Table 1.

Mechanism of action and development of metal nanoparticles (NP)-based strategies for Methicillin-resistant Staphylococcus aureus (MRSA) treatment.

Type	Mode of Action	MICs Reported	Biofilm Effective?	Development Status	Delivery Methods	References
Ag NPs	Bacterial cell membrane disruption Cytochrome and electron transport inhibition DNA/RNA binding and inhibition of replication Ribosomal binding and inhibition of protein synthesis ROS formation Inhibits gram + cell wall formation	0.25–64.5 μg/mL	Yes	In vitro/in vivo validated	Micro-Patterned on titanium implants Topical hydrogel	[32,33,40,41,51,52]
ZnO NPs	Bacterial cell membrane disruption ROS formation	1–10 μg/mL	Yes	In vitro/in vivo validated	Intradermal I.V injection	[53,54,55,56,57]
Cu/CuO NPs	Interacts with amine and carboxyl groups on bacterial cell surface ROS formation	1.87 μg/mL–1 mg/mL	Yes	In vitro validated	n/a	[44,58,59,60,61]
TiO2 NPs	ROS formation following UV stimulation (photocatalysis) UV-independent effects (mechanism unknown)	100 μg/mL–15 mg/mL	Low activity, rarely tested	In vitro validated	n/a	[62,63,64,65,66]
MgX2/MgO NPs	MgX2 enzymatic inhibition ROS formation MgO-induced halogen adsorption	1.5 mg/mL	Yes	In vitro/in vivo validated	coated on titanium implants (osteomyelitis model)	[67,68,69,70]
Au NPs	No intrinsic antimicrobial effect Activity achieved through functionalization or combination therapy	8–32 μg/mL (modification dependent)	Yes (combination therapy)	In vitro/in vivo validated (combination therapy)	Systemic sepsis	[46,71,72,73,74,75,76]
Bi NPs	Radiation-stimulated free radical formation and DNA damage	0.2–11.47 µM	Yes	In vitro validated	n/a	[77,78,79,80]

MIC: Minimum Inhibitory Concentration, Ag NPs: Silver Nanoparticles, ZnO: Zinc Oxide, I.V: intravenous, Cu/CuO: Copper/Copper Oxide, TiO₂: Titanium Oxide, MgX2: Magnesium with X₂ referring to a bonded halide, Au: Gold, Bi: Bismuth.