Fine-tuning the cytotoxicity profile of N,N,N-trimethyl chitosan through trimethylation, molecular weight, and...

N,N,N-trimethyl chitosan (TMC) is a promising biopolymer for pharmaceutical applications due to its enhanced solubility and bioadhesive properties, though its cytotoxic limitations necessitate careful modification to ensure safety and efficacy. This study sought to investigate whether nanoparticle (NP) formation could reduce the anticipated cytotoxic effects of TMC, thus improving its applicability across a wider spectrum of pharmaceutical uses. TMC's capability to form NPs with anionic polyelectrolytes led to the application of chondroitin sulfate (ChS) in this study. Five TMC samples, varying in degree of trimethylation (DTM 23, 32, 46, 50 and 99 %) and molecular weight (M_w, 66-290 kDa) were synthesized, and their biocompatibility with human umbilical vein endothelial cells (HUVECs) was assessed. The results revealed a discernible impact of both DTM and M_w on cell viability, with higher DTM and lower M_w correlating with increased toxicity. Cytotoxicity studies against ovarian cancer cell lines SKOV-3 and OVISE showed a clear indication of a higher cytotoxic effect of TMC samples against cancer cells compared to healthy cells (HUVEC). The cytotoxicity against cancer cells also indicated an optimal DTM for maximum efficacy, deviating from a linear trend. The effects of M_w were cell-dependent, introducing complexity to the observed relationship. Additionally, TMC-ChS NPs were successfully prepared, demonstrating a substantial reduction in cytotoxicity compared to TMC alone in all tested cells. This promising outcome suggests the potential of NP formation to fine-tune the cytotoxicity profile of TMC, paving the way for the development of safer and more effective pharmaceutical formulations.