Moreover, a study by Hamedi et al., revealed that the existence of ammonium lowered the productivity of AgNPs using
F. oxysporum cell-free filtrate and prohibited the nitrate reductase enzyme secretion
[119][63]. Longhi et al., reported that the combination of AgNPs synthesized using
F. oxysporum with FLC (fluconazole) reduced the MIC of FLC around 16 to 64 times towards planktonic cells of
C. albicans and induced a significant dose-dependent inhibition of both initial and mature biofilms of FLC-resistant
C. albicans. Therefore, these AgNPs could represent a new strategy for treating FLC-resistant
C. albicans infections
[49]. Additionally, the combination of simvastatin with these AgNPs demonstrated antibacterial activity towards
E. coli-producing ESBL (extended-spectrum
β-lactamase) and MRSA (methicillin-resistant
S. aureus). This could be a great future alternative in bacterial infection control, where smaller doses of these AgNPs are required with the same antibacterial activity
[120][64]. Besides, its combination with polymyxin B showed a 16-fold reduction of the MIC of polymyxin B and decreased carbapenem-resistant
Acinetobacter baumannii viability with additive and synergic effects, as well as significantly reduced cytotoxicity towards mammalian Vero cells, indicating its pharmacological safety
[121][65]. The AgNPs synthesized with
F. oxysporum f.sp.
pisi were found to have moderate adulticidal potential on
Culex quinquefasciatus (vector of filariasis) (LC
50 0.4, LC
99 4.8, and LC
90 4 μL/cm
2) after 24 h exposure
[122][66]. The synthesized AgNPs using
F. oxysporum aqueous extract had anticancer potential towards MCF7 (IC
50 14 µg/mL) that was characterized using CLSM (confocal laser scanning microscopic) technique
[123][67]. Bawskar et al. stated that the biosynthesized AgNPs using
F. oxysporum possessed more potent antibacterial potential towards
E. coli and
S. aureus than chemo-synthesized AgNPs that may be due to the protein capping and their mode of entry into the bacterial cell, which encouraged biosynthetic method over the chemosynthetic one in AgNPs synthesis
[124][68]. Two types of AgNPs, phyto-synthesized and myco-synthesized NPs were biosynthesized by AgNO
3 reduction with
Azadirachta indica extract and
F. oxysporum cell filtrate, respectively that possessed lower cytotoxic potential on C26 and HaCaT cell lines as compared with citrate coated AgNPs
[125][69]. Santos et al. proved that
F. oxysporum-biosynthesized AgNPs without pluronic F68 (stabilizing agent) had high antibacterial potential towards
E. coli,
P. aeruginosa, and
S. aureus. On the contrary, chemo-synthesized AgNPs exhibited synergism in antibacterial activity in the presence of pluronic F68
[126][70].
Streptococcus agalactiae is an important cause of invasive diseases, mainly in newborns, pregnant women, and elderly individuals
[127][71]. The combination of
F. oxysporum-produced AgNPs (AgNPbio) and eugenol led to a remarkable synergistic effect and significant reduction of the MIC values of both eugenol and AgNPbio towards planktonic cells of
S. agalactiae [127][71]. Thakker et al., reported the synthesis of GNPs (gold nanoparticles) using
F. oxysporum f. sp.
cubense JT1 that showed antibacterial potential versus
Pseudomonas sp.
[128][72]. Moreover, the conjugated GNPs with tetracycline demonstrated powerful antibacterial activity against Gram-negative and -positive bacteria in comparison to tetracycline and free GNPs. Therefore, tetracycline conjugation with these GNPs enhanced the antibacterial potential, which may have significant therapeutic applications
[129][73]. Yahyaei and Pourali studied the conjugation of GNPs with chemotherapeutic agents such as paclitaxel, tamoxifen, and capecitabine. Moreover, the cytotoxic effect of conjugated GNPs was assessed towards MCF7 and AGS cell lines, using MTT assay. Unlike the paclitaxel conjugated GNPs, the tamoxifen and capecitabine conjugated GNPs revealed no toxic effects due to their low half-lives and deactivation
[130][74]. Further, Syed and Ahmad reported the synthesis of stable extracellular platinum nanoparticles, using
F. oxysporum [131][75]. CdSe (cadmium/selenium) quantum dots are often used in industry as fluorescent materials. Kumar et al., and Yamaguchi et al., reported the synthesis of highly luminescent CdSe quantum dots by
F. oxysporum [132,133][76][77]. In 2013, Syed and Ahmad synthesized highly fluorescent CdTe quantum dots using
F. oxysporum at ambient conditions by the reaction with a mixture of TeCl
4 and CdCl
2. These nanoparticles exhibited antibacterial potential towards Gram-negative and -positive bacteria
[53]. Riddin et al., analyzed the biosynthesized platinum (Pt) nanoparticles by
F. oxysporum f. sp.
lycopersici at both intercellular and extracellular levels. It was found that only the extracellular nanoparticle production was proved to be statistically significant with a yield of 4.85 mg/L
[134][78].
2.2. Metal Sulfide Nanoparticles
In addition, Q-state CdS NPs were biosynthesized by the reaction of aqueous CdSO
4 solution with
F. oxysporum [135][79]. The chemically-synthesized CdSQDs inhibited
E. coli cell proliferation in a dose-dependent manner, unlike the biogenic CdSQDs synthesized by
F. oxysporum f. sp.
lycopersici, which showed an antibacterial potential only at high concentration. Additionally, only the biogenic CdSQDs showed no inhibition on seed germination after incubation of biogenic and chemical CdSQDs with
Lactuca sativa seeds
[43]. Bi
2S
3 (bismuth sulfide) NPs have significantly varied applications, including photodiode arrays, photovoltaic materials, and bio-imaging. Uddin et al., synthesized a highly fluorescent, natural protein capped Bi
2S
3NPs by subjecting
F. oxysporum to bismuth nitrate penta-hydrate, along with sodium sulfite under ambient conditions of pressure, temperature, and pH. It was found that they were fundamentally much more fluorescent than fluorophores (toxic fluorescent chemical compounds), which are largely utilized in immunohistochemistry, imaging, and biochemistry
[48].
2.3. Metal Oxide Nanoparticles
It was reported that
F. oxysporum might have vast commercial implications in low-cost, room-temperature, ecofriendly syntheses of technologically significant oxide nanomaterials from available potentially cheap naturally raw materials
[136][80].
F. oxysporum rapidly bio-transformed the naturally occurring amorphous biosilica in rice husk into crystalline silica NPs. This could lead to an economically viable and energy-conserving green approach toward the large-scale synthesis of oxide nanomaterials
[136][80]. Moreover, the mesophilic
F. oxysporum bioleached Fly-ash at ambient conditions produced highly stable, crystalline, fluorescent, water-soluble, and protein-capped silica nanoparticles
[52]. It was found that
F. oxysporum enriched zirconia in zircon sand by a process of selective extracellular bioleaching of silica nanoparticles. It was proposed that the fungal enzymes specifically hydrolyzed the silicates in the sand to form silicic acid, which on condensation by certain other fungal enzymes resulted in silica nanoparticles synthesis at room temperature
[136][80]. A water dispersible and thermo-stable Ag/Ag
2O NPs were produced from silver oxide micro-powder using
F. oxysporum. These Ag/Ag
2O NPs may become a potential candidate for enzyme-free glucose determination and exhibited catalytic potency for MB (methylene blue) degradation in presence of NaBH
4 (reducing agent). Additionally, they showed an excellent antimicrobial potential against
A. niger and
B. subtilis [137][81].