Table 1.

Use of bionanofactories in the synthesis of silver nanoparticles, along with a brief outline of their physicochemical and antimicrobial properties.

Category of Biofactories	Reducing Agent	UV/Vis	FTIR (cm−1)	Structural Analysis	In Vitro Activity Studies	Ref.
Green Algae	Ulva compressa Cladophora glomerata	403 nm (<6 h), 443 nm (after 24 h)	3278, 1634, 1539	AFM ▪For AgNPs (U. compressa): Sa 1.01 nm; Sq 1.48 nm; Sz 9.09nm. ▪For AgNPs (C. glomerata): Sa 0.471n m; Sq 0.848 nm; Sz 5.90 nm. XRD ▪Crystalline ▪Structure—face-centered cubic (FCC) Particle size ▪AgNPs (U. compressa)—66.3 nm ▪AgNPs (C. glomerata)—81.8	▪Antimicrobial efficacy against species such as K. pneumoniae, P. aeruginosa, E. coli, E. faecium, and S. aureus	[36]
	Spirogyra varians	420–430 nm	3423, 2927, 1645, 1515, 1429	XRD ▪Face-centered cubic (FCC) SEM ▪Average size ~35 nm ▪Shape—uniform and quasi-spherical	▪Antibacterial activity against Staphylococcus aureus, Bacillus cereus, Salmonella typhimurium, Escherichia coli, and Listeria monocytogenes	[37]
Brown Algae	Spatoglossum asperum	440 nm	1638, 1034, 3447, 1034.95, 1384.14	SEM ▪Shape—spherical to oval ▪Size—32 to 51 nm TEM ▪Shape—mostly spherical ▪Size—20 to 46 nm XRD ▪Crystalline ▪Structure—face-centered cubic (FCC) EDS ▪Strong signal indicating presence of metallic silver	▪Agar bioassay method showed reduction of bacterial colonies of K. pneumoniae with increasing concentration.	[38]
Red Algae	Spyridia fusiformis	450 nm	3907, 3779, 3410, 2927, 2853, 2593, 1644, 1416, 1170, 749	HR-TEM ▪Shape—variable shapes such as spherical, triangle, pseudo-spherical, and some rounded rectangle shapes ▪Most observed shape and size—spherical and 5 to 50 nm ▪Average size of NPs—32.70 nm XRD ▪Crystalline ▪Structure—face-centered cubic (FCC)	▪Antibacterial activity of AgNPs (concentration = 100 μg/mL) Maximum zone of inhibition: ▪In K. pneumoniae = 26 mm ▪In S. aureus = 24 mm	[39]
	Gracilaria corticata	424 nm; another peak at 220 nm maybe due to the presence of amide bond	2921, 1630, 1,455	EDS ▪Optical absorption peak observed at 3 keV is typical for the absorption of metallic silver XRD ▪Crystalline ▪Structure—Face-centered cubic (FCC) TEM ▪Size range = 10–35 nm	▪Cytotoxic activity—on Hep2 cell lines, IC50 = 62.5 μg/mL	[40]
Blue-Green Algae	Nostoc sp.	419 nm	3443.96, 3385.61, 2923.83, 2853.32 1644.73	SEM ▪Shape—spherical ▪Average size 51–100 nm TEM ▪Spherical and well-dispersed. TEM-SAED pattern ▪Structure—face-centered cubic ▪Nature—crystalline XRD ▪Nature—crystalline	▪No significant cytotoxicity against MCF-7 breast cancer cells at lower concentration; cytotoxicity increased with increasing concentration from 0 μL/mL to 50 μL/mL ▪Good antibacterial and antifungal activity	[41]
	Anabaena sp.	420 nm	3383.72, 2930.60, 1651.13, 1076.58	TEM ▪Size: 10–50 nm XRD ▪Nature—crystalline ▪Structure—face-centered cubic (FCC) ▪Calculated particle size—20 nm	▪Ag-CNP treatment inhibited growth of tumor and cancer cells and induced apoptosis	[42]
Actinomycetes	Streptacidiphilus durhamensis	-	3421, 1384.4, 1623, 1480	TEM ▪Spherical shape EDS ▪Indicated Ag as the major element with a ~3 keV signal ▪Heterogeneous particle size distribution observed in the range of ~8–48 nm.	▪Antimicrobial activity against the tested strains such as S. aureus, B. subtilis, E. coli, P. aeruginosa, K. pneumoniae, and P. mirabilis but not S. infantis ▪Synergistic effects of bio(AgNPs) with various standard antibiotics	[43]
