<div><p>In this work, Cu<sub>2</sub>O nanoparticles of a particular shape were prepared by an eco-friendly, gentle and low-cost synthetic method using lignin as a reducing and capping reagent. Structure and morphology of the Cu<sub>2</sub>O nanoparticles were characterised by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and Fourier-transform (FT-IR) spectroscopy. The results established that Cu<sub>2</sub>O nanoparticles coated by lignin showed a particular shape. The morphology of Cu<sub>2</sub>O nanoparticles presented as some loose accumulation of particles just like broccoli, and the particle size range was between 100 and 200 nm. And, the XRD revealed the structure of crystalline of the Cu<sub>2</sub>O nanoparticles. In addition, the sterilisation of Cu<sub>2</sub>O nanoparticles on <i>Staphylococcus aureus</i> (<i>S. aureus</i>) and <i>Escherichia coli</i> (<i>E. coli</i>) was also investigated. The Cu<sub>2</sub>O nanoparticles showed effective bactericidal activity against <i>E. coli</i> and <i>S. aureus</i>. The antibacterial rate could get 100% after 30 min with 4.0 g/L Cu<sub>2</sub>O nanoparticles. Furthermore, the Cu<sub>2</sub>O nanoparticles were confirmed to have low cytotoxicity.</p></div
