Development of mitochondria-targeted and quercetin-loaded PLGA nanoparticles for reducing ROS production

Mitochondria, which are the primary source of reactive oxygen species (ROS), perform various vital functions within cells. The excessive production of ROS causes oxidative stress, which leads to mitochondrial dysfunctions and chronic inflammatory diseases. Therefore, nanoparticles (NPs) loaded with anti-inflammatory therapeutics and functionalized with triphenylphosphonium (TPP) cations for mitochondrial targeting have emerged as promising candidates to regulate ROS levels and reduce oxidative stress-induced inflammation. In this study, quercetin (QCT)-loaded poly(lactic-co-glycolic acid) (PLGA) NPs were prepared using the nanoprecipitation method. The NPs were designed to specifically target mitochondria by incorporating two distinct targeting conjugates in their structure: TPPTween 80 (TT80) and PLGA-PEG-TPP (PPT). We evaluated the effects of different conjugates and their concentrations for the obtained QCT-loaded PLGA NPs using various characterization methods and in vitro studies. Monodisperse NPs with diameters below 215 nm were obtained, showing drug encapsulation efficiencies of 48.11 +/- 0.67 % to 60.83 +/- 0.79 %. The successful incorporation of TPP was confirmed by a positive shift in zeta potential values. Furthermore, the NPs demonstrated high stability for up to 11 days and exhibited pH-responsive drug release behavior. Our results clearly demonstrated that the synthesized NPs maintain high cellular viability even at high drug concentrations. Furthermore, all targeted NPs significantly reduced ROS production under inflammatory conditions. The JC-1 assay revealed increased J-aggregate formation, confirming the anti-inflammatory healing effect of targeted NPs upon reaching the mitochondria. Therefore, these mitochondria-targeted PLGA NPs were shown to emerge as effective carriers for anti-inflammatory therapeutics, offering a high potential for treating oxidative stress- induced inflammation.