	Streptomyces rochei	410 nm	3420.14, 2932.23, 2362.37, 1639.20, 1430.92, 1115.62, 613.252	EDS ▪Optical absorption peak for AgNPs observed at 3.5 keV SEM ▪Size: 22 to 85 nm	▪AgNPs exhibited synergistic effects with antibiotics such as ciprofloxacin, ampicillin, streptomycin, gentamicin, tetracycline and lincomycin ▪AgNPs reduced the density of bacterial cells and acted as an antibiofouling agent	[44]
	Streptomyces sp.	425 nm	3695.61, 1585.49, 1398.39, 1151.50, 1068.56	XRD ▪Nature—crystalline ▪Structure—face-centered cubic (FCC) SEM ▪Size range = 21–45 nm	▪As compared to the cell-free supernatant, synthesized AgNPs showed high anticandidal activity	[45]
	Nocardiopsis sp. MBRC-1	420 nm	3440, 2923, 2853, 1655, 1460, 685	SEM ▪Average particle size ~45 ± 0.05 nm FE-SEM and EDS ▪The optical absorption peak was observed at 3 keV TEM ▪Size range—30–90 nm ▪Average particle size—45 ± 0.15 nm ▪Shape—spherical	▪Excellent antimicrobial activity by AgNPs observed against Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans ▪Cytotoxicity studies against HeLa cancer cell lines, IC50 = 200 μg/mL	[46]
Fungi	Arthroderma fulvum	420 nm	-	XRD ▪Nature—crystalline ▪Structure—face-centered cubic (FCC) TEM ▪Shape—spherical ▪Average diameter—15.5 ± 2.5 nm Particle size analysis ▪Average diameter = 20.56 nm	▪Potential antifungal activity against fungi such as Candida spp., Aspergillus spp., and Fusarium spp. observed ▪Compared to antifungal drugs such as itraconazole and fluconazole, the biosynthesized AgNPs at concentrations near to 1 mg/mL showed a broader antifungal spectrum	[47]
	Mushroom Pleurotus ostreatus	400–470 nm	3318, 2944, 1612, 1411	HR-TEM and FE-SEM ▪Shape—spherical in shape ▪Average size range—10–40 nm Size distribution analysis ▪Average size—28 nm EDS analysis ▪13% of Ag and rest presence of C & O recorded at 3 keV	▪Antibacterial activity against B. subtilis, B. cereus, S. aureus, E. coli, and P. aeruginosa ▪Bactericidal activity observed against B. cereus, E. coli, and P. aeruginosa	[48]
	Raphanus sativus	426 nm	3145, 1597, 1402, 1109, 1213, 995, 911, 699, 504	XRD ▪Structure—face-centered cubic (FCC) ▪Calculated mean size—~25 nm. TEM ▪Shape—spherical ▪Size range—10–30 nm SAED ▪Nature—crystalline EDS ▪Strong silver peaks at 3 keV AFM ▪Monodispersed AgNPs, ▪Average particle size 4 to 28 nm	▪Antibacterial activity against human pathogenic bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Serratia marcescens	[49]
	Endophytic fungus Curvularialunata	422 nm	3430.86, 1573.16, 1483.37, 1402.84, 1260.95, 1123.70	SEM ▪Shape—spherical ▪Size (diameter) range—10 to 50 nm ▪Average size—26 nm EDS ▪Strong metal signal peak of Ag observed XRD ▪Structure—face-centered cubic (FCC)	▪Synthesized AgNPs, along with antibiotics, exhibited inhibitory activity against Gram-negative and Gram-positive bacterial pathogens such as E. coli, Pseudomonas aeruginosa, Salmonella paratyphi, Bacillus subtillis, Staphylococcus aureus, and Bacillus cereus	[50]
