Development and Evaluation of Nanocarriers against Atherosclerosis

Abstract

The objective of this project was to develop advanced nanocarriers such as nanographene and graphene quantum dots against atherosclerosis. Mannosylated-reduced graphene oxide (Man-rGO) was developed as a targeted nanocarrier and its therapeutic efficacy was evaluated. Near-infrared (NIR) irradiation increased the temperature of Man-rGO solution to approximately 45 °C. Man-rGOs mainly accumulated at the subcellular level of M2-phenotype macrophages (Raw264.7 induced by interleukin-4 (IL 4)). The cell viability of macrophages significantly decreased upon exposure to Man-rGO irradiated with NIR, but no changes were observed from that of mast cells (for mast cells (RBL-2H3), 98.3±0.3%; for macrophages, 67.8±1.3%, p<0.01). The enhanced photothermal ablation activity of Man-rGO triggered by NIR laser irradiation was mediated through their targetability toward overexpressed mannose receptor (CD206), a marker of M2-phenotype macrophage. Thiolated-graphene quantum dots (SH-GQDs) were explored as a theranostic nanocarrier against atherosclerosis. SH-GQDs with high quantum yields can be utilized to label single-cell biophysics in the absence of any extra fluorescent dyes. SH-GQDs treatment for 24 hr was effective to induce oxidized-low density lipoprotein (oxLDL) efflux as compared to the media control (Media: 72.4±2.4% and SH-GQDs: 39.2±2.2% of oxLDL present in macrophages). There was a significant difference in the efflux amount of oxLDL incubated with SH-GQDs between two treatment periods (3 hr: 73.9±1.5% and 24 hr: 39.2±2.2%). The expressions of ABCA1 in macrophages treated with oxLDL decreased (oxLDL: 79.2±1.7%), whereas the level of ABCA1 expression increased as cells were incubated with SH-GQDs in a presence of oxLDL (SH-GQDs: 101.5±3.1%). Disrupted adherence junctions of human umbilical cord-derived vascular endothelial cells (hUVECs) after oxLDL treatment were observed (oxLDL: 67.2±2.2 Ωcm² for 24 hr). SH-GQDs (10 µg/ml) showed an improvement in transepithelial electrical resistance (TEER) (SH-GQDs: 114.6±8.5 Ω-cm² for 24 hr), indicating that adherence junctions were protected by SH-GQD treatment. SH-GQD treatment on in vivo zebrafish larvae showed a protective role of SH-GQDs against oxidative stress induced by H₂O₂. In addition, as the concentration of SH-GQDs increased, the fluorescence intensities lowered, and were close to negative control. The increased reactive oxygen species (ROS) levels caused by oxidative stress were mostly relieved by the addition of SH GQDs.