Nanogold-core multifunctional dendrimer for pulsatile chemo-, photothermal- and photodynamic- therapy of rheumatoid arthritis.

This investigation reports a novel nanoGold-core multifunctional dendrimer for pulsatile chemo-, photothermal- and photodynamic- therapy of rheumatoid arthritis (RA). Architecturally, the nanocomposites comprised of a nanoGold (Au) at the focal whose surface is functionalized by hydroxy-terminated thiolated-dendrons following Au-thiol bond formation to produce nanoGold-core multifunctional dendrimer (Au-DEN). The surface hydroxyl groups of Au-DEN were then conjugated with methotrexate (MTX; a disease-modifying first line anti-rheumatic drug; DMARD; 74.29 ± 0.48% loading) to form Au-DEN-MTX-NPs (Particle size: 100.15 ± 28.36 nm; poly dispersibility index, PDI: 0.39 ± 0.02; surface zeta potential, ζ: -22.45 ± 1.06 mV). MTX was strategically selected to serve as an anti-rheumatic DMARD as well as a targeting ligand to attain selective localization of the formulation in arthritic tissue via folate receptors upregulated on arthritic tissues. The docking study was performed to confirm the viable binding efficiency of MTX towards β-folate receptors that are overexpressed on arthritic tissues taking folic acid as a reference standard. The IR780, a NIR active bioactive was also loaded in Au-DEN-MTX NPs to offer photothermal benefit upon irradiation with NIR laser (wavelength: 808 nm). The hypothesis was tested by elucidation of in vitro drug release profile, photothermal activity, cellular uptake (Fluorescence and confocal laser scanning microscopy; CLSM), cell viability assay (MTT protocol) and Intracellular reactive oxygen species (ROS) generation in mouse macrophage RAW264.7 cells and Lipopolysaccharide (LPS) activated RAW264.7 cells. Furthermore, the hemolytic toxicity and stability studies were also investigated to determine the blood compatibility as well as ideal storage condition of NPs. The outcome of this investigations presents developed multifunctional targeted NPs to be potential therapeutics for the improved treatment of RA. The approach can also be applied to other clinical interventions involving countering inflammatory conditions.