Trends in Sustainable Green Synthesis of Silver Nanoparticles Using Agri-Food Waste Extracts and Their Applications in Health

Table 2

Effect of size and shape on the antibacterial activity mechanisms of silver nanoparticles synthesized from agri-food waste.

Waste	Size (nm) and shape	Bacteria	Concentration effect or inhibition halo	Antibacterial mechanism	Reference
Leaf-stem waste of Carthamus tictorious	8.67 ±4.7, and spherical	S. aureus, P. fluorescens	1.9 μg/mL S. aureus and 15.6 μg/mL P. fluorescens	Generation of ROS, such as radicals OH, hydrogen peroxide. Silver can interact with these components inside and outside the cell membrane, resulting in bacterial inactivation. Silver ion interacts with the phosphorus present in DNA and proteins, causing the inhibition of enzymatic activities. Oxidative stress in the bacteria and attack the lipids of the outer membrane, causing lipid oxidation, as well as damage to proteins, RNA, and DNA	[215]
Non-edible part of fruit of Cynara scolymus L.	Around 10.59, and spherical	S. aureus, B. Subtilis, E. Coli, P. aeruginosa	0.12 and 0.25 μg/mL were effective on Gram-positive S. aureus and B. subtilis. 0.07 and 0.13μ/mL were effective on P. aeruginosa and E. coli in Gram-negative	Silver ions interact with the negatively charged cell membranes of microorganisms cause an increase in reactive ROS and cell-wall structure is disrupted	[262]
Onion peels	Not shown	S. typhimurium, S. aureus	Zone of inhibition of 8 mm and 9 mm respectively	Metal nanoparticles show good activity against both the strains studied	[263]
Raphanus sativus L. waste	10-14, spherical and agglomeration	E. coli, P. aeruginosa, S. typhimurium, S. aureus	65.67 ± 0.91 mm P. aeruginosa of inhibition halo	Antimicrobial effect of phenolics products in Np can involve various modes of action such as enzyme inhibition by the oxidized products, maybe through reaction with sulfhydryl groups or through more nonspecific interactions with the proteins	[264]
Waste banana stem	<20 and spherical	B. subtilis (Gram positive) and E. coli (Gram negative)	Strong bioactivity against both microorganisms. The highest zone of inhibition against B. subtilis (14.2 mm) and E. coli (9.3 mm) is found at concentrations of 4.0 ppm and 2.0 ppm, respectively	Not shown	[265]
Crushed, wasted, and spent Humulus lupulus	92.42 ± 2.41 DLS and 17.40 ± 2.4 nm TEM, and spherical	Gram-positive S. aureus (ATCC 29213) and Gram-negative E. coli (ATCC 25922)	Inhibition zone of 12 ± 0.81 mm against S. aureus and 15.33 ± 0.94 mm for E. coli with 500 μg/mL AgNPs	Disruption of the cell membrane leading to cell lysis, interaction with the genetic materials leading to DNA damage, and formation of ROS causing cellular stress and, finally, death. AgNPs are also known to damage protein synthesis and interfere with the; synthesis of capsular polysaccharides, other cellular functions	[260]
Coconut (Cocos nucifera) outer shell fiber		E. coli O157: H7 ATCC 23514, E. faecium DB01, P. acnes ATCC 6919, and L. monocytogenes ATCC 33090	Among the five tested pathogens, the CS-AgNPs were more active against the L. monocytogenes with 13.07 mm diameter and MIC of 100 μg/mL	A possible mode of action of the CS-AgNPs is due to the existence of Ag^+ ions, which inhibits the bacterial progression through the destruction of the respiratory enzyme and the electron transport mechanisms and also through the interfering with the DNA function	[266]