. 2021 Jul 2;11:693939. doi: 10.3389/fcimb.2021.693939

Table 1.

Engineered titanium alloys with antibacterial properties.

Alloy system	Sample	Preparation	Bacterial Strains	Antibacterial Test	Antibacterial Effect	Antibacterial Mechanisms		Reference
Ti-Cu	Ti-xCu (x = 1 and 5 wt%)	/	S. aureus, E. coli	Plate counting	Evidently inhibited bacteria colonization	Cu-ion release	Prevention of pin tract infection	Shirai et al., 2009
				Rabbit pin tract infection model	Ti-1Cu alloy significantly inhibited inflammation and infection
Ti-Cu	Ti-10 wt% Cu	Powder metallurgy	S. aureus, E. coli	Plate counting	Antibacterial rates for E. coli and S. aureus: 99%, 100%, respectively	Cu-ion release	Dental materials and surgical implant	Zhang et al., 2013
Ti-Cu	Ti–xCu (x = 2, 5, 10 and 25 wt%)	Powder metallurgy	S. aureus, E. coli	Plate counting	Cu content must be at least 5 wt% to obtain strong and stable antibacterial property	Cu-rich phase	Orthopedic and prosthodontic fields	Liu et al., 2014
Ti-Cu	Ti-xCu (x = 5 and 10 wt%)	Sintering	P. gingivalis	Plate counting, live/dead staining, and SEM	Killed anaerobic bacteria and reduced the activity of surviving bacteria	Cu ions released from Ti-Cu alloy	Dental implants	Bai et al., 2016
Ti-Cu	Ti-10Cu	Sintering	S. aureus	Infected rabbit muscle model	Reduced implant-related infection or inflammation	/	Orthopedic surgery and dental implant	Wang et al., 2019
Ti-Cu	Ti-3Cu	Microwave sintering	S. aureus, E. coli	Plate counting	Strong antibacterial ability and comparable elastic modulus with cortical bone	/	Orthopedic and dental implants	Tao et al., 2020
Ti–Cu	Ti-xCu (x = 2, 3 and 4 wt%)	Casting with post-treatment	S. aureus	Plate counting	Heat treatment significantly improved antibacterial rate	Homogeneous distribution and a fine Ti₂Cu phase	Load-bearing implants and dental implants	Zhang et al., 2016a
Ti-Cu	Ti-5wt% Cu	Casting	S. mutans, P. gingivalis	Real-time PCR, live/dead staining, SEM, TEM	Antimicrobial/anti-biofilm activities	Cu ions released from the alloys	Dental implant	Liu et al., 2016b
Ti-Cu	Ti-5wt% Cu	Casting with post-treatment	S. aureus, E. coli	Plate counting, live/dead staining, SEM, TEM	Killed attached bacteria and inhibited biofilm formation	Contact sterilization	Dental application	Liu et al., 2018
				Dog mandibular premolar infection model	Superior capacities in inhibiting bone resorption			Liu et al., 2018
Ti6Al4V-Cu	Ti6Al4V-xCu	Casting with post-treatment	S. aureus, E. coli	Plate counting	Strong antibacterial abilities	/	Surgical implant materials	Ren et al., 2014
Ti6Al4V-Cu	Ti6Al4V-5Cu	Casting with post-treatment	S. aureus	Plate counting, SEM, live/dead staining	Annealing Ti6Al4V-5Cu alloy at 740°C showed the best overall properties	Ti₂Cu phases	Bone implant	Peng et al., 2018
Ti6Al4V-Cu	Ti6Al4V-6.5wt%Cu	As-cast	S. aureus	Live/dead staining	Significant antibacterial effects and inhibited biofilm formation	/	Bone implant	Yang et al., 2021
Ti6Al5V-Cu	Ti6Al-4V-5.56 wt%Cu	As-cast	MRSA	Plate count method, crystal violet staining, SEM, and real-time PCR	Effectively killed MRSA and inhibited biofilm formation	Continuous and stable Cu²⁺ release	Implant material for protection against MRSA-induced IAI	Zhuang et al., 2021
			MRSA	Rat implant-associated infection model	No sign of infection			Zhuang et al., 2021
Ti6Al4V-Cu	Ti6Al4V-xCu (x = 0, 2, 4, 6 wt%) alloy	SLM	S. aureus, E. coli	Plate counting	Alloys with 4 wt% and 6 wt% Cu had strong and stable antibacterial properties	Cu ions release	Dental implant	Guo et al., 2017
Ti5Al2.5Fe-Cu	Ti5Al2.5Fe-xCu (x = 1, 3 and 5 wt%)	Powder metallurgy	S. aureus, E. coli	Plate counting	Antibacterial ability was enhanced by addition of Cu to Ti–5Al–2.5Fe alloy	Ti–Cu phases	Orthopedic and dental implants	Yamanoglu et al., 2018
Ti-Cu-Mn	Ti-xCu-yMn	Powder metallurgy	E. coli	Plate counting	Strong antibacterial activity	Ti₂Cu intermetallic particles	Dental and orthopedic implants	Bolzoni et al., 2020
Ti-Nb-Ta-Zr-Cu	Ti-1.6Nb-10Ta-1.7Zr-xCu (x = 1, 3, 5, 10, and 11 wt%)	Casting with appropriate heat treatment	S. epidermidis	Bacterial luminescence	Good antibacterial effect	Larger amounts of Ti₂Cu	Dental implants	Fowler et al., 2019
Ti-Ag	Ti–xAg (x = 1, 3 and 5 wt%)	Sintering	S. aureus	Plate counting	Ag content should be >3 wt% to achieve strong and stable antibacterial activity	Ti₂Ag and its distribution	Orthopedic and dental implants	Chen et al., 2016
Ti-Ag	Ti-3Ag (sintered); Ti-3, 15Ag (T4); Ti-3, 15 Ag (T6)	Sintering, casting, casting with appropriate post-treatment	S. aureus	Plate counting	T6 treatment provided alloy with strong antibacterial ability	Ag ion release and homogeneously distributed Ti₂Ag particles (key)	Orthopedic and dental implants	Chen et al., 2017
Ti-Ag	Ti-7, 9, 11 wt% Ag (T6); Ti-7, 9, 11 wt% Ag (ST);	Casting with appropriate post-treatment +/- surface treatment (ST)	S. aureus	Plate counting	Antibacterial properties increased with increasing Ag content	Ti₂Ag particles in a contact sterilization mode (key); Ag ion release	Orthopedic and dental implants	Shi et al., 2020
Ti-Ag	Ti-xAg (x = 0, 1, 3 and 5 wt%)	Spark plasma sintering and acid etching	S. aureus	Plate counting	Antibacterial rates of Ti-1, 3, 5 wt% Ag were <21%	Particles with high Ag contents	Orthopedic and dental implants	Lei et al., 2018
Ti-Ga	Ti-8Al-3Si-3Zr-x1Ga (x = 1, 2 and 20 wt%); Ti-23Ga	Powder metallurgy	Multidrug-resistant S. aureus	Plate counting	Metabolic activity reduced by >80%	Surface-exposed Ga	Orthopedic applications	Cochis et al., 2019

“/” means “not mentioned”.