Table 3.

Antibacterial activities shown by cerium oxide nanoparticles

S No	Size of CeNPs	Type of bacteria	Name of bacteria	Mechanism of action	Reference
1	7 nm	Gram-negative	Escherichia coli	ROS generation in a cell due to adsorption of a large number of CeNPs on bacterial membrane	Thill et al. (2006)
2	3.5–6.5 nm	Gram-negative	Escherichia coli	CeNPs showed concentration and size-dependent antibacterial activity to HB101 K-12 strain of E. coli by ROS generation	Dar et al. (2017)
3	140 nm	Gram-negative	Escherichia coli	The semiconductor properties of polymers improved the antibacterial activity of polymer-coated CeNPs	Kartsonakis et al. (2008)
4	7 nm	Gram-negative	Escherichia coli	Intracellular ROS generation inside cells due to direct contact of CeNPs with E. coli was responsible for the obtained antibacterial property	Kuang et al. (2011)
5	10 nm	Gram-negative	Escherichia coli	CeNPs resulted in maximum antibacterial activity at pH 6 and activity started decreasing at alkaline pH	Shah et al. (2012)
6	25–50 nm	Gram negative	Escherichia coli	The redox potential of CeNPs increased ROS generation and hence oxidative stress inside E. coli cells	Li et al. (2012)
7	100 nm	Gram negative	Escherichia coli	CeNPs combined with three different non-ionic surfactants showed improved toxicity to bacterial cells as compared to bare CeNPs (almost 20 times more)	Cuahtecontzi-Delint et al. (2013)
8	25–30 nm	Gram positive and gram-negative	Staphylococcus aureus and Escherichia coli	Inactivation of cellular proteins resulted in antibacterial action	Kannan and Sundrarajan (2014)
9	5 nm	Gram positive and gram-negative	Staphylococcus aureus and Escherichia coli	ROS generation due to uneven ridges and oxygen defects in CeNPs	Arumugam et al. (2015)
10	3.61–24.4 nm	Gram positive and gram-negative	Bacillus subtilis and Escherichia coli	Disruption of cell membrane resulted in antibacterial activity of CeNPs	Senthilkumar et al. (2017)

The types of bacteria and mechanism of action in antibacterial activity of CeNPs are mentioned in the table