A RESEARCH ON GREEN SYNTHESIS, ANALYTICAL CHARACTERISATION AND DEVELOPMENT OF DOXORUBICIN-LOADED SILVER NANOPARTICLES USING COLUMN-FRACTIONATED CATHARANTHUS ROSEUS STEM EXTRACT

This study develops doxorubicin (DOX)-loaded silver nanoparticles (DOX-AgNPs) by green synthesis, using a column-chromatography-purified fraction of Catharanthus roseus stem extract as the reducing and capping agent. Dried stem powder is extracted with methanol, fractionated on a silica gel column (gradient elution, hexane → ethyl acetate → methanol), and the fractions richest in phenolics and flavonoids (by TLC and Folin–Ciocalteu assay) are used to reduce 1 mM AgNO₃. Synthesis is optimised for extract-to-AgNO₃ ratio, pH, temperature and time. DOX is loaded onto the phyto-capped AgNPs by electrostatic adsorption, and unbound drug is removed by centrifugation. The nanoparticles are characterised by UV-Vis spectroscopy (surface plasmon resonance near 420–440 nm), FTIR, XRD, SEM/TEM with EDX, DLS and zeta potential, and TGA/DSC. Drug loading is quantified by UV-Vis at 480 nm and confirmed by RP-HPLC. In vitro release is studied at pH 7.4 and pH 5.5, and cytotoxicity is tested on MCF-7 cells by MTT assay. It is a purified, phenolic-rich fraction gives smaller, more uniform and more reproducible AgNPs than crude extract, and that DOX-AgNPs release drug preferentially at acidic tumour pH with a lower IC₅₀ than free DOX.