	Penicillium polonicum	430 nm	2920.23, 2850.79, 1747.51, 1508.33, 1473.62, 1338.60, 1361.74, 1240.16, 1035.77, 760.88	TEM ▪Common shape—spherical ▪Size range—10 to 15 nm ▪Above size of 30 nm, hexagonal NPs HR-TEM ▪Nature—crystalline SAED ▪Nature—crystalline Particle size analysis ▪Polydisperse AgNPs in the size range of 10–15 nm observed EDS ▪Absorption peak recorded at 3 keV	▪Killing kinetic assay depicted that complete killing of A. baumanii bacterial cells occurred within 6 h of exposure time to AgNPs	[51]
Bacteria	Pseudomonas deceptionensis DC5	428 nm	-	XRD ▪Nature—crystalline FE-TEM ▪Shape—spherical ▪Size range—10 to 30 nm EDS ▪A peak recorded at 3 keV Particle size analysis ▪Average particles size—127 nm	▪Activity efficiency observed in descending order against pathogens V. parahaemolyticus, C. albicans, S. aureus, S. enterica, and B. anthracis ▪AgNPs at concentration of 5 μg/L found to inhibit biofilm formed by S. aureus and P. aeruginosa	[52]
	Weissellaoryzae DC6-	432 nm	-	FE-TEM ▪Shape—spherical ▪Size range—10 to 30 nm EDS ▪Highest peak recorded at 3 keV XRD ▪Nature—crystalline Particle size analysis ▪Average particle size—150.2 nm ▪Polydispersity index (PDI)—0.176	▪Descending order of antimicrobial potential observed against S. aureus, C. albicans, B. cereus, V. parahaemolyticus, E. coli, and B. anthracis ▪AgNPs at a concentration of about 5–6 μg found to inhibit the biofilm formed by S. aureus and P. aeruginosa	[53]
	Bacillus thuringiensis	413 nm	1644, 1549, 1520, 1114, 564, 550, 546, 523	FE-SEM ▪Shape—spherical ▪Average diameter range—10 to 30 nm TEM ▪Size range 10 to 30 nm	▪Purified AgNPs showed relatively stronger antibacterial activity against E. coli than the commercially available AgNPs	[54]
	Halotolerant Bacillus endophyticus SCU-L	420 nm	3400, 2969, 1650, 1560, 1453, 1401, 1227, 1083	XRD ▪Structure—face-centered cubic TEM ▪Shape—spherical ▪Average size ~5.1 nm	▪Antimicrobial activity observed against C. albicans, E. coli, S. typhi, and S. aureus ▪AgNPs showed broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative pathogens, as well as a fungus strain	[55]
	Phenerochaete chrysosporium (MTCC- 787)	430 nm	767, 1642, 2137,3400	TEM ▪Shape—different shapes, such as spherical and oval ▪Size range—34 to 90 nmAFM ▪Agglomerated silver nanostructures	▪Gram-negative clinical pathogens showed a higher susceptibility to AgNPs than Gram-positive pathogens	[56]
Plants (Roots)	Delphinium denudatum	416 nm	3354, 2952, 2063, 1651, 1419, 1383, 1354, 1171, 1093, 780, 672, 605	XRD ▪Structure—face-centered cubic (FCC) ▪Nature—crystalline FE SEM ▪Spherical shape and size not more than 85 nm	▪Antibacterial activity observed against S. aureus, B. cereus NCIM 2106, E. coli, and P. aeruginosa ATCC ▪Susceptibility of dengue vector aegypti larvae to AgNPs increased when exposure time extended to 48 h; the LC50 values of AgNPs were 96 ppm (24 h) and 9.6 ppm (48 h) against second-instar larvae of A. aegypti	[56]
	Alpinia katsumadai	417 nm and during reaction 436 nm	3371–3377, 2980–2978, 1649–1653, 1389–1385, 1045–1049, 888-881	FE-TEM ▪Shape—quasi-spherical ▪Nature—well-dispersed and scattered EDS ▪Strong absorption peak recorded at 3 keV XRD ▪Structure—face-centered cubic ▪Nature—crystalline	▪Antibacterial activity observed against S. aureus, E. coli, and P. aeruginosa; thus, it was concluded that so-prepared AgNPs exhibited effective antioxidant, antibacterial, and anticancer activities	[57]
