Green and gentle synthesis of Cu2O nanoparticles using lignin as reducing and capping reagent with antibacterial properties

In this work, Cu2O 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 Cu2O 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 Cu2O nanoparticles coated by lignin showed a particular shape. The morphology of Cu2O 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 Cu2O nanoparticles. In addition, the sterilisation of Cu2O nanoparticles on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was also investigated. The Cu2O nanoparticles showed effective bactericidal activity against E. coli and S. aureus. The antibacterial rate could get 100% after 30 min with 4.0 g/L Cu2O nanoparticles. Furthermore, the Cu2O nanoparticles were confirmed to have low cytotoxicity.