THESIS
2015
xi, 62 pages : illustrations (some color) ; 30 cm
Abstract
Calcium phosphate (CaP) nanoparticles (NPs), due to its biocompatibility, has been extensively studied as
one kind of gene delivery vectors for cancer therapy. However, its clinical application for gene therapy is
hampered primarily due to its low stability and limited endosomal escape. Even though adsorption of
DNA on the surface of CaP can improve the stability of nanoparticles, surface exposed DNA in blood is
susceptible to enzymatic digestion and albumin interaction, which eventually leads to inefficient gene
transfection. Therefore, we hypothesize that coated of DNA-CaP nanoparticles could be an efficient way
to shield DNA from albumin interaction and facilitate endosomal escape, thus enhance gene transfection.
Polyethylene glycol (PEG) has been frequently utilized to coat d...[
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Calcium phosphate (CaP) nanoparticles (NPs), due to its biocompatibility, has been extensively studied as
one kind of gene delivery vectors for cancer therapy. However, its clinical application for gene therapy is
hampered primarily due to its low stability and limited endosomal escape. Even though adsorption of
DNA on the surface of CaP can improve the stability of nanoparticles, surface exposed DNA in blood is
susceptible to enzymatic digestion and albumin interaction, which eventually leads to inefficient gene
transfection. Therefore, we hypothesize that coated of DNA-CaP nanoparticles could be an efficient way
to shield DNA from albumin interaction and facilitate endosomal escape, thus enhance gene transfection.
Polyethylene glycol (PEG) has been frequently utilized to coat delivery carriers to promote stability and
elongate circulation time by preventing albumin agglomeration. Octaarginine (R8), a cationic cell
penetrating peptide, has been extensively applied to facilitate cellular uptake as well as to promote
endosomal escape. In this study, we combined the properties of PEG and R8 together to afford a
polymer-peptide hybrid PEG
5R8. Stable ternary DNA-CaP-PEG
5R8 nanoparticles were formed by
addition of PEG
5R8 as the third component into DNA-CaP nanoparticles at an N/P ratio of 40. TEM and
DLS showed smaller sized nanoparticles. Systematically formulation-screening studies indicated that the
component ratio as well as the order of component mixing dramatically impact on resulting nanoparticles
physical properties. Biological studies showed that these ternary nanoparticles can protect genes from
DNase I digestion, are biocompatible, and displayed observable gene transfection, implying the potential
gene transfection capability. This study enriches our toolbox to make stable and functional CaP-based
nanoparticles and opens a new avenue to further explore their potential as gene delivery carriers.
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