Table 2.

Antimicrobial activity of bimetallic and trimetallic NPs.

NPs	Size (nm)	Bacteria	Mode of Action	Synthesis	Ref.
Ag/Au	9.7	E. coli, S. aureus	Increased production of ROS	Green	[71]
Ag/Cu	26	E. coli, B. subtilis	Permeability of copper and silver ions into the bacterial cell membrane	Biosynthesis (plant)	[72]
Au/Pt	2–10	S. aureus, P. aeruginosa, C. albicans	Release of Ag+ ions, unbalance of cell metabolism, and ROS generation	Chemical reduction	[73]
Ag/Fe	110	S. aureus, P. aeruginosa	Release of Ag+ ions and ROS generation	Electrical explosion	[74]
Ag/Pt	36	E. faecalis, E. coli	Increased production of ROS	Biosynthesis (plant)	[75]
Cu/Zn	100	A. faecalis, S. aureus, C. freundii	Synergistic properties of Zn2+ and Cu2+ ions together	Biosynthesis (plant)	[76]
Cu–Ni	25	S. mutans, S. aureus, E. coli	Strong adsorption of ions to the bacterial cells	Chemical reduction	[77]
Ag/ZnO	43	S. aureus, P. aeruginosa	Ag+ leaching from metallic silver	Photoreduction	[78]
Ag/SnO2	9	B. subtilis, P. aeruginosa, E. coli	Synergistic properties of Ag and SnO	Biosynthesis (plant)	[79]
Cu/FeO2	32.4	B. subtilis, X. campestris	DNA damage induced by NPs	Hydrothermal	[80]
Au/CuS	2–5	B. anthracis	Disordered and damaged membranes	Seeded	[81]
Fe3S4/Ag	226	S. aureus, E. coli	Release of Ag+ions and ROS generation	Solvothermal	[82]
MgO/ZnO	10	P. mirabilis	Alteration of cell membrane activity, ion release, and ROS production	Precipitation	[83]
CuO/ZnO,	50 and 82	E. coli, S. aureus	Electrostatic interaction causing to change membrane permeability on account of depolarization	Electrical explosion	[84]
CuO/Ag	20–100	L. innocua, S. enteritidis	Binding of the ions released by μCuO/nAg to the thiol groups of many enzymes in cell membrane	Hydrothermal	[85]
Fe3O4/ZnO,	200–800	S. aureus, E. coli	Membrane stress, disrupting and damaging cell membrane	Coprecipitation	[86]
CeO2/FeO2	40 and 25	P. aeruginosa	Combination of NPs with antibiotic ciprofloxacin, causing inhibitory effect on bacterial growth and biofilm formation	Hydrothermal	[87]
Cu/Zn/Fe	42	E. faecalis, E. coli	Interruption of cellular processes by released ions, which can cross cell membranes	Chemical reduction	[88]
Au/Pt/Ag	20–40	E. coli, S. typhi, E. faecalis	Generation of ROS	Microwave	[89]
Cu/Cr/Ni	100–200	E. coli, S. aureus	Antibacterial activity of trimetallic NPs in comparison with pure metals	Biosynthesis (plant)	[63]
CuO/NiO/ZnO	7	S. aureus, E. coli	Ruptured and cracked bacterial cells by the release of intracellular components	Coprecipitation	[90]
Ag/ZnO/TiO2	60–170	E. coli	Reduction in the bandgap energy by increasing the e− & h+ charge separation time	Sol–gel	[91]