Table 1.

Recent studies on nanoparticles showing the source, shape and size, organisms tested, antimicrobial potential and other key findings (cytotoxicity and reported mechanisms)

Nps	Source	Shape and size	Bacteria isolates tested	Antibacterial activity (IZD/MIC/MBC) and other key findings	Reference
AgNps	Acacia rigidula plant extract	Spherical Size distribution:8–66 nm with mean of 22.46 nm Diameter size: 15–25 nm	E. coli, P. aeruginosa, Clinically MDR strain of P. aeruginosa and B. subtilis	In vitro: 62.5, 15.6, 7.8, and 0.5 ppm for E. coli, P. aeruginosa, multi-drug resistant P. aeruginosa and B. subtilis respectively In vivo: antimicrobial effect against the resistant pathogens tested in a murine skin infection model. Effective and safety use of Nps as therapeutic agents in animal models	Escarcega-Gonzalez et al. (2018)
AgNps	Biosynthesized using Pseudoduganella eburnean MAHUQ-39	Spherical 8–24 nm	Multidrug resistant pathogenic microbes S. aureus, P. aeruginosa, E. coli	MIC of S. aueus and P. aeruginosa were 100 µg/ml respectively. MBC of S. aureus and and P. aeruginosa were 200 and 50 µg/ml respectively Mechanism: structural alterations Disruption of the membrane integrity of strains S. aureus and P. aeruginosa	Huq (2020)
AgNps	Biosynthesized using Sphingobium sp-MAH-11	Spherical 7–22 nm	Drug resistant microbes P. aeruginosa, E. coli, S. aureus	MIC of E. coli and S. aureus were 6.25 and 50 µg/ml respectively and MBC of E. coli and S. aureus were 25 and 100 µg/ml respectively Mechanism: using E. coli and S. aureus, causes morphological alterations and disrupt membrane integrity of the isolates	Akter and Huq (2020)
AgNps	Green synthetic method and casein hydrolysate as a reducing reagent and NaOH as a catalyst	Spherical Average sizes: 10 ± 5 nm, 30 ± 5 nm, 60 ± 5 nm, 90 ± 5 nm	Vibrio natriegens	MIC and MBC were dose dependent. The smaller the particle the more bacterial damage. MIC ranges from 1 to 11.5 µg/ml and MBC, 1.1–11.7 µg/ml Mechanism: generation of ROS by bacteria and bacteria membrane damage	Dong et al. (2019)
AgNps	Synthesized using aqueous and ethanolic extract of Adrographis paniculata stem	Spherical Ag-bAgNps- 24.90 nm Et-bAgNps-25.24 nm	Enteropathogenic E. coli, S. typhi, S. aureus, V. cholerae, E. faecalis, Hafnia alvei, Acninetobacter baumannii, E. coli DH5α, E. coli K12 and B. cereus	Lowest MIC for both the bAgNps was 0.125 µg. Et-bAgNps had the highest antibacterial activity against S. aureus at 60 µg after 16 h and IZD was 28 mm Cytotoxicity: showed excellent hemocompatibility against human as well as rat RBC. No significant cytoxicity observed when the levels of rat serum ALT, AST, ϒ-GT (liver function biomarkers) and creatinine (kidney function biomarker) were evaluated	Hossain et al. (2019)
AgNps	Synthesized using methanolic extract of Oscillatoria spp.	Spherical 10 nm	S. aureus, E. coli 11,775, E. coli 35,218, P. aeruginosa, Citrobacter Spp., Salmonella typhi 14,028, B. cereus	Effective antibacterial activity against all pathogens with IZD ranging from 1 to 21 mm Antibiofilm: exhibit strong antibiofil activity Cytotoxicity: Using Artemia salina (brine shrimp), it was observed to be insignificant with the highest mortality at 4000 µg/ml and LC50 of 2630.3 µg/ml	Adebayo-Tayo et al.(2019)
