Development of <i>Nigella sativa</i> (black seed) extract-loaded chitosan nanoparticles for targeting </i>Klebsiella pneumoniae</i>-induced metastatic colon cancer

Metastatic colon cancer remains a significant global health challenge, with increasing evidence linking microbial infections, such as Klebsiella pneumoniae, to cancer progression. This study focuses on the development of Nigella sativa (black seed) extract-loaded chitosan nanoparticles (NS-CNPs) as a targeted therapeutic approach against K. pneumoniae-induced metastatic colon cancer. NS-CNPs were synthesized using ionic gelation, yielding nanoparticles with an average size of 140 ± 5 nm, a polydispersity index (PDI) of 0.23 ± 0.02, and an encapsulation efficiency of 85.7 ± 4.3%. Morphological analysis confirmed their spherical shape. The NS-CNPs exhibited superior antibacterial efficacy against K. pneumoniae (zone of inhibition 22.00 ± 2.5 mm) compared to the crude extract (zone of inhibition 12.3 ± 0.1 mm), highlighting improved bioavailability and targeted delivery. Cytotoxicity studies on colon cancer cell lines showed a significant reduction in cell viability (IC50 = 0.16 ± 0.01 µg/mL), accompanied by modulation of key cancer biomarkers such as TNF-α with values of 12.50 ± 1.2 and 13.70 ± 1.5 pg/mL. The treatment elevated malondialdehyde (MDA) levels by 48%, increased caspase-3 and Bax expression by 2.5-fold and 1.8-fold, respectively, while reducing anti-apoptotic Bcl-2 expression by 40%. These effects indicate oxidative stress induction and apoptosis activation. Furthermore, NS-CNPs suppressed tumor-promoting pathways and enhanced pro-apoptotic mechanisms, demonstrating dual antibacterial and anticancer functionalities. These findings underscore the therapeutic potential of NS-CNPs as a novel nanoplatform for combating K. pneumoniae-associated metastatic colon cancer, paving the way for integrative strategies in cancer treatment that address both microbial and tumorigenic factors.