Quality-by-design-engineered mitochondrial targeted nanoparticles for glioblastoma therapy

Glioblastoma (GB, IDH-wildtype) constitutes the most aggressive primary malignant neoplasm with limited treatment modalities due to the blood-brain barrier (BBB) often restricting drug delivery. It also has an overall low survival rate with no curative solution, reinforcing the need for innovative formulation development for effective management of GB. This study explores a novel approach using triphenylphosphonium (TPP⁺)-conjugated chitosan nanoparticles for targeted mitochondrial delivery of temozolomide (TMZ) to GB cells. The conjugated nanoparticles were designed to leverage chitosan's biocompatibility and TPP's mitochondrial targeting ability. TMZ-loaded chitosan nanoparticles were systematically developed and optimized employing a Quality-by-Design (QbD) approach with a screening of factors (Taguchi design) followed by optimization (Box-Behnken design). The optimized nanoparticles had an average particle size of 138.1 ± 5 nm, PDI of 0.242 ± 0.04, and entrapment efficiency of 93.59 ± 3%. Further, a conjugate chitosan-TPP⁺ (CS-TPP⁺) was synthesized and validated, employing varied techniques such as NMR, FTIR, HPLC, zeta potential, and EDAX analysis. In vitro drug release in pH 5 phosphate buffer showed a sustained release for nanoparticulate formulations compared to the free drug solution further indicating that conjugation did not alter the release pattern of nanoparticles. With regards to intranasal delivery of the formulation, an ex vivo study carried out on goat nasal mucosa demonstrated greater retention of conjugated chitosan nanoparticles on nasal mucosa than free drug solution, and a mucin interaction study also corroborated this finding. In vitro cell line studies indicated nanoparticles' cytotoxic potential compared to TMZ solution. Overall, this study highlights the potential of TPP⁺-conjugated chitosan nanoparticles developed strategically for the targeted delivery of TMZ to mitochondria.