	Aloe vera leaves	420 nm	-	SEM ▪Shape—spherical ▪Size range—70.7 to 192.02 nm (size varied with temperature) XRD ▪Structure—face-centered cubic (FCC)	▪Minimal cytotoxicity to human PBMCs	[58]
	Piper nigrum leaf and stem	460 nm	3697, 3313, 3195, 2298, 1670, 1456, 1336, 1193, 1118, 811, 750, 651, 601	XRD ▪Structure—face-centered cubic ▪Nature—crystalline SEM ▪Shape—spherical EDS ▪Intense signal at 3 keV TEM ▪Stem extracts of P. nigrum 9 to 30 nm ▪ Leaf extracts of P. nigrum - Small-sized AgNPs: 4 to 14 nm - Large-sized AgNPs: 20 to 50 nm	▪Antibacterial activity—Stem and leaf synthesized AgNPs (at 50 μL) showed activity against Citrobacter freundii and Erwinia cacticida	[59]
Plants (Fruit and Peel)	Banana peel	430nm	2353–2351, 1732–1755, 1640–1643, 1532–1537, 1445–1454	SEM–EDS ▪A distinct signal and high atomic percent values for silver were obtained XRD ▪Structure—face-centered cubic (FCC) ▪Nature—crystalline	▪AgNPs exhibited potent antifungal activity against the tested pathogenic strains of C. albicans and C. lipolytica ▪The antibacterial activity of AgNPs was observed against E. coli, E. aerogenes, Klebsiella sp., and Shigella sp.	[60]
	Tribulus terrestris dried fruit	435 nm	-	XRD ▪Nature—crystalline AFM ▪Shape—spherical ▪Particle size ~24.631 nm TEM ▪Shape—spherical shape ▪Average size—22 nm	▪Antimicrobial activity against S. pyogens, S. aureus, B. subtilis, P. aeruginosa, and E. coli.	[61]
	Lemon	400–430 nm	-	AFM ▪Particle dimensions—height 12 nm, width 100 nm ▪SEM—NPs consisted of agglomerates of small grains with diameter of approximately 75 nm	▪Disc diffusion method showed that NPs reduced the growth of both E. coli and Bacillus subtilis	[62]
Other biosynthesizing Agents	Gum kondagogu (Cochlospermum gossypium)	416 nm	3443, 2916, 2850, 1727, 1630, 1597, 1384, 1351, 1254, 1148, 1043	TEM ▪Shape—anisotropic nanostructures such as nanotriangles, a few nanorods, hexagonal and polygonal nanoprisms, and abundant unevenly shaped nanoparticles were observed ▪Nature—polydisperse ▪For 30 min of reaction time, size of 55.0 nm; for 60 min of reaction time, size of 18.9 nm SAED ▪Nature—crystalline ▪Structure—face-centered cubic (FCC) TEM ▪Shape—spherical ▪Average particle size: for 30 min of reaction time, 11.2 nm; for 60 min of reaction time, 4.5nm XRD ▪Nature—crystalline ▪Structure—face-centered cubic	▪Antibacterial activity was observed against S. aureus ATCC 25923, E. coli ATCC 25922, E. coli ATCC 35218, and P. aeruginosa ATCC 27853	[63]
	Dextran T40	423 nm	-	AFM ▪Particle size range—10 to 60 nm TEM ▪Shape—spherical ▪Size ~5–10 nm SAED ▪Nature—crystalline. EDS ▪Optical absorption peak at 3 keV XRD ▪Structure—face-centered cubic (FCC)	▪Antimicrobial activity observed against B. subtilis, B. cereus, E. coli, S. aureus, and P. aeruginosa.	[64]
	Casein (milk protein)	400 to 500 nm	1644, 1514	SEM and TEM ▪Shape—spherical agglomerates formed upon carefully decreasing the pH to 3.32 ▪Size—average diameter of about 60 to 80 nm	▪AgNPs at a dose of 0.025 µg/mL, i.e., below LD50 value, was observed to be fairly distributed in cytoplasm of living cells imaged by CLSM	[65]

Sa—average roughness, Sq—root-mean-square roughness, Sz—ten-point height.