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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. [ABSTRACT FROM AUTHOR]

The femtosecond laser direct writing of metals has gained significant attention for micro/nanostructuring. Copper (I) oxide nanospheres (NSs), a promising material for multi-photon metallization, can be reduced to copper (Cu) and sintered through near-infrared femtosecond laser pulse irradiation. In this study, we investigated the size effect of copper (I) oxide nanospheres on their morphology when coated on Cu thin films and irradiated by near-infrared femtosecond laser pulses. Three Cu2O NS inks were prepared, consisting of small (φ100 nm), large (φ200 nm), and a mixture of φ100 nm and φ200 nm NSs. A unique phenomenon was observed at low laser pulse energy: both sizes of NSs bonded as single layers when the mixed NSs were used. At higher pulse energies, the small NSs melted readily compared to the large NSs. In comparisons between the large and mixed NSs, some large NSs remained intact, suggesting that the morphology of the NSs can be controlled by varying the concentration of different-sized NSs. Considering the simulation results indicating that the electromagnetic fields between large and small NSs are nearly identical, this differential morphology is likely attributed to the differences in the heat capacity of the NSs. [ABSTRACT FROM AUTHOR]

The femtosecond laser direct writing of metals has gained significant attention for micro/nanostructuring. Copper (I) oxide nanospheres (NSs), a promising material for multi-photon metallization, can be reduced to copper (Cu) and sintered through near-infrared femtosecond laser pulse irradiation. In this study, we investigated the size effect of copper (I) oxide nanospheres on their morphology when coated on Cu thin films and irradiated by near-infrared femtosecond laser pulses. Three Cu2O NS inks were prepared, consisting of small (φ100 nm), large (φ200 nm), and a mixture of φ100 nm and φ200 nm NSs. A unique phenomenon was observed at low laser pulse energy: both sizes of NSs bonded as single layers when the mixed NSs were used. At higher pulse energies, the small NSs melted readily compared to the large NSs. In comparisons between the large and mixed NSs, some large NSs remained intact, suggesting that the morphology of the NSs can be controlled by varying the concentration of different-sized NSs. Considering the simulation results indicating that the electromagnetic fields between large and small NSs are nearly identical, this differential morphology is likely attributed to the differences in the heat capacity of the NSs.