Discipline: Technology and Engineering
Paul A. Millard - Howard University
Co-Author(s): Danielle N. Miller and Preethi L. Chandran
Poly-Ethylenimine (PEI) has been demonstrated as an alternative vector of gene delivery to targeted cells. Its cationic properties are effective in neutralizing the anionic properties of DNA and causes the DNA to be compacted into nanometer size particles. In this compact form, DNA can easily be transported into the cells for molecular biology studies, drug delivery applications and possibly genetic therapy. Since PEI is a hydrophobic weak-base polyelectrolyte, it switches between regimes of inter-chain and intra-chain charge repulsion as a function of salt and polymer concentrations. Its hydrophobic nature also causes aggregated phases to co-exist in solution. It is not known how the PEI polyelectrolyte regime alters its interactions with DNA and therefore the packing of DNA-PEI complexes. We investigate the effect of PEI polyelectrolyte dynamics on the coarse packing of DNA-PEI complexes by complementary solution studies with varying concentrations of sodium chloride and Dynamic Light Scattering (DLS) techniques. Increasing PEI polymer concentrations from 2.72mM to 6.08mM were combined with varying concentrations of sodium chloride. A 2.0 ng/ul concentration of DNA was added to each PEI-NaCl solution. The solutions were monitored for changes in pH and analyzed for hydrodynamic sizes using the DLS. The data analysis indicated that increasing NaCl concentrations led to a shift from interchain to intrachain repulsion in the PEI polymer. Results also indicate changes in the hydrodynamic diameter of the nanoparticle in response to the NaCl concentrations.
Funder Acknowledgement(s): This material is based upon work supported by National Science Foundation under grant no. 1407891 awarded to Preethi Chandran and by a mini-grant awarded to Preethi Chandran under NSF grant no. 1208880 (PI: Dr. Sonya Smith).
Faculty Advisor: Preethi L. Chandran, email@example.com