AgNps	Synthesized using mycelial extract of endophytic fungus Talaromyces purpureogenus	Triangular shaped 25 nm	S. aureus, B. cereus, S. enterica, P. aeruginosa, E. coli	MIC of 16.12 µg/ml for gram positive and 13.98 µg/ml for gram negative Cytotoxicity: Not toxic to normal NIH3T3 cells. Showed cytotoxicity in A549 cells even at the lowest concentration of 2 µg/ml. cytotoxicity increases with the increase of Nps concentration. IC50 for AgNps and AgNO3 was 376.24 and 250.31 µg/ml respectively. 5.92% of cell apoptosis was induced by the Nps	Hu et al. (2019)
AgNps	Fusarium scirpi (fungi)	Quasi-spherical 2-20 nm	Uropathogenic E. coli	MIC of 25 mg/ml. Sub-MIC concentration (7.5 mg/l) was enough to inhibit the pathogen biofilm formation about 97% or produce the disruption of 80% of mature biofilm	Rodriguez-Serrano et al. (2020)
AgNps	Aqueous extract of Cyanobacterium oscillatoria	Spherical 3.30–17.97 nm	E. coli, B. cereus	IZD of 22 mm and 20 mm Mechanism: damage to cell membrane, leakage of cytoplasm exterior to cell, Internal diffusing of AgNps to cell, cell disruption, disintegration, Shrinking of protoplasm and, detachment of cellular membrane Cytotoxicity: hemolytic activity showed that it was non-toxic to human RBC in low concentrations	Hamouda et al., (2019)
AgNps	Aqueous extract of black pomegranate peels	Spherical 32–85 nm	P. aeruginosa	Showed strong inhibition against biofilm formation at 0.1–0.5 mg/ml Cytotoxicity: no significant toxicity against L929 cell line at 400 µg/ml	Habibipour et al. (2019)
AgNps	Synthesized by Fusarium solani	Spherical 13.70 nm	Multidrug resistant P. aeruginosa and S. aureus	Showed significant effect against P. aeruginosa (22.4 mm) and MIC of 21.33 µg/ml Mechanism: formation of cracks and pits in the cell wall when nanoparticles were internalized	El-Sayed and El-Sayed (2020)
AgNps	Biosynthesized using Xianghaiensis OF1 strain	Spherical 64 nm	P. aeruginosa, M. furfur, B. subtilis, E. coli, S. aureus and K. pneumonia	MIC of 16, 32, 64, 64, 256, 26 µg/ml respectively Cytotoxicity: in vitro cytotoxicity against mouse fibroblasts and cancer HeLa cell lines showed dose dependent activity. IC50 was found in concentration of 4 and 3.8 µg/ml	Wypig et al. (2018)
AuNps	Aqueous extract of Euprasia officinalis	Quasi-spherical 49.72 ± 1.2 nm	P. aeruginosa, E. coli, S. aureus and Vibrio parahaemolyticus	Antibacterial activity: 15.3 ± 0.5 ppm, 11.7 ± 0.5 ppm, 14.7 ± 0.9 ppm and 13.7 ± 1.1 ppm Cytotoxicity: inhibit human cervical cancer cells (HeLa) at 10 µg/ml but did not inhibit human lung cancer cells (A549)	Singh et al. (2018)
AuNps	Leaf extract of Annona muricata	Spherical 25.5 nm	S. aureus, Clostridium sporogenes, E. faecalis and K. pneumonia	Exhibit good antimicrobial activity with increase in concentration	Folorunso et al. (2019)
ZnONps	Albizia lebbeck stem bark	Spherical 66.25 nm	B. cereus, S. aureus, E. coli, K. pneumonia, and S. typhi	Exhibit strong antimicrobial activity which was dose dependent Cytotoxicity: MDA-MB231 and MCF-7 cell lines Cytotoxic effect was concentration dependent	Umar et al. (2019)
ZnONps	Bacillus haynesii	Spherical 50 ± 5 nm	E. coli ATCC 35,218, S. aureus ATCC 29,213	MIC and MBC values were > 8 and 16 mg/ml respectively for E. coli and 4 and 8 mg/ml respectively for S. aureus	Rehman et al. (2019)
ZnONps	Cinnamomum verum bark extract	Hexagonal wurtzite 45 nm	E. coli MTCC 7443 and S. aureus MTCC 7410	MIC of 125 µg/ml for E. coli and MIC OF 62.5 µg/ml for S. aureus	Ansari et al. (2020)
ZnONps	Boswellia ovalifoliolata	Spherical 20.3 nm	Sphingobacterium sp., Acinetobacter sp., Ochrobactrum sp.	IZD: 3 mm, 1.7 mm and 4 mm	Supraja et al. (2016)
