252 mV was observed from citrate capped gold nanoparticles. A statistically significant increase to 31.0 ± 4.09 mV was obtained with addition of PEI indicating presence on the surface, due to the highly cationic nature of the polymer, and high positive charge preventing particle aggregation. Crosslinking of PEI on the surface of the particles showed statistically significant decrease of zeta potential to a value of 23.3 ± 1.23 mV, indicating cationic primary amines decreased as they were used to crosslink between PEI molecules on the surface. It was determined that a significant increase in drug was loaded to larger DNA strands. We hypothesize that longer DNA strands contain more sites for drug intercalation, as the daunorubicin utilizes the base pairs of DNA as the binding site. The average total mass of daunorubicin released from HCPNPs was 40.22 ± 5.11 mg, 33.96 ± 1.44 mg, 31.51 ± 1.24 mg for HCPNPs with 43, 31, and 19 AGC sequences. For all particles, this quantity of release is clinically applicable when compared to a normal dosage regimen for daunorubicin. The release of HCPP-DNA-Daun lasted for a duration of 12 hours, whereas PEI-X-AuNP-DNA-Daun fractional release was reduced, with the totality of the payload releasing in 1 hour. Prolonged drug release experienced by HCPPs may imply the nature of the hollow shell enables greater retainment of drug for a more gradual and extended-release period of drug. Comparison of mass release between these two groups provides a clearer understanding of the larger quantity of drug mass that HCPPs can load. HCPPs were able to load and release 225 ± 44.6 mg more of drug per cm3 than the solid core counterpart synthesized for comparison.

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