Green Synthesis of Chitosan-Coated Selenium Nanoparticles for Paclitaxel Delivery

Selenium nanoparticles (Se NPs) were synthesized from Na₂SeO₃ using <i>Foeniculum vulgare</i> (fennel) seed extract as mild sustainable reductant, coated with chitosan (Ch), and loaded with Paclitaxel (PTX). The PTX release from the Se@Ch-PTX NPs and their cytotoxicity against MDA-MB-231 breast cancer cells was studied in view of an application as drug delivery platform. Thermogravimetric analysis (TGA) showed the thermal stability of the NPs up to 300 °C. UV-vis absorption and Fourier transform IR (FT-IR) spectroscopy allowed to trace surface species originating from the <i>F. vulgare</i> extract on the Se NPs, while the surface of the Se@Ch-PTX NPs is characterized from Ch and PTX functionalities. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed approximate spherical shaped NPs with sizes ranging from 10 to 40 nm. Zeta potential measurements showed a clear distinction between the -39 mV found the Se NPs and +57 mV for the Ch-PTX coated NPs. The NPs showed good biocompatibility with red blood cells (RBCs) in hemolytic activity assays, exhibiting no hemolytic effects at concentrations ranging from 50 to 400 µg/mL. In vitro release studies showed a sustained and pH-responsive release pattern with a maximum release of about 80% within 22 h for Se@Ch-PTX at pH = 3.5. The Se@Ch-PTX NPs showed high antiproliferative activity against MDA-MB-231 cells with an IC₅₀ value of 12.3 µg/mL compared to about 36 for PTX and 52 µg/mL for the Se NPs. The reactive oxygen species (ROS) activity as studied through DPPH scavenging showed higher values for the Se@Ch-PTX NPs compared to the Se NP.