Comparison studies on the physicochemical properties and antimicrobial activities of copper (I) oxide nanoparticles synthesized using bulk and microfluidic methods

Microfluidic (MF) technology offers significant advantages for nanomaterial synthesis due to precise process control and automation. This study compares the physicochemical properties and antimicrobial activities of copper (I) oxide nanoparticles (Cu₂O NPs) synthesized using conventional batch and MF methods, with glucose as a reducing agent for CuSO₄ and starch as a capping agent. The reaction was carried out with NaOH concentrations ranging from 0.06 to 0.5 M. In the range of 0.08–0.15 M NaOH, X-ray diffraction analysis and scanning electron microscope images revealed smaller particles (< 100 nm), with the MF method producing more uniform particles. Dynamic light scattering results showed larger particles formed outside this NaOH concentration range. The conventional batch method produced more stable Cu₂O NPs, while MF NPs tended to agglomerate over time. Zeta potentials of all Cu₂O NPs were higher than −20 mV, indicating stabilization by polymeric starch adsorption. Antimicrobial activity was evaluated by incubating Escherichia coli and Colletotrichum gloeosporioides with Cu₂O NPs. Batch Cu₂O NPs exhibited higher antimicrobial activity than MF Cu₂O NPs. The highest inactivation was achieved with 0.15 M NaOH batch Cu₂O NPs, showing a 5.55 log reduction of E. coli and 96% growth inactivation of C. gloeosporioides.