ZnONps	Withania somnifera (ws) leaf extract	Hexagonal wurtzite 15.6 nm	E. faecalis, S. aureus, E. coli and P. aeruginosa	A greater antibacterial effect of ws-ZnONps was noticed against E. faecalis and S. aureus at 100µg/ml. The biofilm of E. faecalis and S. aureus were greatly inhibited at 100µg/ml compared to E. coli and P. aeruginosa. Cytotoxicity: laval and pupal development delayed at 25µg/ml. A complete mortality (100%) was observed at 25µg/ml. ws-ZnONps showed least LC50 value (9.65µg/ml) compared to the uncoated ZnONps (38.8µg/ml) and leaf extract (13.06µg/ml)	Malaikozhundan et al. (2020)
CuONps	Aqueous extract of Abutilon indicum	Hexagonal, wurtzite and sponge crystal structure 16.78	Klebsiella, E. coli, S. aureus, B. subtilis	Significant bactericidal activity of nanoparticle against Klebsiella and B. subtilis with IZD of 14 ± 005 and 15 ± 0.11 mm respectively. At 5 mg, the CuONps showed effective activity against S. aureus, Klebsiella, B. subtilis with IZD of 10 ± 0.11, 14 ± 0.05 and 15 ± 0.11 mm respectively	Ijaz et al. (2017)
CuONps	Aqueous extract of Tamarindus indica fruit	Cube shaped 40-50 nm	Proteus mirabilis, S. aureus	Significant synergistic effect with β-lactam antibiotics Reduction in biofilm formation of the two organisms by 85% and 93% respectively	Selvaraj et al. (2019)
CuONps	Leaf extract of Aloe barbadensis	Spherical 33.4–64.9 nm	Pseudomonas, Klebsiella, Staphylococcus, E. coli	IZD of 11, 12, 8 and 9 mm respectively	Saruchi et al. (2019)
TiO2Nps	Synthesized using S. aureus	Spherical 20 nm-30 nm	E. coli, B. cereus, S. aureus	Highly effective against B. subtilis (9 mm) and E. coli (14 mm) Showed antibiofilm activity against the pathogens	Landage et al. (2020)
TiO2Nps	Laser ablation	Round (circular) 36 nm	S. aureus, E. coli	In distilled water, the MIC is 9.45 mg/ml and 18.91 mg/ml for E. coli and S. aureus respectively. In alcohol, the MIC is 4.72 mg/l for E. coli and 9.45 mg/l for S. aureus	Abdul-Hussan et al. (2018)
MgONps	Aqueous extract of Swertia chirayaita	Spherical  < 20 nm	S. aureus MTCC9442, S. epidermidis MTCC 2639, B. cereus MTCC-9017, E coli MTCC 9721, Proteus vulgaris MTCC7299, K. pneumonia MTCC9751	Antimicrobial activity was dose dependent The IZD of the various MgONps concentrations (10, 20, 30 and 40 µl)(0.25 µg/ml) were 18 mm for E. coli and 17 mm for S. aureus, which were also the maximum IZD for all the tested bacteria respectively. Moreover, a 16 mm IZD was obtained for B. cereus, K. pneumonia and P. vulgaris	Sharma et al. (2017)
MgONps	Leaf extracts of Rhododendron arboretum	Sphere shaped –	E. coli, Streptococcus mutants, Proteus vulgaris	Inhibition was dose-dépendent and increased with increase in concentration. At 10 mg/ml of MgONps, IZD were 36 mm, 32 mm, 24 mm for E. coli, S. mutans and Proteus vulgaris respectively	Singh et al. (2019)
MgONps	Trigonella foenum-graecum leaf extract	Spherical 13 nm	E. coli, Bacillus, S. aureus	Good antibacterial activity: 125 µg, 250 µg, 125 µg	Vergheese ans Vishal (2018)
MgONps	Commercial	Polyhedral morphology 20 nm	E. coli, P. aeruginosa, S. aureus, S. epidermidis, MRSA	The MIC varied from 0.5 to 1.2 mg/ml. The minimal lethal concentration (MLC) at 90% killing varied from 0.7 to 1.4 mg/ml against the various pathogens. The most potent concentration (MPC) was 1.4 and or 1.6 mg/ml—this depends on the organism tested Mechanism: reduction in adhesion, disruption of biofilm formation, production of ROS, quorum sensing and Ca2+ concentrations	Nguyen et al. (2018)