Elucidating the structural organization of a novel low-density lipoprotein nanoparticle reconstituted with docosahexaenoic acid

Abstract

Low-density lipoprotein nanoparticles reconstituted with unesterified docosahexaenoic acid (LDL-DHA) is promising nanomedicine with enhanced physicochemical stability and selective anticancer cytotoxic activity. The unique functionality of LDL-DHA ultimately relates to the structure of this nanoparticle. To date, however, little is known about the structural organization of this nanoparticle. In this study chemical, spectroscopic and electron microscopy analyses were undertaken to elucidate the structural and molecular organization of LDL-DHA nanoparticles. Unesterified DHA preferentially incorporates into the outer surface layer of LDL, where in this orientation the anionic carboxyl end of DHA is exposed to the LDL surface and imparts an electronegative charge to the nanoparticles surface. This negative surface charge promotes the monodisperse and homogeneous distribution of LDL-DHA nanoparticles in solution. Further structural analyses with cryo-electron microscopy revealed that the LDL-DHA nanostructure consist of a phospholipid bilayer surrounding an aqueous core, which is distinctly different from the phospholipid monolayer/apolar core organization of plasma LDL. Lastly, apolipoprotein B-100 remains strongly associated with this complex and maintains a discrete size and shape of the LDL-DHA nanoparticles similar to plasma LDL. This preliminary structural assessment of LDL-DHA now affords the opportunity to understand the important structure-function relationships of this novel nanoparticle.

Docosahexaenoic Acid Delivery Systems, Bioavailability, Functionality, and Applications: A Review

“…Interestingly, LDL reconstructed from unesterified DHA exhibited higher physicochemical stability and selective anti-cancer cytotoxic activity. Mulik et al [ 79 ] analyzed the structure of the nanoparticles. They found that unesterified DHA preferentially added to the outer surface of LDL, where the anionic carboxyl terminal of DHA was exposed to the LDL surface, gave the surface of the nanoparticles a negative electric charge.…”

Repeated trans-arterial treatments of LDL-DHA nanoparticles induce multiple pathways of tumor cell death in hepatocellular carcinoma bearing rats

“…Extensive physicochemical and morphological characterization of the LDL- nanoparticles has been reported previously by our group ( 31 , 39 ). In the following study the LDL-DHA nanoparticles displayed an average hydrodynamic diameter of 30.1 ± 0.5 nm and a negative zeta potential of -23.4 ± 0.9 mV.…”

Membrane therapy using DHA suppresses epidermal growth factor receptor signaling by disrupting nanocluster formation

“…To determine the effect of DHA supplementation on EGFR-dependent growth, we utilized a DHA-based therapeutic consisting of DHA free fatty acid inserted into human LDL particles ( 26 ). Each LDL nanoparticle is devoid of cholesterol, contains approximately 1,100 unesterified DHA fatty acid molecules (LDL-DHA), and is approximately 22 nm in diameter ( 38 ). These nanoparticles have been shown to preferentially and efficiently target liver cancer versus noncancer cells in vitro ( 26 , 39 ) and reduce proliferation of xenografts of hepatocellular carcinoma (HepG2) in vivo.…”